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- /*
- * Generic process-grouping system.
- *
- * Based originally on the cpuset system, extracted by Paul Menage
- * Copyright (C) 2006 Google, Inc
- *
- * Notifications support
- * Copyright (C) 2009 Nokia Corporation
- * Author: Kirill A. Shutemov
- *
- * Copyright notices from the original cpuset code:
- * --------------------------------------------------
- * Copyright (C) 2003 BULL SA.
- * Copyright (C) 2004-2006 Silicon Graphics, Inc.
- *
- * Portions derived from Patrick Mochel's sysfs code.
- * sysfs is Copyright (c) 2001-3 Patrick Mochel
- *
- * 2003-10-10 Written by Simon Derr.
- * 2003-10-22 Updates by Stephen Hemminger.
- * 2004 May-July Rework by Paul Jackson.
- * ---------------------------------------------------
- *
- * This file is subject to the terms and conditions of the GNU General Public
- * License. See the file COPYING in the main directory of the Linux
- * distribution for more details.
- */
- #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
- #include "cgroup-internal.h"
- #include <linux/cred.h>
- #include <linux/errno.h>
- #include <linux/init_task.h>
- #include <linux/kernel.h>
- #include <linux/magic.h>
- #include <linux/mutex.h>
- #include <linux/mount.h>
- #include <linux/pagemap.h>
- #include <linux/proc_fs.h>
- #include <linux/rcupdate.h>
- #include <linux/sched.h>
- #include <linux/sched/task.h>
- #include <linux/slab.h>
- #include <linux/spinlock.h>
- #include <linux/percpu-rwsem.h>
- #include <linux/string.h>
- #include <linux/hashtable.h>
- #include <linux/idr.h>
- #include <linux/kthread.h>
- #include <linux/atomic.h>
- #include <linux/cpuset.h>
- #include <linux/proc_ns.h>
- #include <linux/nsproxy.h>
- #include <linux/file.h>
- #include <linux/fs_parser.h>
- #include <linux/sched/cputime.h>
- #include <linux/psi.h>
- #include <net/sock.h>
- #define CREATE_TRACE_POINTS
- #include <trace/events/cgroup.h>
- #undef CREATE_TRACE_POINTS
- #include <trace/hooks/cgroup.h>
- #define CGROUP_FILE_NAME_MAX (MAX_CGROUP_TYPE_NAMELEN + \
- MAX_CFTYPE_NAME + 2)
- /* let's not notify more than 100 times per second */
- #define CGROUP_FILE_NOTIFY_MIN_INTV DIV_ROUND_UP(HZ, 100)
- /*
- * cgroup_mutex is the master lock. Any modification to cgroup or its
- * hierarchy must be performed while holding it.
- *
- * css_set_lock protects task->cgroups pointer, the list of css_set
- * objects, and the chain of tasks off each css_set.
- *
- * These locks are exported if CONFIG_PROVE_RCU so that accessors in
- * cgroup.h can use them for lockdep annotations.
- */
- DEFINE_MUTEX(cgroup_mutex);
- DEFINE_SPINLOCK(css_set_lock);
- #ifdef CONFIG_PROVE_RCU
- EXPORT_SYMBOL_GPL(cgroup_mutex);
- EXPORT_SYMBOL_GPL(css_set_lock);
- #endif
- DEFINE_SPINLOCK(trace_cgroup_path_lock);
- char trace_cgroup_path[TRACE_CGROUP_PATH_LEN];
- bool cgroup_debug __read_mostly;
- /*
- * Protects cgroup_idr and css_idr so that IDs can be released without
- * grabbing cgroup_mutex.
- */
- static DEFINE_SPINLOCK(cgroup_idr_lock);
- /*
- * Protects cgroup_file->kn for !self csses. It synchronizes notifications
- * against file removal/re-creation across css hiding.
- */
- static DEFINE_SPINLOCK(cgroup_file_kn_lock);
- DEFINE_PERCPU_RWSEM(cgroup_threadgroup_rwsem);
- #define cgroup_assert_mutex_or_rcu_locked() \
- RCU_LOCKDEP_WARN(!rcu_read_lock_held() && \
- !lockdep_is_held(&cgroup_mutex), \
- "cgroup_mutex or RCU read lock required");
- /*
- * cgroup destruction makes heavy use of work items and there can be a lot
- * of concurrent destructions. Use a separate workqueue so that cgroup
- * destruction work items don't end up filling up max_active of system_wq
- * which may lead to deadlock.
- */
- static struct workqueue_struct *cgroup_destroy_wq;
- /* generate an array of cgroup subsystem pointers */
- #define SUBSYS(_x) [_x ## _cgrp_id] = &_x ## _cgrp_subsys,
- struct cgroup_subsys *cgroup_subsys[] = {
- #include <linux/cgroup_subsys.h>
- };
- #undef SUBSYS
- /* array of cgroup subsystem names */
- #define SUBSYS(_x) [_x ## _cgrp_id] = #_x,
- static const char *cgroup_subsys_name[] = {
- #include <linux/cgroup_subsys.h>
- };
- #undef SUBSYS
- /* array of static_keys for cgroup_subsys_enabled() and cgroup_subsys_on_dfl() */
- #define SUBSYS(_x) \
- DEFINE_STATIC_KEY_TRUE(_x ## _cgrp_subsys_enabled_key); \
- DEFINE_STATIC_KEY_TRUE(_x ## _cgrp_subsys_on_dfl_key); \
- EXPORT_SYMBOL_GPL(_x ## _cgrp_subsys_enabled_key); \
- EXPORT_SYMBOL_GPL(_x ## _cgrp_subsys_on_dfl_key);
- #include <linux/cgroup_subsys.h>
- #undef SUBSYS
- #define SUBSYS(_x) [_x ## _cgrp_id] = &_x ## _cgrp_subsys_enabled_key,
- static struct static_key_true *cgroup_subsys_enabled_key[] = {
- #include <linux/cgroup_subsys.h>
- };
- #undef SUBSYS
- #define SUBSYS(_x) [_x ## _cgrp_id] = &_x ## _cgrp_subsys_on_dfl_key,
- static struct static_key_true *cgroup_subsys_on_dfl_key[] = {
- #include <linux/cgroup_subsys.h>
- };
- #undef SUBSYS
- static DEFINE_PER_CPU(struct cgroup_rstat_cpu, cgrp_dfl_root_rstat_cpu);
- /* the default hierarchy */
- struct cgroup_root cgrp_dfl_root = { .cgrp.rstat_cpu = &cgrp_dfl_root_rstat_cpu };
- EXPORT_SYMBOL_GPL(cgrp_dfl_root);
- /*
- * The default hierarchy always exists but is hidden until mounted for the
- * first time. This is for backward compatibility.
- */
- static bool cgrp_dfl_visible;
- /* some controllers are not supported in the default hierarchy */
- static u16 cgrp_dfl_inhibit_ss_mask;
- /* some controllers are implicitly enabled on the default hierarchy */
- static u16 cgrp_dfl_implicit_ss_mask;
- /* some controllers can be threaded on the default hierarchy */
- static u16 cgrp_dfl_threaded_ss_mask;
- /* The list of hierarchy roots */
- LIST_HEAD(cgroup_roots);
- static int cgroup_root_count;
- /* hierarchy ID allocation and mapping, protected by cgroup_mutex */
- static DEFINE_IDR(cgroup_hierarchy_idr);
- /*
- * Assign a monotonically increasing serial number to csses. It guarantees
- * cgroups with bigger numbers are newer than those with smaller numbers.
- * Also, as csses are always appended to the parent's ->children list, it
- * guarantees that sibling csses are always sorted in the ascending serial
- * number order on the list. Protected by cgroup_mutex.
- */
- static u64 css_serial_nr_next = 1;
- /*
- * These bitmasks identify subsystems with specific features to avoid
- * having to do iterative checks repeatedly.
- */
- static u16 have_fork_callback __read_mostly;
- static u16 have_exit_callback __read_mostly;
- static u16 have_release_callback __read_mostly;
- static u16 have_canfork_callback __read_mostly;
- /* cgroup namespace for init task */
- struct cgroup_namespace init_cgroup_ns = {
- .count = REFCOUNT_INIT(2),
- .user_ns = &init_user_ns,
- .ns.ops = &cgroupns_operations,
- .ns.inum = PROC_CGROUP_INIT_INO,
- .root_cset = &init_css_set,
- };
- static struct file_system_type cgroup2_fs_type;
- static struct cftype cgroup_base_files[];
- /* cgroup optional features */
- enum cgroup_opt_features {
- #ifdef CONFIG_PSI
- OPT_FEATURE_PRESSURE,
- #endif
- OPT_FEATURE_COUNT
- };
- static const char *cgroup_opt_feature_names[OPT_FEATURE_COUNT] = {
- #ifdef CONFIG_PSI
- "pressure",
- #endif
- };
- static u16 cgroup_feature_disable_mask __read_mostly;
- static int cgroup_apply_control(struct cgroup *cgrp);
- static void cgroup_finalize_control(struct cgroup *cgrp, int ret);
- static void css_task_iter_skip(struct css_task_iter *it,
- struct task_struct *task);
- static int cgroup_destroy_locked(struct cgroup *cgrp);
- static struct cgroup_subsys_state *css_create(struct cgroup *cgrp,
- struct cgroup_subsys *ss);
- static void css_release(struct percpu_ref *ref);
- static void kill_css(struct cgroup_subsys_state *css);
- static int cgroup_addrm_files(struct cgroup_subsys_state *css,
- struct cgroup *cgrp, struct cftype cfts[],
- bool is_add);
- /**
- * cgroup_ssid_enabled - cgroup subsys enabled test by subsys ID
- * @ssid: subsys ID of interest
- *
- * cgroup_subsys_enabled() can only be used with literal subsys names which
- * is fine for individual subsystems but unsuitable for cgroup core. This
- * is slower static_key_enabled() based test indexed by @ssid.
- */
- bool cgroup_ssid_enabled(int ssid)
- {
- if (CGROUP_SUBSYS_COUNT == 0)
- return false;
- return static_key_enabled(cgroup_subsys_enabled_key[ssid]);
- }
- /**
- * cgroup_on_dfl - test whether a cgroup is on the default hierarchy
- * @cgrp: the cgroup of interest
- *
- * The default hierarchy is the v2 interface of cgroup and this function
- * can be used to test whether a cgroup is on the default hierarchy for
- * cases where a subsystem should behave differnetly depending on the
- * interface version.
- *
- * List of changed behaviors:
- *
- * - Mount options "noprefix", "xattr", "clone_children", "release_agent"
- * and "name" are disallowed.
- *
- * - When mounting an existing superblock, mount options should match.
- *
- * - Remount is disallowed.
- *
- * - rename(2) is disallowed.
- *
- * - "tasks" is removed. Everything should be at process granularity. Use
- * "cgroup.procs" instead.
- *
- * - "cgroup.procs" is not sorted. pids will be unique unless they got
- * recycled inbetween reads.
- *
- * - "release_agent" and "notify_on_release" are removed. Replacement
- * notification mechanism will be implemented.
- *
- * - "cgroup.clone_children" is removed.
- *
- * - "cgroup.subtree_populated" is available. Its value is 0 if the cgroup
- * and its descendants contain no task; otherwise, 1. The file also
- * generates kernfs notification which can be monitored through poll and
- * [di]notify when the value of the file changes.
- *
- * - cpuset: tasks will be kept in empty cpusets when hotplug happens and
- * take masks of ancestors with non-empty cpus/mems, instead of being
- * moved to an ancestor.
- *
- * - cpuset: a task can be moved into an empty cpuset, and again it takes
- * masks of ancestors.
- *
- * - memcg: use_hierarchy is on by default and the cgroup file for the flag
- * is not created.
- *
- * - blkcg: blk-throttle becomes properly hierarchical.
- *
- * - debug: disallowed on the default hierarchy.
- */
- bool cgroup_on_dfl(const struct cgroup *cgrp)
- {
- return cgrp->root == &cgrp_dfl_root;
- }
- /* IDR wrappers which synchronize using cgroup_idr_lock */
- static int cgroup_idr_alloc(struct idr *idr, void *ptr, int start, int end,
- gfp_t gfp_mask)
- {
- int ret;
- idr_preload(gfp_mask);
- spin_lock_bh(&cgroup_idr_lock);
- ret = idr_alloc(idr, ptr, start, end, gfp_mask & ~__GFP_DIRECT_RECLAIM);
- spin_unlock_bh(&cgroup_idr_lock);
- idr_preload_end();
- return ret;
- }
- static void *cgroup_idr_replace(struct idr *idr, void *ptr, int id)
- {
- void *ret;
- spin_lock_bh(&cgroup_idr_lock);
- ret = idr_replace(idr, ptr, id);
- spin_unlock_bh(&cgroup_idr_lock);
- return ret;
- }
- static void cgroup_idr_remove(struct idr *idr, int id)
- {
- spin_lock_bh(&cgroup_idr_lock);
- idr_remove(idr, id);
- spin_unlock_bh(&cgroup_idr_lock);
- }
- static bool cgroup_has_tasks(struct cgroup *cgrp)
- {
- return cgrp->nr_populated_csets;
- }
- bool cgroup_is_threaded(struct cgroup *cgrp)
- {
- return cgrp->dom_cgrp != cgrp;
- }
- /* can @cgrp host both domain and threaded children? */
- static bool cgroup_is_mixable(struct cgroup *cgrp)
- {
- /*
- * Root isn't under domain level resource control exempting it from
- * the no-internal-process constraint, so it can serve as a thread
- * root and a parent of resource domains at the same time.
- */
- return !cgroup_parent(cgrp);
- }
- /* can @cgrp become a thread root? should always be true for a thread root */
- static bool cgroup_can_be_thread_root(struct cgroup *cgrp)
- {
- /* mixables don't care */
- if (cgroup_is_mixable(cgrp))
- return true;
- /* domain roots can't be nested under threaded */
- if (cgroup_is_threaded(cgrp))
- return false;
- /* can only have either domain or threaded children */
- if (cgrp->nr_populated_domain_children)
- return false;
- /* and no domain controllers can be enabled */
- if (cgrp->subtree_control & ~cgrp_dfl_threaded_ss_mask)
- return false;
- return true;
- }
- /* is @cgrp root of a threaded subtree? */
- bool cgroup_is_thread_root(struct cgroup *cgrp)
- {
- /* thread root should be a domain */
- if (cgroup_is_threaded(cgrp))
- return false;
- /* a domain w/ threaded children is a thread root */
- if (cgrp->nr_threaded_children)
- return true;
- /*
- * A domain which has tasks and explicit threaded controllers
- * enabled is a thread root.
- */
- if (cgroup_has_tasks(cgrp) &&
- (cgrp->subtree_control & cgrp_dfl_threaded_ss_mask))
- return true;
- return false;
- }
- /* a domain which isn't connected to the root w/o brekage can't be used */
- static bool cgroup_is_valid_domain(struct cgroup *cgrp)
- {
- /* the cgroup itself can be a thread root */
- if (cgroup_is_threaded(cgrp))
- return false;
- /* but the ancestors can't be unless mixable */
- while ((cgrp = cgroup_parent(cgrp))) {
- if (!cgroup_is_mixable(cgrp) && cgroup_is_thread_root(cgrp))
- return false;
- if (cgroup_is_threaded(cgrp))
- return false;
- }
- return true;
- }
- /* subsystems visibly enabled on a cgroup */
- static u16 cgroup_control(struct cgroup *cgrp)
- {
- struct cgroup *parent = cgroup_parent(cgrp);
- u16 root_ss_mask = cgrp->root->subsys_mask;
- if (parent) {
- u16 ss_mask = parent->subtree_control;
- /* threaded cgroups can only have threaded controllers */
- if (cgroup_is_threaded(cgrp))
- ss_mask &= cgrp_dfl_threaded_ss_mask;
- return ss_mask;
- }
- if (cgroup_on_dfl(cgrp))
- root_ss_mask &= ~(cgrp_dfl_inhibit_ss_mask |
- cgrp_dfl_implicit_ss_mask);
- return root_ss_mask;
- }
- /* subsystems enabled on a cgroup */
- static u16 cgroup_ss_mask(struct cgroup *cgrp)
- {
- struct cgroup *parent = cgroup_parent(cgrp);
- if (parent) {
- u16 ss_mask = parent->subtree_ss_mask;
- /* threaded cgroups can only have threaded controllers */
- if (cgroup_is_threaded(cgrp))
- ss_mask &= cgrp_dfl_threaded_ss_mask;
- return ss_mask;
- }
- return cgrp->root->subsys_mask;
- }
- /**
- * cgroup_css - obtain a cgroup's css for the specified subsystem
- * @cgrp: the cgroup of interest
- * @ss: the subsystem of interest (%NULL returns @cgrp->self)
- *
- * Return @cgrp's css (cgroup_subsys_state) associated with @ss. This
- * function must be called either under cgroup_mutex or rcu_read_lock() and
- * the caller is responsible for pinning the returned css if it wants to
- * keep accessing it outside the said locks. This function may return
- * %NULL if @cgrp doesn't have @subsys_id enabled.
- */
- static struct cgroup_subsys_state *cgroup_css(struct cgroup *cgrp,
- struct cgroup_subsys *ss)
- {
- if (ss)
- return rcu_dereference_check(cgrp->subsys[ss->id],
- lockdep_is_held(&cgroup_mutex));
- else
- return &cgrp->self;
- }
- /**
- * cgroup_tryget_css - try to get a cgroup's css for the specified subsystem
- * @cgrp: the cgroup of interest
- * @ss: the subsystem of interest
- *
- * Find and get @cgrp's css assocaited with @ss. If the css doesn't exist
- * or is offline, %NULL is returned.
- */
- static struct cgroup_subsys_state *cgroup_tryget_css(struct cgroup *cgrp,
- struct cgroup_subsys *ss)
- {
- struct cgroup_subsys_state *css;
- rcu_read_lock();
- css = cgroup_css(cgrp, ss);
- if (css && !css_tryget_online(css))
- css = NULL;
- rcu_read_unlock();
- return css;
- }
- /**
- * cgroup_e_css_by_mask - obtain a cgroup's effective css for the specified ss
- * @cgrp: the cgroup of interest
- * @ss: the subsystem of interest (%NULL returns @cgrp->self)
- *
- * Similar to cgroup_css() but returns the effective css, which is defined
- * as the matching css of the nearest ancestor including self which has @ss
- * enabled. If @ss is associated with the hierarchy @cgrp is on, this
- * function is guaranteed to return non-NULL css.
- */
- static struct cgroup_subsys_state *cgroup_e_css_by_mask(struct cgroup *cgrp,
- struct cgroup_subsys *ss)
- {
- lockdep_assert_held(&cgroup_mutex);
- if (!ss)
- return &cgrp->self;
- /*
- * This function is used while updating css associations and thus
- * can't test the csses directly. Test ss_mask.
- */
- while (!(cgroup_ss_mask(cgrp) & (1 << ss->id))) {
- cgrp = cgroup_parent(cgrp);
- if (!cgrp)
- return NULL;
- }
- return cgroup_css(cgrp, ss);
- }
- /**
- * cgroup_e_css - obtain a cgroup's effective css for the specified subsystem
- * @cgrp: the cgroup of interest
- * @ss: the subsystem of interest
- *
- * Find and get the effective css of @cgrp for @ss. The effective css is
- * defined as the matching css of the nearest ancestor including self which
- * has @ss enabled. If @ss is not mounted on the hierarchy @cgrp is on,
- * the root css is returned, so this function always returns a valid css.
- *
- * The returned css is not guaranteed to be online, and therefore it is the
- * callers responsiblity to tryget a reference for it.
- */
- struct cgroup_subsys_state *cgroup_e_css(struct cgroup *cgrp,
- struct cgroup_subsys *ss)
- {
- struct cgroup_subsys_state *css;
- do {
- css = cgroup_css(cgrp, ss);
- if (css)
- return css;
- cgrp = cgroup_parent(cgrp);
- } while (cgrp);
- return init_css_set.subsys[ss->id];
- }
- /**
- * cgroup_get_e_css - get a cgroup's effective css for the specified subsystem
- * @cgrp: the cgroup of interest
- * @ss: the subsystem of interest
- *
- * Find and get the effective css of @cgrp for @ss. The effective css is
- * defined as the matching css of the nearest ancestor including self which
- * has @ss enabled. If @ss is not mounted on the hierarchy @cgrp is on,
- * the root css is returned, so this function always returns a valid css.
- * The returned css must be put using css_put().
- */
- struct cgroup_subsys_state *cgroup_get_e_css(struct cgroup *cgrp,
- struct cgroup_subsys *ss)
- {
- struct cgroup_subsys_state *css;
- rcu_read_lock();
- do {
- css = cgroup_css(cgrp, ss);
- if (css && css_tryget_online(css))
- goto out_unlock;
- cgrp = cgroup_parent(cgrp);
- } while (cgrp);
- css = init_css_set.subsys[ss->id];
- css_get(css);
- out_unlock:
- rcu_read_unlock();
- return css;
- }
- static void cgroup_get_live(struct cgroup *cgrp)
- {
- WARN_ON_ONCE(cgroup_is_dead(cgrp));
- css_get(&cgrp->self);
- }
- /**
- * __cgroup_task_count - count the number of tasks in a cgroup. The caller
- * is responsible for taking the css_set_lock.
- * @cgrp: the cgroup in question
- */
- int __cgroup_task_count(const struct cgroup *cgrp)
- {
- int count = 0;
- struct cgrp_cset_link *link;
- lockdep_assert_held(&css_set_lock);
- list_for_each_entry(link, &cgrp->cset_links, cset_link)
- count += link->cset->nr_tasks;
- return count;
- }
- /**
- * cgroup_task_count - count the number of tasks in a cgroup.
- * @cgrp: the cgroup in question
- */
- int cgroup_task_count(const struct cgroup *cgrp)
- {
- int count;
- spin_lock_irq(&css_set_lock);
- count = __cgroup_task_count(cgrp);
- spin_unlock_irq(&css_set_lock);
- return count;
- }
- struct cgroup_subsys_state *of_css(struct kernfs_open_file *of)
- {
- struct cgroup *cgrp = of->kn->parent->priv;
- struct cftype *cft = of_cft(of);
- /*
- * This is open and unprotected implementation of cgroup_css().
- * seq_css() is only called from a kernfs file operation which has
- * an active reference on the file. Because all the subsystem
- * files are drained before a css is disassociated with a cgroup,
- * the matching css from the cgroup's subsys table is guaranteed to
- * be and stay valid until the enclosing operation is complete.
- */
- if (cft->ss)
- return rcu_dereference_raw(cgrp->subsys[cft->ss->id]);
- else
- return &cgrp->self;
- }
- EXPORT_SYMBOL_GPL(of_css);
- /**
- * for_each_css - iterate all css's of a cgroup
- * @css: the iteration cursor
- * @ssid: the index of the subsystem, CGROUP_SUBSYS_COUNT after reaching the end
- * @cgrp: the target cgroup to iterate css's of
- *
- * Should be called under cgroup_[tree_]mutex.
- */
- #define for_each_css(css, ssid, cgrp) \
- for ((ssid) = 0; (ssid) < CGROUP_SUBSYS_COUNT; (ssid)++) \
- if (!((css) = rcu_dereference_check( \
- (cgrp)->subsys[(ssid)], \
- lockdep_is_held(&cgroup_mutex)))) { } \
- else
- /**
- * for_each_e_css - iterate all effective css's of a cgroup
- * @css: the iteration cursor
- * @ssid: the index of the subsystem, CGROUP_SUBSYS_COUNT after reaching the end
- * @cgrp: the target cgroup to iterate css's of
- *
- * Should be called under cgroup_[tree_]mutex.
- */
- #define for_each_e_css(css, ssid, cgrp) \
- for ((ssid) = 0; (ssid) < CGROUP_SUBSYS_COUNT; (ssid)++) \
- if (!((css) = cgroup_e_css_by_mask(cgrp, \
- cgroup_subsys[(ssid)]))) \
- ; \
- else
- /**
- * do_each_subsys_mask - filter for_each_subsys with a bitmask
- * @ss: the iteration cursor
- * @ssid: the index of @ss, CGROUP_SUBSYS_COUNT after reaching the end
- * @ss_mask: the bitmask
- *
- * The block will only run for cases where the ssid-th bit (1 << ssid) of
- * @ss_mask is set.
- */
- #define do_each_subsys_mask(ss, ssid, ss_mask) do { \
- unsigned long __ss_mask = (ss_mask); \
- if (!CGROUP_SUBSYS_COUNT) { /* to avoid spurious gcc warning */ \
- (ssid) = 0; \
- break; \
- } \
- for_each_set_bit(ssid, &__ss_mask, CGROUP_SUBSYS_COUNT) { \
- (ss) = cgroup_subsys[ssid]; \
- {
- #define while_each_subsys_mask() \
- } \
- } \
- } while (false)
- /* iterate over child cgrps, lock should be held throughout iteration */
- #define cgroup_for_each_live_child(child, cgrp) \
- list_for_each_entry((child), &(cgrp)->self.children, self.sibling) \
- if (({ lockdep_assert_held(&cgroup_mutex); \
- cgroup_is_dead(child); })) \
- ; \
- else
- /* walk live descendants in preorder */
- #define cgroup_for_each_live_descendant_pre(dsct, d_css, cgrp) \
- css_for_each_descendant_pre((d_css), cgroup_css((cgrp), NULL)) \
- if (({ lockdep_assert_held(&cgroup_mutex); \
- (dsct) = (d_css)->cgroup; \
- cgroup_is_dead(dsct); })) \
- ; \
- else
- /* walk live descendants in postorder */
- #define cgroup_for_each_live_descendant_post(dsct, d_css, cgrp) \
- css_for_each_descendant_post((d_css), cgroup_css((cgrp), NULL)) \
- if (({ lockdep_assert_held(&cgroup_mutex); \
- (dsct) = (d_css)->cgroup; \
- cgroup_is_dead(dsct); })) \
- ; \
- else
- /*
- * The default css_set - used by init and its children prior to any
- * hierarchies being mounted. It contains a pointer to the root state
- * for each subsystem. Also used to anchor the list of css_sets. Not
- * reference-counted, to improve performance when child cgroups
- * haven't been created.
- */
- struct css_set init_css_set = {
- .refcount = REFCOUNT_INIT(1),
- .dom_cset = &init_css_set,
- .tasks = LIST_HEAD_INIT(init_css_set.tasks),
- .mg_tasks = LIST_HEAD_INIT(init_css_set.mg_tasks),
- .dying_tasks = LIST_HEAD_INIT(init_css_set.dying_tasks),
- .task_iters = LIST_HEAD_INIT(init_css_set.task_iters),
- .threaded_csets = LIST_HEAD_INIT(init_css_set.threaded_csets),
- .cgrp_links = LIST_HEAD_INIT(init_css_set.cgrp_links),
- .mg_preload_node = LIST_HEAD_INIT(init_css_set.mg_preload_node),
- .mg_node = LIST_HEAD_INIT(init_css_set.mg_node),
- /*
- * The following field is re-initialized when this cset gets linked
- * in cgroup_init(). However, let's initialize the field
- * statically too so that the default cgroup can be accessed safely
- * early during boot.
- */
- .dfl_cgrp = &cgrp_dfl_root.cgrp,
- };
- static int css_set_count = 1; /* 1 for init_css_set */
- static bool css_set_threaded(struct css_set *cset)
- {
- return cset->dom_cset != cset;
- }
- /**
- * css_set_populated - does a css_set contain any tasks?
- * @cset: target css_set
- *
- * css_set_populated() should be the same as !!cset->nr_tasks at steady
- * state. However, css_set_populated() can be called while a task is being
- * added to or removed from the linked list before the nr_tasks is
- * properly updated. Hence, we can't just look at ->nr_tasks here.
- */
- static bool css_set_populated(struct css_set *cset)
- {
- lockdep_assert_held(&css_set_lock);
- return !list_empty(&cset->tasks) || !list_empty(&cset->mg_tasks);
- }
- /**
- * cgroup_update_populated - update the populated count of a cgroup
- * @cgrp: the target cgroup
- * @populated: inc or dec populated count
- *
- * One of the css_sets associated with @cgrp is either getting its first
- * task or losing the last. Update @cgrp->nr_populated_* accordingly. The
- * count is propagated towards root so that a given cgroup's
- * nr_populated_children is zero iff none of its descendants contain any
- * tasks.
- *
- * @cgrp's interface file "cgroup.populated" is zero if both
- * @cgrp->nr_populated_csets and @cgrp->nr_populated_children are zero and
- * 1 otherwise. When the sum changes from or to zero, userland is notified
- * that the content of the interface file has changed. This can be used to
- * detect when @cgrp and its descendants become populated or empty.
- */
- static void cgroup_update_populated(struct cgroup *cgrp, bool populated)
- {
- struct cgroup *child = NULL;
- int adj = populated ? 1 : -1;
- lockdep_assert_held(&css_set_lock);
- do {
- bool was_populated = cgroup_is_populated(cgrp);
- if (!child) {
- cgrp->nr_populated_csets += adj;
- } else {
- if (cgroup_is_threaded(child))
- cgrp->nr_populated_threaded_children += adj;
- else
- cgrp->nr_populated_domain_children += adj;
- }
- if (was_populated == cgroup_is_populated(cgrp))
- break;
- cgroup1_check_for_release(cgrp);
- TRACE_CGROUP_PATH(notify_populated, cgrp,
- cgroup_is_populated(cgrp));
- cgroup_file_notify(&cgrp->events_file);
- child = cgrp;
- cgrp = cgroup_parent(cgrp);
- } while (cgrp);
- }
- /**
- * css_set_update_populated - update populated state of a css_set
- * @cset: target css_set
- * @populated: whether @cset is populated or depopulated
- *
- * @cset is either getting the first task or losing the last. Update the
- * populated counters of all associated cgroups accordingly.
- */
- static void css_set_update_populated(struct css_set *cset, bool populated)
- {
- struct cgrp_cset_link *link;
- lockdep_assert_held(&css_set_lock);
- list_for_each_entry(link, &cset->cgrp_links, cgrp_link)
- cgroup_update_populated(link->cgrp, populated);
- }
- /*
- * @task is leaving, advance task iterators which are pointing to it so
- * that they can resume at the next position. Advancing an iterator might
- * remove it from the list, use safe walk. See css_task_iter_skip() for
- * details.
- */
- static void css_set_skip_task_iters(struct css_set *cset,
- struct task_struct *task)
- {
- struct css_task_iter *it, *pos;
- list_for_each_entry_safe(it, pos, &cset->task_iters, iters_node)
- css_task_iter_skip(it, task);
- }
- /**
- * css_set_move_task - move a task from one css_set to another
- * @task: task being moved
- * @from_cset: css_set @task currently belongs to (may be NULL)
- * @to_cset: new css_set @task is being moved to (may be NULL)
- * @use_mg_tasks: move to @to_cset->mg_tasks instead of ->tasks
- *
- * Move @task from @from_cset to @to_cset. If @task didn't belong to any
- * css_set, @from_cset can be NULL. If @task is being disassociated
- * instead of moved, @to_cset can be NULL.
- *
- * This function automatically handles populated counter updates and
- * css_task_iter adjustments but the caller is responsible for managing
- * @from_cset and @to_cset's reference counts.
- */
- static void css_set_move_task(struct task_struct *task,
- struct css_set *from_cset, struct css_set *to_cset,
- bool use_mg_tasks)
- {
- lockdep_assert_held(&css_set_lock);
- if (to_cset && !css_set_populated(to_cset))
- css_set_update_populated(to_cset, true);
- if (from_cset) {
- WARN_ON_ONCE(list_empty(&task->cg_list));
- css_set_skip_task_iters(from_cset, task);
- list_del_init(&task->cg_list);
- if (!css_set_populated(from_cset))
- css_set_update_populated(from_cset, false);
- } else {
- WARN_ON_ONCE(!list_empty(&task->cg_list));
- }
- if (to_cset) {
- /*
- * We are synchronized through cgroup_threadgroup_rwsem
- * against PF_EXITING setting such that we can't race
- * against cgroup_exit()/cgroup_free() dropping the css_set.
- */
- WARN_ON_ONCE(task->flags & PF_EXITING);
- cgroup_move_task(task, to_cset);
- list_add_tail(&task->cg_list, use_mg_tasks ? &to_cset->mg_tasks :
- &to_cset->tasks);
- }
- }
- /*
- * hash table for cgroup groups. This improves the performance to find
- * an existing css_set. This hash doesn't (currently) take into
- * account cgroups in empty hierarchies.
- */
- #define CSS_SET_HASH_BITS 7
- static DEFINE_HASHTABLE(css_set_table, CSS_SET_HASH_BITS);
- static unsigned long css_set_hash(struct cgroup_subsys_state *css[])
- {
- unsigned long key = 0UL;
- struct cgroup_subsys *ss;
- int i;
- for_each_subsys(ss, i)
- key += (unsigned long)css[i];
- key = (key >> 16) ^ key;
- return key;
- }
- void put_css_set_locked(struct css_set *cset)
- {
- struct cgrp_cset_link *link, *tmp_link;
- struct cgroup_subsys *ss;
- int ssid;
- lockdep_assert_held(&css_set_lock);
- if (!refcount_dec_and_test(&cset->refcount))
- return;
- WARN_ON_ONCE(!list_empty(&cset->threaded_csets));
- /* This css_set is dead. unlink it and release cgroup and css refs */
- for_each_subsys(ss, ssid) {
- list_del(&cset->e_cset_node[ssid]);
- css_put(cset->subsys[ssid]);
- }
- hash_del(&cset->hlist);
- css_set_count--;
- list_for_each_entry_safe(link, tmp_link, &cset->cgrp_links, cgrp_link) {
- list_del(&link->cset_link);
- list_del(&link->cgrp_link);
- if (cgroup_parent(link->cgrp))
- cgroup_put(link->cgrp);
- kfree(link);
- }
- if (css_set_threaded(cset)) {
- list_del(&cset->threaded_csets_node);
- put_css_set_locked(cset->dom_cset);
- }
- kfree_rcu(cset, rcu_head);
- }
- /**
- * compare_css_sets - helper function for find_existing_css_set().
- * @cset: candidate css_set being tested
- * @old_cset: existing css_set for a task
- * @new_cgrp: cgroup that's being entered by the task
- * @template: desired set of css pointers in css_set (pre-calculated)
- *
- * Returns true if "cset" matches "old_cset" except for the hierarchy
- * which "new_cgrp" belongs to, for which it should match "new_cgrp".
- */
- static bool compare_css_sets(struct css_set *cset,
- struct css_set *old_cset,
- struct cgroup *new_cgrp,
- struct cgroup_subsys_state *template[])
- {
- struct cgroup *new_dfl_cgrp;
- struct list_head *l1, *l2;
- /*
- * On the default hierarchy, there can be csets which are
- * associated with the same set of cgroups but different csses.
- * Let's first ensure that csses match.
- */
- if (memcmp(template, cset->subsys, sizeof(cset->subsys)))
- return false;
- /* @cset's domain should match the default cgroup's */
- if (cgroup_on_dfl(new_cgrp))
- new_dfl_cgrp = new_cgrp;
- else
- new_dfl_cgrp = old_cset->dfl_cgrp;
- if (new_dfl_cgrp->dom_cgrp != cset->dom_cset->dfl_cgrp)
- return false;
- /*
- * Compare cgroup pointers in order to distinguish between
- * different cgroups in hierarchies. As different cgroups may
- * share the same effective css, this comparison is always
- * necessary.
- */
- l1 = &cset->cgrp_links;
- l2 = &old_cset->cgrp_links;
- while (1) {
- struct cgrp_cset_link *link1, *link2;
- struct cgroup *cgrp1, *cgrp2;
- l1 = l1->next;
- l2 = l2->next;
- /* See if we reached the end - both lists are equal length. */
- if (l1 == &cset->cgrp_links) {
- BUG_ON(l2 != &old_cset->cgrp_links);
- break;
- } else {
- BUG_ON(l2 == &old_cset->cgrp_links);
- }
- /* Locate the cgroups associated with these links. */
- link1 = list_entry(l1, struct cgrp_cset_link, cgrp_link);
- link2 = list_entry(l2, struct cgrp_cset_link, cgrp_link);
- cgrp1 = link1->cgrp;
- cgrp2 = link2->cgrp;
- /* Hierarchies should be linked in the same order. */
- BUG_ON(cgrp1->root != cgrp2->root);
- /*
- * If this hierarchy is the hierarchy of the cgroup
- * that's changing, then we need to check that this
- * css_set points to the new cgroup; if it's any other
- * hierarchy, then this css_set should point to the
- * same cgroup as the old css_set.
- */
- if (cgrp1->root == new_cgrp->root) {
- if (cgrp1 != new_cgrp)
- return false;
- } else {
- if (cgrp1 != cgrp2)
- return false;
- }
- }
- return true;
- }
- /**
- * find_existing_css_set - init css array and find the matching css_set
- * @old_cset: the css_set that we're using before the cgroup transition
- * @cgrp: the cgroup that we're moving into
- * @template: out param for the new set of csses, should be clear on entry
- */
- static struct css_set *find_existing_css_set(struct css_set *old_cset,
- struct cgroup *cgrp,
- struct cgroup_subsys_state *template[])
- {
- struct cgroup_root *root = cgrp->root;
- struct cgroup_subsys *ss;
- struct css_set *cset;
- unsigned long key;
- int i;
- /*
- * Build the set of subsystem state objects that we want to see in the
- * new css_set. while subsystems can change globally, the entries here
- * won't change, so no need for locking.
- */
- for_each_subsys(ss, i) {
- if (root->subsys_mask & (1UL << i)) {
- /*
- * @ss is in this hierarchy, so we want the
- * effective css from @cgrp.
- */
- template[i] = cgroup_e_css_by_mask(cgrp, ss);
- } else {
- /*
- * @ss is not in this hierarchy, so we don't want
- * to change the css.
- */
- template[i] = old_cset->subsys[i];
- }
- }
- key = css_set_hash(template);
- hash_for_each_possible(css_set_table, cset, hlist, key) {
- if (!compare_css_sets(cset, old_cset, cgrp, template))
- continue;
- /* This css_set matches what we need */
- return cset;
- }
- /* No existing cgroup group matched */
- return NULL;
- }
- static void free_cgrp_cset_links(struct list_head *links_to_free)
- {
- struct cgrp_cset_link *link, *tmp_link;
- list_for_each_entry_safe(link, tmp_link, links_to_free, cset_link) {
- list_del(&link->cset_link);
- kfree(link);
- }
- }
- /**
- * allocate_cgrp_cset_links - allocate cgrp_cset_links
- * @count: the number of links to allocate
- * @tmp_links: list_head the allocated links are put on
- *
- * Allocate @count cgrp_cset_link structures and chain them on @tmp_links
- * through ->cset_link. Returns 0 on success or -errno.
- */
- static int allocate_cgrp_cset_links(int count, struct list_head *tmp_links)
- {
- struct cgrp_cset_link *link;
- int i;
- INIT_LIST_HEAD(tmp_links);
- for (i = 0; i < count; i++) {
- link = kzalloc(sizeof(*link), GFP_KERNEL);
- if (!link) {
- free_cgrp_cset_links(tmp_links);
- return -ENOMEM;
- }
- list_add(&link->cset_link, tmp_links);
- }
- return 0;
- }
- /**
- * link_css_set - a helper function to link a css_set to a cgroup
- * @tmp_links: cgrp_cset_link objects allocated by allocate_cgrp_cset_links()
- * @cset: the css_set to be linked
- * @cgrp: the destination cgroup
- */
- static void link_css_set(struct list_head *tmp_links, struct css_set *cset,
- struct cgroup *cgrp)
- {
- struct cgrp_cset_link *link;
- BUG_ON(list_empty(tmp_links));
- if (cgroup_on_dfl(cgrp))
- cset->dfl_cgrp = cgrp;
- link = list_first_entry(tmp_links, struct cgrp_cset_link, cset_link);
- link->cset = cset;
- link->cgrp = cgrp;
- /*
- * Always add links to the tail of the lists so that the lists are
- * in choronological order.
- */
- list_move_tail(&link->cset_link, &cgrp->cset_links);
- list_add_tail(&link->cgrp_link, &cset->cgrp_links);
- if (cgroup_parent(cgrp))
- cgroup_get_live(cgrp);
- }
- /**
- * find_css_set - return a new css_set with one cgroup updated
- * @old_cset: the baseline css_set
- * @cgrp: the cgroup to be updated
- *
- * Return a new css_set that's equivalent to @old_cset, but with @cgrp
- * substituted into the appropriate hierarchy.
- */
- static struct css_set *find_css_set(struct css_set *old_cset,
- struct cgroup *cgrp)
- {
- struct cgroup_subsys_state *template[CGROUP_SUBSYS_COUNT] = { };
- struct css_set *cset;
- struct list_head tmp_links;
- struct cgrp_cset_link *link;
- struct cgroup_subsys *ss;
- unsigned long key;
- int ssid;
- lockdep_assert_held(&cgroup_mutex);
- /* First see if we already have a cgroup group that matches
- * the desired set */
- spin_lock_irq(&css_set_lock);
- cset = find_existing_css_set(old_cset, cgrp, template);
- if (cset)
- get_css_set(cset);
- spin_unlock_irq(&css_set_lock);
- if (cset)
- return cset;
- cset = kzalloc(sizeof(*cset), GFP_KERNEL);
- if (!cset)
- return NULL;
- /* Allocate all the cgrp_cset_link objects that we'll need */
- if (allocate_cgrp_cset_links(cgroup_root_count, &tmp_links) < 0) {
- kfree(cset);
- return NULL;
- }
- refcount_set(&cset->refcount, 1);
- cset->dom_cset = cset;
- INIT_LIST_HEAD(&cset->tasks);
- INIT_LIST_HEAD(&cset->mg_tasks);
- INIT_LIST_HEAD(&cset->dying_tasks);
- INIT_LIST_HEAD(&cset->task_iters);
- INIT_LIST_HEAD(&cset->threaded_csets);
- INIT_HLIST_NODE(&cset->hlist);
- INIT_LIST_HEAD(&cset->cgrp_links);
- INIT_LIST_HEAD(&cset->mg_preload_node);
- INIT_LIST_HEAD(&cset->mg_node);
- /* Copy the set of subsystem state objects generated in
- * find_existing_css_set() */
- memcpy(cset->subsys, template, sizeof(cset->subsys));
- spin_lock_irq(&css_set_lock);
- /* Add reference counts and links from the new css_set. */
- list_for_each_entry(link, &old_cset->cgrp_links, cgrp_link) {
- struct cgroup *c = link->cgrp;
- if (c->root == cgrp->root)
- c = cgrp;
- link_css_set(&tmp_links, cset, c);
- }
- BUG_ON(!list_empty(&tmp_links));
- css_set_count++;
- /* Add @cset to the hash table */
- key = css_set_hash(cset->subsys);
- hash_add(css_set_table, &cset->hlist, key);
- for_each_subsys(ss, ssid) {
- struct cgroup_subsys_state *css = cset->subsys[ssid];
- list_add_tail(&cset->e_cset_node[ssid],
- &css->cgroup->e_csets[ssid]);
- css_get(css);
- }
- spin_unlock_irq(&css_set_lock);
- /*
- * If @cset should be threaded, look up the matching dom_cset and
- * link them up. We first fully initialize @cset then look for the
- * dom_cset. It's simpler this way and safe as @cset is guaranteed
- * to stay empty until we return.
- */
- if (cgroup_is_threaded(cset->dfl_cgrp)) {
- struct css_set *dcset;
- dcset = find_css_set(cset, cset->dfl_cgrp->dom_cgrp);
- if (!dcset) {
- put_css_set(cset);
- return NULL;
- }
- spin_lock_irq(&css_set_lock);
- cset->dom_cset = dcset;
- list_add_tail(&cset->threaded_csets_node,
- &dcset->threaded_csets);
- spin_unlock_irq(&css_set_lock);
- }
- return cset;
- }
- struct cgroup_root *cgroup_root_from_kf(struct kernfs_root *kf_root)
- {
- struct cgroup *root_cgrp = kf_root->kn->priv;
- return root_cgrp->root;
- }
- static int cgroup_init_root_id(struct cgroup_root *root)
- {
- int id;
- lockdep_assert_held(&cgroup_mutex);
- id = idr_alloc_cyclic(&cgroup_hierarchy_idr, root, 0, 0, GFP_KERNEL);
- if (id < 0)
- return id;
- root->hierarchy_id = id;
- return 0;
- }
- static void cgroup_exit_root_id(struct cgroup_root *root)
- {
- lockdep_assert_held(&cgroup_mutex);
- idr_remove(&cgroup_hierarchy_idr, root->hierarchy_id);
- }
- void cgroup_free_root(struct cgroup_root *root)
- {
- kfree(root);
- }
- static void cgroup_destroy_root(struct cgroup_root *root)
- {
- struct cgroup *cgrp = &root->cgrp;
- struct cgrp_cset_link *link, *tmp_link;
- trace_cgroup_destroy_root(root);
- cgroup_lock_and_drain_offline(&cgrp_dfl_root.cgrp);
- BUG_ON(atomic_read(&root->nr_cgrps));
- BUG_ON(!list_empty(&cgrp->self.children));
- /* Rebind all subsystems back to the default hierarchy */
- WARN_ON(rebind_subsystems(&cgrp_dfl_root, root->subsys_mask));
- /*
- * Release all the links from cset_links to this hierarchy's
- * root cgroup
- */
- spin_lock_irq(&css_set_lock);
- list_for_each_entry_safe(link, tmp_link, &cgrp->cset_links, cset_link) {
- list_del(&link->cset_link);
- list_del(&link->cgrp_link);
- kfree(link);
- }
- spin_unlock_irq(&css_set_lock);
- if (!list_empty(&root->root_list)) {
- list_del(&root->root_list);
- cgroup_root_count--;
- }
- cgroup_exit_root_id(root);
- mutex_unlock(&cgroup_mutex);
- kernfs_destroy_root(root->kf_root);
- cgroup_free_root(root);
- }
- /*
- * look up cgroup associated with current task's cgroup namespace on the
- * specified hierarchy
- */
- static struct cgroup *
- current_cgns_cgroup_from_root(struct cgroup_root *root)
- {
- struct cgroup *res = NULL;
- struct css_set *cset;
- lockdep_assert_held(&css_set_lock);
- rcu_read_lock();
- cset = current->nsproxy->cgroup_ns->root_cset;
- if (cset == &init_css_set) {
- res = &root->cgrp;
- } else if (root == &cgrp_dfl_root) {
- res = cset->dfl_cgrp;
- } else {
- struct cgrp_cset_link *link;
- list_for_each_entry(link, &cset->cgrp_links, cgrp_link) {
- struct cgroup *c = link->cgrp;
- if (c->root == root) {
- res = c;
- break;
- }
- }
- }
- rcu_read_unlock();
- BUG_ON(!res);
- return res;
- }
- /* look up cgroup associated with given css_set on the specified hierarchy */
- static struct cgroup *cset_cgroup_from_root(struct css_set *cset,
- struct cgroup_root *root)
- {
- struct cgroup *res = NULL;
- lockdep_assert_held(&cgroup_mutex);
- lockdep_assert_held(&css_set_lock);
- if (cset == &init_css_set) {
- res = &root->cgrp;
- } else if (root == &cgrp_dfl_root) {
- res = cset->dfl_cgrp;
- } else {
- struct cgrp_cset_link *link;
- list_for_each_entry(link, &cset->cgrp_links, cgrp_link) {
- struct cgroup *c = link->cgrp;
- if (c->root == root) {
- res = c;
- break;
- }
- }
- }
- BUG_ON(!res);
- return res;
- }
- /*
- * Return the cgroup for "task" from the given hierarchy. Must be
- * called with cgroup_mutex and css_set_lock held.
- */
- struct cgroup *task_cgroup_from_root(struct task_struct *task,
- struct cgroup_root *root)
- {
- /*
- * No need to lock the task - since we hold css_set_lock the
- * task can't change groups.
- */
- return cset_cgroup_from_root(task_css_set(task), root);
- }
- /*
- * A task must hold cgroup_mutex to modify cgroups.
- *
- * Any task can increment and decrement the count field without lock.
- * So in general, code holding cgroup_mutex can't rely on the count
- * field not changing. However, if the count goes to zero, then only
- * cgroup_attach_task() can increment it again. Because a count of zero
- * means that no tasks are currently attached, therefore there is no
- * way a task attached to that cgroup can fork (the other way to
- * increment the count). So code holding cgroup_mutex can safely
- * assume that if the count is zero, it will stay zero. Similarly, if
- * a task holds cgroup_mutex on a cgroup with zero count, it
- * knows that the cgroup won't be removed, as cgroup_rmdir()
- * needs that mutex.
- *
- * A cgroup can only be deleted if both its 'count' of using tasks
- * is zero, and its list of 'children' cgroups is empty. Since all
- * tasks in the system use _some_ cgroup, and since there is always at
- * least one task in the system (init, pid == 1), therefore, root cgroup
- * always has either children cgroups and/or using tasks. So we don't
- * need a special hack to ensure that root cgroup cannot be deleted.
- *
- * P.S. One more locking exception. RCU is used to guard the
- * update of a tasks cgroup pointer by cgroup_attach_task()
- */
- static struct kernfs_syscall_ops cgroup_kf_syscall_ops;
- static char *cgroup_file_name(struct cgroup *cgrp, const struct cftype *cft,
- char *buf)
- {
- struct cgroup_subsys *ss = cft->ss;
- if (cft->ss && !(cft->flags & CFTYPE_NO_PREFIX) &&
- !(cgrp->root->flags & CGRP_ROOT_NOPREFIX)) {
- const char *dbg = (cft->flags & CFTYPE_DEBUG) ? ".__DEBUG__." : "";
- snprintf(buf, CGROUP_FILE_NAME_MAX, "%s%s.%s",
- dbg, cgroup_on_dfl(cgrp) ? ss->name : ss->legacy_name,
- cft->name);
- } else {
- strscpy(buf, cft->name, CGROUP_FILE_NAME_MAX);
- }
- return buf;
- }
- /**
- * cgroup_file_mode - deduce file mode of a control file
- * @cft: the control file in question
- *
- * S_IRUGO for read, S_IWUSR for write.
- */
- static umode_t cgroup_file_mode(const struct cftype *cft)
- {
- umode_t mode = 0;
- if (cft->read_u64 || cft->read_s64 || cft->seq_show)
- mode |= S_IRUGO;
- if (cft->write_u64 || cft->write_s64 || cft->write) {
- if (cft->flags & CFTYPE_WORLD_WRITABLE)
- mode |= S_IWUGO;
- else
- mode |= S_IWUSR;
- }
- return mode;
- }
- /**
- * cgroup_calc_subtree_ss_mask - calculate subtree_ss_mask
- * @subtree_control: the new subtree_control mask to consider
- * @this_ss_mask: available subsystems
- *
- * On the default hierarchy, a subsystem may request other subsystems to be
- * enabled together through its ->depends_on mask. In such cases, more
- * subsystems than specified in "cgroup.subtree_control" may be enabled.
- *
- * This function calculates which subsystems need to be enabled if
- * @subtree_control is to be applied while restricted to @this_ss_mask.
- */
- static u16 cgroup_calc_subtree_ss_mask(u16 subtree_control, u16 this_ss_mask)
- {
- u16 cur_ss_mask = subtree_control;
- struct cgroup_subsys *ss;
- int ssid;
- lockdep_assert_held(&cgroup_mutex);
- cur_ss_mask |= cgrp_dfl_implicit_ss_mask;
- while (true) {
- u16 new_ss_mask = cur_ss_mask;
- do_each_subsys_mask(ss, ssid, cur_ss_mask) {
- new_ss_mask |= ss->depends_on;
- } while_each_subsys_mask();
- /*
- * Mask out subsystems which aren't available. This can
- * happen only if some depended-upon subsystems were bound
- * to non-default hierarchies.
- */
- new_ss_mask &= this_ss_mask;
- if (new_ss_mask == cur_ss_mask)
- break;
- cur_ss_mask = new_ss_mask;
- }
- return cur_ss_mask;
- }
- /**
- * cgroup_kn_unlock - unlocking helper for cgroup kernfs methods
- * @kn: the kernfs_node being serviced
- *
- * This helper undoes cgroup_kn_lock_live() and should be invoked before
- * the method finishes if locking succeeded. Note that once this function
- * returns the cgroup returned by cgroup_kn_lock_live() may become
- * inaccessible any time. If the caller intends to continue to access the
- * cgroup, it should pin it before invoking this function.
- */
- void cgroup_kn_unlock(struct kernfs_node *kn)
- {
- struct cgroup *cgrp;
- if (kernfs_type(kn) == KERNFS_DIR)
- cgrp = kn->priv;
- else
- cgrp = kn->parent->priv;
- mutex_unlock(&cgroup_mutex);
- kernfs_unbreak_active_protection(kn);
- cgroup_put(cgrp);
- }
- /**
- * cgroup_kn_lock_live - locking helper for cgroup kernfs methods
- * @kn: the kernfs_node being serviced
- * @drain_offline: perform offline draining on the cgroup
- *
- * This helper is to be used by a cgroup kernfs method currently servicing
- * @kn. It breaks the active protection, performs cgroup locking and
- * verifies that the associated cgroup is alive. Returns the cgroup if
- * alive; otherwise, %NULL. A successful return should be undone by a
- * matching cgroup_kn_unlock() invocation. If @drain_offline is %true, the
- * cgroup is drained of offlining csses before return.
- *
- * Any cgroup kernfs method implementation which requires locking the
- * associated cgroup should use this helper. It avoids nesting cgroup
- * locking under kernfs active protection and allows all kernfs operations
- * including self-removal.
- */
- struct cgroup *cgroup_kn_lock_live(struct kernfs_node *kn, bool drain_offline)
- {
- struct cgroup *cgrp;
- if (kernfs_type(kn) == KERNFS_DIR)
- cgrp = kn->priv;
- else
- cgrp = kn->parent->priv;
- /*
- * We're gonna grab cgroup_mutex which nests outside kernfs
- * active_ref. cgroup liveliness check alone provides enough
- * protection against removal. Ensure @cgrp stays accessible and
- * break the active_ref protection.
- */
- if (!cgroup_tryget(cgrp))
- return NULL;
- kernfs_break_active_protection(kn);
- if (drain_offline)
- cgroup_lock_and_drain_offline(cgrp);
- else
- mutex_lock(&cgroup_mutex);
- if (!cgroup_is_dead(cgrp))
- return cgrp;
- cgroup_kn_unlock(kn);
- return NULL;
- }
- static void cgroup_rm_file(struct cgroup *cgrp, const struct cftype *cft)
- {
- char name[CGROUP_FILE_NAME_MAX];
- lockdep_assert_held(&cgroup_mutex);
- if (cft->file_offset) {
- struct cgroup_subsys_state *css = cgroup_css(cgrp, cft->ss);
- struct cgroup_file *cfile = (void *)css + cft->file_offset;
- spin_lock_irq(&cgroup_file_kn_lock);
- cfile->kn = NULL;
- spin_unlock_irq(&cgroup_file_kn_lock);
- del_timer_sync(&cfile->notify_timer);
- }
- kernfs_remove_by_name(cgrp->kn, cgroup_file_name(cgrp, cft, name));
- }
- /**
- * css_clear_dir - remove subsys files in a cgroup directory
- * @css: taget css
- */
- static void css_clear_dir(struct cgroup_subsys_state *css)
- {
- struct cgroup *cgrp = css->cgroup;
- struct cftype *cfts;
- if (!(css->flags & CSS_VISIBLE))
- return;
- css->flags &= ~CSS_VISIBLE;
- if (!css->ss) {
- if (cgroup_on_dfl(cgrp))
- cfts = cgroup_base_files;
- else
- cfts = cgroup1_base_files;
- cgroup_addrm_files(css, cgrp, cfts, false);
- } else {
- list_for_each_entry(cfts, &css->ss->cfts, node)
- cgroup_addrm_files(css, cgrp, cfts, false);
- }
- }
- /**
- * css_populate_dir - create subsys files in a cgroup directory
- * @css: target css
- *
- * On failure, no file is added.
- */
- static int css_populate_dir(struct cgroup_subsys_state *css)
- {
- struct cgroup *cgrp = css->cgroup;
- struct cftype *cfts, *failed_cfts;
- int ret;
- if ((css->flags & CSS_VISIBLE) || !cgrp->kn)
- return 0;
- if (!css->ss) {
- if (cgroup_on_dfl(cgrp))
- cfts = cgroup_base_files;
- else
- cfts = cgroup1_base_files;
- ret = cgroup_addrm_files(&cgrp->self, cgrp, cfts, true);
- if (ret < 0)
- return ret;
- } else {
- list_for_each_entry(cfts, &css->ss->cfts, node) {
- ret = cgroup_addrm_files(css, cgrp, cfts, true);
- if (ret < 0) {
- failed_cfts = cfts;
- goto err;
- }
- }
- }
- css->flags |= CSS_VISIBLE;
- return 0;
- err:
- list_for_each_entry(cfts, &css->ss->cfts, node) {
- if (cfts == failed_cfts)
- break;
- cgroup_addrm_files(css, cgrp, cfts, false);
- }
- return ret;
- }
- int rebind_subsystems(struct cgroup_root *dst_root, u16 ss_mask)
- {
- struct cgroup *dcgrp = &dst_root->cgrp;
- struct cgroup_subsys *ss;
- int ssid, i, ret;
- u16 dfl_disable_ss_mask = 0;
- lockdep_assert_held(&cgroup_mutex);
- do_each_subsys_mask(ss, ssid, ss_mask) {
- /*
- * If @ss has non-root csses attached to it, can't move.
- * If @ss is an implicit controller, it is exempt from this
- * rule and can be stolen.
- */
- if (css_next_child(NULL, cgroup_css(&ss->root->cgrp, ss)) &&
- !ss->implicit_on_dfl)
- return -EBUSY;
- /* can't move between two non-dummy roots either */
- if (ss->root != &cgrp_dfl_root && dst_root != &cgrp_dfl_root)
- return -EBUSY;
- /*
- * Collect ssid's that need to be disabled from default
- * hierarchy.
- */
- if (ss->root == &cgrp_dfl_root)
- dfl_disable_ss_mask |= 1 << ssid;
- } while_each_subsys_mask();
- if (dfl_disable_ss_mask) {
- struct cgroup *scgrp = &cgrp_dfl_root.cgrp;
- /*
- * Controllers from default hierarchy that need to be rebound
- * are all disabled together in one go.
- */
- cgrp_dfl_root.subsys_mask &= ~dfl_disable_ss_mask;
- WARN_ON(cgroup_apply_control(scgrp));
- cgroup_finalize_control(scgrp, 0);
- }
- do_each_subsys_mask(ss, ssid, ss_mask) {
- struct cgroup_root *src_root = ss->root;
- struct cgroup *scgrp = &src_root->cgrp;
- struct cgroup_subsys_state *css = cgroup_css(scgrp, ss);
- struct css_set *cset;
- WARN_ON(!css || cgroup_css(dcgrp, ss));
- if (src_root != &cgrp_dfl_root) {
- /* disable from the source */
- src_root->subsys_mask &= ~(1 << ssid);
- WARN_ON(cgroup_apply_control(scgrp));
- cgroup_finalize_control(scgrp, 0);
- }
- /* rebind */
- RCU_INIT_POINTER(scgrp->subsys[ssid], NULL);
- rcu_assign_pointer(dcgrp->subsys[ssid], css);
- ss->root = dst_root;
- css->cgroup = dcgrp;
- spin_lock_irq(&css_set_lock);
- hash_for_each(css_set_table, i, cset, hlist)
- list_move_tail(&cset->e_cset_node[ss->id],
- &dcgrp->e_csets[ss->id]);
- spin_unlock_irq(&css_set_lock);
- /* default hierarchy doesn't enable controllers by default */
- dst_root->subsys_mask |= 1 << ssid;
- if (dst_root == &cgrp_dfl_root) {
- static_branch_enable(cgroup_subsys_on_dfl_key[ssid]);
- } else {
- dcgrp->subtree_control |= 1 << ssid;
- static_branch_disable(cgroup_subsys_on_dfl_key[ssid]);
- }
- ret = cgroup_apply_control(dcgrp);
- if (ret)
- pr_warn("partial failure to rebind %s controller (err=%d)\n",
- ss->name, ret);
- if (ss->bind)
- ss->bind(css);
- } while_each_subsys_mask();
- kernfs_activate(dcgrp->kn);
- return 0;
- }
- int cgroup_show_path(struct seq_file *sf, struct kernfs_node *kf_node,
- struct kernfs_root *kf_root)
- {
- int len = 0;
- char *buf = NULL;
- struct cgroup_root *kf_cgroot = cgroup_root_from_kf(kf_root);
- struct cgroup *ns_cgroup;
- buf = kmalloc(PATH_MAX, GFP_KERNEL);
- if (!buf)
- return -ENOMEM;
- spin_lock_irq(&css_set_lock);
- ns_cgroup = current_cgns_cgroup_from_root(kf_cgroot);
- len = kernfs_path_from_node(kf_node, ns_cgroup->kn, buf, PATH_MAX);
- spin_unlock_irq(&css_set_lock);
- if (len >= PATH_MAX)
- len = -ERANGE;
- else if (len > 0) {
- seq_escape(sf, buf, " \t\n\\");
- len = 0;
- }
- kfree(buf);
- return len;
- }
- enum cgroup2_param {
- Opt_nsdelegate,
- Opt_memory_localevents,
- Opt_memory_recursiveprot,
- nr__cgroup2_params
- };
- static const struct fs_parameter_spec cgroup2_fs_parameters[] = {
- fsparam_flag("nsdelegate", Opt_nsdelegate),
- fsparam_flag("memory_localevents", Opt_memory_localevents),
- fsparam_flag("memory_recursiveprot", Opt_memory_recursiveprot),
- {}
- };
- static int cgroup2_parse_param(struct fs_context *fc, struct fs_parameter *param)
- {
- struct cgroup_fs_context *ctx = cgroup_fc2context(fc);
- struct fs_parse_result result;
- int opt;
- opt = fs_parse(fc, cgroup2_fs_parameters, param, &result);
- if (opt < 0)
- return opt;
- switch (opt) {
- case Opt_nsdelegate:
- ctx->flags |= CGRP_ROOT_NS_DELEGATE;
- return 0;
- case Opt_memory_localevents:
- ctx->flags |= CGRP_ROOT_MEMORY_LOCAL_EVENTS;
- return 0;
- case Opt_memory_recursiveprot:
- ctx->flags |= CGRP_ROOT_MEMORY_RECURSIVE_PROT;
- return 0;
- }
- return -EINVAL;
- }
- static void apply_cgroup_root_flags(unsigned int root_flags)
- {
- if (current->nsproxy->cgroup_ns == &init_cgroup_ns) {
- if (root_flags & CGRP_ROOT_NS_DELEGATE)
- cgrp_dfl_root.flags |= CGRP_ROOT_NS_DELEGATE;
- else
- cgrp_dfl_root.flags &= ~CGRP_ROOT_NS_DELEGATE;
- if (root_flags & CGRP_ROOT_MEMORY_LOCAL_EVENTS)
- cgrp_dfl_root.flags |= CGRP_ROOT_MEMORY_LOCAL_EVENTS;
- else
- cgrp_dfl_root.flags &= ~CGRP_ROOT_MEMORY_LOCAL_EVENTS;
- if (root_flags & CGRP_ROOT_MEMORY_RECURSIVE_PROT)
- cgrp_dfl_root.flags |= CGRP_ROOT_MEMORY_RECURSIVE_PROT;
- else
- cgrp_dfl_root.flags &= ~CGRP_ROOT_MEMORY_RECURSIVE_PROT;
- }
- }
- static int cgroup_show_options(struct seq_file *seq, struct kernfs_root *kf_root)
- {
- if (cgrp_dfl_root.flags & CGRP_ROOT_NS_DELEGATE)
- seq_puts(seq, ",nsdelegate");
- if (cgrp_dfl_root.flags & CGRP_ROOT_MEMORY_LOCAL_EVENTS)
- seq_puts(seq, ",memory_localevents");
- if (cgrp_dfl_root.flags & CGRP_ROOT_MEMORY_RECURSIVE_PROT)
- seq_puts(seq, ",memory_recursiveprot");
- return 0;
- }
- static int cgroup_reconfigure(struct fs_context *fc)
- {
- struct cgroup_fs_context *ctx = cgroup_fc2context(fc);
- apply_cgroup_root_flags(ctx->flags);
- return 0;
- }
- static void init_cgroup_housekeeping(struct cgroup *cgrp)
- {
- struct cgroup_subsys *ss;
- int ssid;
- INIT_LIST_HEAD(&cgrp->self.sibling);
- INIT_LIST_HEAD(&cgrp->self.children);
- INIT_LIST_HEAD(&cgrp->cset_links);
- INIT_LIST_HEAD(&cgrp->pidlists);
- mutex_init(&cgrp->pidlist_mutex);
- cgrp->self.cgroup = cgrp;
- cgrp->self.flags |= CSS_ONLINE;
- cgrp->dom_cgrp = cgrp;
- cgrp->max_descendants = INT_MAX;
- cgrp->max_depth = INT_MAX;
- INIT_LIST_HEAD(&cgrp->rstat_css_list);
- prev_cputime_init(&cgrp->prev_cputime);
- for_each_subsys(ss, ssid)
- INIT_LIST_HEAD(&cgrp->e_csets[ssid]);
- init_waitqueue_head(&cgrp->offline_waitq);
- INIT_WORK(&cgrp->release_agent_work, cgroup1_release_agent);
- }
- void init_cgroup_root(struct cgroup_fs_context *ctx)
- {
- struct cgroup_root *root = ctx->root;
- struct cgroup *cgrp = &root->cgrp;
- INIT_LIST_HEAD(&root->root_list);
- atomic_set(&root->nr_cgrps, 1);
- cgrp->root = root;
- init_cgroup_housekeeping(cgrp);
- root->flags = ctx->flags;
- if (ctx->release_agent)
- strscpy(root->release_agent_path, ctx->release_agent, PATH_MAX);
- if (ctx->name)
- strscpy(root->name, ctx->name, MAX_CGROUP_ROOT_NAMELEN);
- if (ctx->cpuset_clone_children)
- set_bit(CGRP_CPUSET_CLONE_CHILDREN, &root->cgrp.flags);
- }
- int cgroup_setup_root(struct cgroup_root *root, u16 ss_mask)
- {
- LIST_HEAD(tmp_links);
- struct cgroup *root_cgrp = &root->cgrp;
- struct kernfs_syscall_ops *kf_sops;
- struct css_set *cset;
- int i, ret;
- lockdep_assert_held(&cgroup_mutex);
- ret = percpu_ref_init(&root_cgrp->self.refcnt, css_release,
- 0, GFP_KERNEL);
- if (ret)
- goto out;
- /*
- * We're accessing css_set_count without locking css_set_lock here,
- * but that's OK - it can only be increased by someone holding
- * cgroup_lock, and that's us. Later rebinding may disable
- * controllers on the default hierarchy and thus create new csets,
- * which can't be more than the existing ones. Allocate 2x.
- */
- ret = allocate_cgrp_cset_links(2 * css_set_count, &tmp_links);
- if (ret)
- goto cancel_ref;
- ret = cgroup_init_root_id(root);
- if (ret)
- goto cancel_ref;
- kf_sops = root == &cgrp_dfl_root ?
- &cgroup_kf_syscall_ops : &cgroup1_kf_syscall_ops;
- root->kf_root = kernfs_create_root(kf_sops,
- KERNFS_ROOT_CREATE_DEACTIVATED |
- KERNFS_ROOT_SUPPORT_EXPORTOP |
- KERNFS_ROOT_SUPPORT_USER_XATTR,
- root_cgrp);
- if (IS_ERR(root->kf_root)) {
- ret = PTR_ERR(root->kf_root);
- goto exit_root_id;
- }
- root_cgrp->kn = root->kf_root->kn;
- WARN_ON_ONCE(cgroup_ino(root_cgrp) != 1);
- root_cgrp->ancestor_ids[0] = cgroup_id(root_cgrp);
- ret = css_populate_dir(&root_cgrp->self);
- if (ret)
- goto destroy_root;
- ret = rebind_subsystems(root, ss_mask);
- if (ret)
- goto destroy_root;
- ret = cgroup_bpf_inherit(root_cgrp);
- WARN_ON_ONCE(ret);
- trace_cgroup_setup_root(root);
- /*
- * There must be no failure case after here, since rebinding takes
- * care of subsystems' refcounts, which are explicitly dropped in
- * the failure exit path.
- */
- list_add(&root->root_list, &cgroup_roots);
- cgroup_root_count++;
- /*
- * Link the root cgroup in this hierarchy into all the css_set
- * objects.
- */
- spin_lock_irq(&css_set_lock);
- hash_for_each(css_set_table, i, cset, hlist) {
- link_css_set(&tmp_links, cset, root_cgrp);
- if (css_set_populated(cset))
- cgroup_update_populated(root_cgrp, true);
- }
- spin_unlock_irq(&css_set_lock);
- BUG_ON(!list_empty(&root_cgrp->self.children));
- BUG_ON(atomic_read(&root->nr_cgrps) != 1);
- ret = 0;
- goto out;
- destroy_root:
- kernfs_destroy_root(root->kf_root);
- root->kf_root = NULL;
- exit_root_id:
- cgroup_exit_root_id(root);
- cancel_ref:
- percpu_ref_exit(&root_cgrp->self.refcnt);
- out:
- free_cgrp_cset_links(&tmp_links);
- return ret;
- }
- int cgroup_do_get_tree(struct fs_context *fc)
- {
- struct cgroup_fs_context *ctx = cgroup_fc2context(fc);
- int ret;
- ctx->kfc.root = ctx->root->kf_root;
- if (fc->fs_type == &cgroup2_fs_type)
- ctx->kfc.magic = CGROUP2_SUPER_MAGIC;
- else
- ctx->kfc.magic = CGROUP_SUPER_MAGIC;
- ret = kernfs_get_tree(fc);
- /*
- * In non-init cgroup namespace, instead of root cgroup's dentry,
- * we return the dentry corresponding to the cgroupns->root_cgrp.
- */
- if (!ret && ctx->ns != &init_cgroup_ns) {
- struct dentry *nsdentry;
- struct super_block *sb = fc->root->d_sb;
- struct cgroup *cgrp;
- mutex_lock(&cgroup_mutex);
- spin_lock_irq(&css_set_lock);
- cgrp = cset_cgroup_from_root(ctx->ns->root_cset, ctx->root);
- spin_unlock_irq(&css_set_lock);
- mutex_unlock(&cgroup_mutex);
- nsdentry = kernfs_node_dentry(cgrp->kn, sb);
- dput(fc->root);
- if (IS_ERR(nsdentry)) {
- deactivate_locked_super(sb);
- ret = PTR_ERR(nsdentry);
- nsdentry = NULL;
- }
- fc->root = nsdentry;
- }
- if (!ctx->kfc.new_sb_created)
- cgroup_put(&ctx->root->cgrp);
- return ret;
- }
- /*
- * Destroy a cgroup filesystem context.
- */
- static void cgroup_fs_context_free(struct fs_context *fc)
- {
- struct cgroup_fs_context *ctx = cgroup_fc2context(fc);
- kfree(ctx->name);
- kfree(ctx->release_agent);
- put_cgroup_ns(ctx->ns);
- kernfs_free_fs_context(fc);
- kfree(ctx);
- }
- static int cgroup_get_tree(struct fs_context *fc)
- {
- struct cgroup_fs_context *ctx = cgroup_fc2context(fc);
- int ret;
- cgrp_dfl_visible = true;
- cgroup_get_live(&cgrp_dfl_root.cgrp);
- ctx->root = &cgrp_dfl_root;
- ret = cgroup_do_get_tree(fc);
- if (!ret)
- apply_cgroup_root_flags(ctx->flags);
- return ret;
- }
- static const struct fs_context_operations cgroup_fs_context_ops = {
- .free = cgroup_fs_context_free,
- .parse_param = cgroup2_parse_param,
- .get_tree = cgroup_get_tree,
- .reconfigure = cgroup_reconfigure,
- };
- static const struct fs_context_operations cgroup1_fs_context_ops = {
- .free = cgroup_fs_context_free,
- .parse_param = cgroup1_parse_param,
- .get_tree = cgroup1_get_tree,
- .reconfigure = cgroup1_reconfigure,
- };
- /*
- * Initialise the cgroup filesystem creation/reconfiguration context. Notably,
- * we select the namespace we're going to use.
- */
- static int cgroup_init_fs_context(struct fs_context *fc)
- {
- struct cgroup_fs_context *ctx;
- ctx = kzalloc(sizeof(struct cgroup_fs_context), GFP_KERNEL);
- if (!ctx)
- return -ENOMEM;
- ctx->ns = current->nsproxy->cgroup_ns;
- get_cgroup_ns(ctx->ns);
- fc->fs_private = &ctx->kfc;
- if (fc->fs_type == &cgroup2_fs_type)
- fc->ops = &cgroup_fs_context_ops;
- else
- fc->ops = &cgroup1_fs_context_ops;
- put_user_ns(fc->user_ns);
- fc->user_ns = get_user_ns(ctx->ns->user_ns);
- fc->global = true;
- return 0;
- }
- static void cgroup_kill_sb(struct super_block *sb)
- {
- struct kernfs_root *kf_root = kernfs_root_from_sb(sb);
- struct cgroup_root *root = cgroup_root_from_kf(kf_root);
- /*
- * If @root doesn't have any children, start killing it.
- * This prevents new mounts by disabling percpu_ref_tryget_live().
- * cgroup_mount() may wait for @root's release.
- *
- * And don't kill the default root.
- */
- if (list_empty(&root->cgrp.self.children) && root != &cgrp_dfl_root &&
- !percpu_ref_is_dying(&root->cgrp.self.refcnt)) {
- cgroup_bpf_offline(&root->cgrp);
- percpu_ref_kill(&root->cgrp.self.refcnt);
- }
- cgroup_put(&root->cgrp);
- kernfs_kill_sb(sb);
- }
- struct file_system_type cgroup_fs_type = {
- .name = "cgroup",
- .init_fs_context = cgroup_init_fs_context,
- .parameters = cgroup1_fs_parameters,
- .kill_sb = cgroup_kill_sb,
- .fs_flags = FS_USERNS_MOUNT,
- };
- static struct file_system_type cgroup2_fs_type = {
- .name = "cgroup2",
- .init_fs_context = cgroup_init_fs_context,
- .parameters = cgroup2_fs_parameters,
- .kill_sb = cgroup_kill_sb,
- .fs_flags = FS_USERNS_MOUNT,
- };
- #ifdef CONFIG_CPUSETS
- static const struct fs_context_operations cpuset_fs_context_ops = {
- .get_tree = cgroup1_get_tree,
- .free = cgroup_fs_context_free,
- };
- /*
- * This is ugly, but preserves the userspace API for existing cpuset
- * users. If someone tries to mount the "cpuset" filesystem, we
- * silently switch it to mount "cgroup" instead
- */
- static int cpuset_init_fs_context(struct fs_context *fc)
- {
- char *agent = kstrdup("/sbin/cpuset_release_agent", GFP_USER);
- struct cgroup_fs_context *ctx;
- int err;
- err = cgroup_init_fs_context(fc);
- if (err) {
- kfree(agent);
- return err;
- }
- fc->ops = &cpuset_fs_context_ops;
- ctx = cgroup_fc2context(fc);
- ctx->subsys_mask = 1 << cpuset_cgrp_id;
- ctx->flags |= CGRP_ROOT_NOPREFIX;
- ctx->release_agent = agent;
- get_filesystem(&cgroup_fs_type);
- put_filesystem(fc->fs_type);
- fc->fs_type = &cgroup_fs_type;
- return 0;
- }
- static struct file_system_type cpuset_fs_type = {
- .name = "cpuset",
- .init_fs_context = cpuset_init_fs_context,
- .fs_flags = FS_USERNS_MOUNT,
- };
- #endif
- int cgroup_path_ns_locked(struct cgroup *cgrp, char *buf, size_t buflen,
- struct cgroup_namespace *ns)
- {
- struct cgroup *root = cset_cgroup_from_root(ns->root_cset, cgrp->root);
- return kernfs_path_from_node(cgrp->kn, root->kn, buf, buflen);
- }
- int cgroup_path_ns(struct cgroup *cgrp, char *buf, size_t buflen,
- struct cgroup_namespace *ns)
- {
- int ret;
- mutex_lock(&cgroup_mutex);
- spin_lock_irq(&css_set_lock);
- ret = cgroup_path_ns_locked(cgrp, buf, buflen, ns);
- spin_unlock_irq(&css_set_lock);
- mutex_unlock(&cgroup_mutex);
- return ret;
- }
- EXPORT_SYMBOL_GPL(cgroup_path_ns);
- /**
- * task_cgroup_path - cgroup path of a task in the first cgroup hierarchy
- * @task: target task
- * @buf: the buffer to write the path into
- * @buflen: the length of the buffer
- *
- * Determine @task's cgroup on the first (the one with the lowest non-zero
- * hierarchy_id) cgroup hierarchy and copy its path into @buf. This
- * function grabs cgroup_mutex and shouldn't be used inside locks used by
- * cgroup controller callbacks.
- *
- * Return value is the same as kernfs_path().
- */
- int task_cgroup_path(struct task_struct *task, char *buf, size_t buflen)
- {
- struct cgroup_root *root;
- struct cgroup *cgrp;
- int hierarchy_id = 1;
- int ret;
- mutex_lock(&cgroup_mutex);
- spin_lock_irq(&css_set_lock);
- root = idr_get_next(&cgroup_hierarchy_idr, &hierarchy_id);
- if (root) {
- cgrp = task_cgroup_from_root(task, root);
- ret = cgroup_path_ns_locked(cgrp, buf, buflen, &init_cgroup_ns);
- } else {
- /* if no hierarchy exists, everyone is in "/" */
- ret = strlcpy(buf, "/", buflen);
- }
- spin_unlock_irq(&css_set_lock);
- mutex_unlock(&cgroup_mutex);
- return ret;
- }
- EXPORT_SYMBOL_GPL(task_cgroup_path);
- /**
- * cgroup_migrate_add_task - add a migration target task to a migration context
- * @task: target task
- * @mgctx: target migration context
- *
- * Add @task, which is a migration target, to @mgctx->tset. This function
- * becomes noop if @task doesn't need to be migrated. @task's css_set
- * should have been added as a migration source and @task->cg_list will be
- * moved from the css_set's tasks list to mg_tasks one.
- */
- static void cgroup_migrate_add_task(struct task_struct *task,
- struct cgroup_mgctx *mgctx)
- {
- struct css_set *cset;
- lockdep_assert_held(&css_set_lock);
- /* @task either already exited or can't exit until the end */
- if (task->flags & PF_EXITING)
- return;
- /* cgroup_threadgroup_rwsem protects racing against forks */
- WARN_ON_ONCE(list_empty(&task->cg_list));
- cset = task_css_set(task);
- if (!cset->mg_src_cgrp)
- return;
- mgctx->tset.nr_tasks++;
- list_move_tail(&task->cg_list, &cset->mg_tasks);
- if (list_empty(&cset->mg_node))
- list_add_tail(&cset->mg_node,
- &mgctx->tset.src_csets);
- if (list_empty(&cset->mg_dst_cset->mg_node))
- list_add_tail(&cset->mg_dst_cset->mg_node,
- &mgctx->tset.dst_csets);
- }
- /**
- * cgroup_taskset_first - reset taskset and return the first task
- * @tset: taskset of interest
- * @dst_cssp: output variable for the destination css
- *
- * @tset iteration is initialized and the first task is returned.
- */
- struct task_struct *cgroup_taskset_first(struct cgroup_taskset *tset,
- struct cgroup_subsys_state **dst_cssp)
- {
- tset->cur_cset = list_first_entry(tset->csets, struct css_set, mg_node);
- tset->cur_task = NULL;
- return cgroup_taskset_next(tset, dst_cssp);
- }
- EXPORT_SYMBOL_GPL(cgroup_taskset_first);
- /**
- * cgroup_taskset_next - iterate to the next task in taskset
- * @tset: taskset of interest
- * @dst_cssp: output variable for the destination css
- *
- * Return the next task in @tset. Iteration must have been initialized
- * with cgroup_taskset_first().
- */
- struct task_struct *cgroup_taskset_next(struct cgroup_taskset *tset,
- struct cgroup_subsys_state **dst_cssp)
- {
- struct css_set *cset = tset->cur_cset;
- struct task_struct *task = tset->cur_task;
- while (&cset->mg_node != tset->csets) {
- if (!task)
- task = list_first_entry(&cset->mg_tasks,
- struct task_struct, cg_list);
- else
- task = list_next_entry(task, cg_list);
- if (&task->cg_list != &cset->mg_tasks) {
- tset->cur_cset = cset;
- tset->cur_task = task;
- /*
- * This function may be called both before and
- * after cgroup_taskset_migrate(). The two cases
- * can be distinguished by looking at whether @cset
- * has its ->mg_dst_cset set.
- */
- if (cset->mg_dst_cset)
- *dst_cssp = cset->mg_dst_cset->subsys[tset->ssid];
- else
- *dst_cssp = cset->subsys[tset->ssid];
- return task;
- }
- cset = list_next_entry(cset, mg_node);
- task = NULL;
- }
- return NULL;
- }
- EXPORT_SYMBOL_GPL(cgroup_taskset_next);
- /**
- * cgroup_taskset_migrate - migrate a taskset
- * @mgctx: migration context
- *
- * Migrate tasks in @mgctx as setup by migration preparation functions.
- * This function fails iff one of the ->can_attach callbacks fails and
- * guarantees that either all or none of the tasks in @mgctx are migrated.
- * @mgctx is consumed regardless of success.
- */
- static int cgroup_migrate_execute(struct cgroup_mgctx *mgctx)
- {
- struct cgroup_taskset *tset = &mgctx->tset;
- struct cgroup_subsys *ss;
- struct task_struct *task, *tmp_task;
- struct css_set *cset, *tmp_cset;
- int ssid, failed_ssid, ret;
- /* check that we can legitimately attach to the cgroup */
- if (tset->nr_tasks) {
- do_each_subsys_mask(ss, ssid, mgctx->ss_mask) {
- if (ss->can_attach) {
- tset->ssid = ssid;
- ret = ss->can_attach(tset);
- if (ret) {
- failed_ssid = ssid;
- goto out_cancel_attach;
- }
- }
- } while_each_subsys_mask();
- }
- /*
- * Now that we're guaranteed success, proceed to move all tasks to
- * the new cgroup. There are no failure cases after here, so this
- * is the commit point.
- */
- spin_lock_irq(&css_set_lock);
- list_for_each_entry(cset, &tset->src_csets, mg_node) {
- list_for_each_entry_safe(task, tmp_task, &cset->mg_tasks, cg_list) {
- struct css_set *from_cset = task_css_set(task);
- struct css_set *to_cset = cset->mg_dst_cset;
- get_css_set(to_cset);
- to_cset->nr_tasks++;
- css_set_move_task(task, from_cset, to_cset, true);
- from_cset->nr_tasks--;
- /*
- * If the source or destination cgroup is frozen,
- * the task might require to change its state.
- */
- cgroup_freezer_migrate_task(task, from_cset->dfl_cgrp,
- to_cset->dfl_cgrp);
- put_css_set_locked(from_cset);
- }
- }
- spin_unlock_irq(&css_set_lock);
- /*
- * Migration is committed, all target tasks are now on dst_csets.
- * Nothing is sensitive to fork() after this point. Notify
- * controllers that migration is complete.
- */
- tset->csets = &tset->dst_csets;
- if (tset->nr_tasks) {
- do_each_subsys_mask(ss, ssid, mgctx->ss_mask) {
- if (ss->attach) {
- tset->ssid = ssid;
- trace_android_vh_cgroup_attach(ss, tset);
- ss->attach(tset);
- }
- } while_each_subsys_mask();
- }
- ret = 0;
- goto out_release_tset;
- out_cancel_attach:
- if (tset->nr_tasks) {
- do_each_subsys_mask(ss, ssid, mgctx->ss_mask) {
- if (ssid == failed_ssid)
- break;
- if (ss->cancel_attach) {
- tset->ssid = ssid;
- ss->cancel_attach(tset);
- }
- } while_each_subsys_mask();
- }
- out_release_tset:
- spin_lock_irq(&css_set_lock);
- list_splice_init(&tset->dst_csets, &tset->src_csets);
- list_for_each_entry_safe(cset, tmp_cset, &tset->src_csets, mg_node) {
- list_splice_tail_init(&cset->mg_tasks, &cset->tasks);
- list_del_init(&cset->mg_node);
- }
- spin_unlock_irq(&css_set_lock);
- /*
- * Re-initialize the cgroup_taskset structure in case it is reused
- * again in another cgroup_migrate_add_task()/cgroup_migrate_execute()
- * iteration.
- */
- tset->nr_tasks = 0;
- tset->csets = &tset->src_csets;
- return ret;
- }
- /**
- * cgroup_migrate_vet_dst - verify whether a cgroup can be migration destination
- * @dst_cgrp: destination cgroup to test
- *
- * On the default hierarchy, except for the mixable, (possible) thread root
- * and threaded cgroups, subtree_control must be zero for migration
- * destination cgroups with tasks so that child cgroups don't compete
- * against tasks.
- */
- int cgroup_migrate_vet_dst(struct cgroup *dst_cgrp)
- {
- /* v1 doesn't have any restriction */
- if (!cgroup_on_dfl(dst_cgrp))
- return 0;
- /* verify @dst_cgrp can host resources */
- if (!cgroup_is_valid_domain(dst_cgrp->dom_cgrp))
- return -EOPNOTSUPP;
- /* mixables don't care */
- if (cgroup_is_mixable(dst_cgrp))
- return 0;
- /*
- * If @dst_cgrp is already or can become a thread root or is
- * threaded, it doesn't matter.
- */
- if (cgroup_can_be_thread_root(dst_cgrp) || cgroup_is_threaded(dst_cgrp))
- return 0;
- /* apply no-internal-process constraint */
- if (dst_cgrp->subtree_control)
- return -EBUSY;
- return 0;
- }
- /**
- * cgroup_migrate_finish - cleanup after attach
- * @mgctx: migration context
- *
- * Undo cgroup_migrate_add_src() and cgroup_migrate_prepare_dst(). See
- * those functions for details.
- */
- void cgroup_migrate_finish(struct cgroup_mgctx *mgctx)
- {
- LIST_HEAD(preloaded);
- struct css_set *cset, *tmp_cset;
- lockdep_assert_held(&cgroup_mutex);
- spin_lock_irq(&css_set_lock);
- list_splice_tail_init(&mgctx->preloaded_src_csets, &preloaded);
- list_splice_tail_init(&mgctx->preloaded_dst_csets, &preloaded);
- list_for_each_entry_safe(cset, tmp_cset, &preloaded, mg_preload_node) {
- cset->mg_src_cgrp = NULL;
- cset->mg_dst_cgrp = NULL;
- cset->mg_dst_cset = NULL;
- list_del_init(&cset->mg_preload_node);
- put_css_set_locked(cset);
- }
- spin_unlock_irq(&css_set_lock);
- }
- /**
- * cgroup_migrate_add_src - add a migration source css_set
- * @src_cset: the source css_set to add
- * @dst_cgrp: the destination cgroup
- * @mgctx: migration context
- *
- * Tasks belonging to @src_cset are about to be migrated to @dst_cgrp. Pin
- * @src_cset and add it to @mgctx->src_csets, which should later be cleaned
- * up by cgroup_migrate_finish().
- *
- * This function may be called without holding cgroup_threadgroup_rwsem
- * even if the target is a process. Threads may be created and destroyed
- * but as long as cgroup_mutex is not dropped, no new css_set can be put
- * into play and the preloaded css_sets are guaranteed to cover all
- * migrations.
- */
- void cgroup_migrate_add_src(struct css_set *src_cset,
- struct cgroup *dst_cgrp,
- struct cgroup_mgctx *mgctx)
- {
- struct cgroup *src_cgrp;
- lockdep_assert_held(&cgroup_mutex);
- lockdep_assert_held(&css_set_lock);
- /*
- * If ->dead, @src_set is associated with one or more dead cgroups
- * and doesn't contain any migratable tasks. Ignore it early so
- * that the rest of migration path doesn't get confused by it.
- */
- if (src_cset->dead)
- return;
- src_cgrp = cset_cgroup_from_root(src_cset, dst_cgrp->root);
- if (!list_empty(&src_cset->mg_preload_node))
- return;
- WARN_ON(src_cset->mg_src_cgrp);
- WARN_ON(src_cset->mg_dst_cgrp);
- WARN_ON(!list_empty(&src_cset->mg_tasks));
- WARN_ON(!list_empty(&src_cset->mg_node));
- src_cset->mg_src_cgrp = src_cgrp;
- src_cset->mg_dst_cgrp = dst_cgrp;
- get_css_set(src_cset);
- list_add_tail(&src_cset->mg_preload_node, &mgctx->preloaded_src_csets);
- }
- /**
- * cgroup_migrate_prepare_dst - prepare destination css_sets for migration
- * @mgctx: migration context
- *
- * Tasks are about to be moved and all the source css_sets have been
- * preloaded to @mgctx->preloaded_src_csets. This function looks up and
- * pins all destination css_sets, links each to its source, and append them
- * to @mgctx->preloaded_dst_csets.
- *
- * This function must be called after cgroup_migrate_add_src() has been
- * called on each migration source css_set. After migration is performed
- * using cgroup_migrate(), cgroup_migrate_finish() must be called on
- * @mgctx.
- */
- int cgroup_migrate_prepare_dst(struct cgroup_mgctx *mgctx)
- {
- struct css_set *src_cset, *tmp_cset;
- lockdep_assert_held(&cgroup_mutex);
- /* look up the dst cset for each src cset and link it to src */
- list_for_each_entry_safe(src_cset, tmp_cset, &mgctx->preloaded_src_csets,
- mg_preload_node) {
- struct css_set *dst_cset;
- struct cgroup_subsys *ss;
- int ssid;
- dst_cset = find_css_set(src_cset, src_cset->mg_dst_cgrp);
- if (!dst_cset)
- return -ENOMEM;
- WARN_ON_ONCE(src_cset->mg_dst_cset || dst_cset->mg_dst_cset);
- /*
- * If src cset equals dst, it's noop. Drop the src.
- * cgroup_migrate() will skip the cset too. Note that we
- * can't handle src == dst as some nodes are used by both.
- */
- if (src_cset == dst_cset) {
- src_cset->mg_src_cgrp = NULL;
- src_cset->mg_dst_cgrp = NULL;
- list_del_init(&src_cset->mg_preload_node);
- put_css_set(src_cset);
- put_css_set(dst_cset);
- continue;
- }
- src_cset->mg_dst_cset = dst_cset;
- if (list_empty(&dst_cset->mg_preload_node))
- list_add_tail(&dst_cset->mg_preload_node,
- &mgctx->preloaded_dst_csets);
- else
- put_css_set(dst_cset);
- for_each_subsys(ss, ssid)
- if (src_cset->subsys[ssid] != dst_cset->subsys[ssid])
- mgctx->ss_mask |= 1 << ssid;
- }
- return 0;
- }
- /**
- * cgroup_migrate - migrate a process or task to a cgroup
- * @leader: the leader of the process or the task to migrate
- * @threadgroup: whether @leader points to the whole process or a single task
- * @mgctx: migration context
- *
- * Migrate a process or task denoted by @leader. If migrating a process,
- * the caller must be holding cgroup_threadgroup_rwsem. The caller is also
- * responsible for invoking cgroup_migrate_add_src() and
- * cgroup_migrate_prepare_dst() on the targets before invoking this
- * function and following up with cgroup_migrate_finish().
- *
- * As long as a controller's ->can_attach() doesn't fail, this function is
- * guaranteed to succeed. This means that, excluding ->can_attach()
- * failure, when migrating multiple targets, the success or failure can be
- * decided for all targets by invoking group_migrate_prepare_dst() before
- * actually starting migrating.
- */
- int cgroup_migrate(struct task_struct *leader, bool threadgroup,
- struct cgroup_mgctx *mgctx)
- {
- struct task_struct *task;
- /*
- * Prevent freeing of tasks while we take a snapshot. Tasks that are
- * already PF_EXITING could be freed from underneath us unless we
- * take an rcu_read_lock.
- */
- spin_lock_irq(&css_set_lock);
- rcu_read_lock();
- task = leader;
- do {
- cgroup_migrate_add_task(task, mgctx);
- if (!threadgroup)
- break;
- } while_each_thread(leader, task);
- rcu_read_unlock();
- spin_unlock_irq(&css_set_lock);
- return cgroup_migrate_execute(mgctx);
- }
- /**
- * cgroup_attach_task - attach a task or a whole threadgroup to a cgroup
- * @dst_cgrp: the cgroup to attach to
- * @leader: the task or the leader of the threadgroup to be attached
- * @threadgroup: attach the whole threadgroup?
- *
- * Call holding cgroup_mutex and cgroup_threadgroup_rwsem.
- */
- int cgroup_attach_task(struct cgroup *dst_cgrp, struct task_struct *leader,
- bool threadgroup)
- {
- DEFINE_CGROUP_MGCTX(mgctx);
- struct task_struct *task;
- int ret = 0;
- /* look up all src csets */
- spin_lock_irq(&css_set_lock);
- rcu_read_lock();
- task = leader;
- do {
- cgroup_migrate_add_src(task_css_set(task), dst_cgrp, &mgctx);
- if (!threadgroup)
- break;
- } while_each_thread(leader, task);
- rcu_read_unlock();
- spin_unlock_irq(&css_set_lock);
- /* prepare dst csets and commit */
- ret = cgroup_migrate_prepare_dst(&mgctx);
- if (!ret)
- ret = cgroup_migrate(leader, threadgroup, &mgctx);
- cgroup_migrate_finish(&mgctx);
- if (!ret)
- TRACE_CGROUP_PATH(attach_task, dst_cgrp, leader, threadgroup);
- return ret;
- }
- struct task_struct *cgroup_procs_write_start(char *buf, bool threadgroup,
- bool *locked,
- struct cgroup *dst_cgrp)
- __acquires(&cgroup_threadgroup_rwsem)
- {
- struct task_struct *tsk;
- pid_t pid;
- bool force_migration = false;
- if (kstrtoint(strstrip(buf), 0, &pid) || pid < 0)
- return ERR_PTR(-EINVAL);
- /*
- * If we migrate a single thread, we don't care about threadgroup
- * stability. If the thread is `current`, it won't exit(2) under our
- * hands or change PID through exec(2). We exclude
- * cgroup_update_dfl_csses and other cgroup_{proc,thread}s_write
- * callers by cgroup_mutex.
- * Therefore, we can skip the global lock.
- */
- lockdep_assert_held(&cgroup_mutex);
- if (pid || threadgroup) {
- percpu_down_write(&cgroup_threadgroup_rwsem);
- *locked = true;
- } else {
- *locked = false;
- }
- rcu_read_lock();
- if (pid) {
- tsk = find_task_by_vpid(pid);
- if (!tsk) {
- tsk = ERR_PTR(-ESRCH);
- goto out_unlock_threadgroup;
- }
- } else {
- tsk = current;
- }
- if (threadgroup)
- tsk = tsk->group_leader;
- if (tsk->flags & PF_KTHREAD)
- trace_android_rvh_cgroup_force_kthread_migration(tsk, dst_cgrp, &force_migration);
- /*
- * kthreads may acquire PF_NO_SETAFFINITY during initialization.
- * If userland migrates such a kthread to a non-root cgroup, it can
- * become trapped in a cpuset, or RT kthread may be born in a
- * cgroup with no rt_runtime allocated. Just say no.
- */
- if (!force_migration && (tsk->no_cgroup_migration || (tsk->flags & PF_NO_SETAFFINITY))) {
- tsk = ERR_PTR(-EINVAL);
- goto out_unlock_threadgroup;
- }
- get_task_struct(tsk);
- goto out_unlock_rcu;
- out_unlock_threadgroup:
- if (*locked) {
- percpu_up_write(&cgroup_threadgroup_rwsem);
- *locked = false;
- }
- out_unlock_rcu:
- rcu_read_unlock();
- return tsk;
- }
- void cgroup_procs_write_finish(struct task_struct *task, bool locked)
- __releases(&cgroup_threadgroup_rwsem)
- {
- struct cgroup_subsys *ss;
- int ssid;
- /* release reference from cgroup_procs_write_start() */
- put_task_struct(task);
- if (locked)
- percpu_up_write(&cgroup_threadgroup_rwsem);
- for_each_subsys(ss, ssid)
- if (ss->post_attach)
- ss->post_attach();
- }
- static void cgroup_print_ss_mask(struct seq_file *seq, u16 ss_mask)
- {
- struct cgroup_subsys *ss;
- bool printed = false;
- int ssid;
- do_each_subsys_mask(ss, ssid, ss_mask) {
- if (printed)
- seq_putc(seq, ' ');
- seq_puts(seq, ss->name);
- printed = true;
- } while_each_subsys_mask();
- if (printed)
- seq_putc(seq, '\n');
- }
- /* show controllers which are enabled from the parent */
- static int cgroup_controllers_show(struct seq_file *seq, void *v)
- {
- struct cgroup *cgrp = seq_css(seq)->cgroup;
- cgroup_print_ss_mask(seq, cgroup_control(cgrp));
- return 0;
- }
- /* show controllers which are enabled for a given cgroup's children */
- static int cgroup_subtree_control_show(struct seq_file *seq, void *v)
- {
- struct cgroup *cgrp = seq_css(seq)->cgroup;
- cgroup_print_ss_mask(seq, cgrp->subtree_control);
- return 0;
- }
- /**
- * cgroup_update_dfl_csses - update css assoc of a subtree in default hierarchy
- * @cgrp: root of the subtree to update csses for
- *
- * @cgrp's control masks have changed and its subtree's css associations
- * need to be updated accordingly. This function looks up all css_sets
- * which are attached to the subtree, creates the matching updated css_sets
- * and migrates the tasks to the new ones.
- */
- static int cgroup_update_dfl_csses(struct cgroup *cgrp)
- {
- DEFINE_CGROUP_MGCTX(mgctx);
- struct cgroup_subsys_state *d_css;
- struct cgroup *dsct;
- struct css_set *src_cset;
- int ret;
- lockdep_assert_held(&cgroup_mutex);
- percpu_down_write(&cgroup_threadgroup_rwsem);
- /* look up all csses currently attached to @cgrp's subtree */
- spin_lock_irq(&css_set_lock);
- cgroup_for_each_live_descendant_pre(dsct, d_css, cgrp) {
- struct cgrp_cset_link *link;
- list_for_each_entry(link, &dsct->cset_links, cset_link)
- cgroup_migrate_add_src(link->cset, dsct, &mgctx);
- }
- spin_unlock_irq(&css_set_lock);
- /* NULL dst indicates self on default hierarchy */
- ret = cgroup_migrate_prepare_dst(&mgctx);
- if (ret)
- goto out_finish;
- spin_lock_irq(&css_set_lock);
- list_for_each_entry(src_cset, &mgctx.preloaded_src_csets, mg_preload_node) {
- struct task_struct *task, *ntask;
- /* all tasks in src_csets need to be migrated */
- list_for_each_entry_safe(task, ntask, &src_cset->tasks, cg_list)
- cgroup_migrate_add_task(task, &mgctx);
- }
- spin_unlock_irq(&css_set_lock);
- ret = cgroup_migrate_execute(&mgctx);
- out_finish:
- cgroup_migrate_finish(&mgctx);
- percpu_up_write(&cgroup_threadgroup_rwsem);
- return ret;
- }
- /**
- * cgroup_lock_and_drain_offline - lock cgroup_mutex and drain offlined csses
- * @cgrp: root of the target subtree
- *
- * Because css offlining is asynchronous, userland may try to re-enable a
- * controller while the previous css is still around. This function grabs
- * cgroup_mutex and drains the previous css instances of @cgrp's subtree.
- */
- void cgroup_lock_and_drain_offline(struct cgroup *cgrp)
- __acquires(&cgroup_mutex)
- {
- struct cgroup *dsct;
- struct cgroup_subsys_state *d_css;
- struct cgroup_subsys *ss;
- int ssid;
- restart:
- mutex_lock(&cgroup_mutex);
- cgroup_for_each_live_descendant_post(dsct, d_css, cgrp) {
- for_each_subsys(ss, ssid) {
- struct cgroup_subsys_state *css = cgroup_css(dsct, ss);
- DEFINE_WAIT(wait);
- if (!css || !percpu_ref_is_dying(&css->refcnt))
- continue;
- cgroup_get_live(dsct);
- prepare_to_wait(&dsct->offline_waitq, &wait,
- TASK_UNINTERRUPTIBLE);
- mutex_unlock(&cgroup_mutex);
- schedule();
- finish_wait(&dsct->offline_waitq, &wait);
- cgroup_put(dsct);
- goto restart;
- }
- }
- }
- /**
- * cgroup_save_control - save control masks and dom_cgrp of a subtree
- * @cgrp: root of the target subtree
- *
- * Save ->subtree_control, ->subtree_ss_mask and ->dom_cgrp to the
- * respective old_ prefixed fields for @cgrp's subtree including @cgrp
- * itself.
- */
- static void cgroup_save_control(struct cgroup *cgrp)
- {
- struct cgroup *dsct;
- struct cgroup_subsys_state *d_css;
- cgroup_for_each_live_descendant_pre(dsct, d_css, cgrp) {
- dsct->old_subtree_control = dsct->subtree_control;
- dsct->old_subtree_ss_mask = dsct->subtree_ss_mask;
- dsct->old_dom_cgrp = dsct->dom_cgrp;
- }
- }
- /**
- * cgroup_propagate_control - refresh control masks of a subtree
- * @cgrp: root of the target subtree
- *
- * For @cgrp and its subtree, ensure ->subtree_ss_mask matches
- * ->subtree_control and propagate controller availability through the
- * subtree so that descendants don't have unavailable controllers enabled.
- */
- static void cgroup_propagate_control(struct cgroup *cgrp)
- {
- struct cgroup *dsct;
- struct cgroup_subsys_state *d_css;
- cgroup_for_each_live_descendant_pre(dsct, d_css, cgrp) {
- dsct->subtree_control &= cgroup_control(dsct);
- dsct->subtree_ss_mask =
- cgroup_calc_subtree_ss_mask(dsct->subtree_control,
- cgroup_ss_mask(dsct));
- }
- }
- /**
- * cgroup_restore_control - restore control masks and dom_cgrp of a subtree
- * @cgrp: root of the target subtree
- *
- * Restore ->subtree_control, ->subtree_ss_mask and ->dom_cgrp from the
- * respective old_ prefixed fields for @cgrp's subtree including @cgrp
- * itself.
- */
- static void cgroup_restore_control(struct cgroup *cgrp)
- {
- struct cgroup *dsct;
- struct cgroup_subsys_state *d_css;
- cgroup_for_each_live_descendant_post(dsct, d_css, cgrp) {
- dsct->subtree_control = dsct->old_subtree_control;
- dsct->subtree_ss_mask = dsct->old_subtree_ss_mask;
- dsct->dom_cgrp = dsct->old_dom_cgrp;
- }
- }
- static bool css_visible(struct cgroup_subsys_state *css)
- {
- struct cgroup_subsys *ss = css->ss;
- struct cgroup *cgrp = css->cgroup;
- if (cgroup_control(cgrp) & (1 << ss->id))
- return true;
- if (!(cgroup_ss_mask(cgrp) & (1 << ss->id)))
- return false;
- return cgroup_on_dfl(cgrp) && ss->implicit_on_dfl;
- }
- /**
- * cgroup_apply_control_enable - enable or show csses according to control
- * @cgrp: root of the target subtree
- *
- * Walk @cgrp's subtree and create new csses or make the existing ones
- * visible. A css is created invisible if it's being implicitly enabled
- * through dependency. An invisible css is made visible when the userland
- * explicitly enables it.
- *
- * Returns 0 on success, -errno on failure. On failure, csses which have
- * been processed already aren't cleaned up. The caller is responsible for
- * cleaning up with cgroup_apply_control_disable().
- */
- static int cgroup_apply_control_enable(struct cgroup *cgrp)
- {
- struct cgroup *dsct;
- struct cgroup_subsys_state *d_css;
- struct cgroup_subsys *ss;
- int ssid, ret;
- cgroup_for_each_live_descendant_pre(dsct, d_css, cgrp) {
- for_each_subsys(ss, ssid) {
- struct cgroup_subsys_state *css = cgroup_css(dsct, ss);
- if (!(cgroup_ss_mask(dsct) & (1 << ss->id)))
- continue;
- if (!css) {
- css = css_create(dsct, ss);
- if (IS_ERR(css))
- return PTR_ERR(css);
- }
- WARN_ON_ONCE(percpu_ref_is_dying(&css->refcnt));
- if (css_visible(css)) {
- ret = css_populate_dir(css);
- if (ret)
- return ret;
- }
- }
- }
- return 0;
- }
- /**
- * cgroup_apply_control_disable - kill or hide csses according to control
- * @cgrp: root of the target subtree
- *
- * Walk @cgrp's subtree and kill and hide csses so that they match
- * cgroup_ss_mask() and cgroup_visible_mask().
- *
- * A css is hidden when the userland requests it to be disabled while other
- * subsystems are still depending on it. The css must not actively control
- * resources and be in the vanilla state if it's made visible again later.
- * Controllers which may be depended upon should provide ->css_reset() for
- * this purpose.
- */
- static void cgroup_apply_control_disable(struct cgroup *cgrp)
- {
- struct cgroup *dsct;
- struct cgroup_subsys_state *d_css;
- struct cgroup_subsys *ss;
- int ssid;
- cgroup_for_each_live_descendant_post(dsct, d_css, cgrp) {
- for_each_subsys(ss, ssid) {
- struct cgroup_subsys_state *css = cgroup_css(dsct, ss);
- if (!css)
- continue;
- WARN_ON_ONCE(percpu_ref_is_dying(&css->refcnt));
- if (css->parent &&
- !(cgroup_ss_mask(dsct) & (1 << ss->id))) {
- kill_css(css);
- } else if (!css_visible(css)) {
- css_clear_dir(css);
- if (ss->css_reset)
- ss->css_reset(css);
- }
- }
- }
- }
- /**
- * cgroup_apply_control - apply control mask updates to the subtree
- * @cgrp: root of the target subtree
- *
- * subsystems can be enabled and disabled in a subtree using the following
- * steps.
- *
- * 1. Call cgroup_save_control() to stash the current state.
- * 2. Update ->subtree_control masks in the subtree as desired.
- * 3. Call cgroup_apply_control() to apply the changes.
- * 4. Optionally perform other related operations.
- * 5. Call cgroup_finalize_control() to finish up.
- *
- * This function implements step 3 and propagates the mask changes
- * throughout @cgrp's subtree, updates csses accordingly and perform
- * process migrations.
- */
- static int cgroup_apply_control(struct cgroup *cgrp)
- {
- int ret;
- cgroup_propagate_control(cgrp);
- ret = cgroup_apply_control_enable(cgrp);
- if (ret)
- return ret;
- /*
- * At this point, cgroup_e_css_by_mask() results reflect the new csses
- * making the following cgroup_update_dfl_csses() properly update
- * css associations of all tasks in the subtree.
- */
- ret = cgroup_update_dfl_csses(cgrp);
- if (ret)
- return ret;
- return 0;
- }
- /**
- * cgroup_finalize_control - finalize control mask update
- * @cgrp: root of the target subtree
- * @ret: the result of the update
- *
- * Finalize control mask update. See cgroup_apply_control() for more info.
- */
- static void cgroup_finalize_control(struct cgroup *cgrp, int ret)
- {
- if (ret) {
- cgroup_restore_control(cgrp);
- cgroup_propagate_control(cgrp);
- }
- cgroup_apply_control_disable(cgrp);
- }
- static int cgroup_vet_subtree_control_enable(struct cgroup *cgrp, u16 enable)
- {
- u16 domain_enable = enable & ~cgrp_dfl_threaded_ss_mask;
- /* if nothing is getting enabled, nothing to worry about */
- if (!enable)
- return 0;
- /* can @cgrp host any resources? */
- if (!cgroup_is_valid_domain(cgrp->dom_cgrp))
- return -EOPNOTSUPP;
- /* mixables don't care */
- if (cgroup_is_mixable(cgrp))
- return 0;
- if (domain_enable) {
- /* can't enable domain controllers inside a thread subtree */
- if (cgroup_is_thread_root(cgrp) || cgroup_is_threaded(cgrp))
- return -EOPNOTSUPP;
- } else {
- /*
- * Threaded controllers can handle internal competitions
- * and are always allowed inside a (prospective) thread
- * subtree.
- */
- if (cgroup_can_be_thread_root(cgrp) || cgroup_is_threaded(cgrp))
- return 0;
- }
- /*
- * Controllers can't be enabled for a cgroup with tasks to avoid
- * child cgroups competing against tasks.
- */
- if (cgroup_has_tasks(cgrp))
- return -EBUSY;
- return 0;
- }
- /* change the enabled child controllers for a cgroup in the default hierarchy */
- static ssize_t cgroup_subtree_control_write(struct kernfs_open_file *of,
- char *buf, size_t nbytes,
- loff_t off)
- {
- u16 enable = 0, disable = 0;
- struct cgroup *cgrp, *child;
- struct cgroup_subsys *ss;
- char *tok;
- int ssid, ret;
- /*
- * Parse input - space separated list of subsystem names prefixed
- * with either + or -.
- */
- buf = strstrip(buf);
- while ((tok = strsep(&buf, " "))) {
- if (tok[0] == '\0')
- continue;
- do_each_subsys_mask(ss, ssid, ~cgrp_dfl_inhibit_ss_mask) {
- if (!cgroup_ssid_enabled(ssid) ||
- strcmp(tok + 1, ss->name))
- continue;
- if (*tok == '+') {
- enable |= 1 << ssid;
- disable &= ~(1 << ssid);
- } else if (*tok == '-') {
- disable |= 1 << ssid;
- enable &= ~(1 << ssid);
- } else {
- return -EINVAL;
- }
- break;
- } while_each_subsys_mask();
- if (ssid == CGROUP_SUBSYS_COUNT)
- return -EINVAL;
- }
- cgrp = cgroup_kn_lock_live(of->kn, true);
- if (!cgrp)
- return -ENODEV;
- for_each_subsys(ss, ssid) {
- if (enable & (1 << ssid)) {
- if (cgrp->subtree_control & (1 << ssid)) {
- enable &= ~(1 << ssid);
- continue;
- }
- if (!(cgroup_control(cgrp) & (1 << ssid))) {
- ret = -ENOENT;
- goto out_unlock;
- }
- } else if (disable & (1 << ssid)) {
- if (!(cgrp->subtree_control & (1 << ssid))) {
- disable &= ~(1 << ssid);
- continue;
- }
- /* a child has it enabled? */
- cgroup_for_each_live_child(child, cgrp) {
- if (child->subtree_control & (1 << ssid)) {
- ret = -EBUSY;
- goto out_unlock;
- }
- }
- }
- }
- if (!enable && !disable) {
- ret = 0;
- goto out_unlock;
- }
- ret = cgroup_vet_subtree_control_enable(cgrp, enable);
- if (ret)
- goto out_unlock;
- /* save and update control masks and prepare csses */
- cgroup_save_control(cgrp);
- cgrp->subtree_control |= enable;
- cgrp->subtree_control &= ~disable;
- ret = cgroup_apply_control(cgrp);
- cgroup_finalize_control(cgrp, ret);
- if (ret)
- goto out_unlock;
- kernfs_activate(cgrp->kn);
- out_unlock:
- cgroup_kn_unlock(of->kn);
- return ret ?: nbytes;
- }
- /**
- * cgroup_enable_threaded - make @cgrp threaded
- * @cgrp: the target cgroup
- *
- * Called when "threaded" is written to the cgroup.type interface file and
- * tries to make @cgrp threaded and join the parent's resource domain.
- * This function is never called on the root cgroup as cgroup.type doesn't
- * exist on it.
- */
- static int cgroup_enable_threaded(struct cgroup *cgrp)
- {
- struct cgroup *parent = cgroup_parent(cgrp);
- struct cgroup *dom_cgrp = parent->dom_cgrp;
- struct cgroup *dsct;
- struct cgroup_subsys_state *d_css;
- int ret;
- lockdep_assert_held(&cgroup_mutex);
- /* noop if already threaded */
- if (cgroup_is_threaded(cgrp))
- return 0;
- /*
- * If @cgroup is populated or has domain controllers enabled, it
- * can't be switched. While the below cgroup_can_be_thread_root()
- * test can catch the same conditions, that's only when @parent is
- * not mixable, so let's check it explicitly.
- */
- if (cgroup_is_populated(cgrp) ||
- cgrp->subtree_control & ~cgrp_dfl_threaded_ss_mask)
- return -EOPNOTSUPP;
- /* we're joining the parent's domain, ensure its validity */
- if (!cgroup_is_valid_domain(dom_cgrp) ||
- !cgroup_can_be_thread_root(dom_cgrp))
- return -EOPNOTSUPP;
- /*
- * The following shouldn't cause actual migrations and should
- * always succeed.
- */
- cgroup_save_control(cgrp);
- cgroup_for_each_live_descendant_pre(dsct, d_css, cgrp)
- if (dsct == cgrp || cgroup_is_threaded(dsct))
- dsct->dom_cgrp = dom_cgrp;
- ret = cgroup_apply_control(cgrp);
- if (!ret)
- parent->nr_threaded_children++;
- cgroup_finalize_control(cgrp, ret);
- return ret;
- }
- static int cgroup_type_show(struct seq_file *seq, void *v)
- {
- struct cgroup *cgrp = seq_css(seq)->cgroup;
- if (cgroup_is_threaded(cgrp))
- seq_puts(seq, "threaded\n");
- else if (!cgroup_is_valid_domain(cgrp))
- seq_puts(seq, "domain invalid\n");
- else if (cgroup_is_thread_root(cgrp))
- seq_puts(seq, "domain threaded\n");
- else
- seq_puts(seq, "domain\n");
- return 0;
- }
- static ssize_t cgroup_type_write(struct kernfs_open_file *of, char *buf,
- size_t nbytes, loff_t off)
- {
- struct cgroup *cgrp;
- int ret;
- /* only switching to threaded mode is supported */
- if (strcmp(strstrip(buf), "threaded"))
- return -EINVAL;
- /* drain dying csses before we re-apply (threaded) subtree control */
- cgrp = cgroup_kn_lock_live(of->kn, true);
- if (!cgrp)
- return -ENOENT;
- /* threaded can only be enabled */
- ret = cgroup_enable_threaded(cgrp);
- cgroup_kn_unlock(of->kn);
- return ret ?: nbytes;
- }
- static int cgroup_max_descendants_show(struct seq_file *seq, void *v)
- {
- struct cgroup *cgrp = seq_css(seq)->cgroup;
- int descendants = READ_ONCE(cgrp->max_descendants);
- if (descendants == INT_MAX)
- seq_puts(seq, "max\n");
- else
- seq_printf(seq, "%d\n", descendants);
- return 0;
- }
- static ssize_t cgroup_max_descendants_write(struct kernfs_open_file *of,
- char *buf, size_t nbytes, loff_t off)
- {
- struct cgroup *cgrp;
- int descendants;
- ssize_t ret;
- buf = strstrip(buf);
- if (!strcmp(buf, "max")) {
- descendants = INT_MAX;
- } else {
- ret = kstrtoint(buf, 0, &descendants);
- if (ret)
- return ret;
- }
- if (descendants < 0)
- return -ERANGE;
- cgrp = cgroup_kn_lock_live(of->kn, false);
- if (!cgrp)
- return -ENOENT;
- cgrp->max_descendants = descendants;
- cgroup_kn_unlock(of->kn);
- return nbytes;
- }
- static int cgroup_max_depth_show(struct seq_file *seq, void *v)
- {
- struct cgroup *cgrp = seq_css(seq)->cgroup;
- int depth = READ_ONCE(cgrp->max_depth);
- if (depth == INT_MAX)
- seq_puts(seq, "max\n");
- else
- seq_printf(seq, "%d\n", depth);
- return 0;
- }
- static ssize_t cgroup_max_depth_write(struct kernfs_open_file *of,
- char *buf, size_t nbytes, loff_t off)
- {
- struct cgroup *cgrp;
- ssize_t ret;
- int depth;
- buf = strstrip(buf);
- if (!strcmp(buf, "max")) {
- depth = INT_MAX;
- } else {
- ret = kstrtoint(buf, 0, &depth);
- if (ret)
- return ret;
- }
- if (depth < 0)
- return -ERANGE;
- cgrp = cgroup_kn_lock_live(of->kn, false);
- if (!cgrp)
- return -ENOENT;
- cgrp->max_depth = depth;
- cgroup_kn_unlock(of->kn);
- return nbytes;
- }
- static int cgroup_events_show(struct seq_file *seq, void *v)
- {
- struct cgroup *cgrp = seq_css(seq)->cgroup;
- seq_printf(seq, "populated %d\n", cgroup_is_populated(cgrp));
- seq_printf(seq, "frozen %d\n", test_bit(CGRP_FROZEN, &cgrp->flags));
- return 0;
- }
- static int cgroup_stat_show(struct seq_file *seq, void *v)
- {
- struct cgroup *cgroup = seq_css(seq)->cgroup;
- seq_printf(seq, "nr_descendants %d\n",
- cgroup->nr_descendants);
- seq_printf(seq, "nr_dying_descendants %d\n",
- cgroup->nr_dying_descendants);
- return 0;
- }
- static int __maybe_unused cgroup_extra_stat_show(struct seq_file *seq,
- struct cgroup *cgrp, int ssid)
- {
- struct cgroup_subsys *ss = cgroup_subsys[ssid];
- struct cgroup_subsys_state *css;
- int ret;
- if (!ss->css_extra_stat_show)
- return 0;
- css = cgroup_tryget_css(cgrp, ss);
- if (!css)
- return 0;
- ret = ss->css_extra_stat_show(seq, css);
- css_put(css);
- return ret;
- }
- static int cpu_stat_show(struct seq_file *seq, void *v)
- {
- struct cgroup __maybe_unused *cgrp = seq_css(seq)->cgroup;
- int ret = 0;
- cgroup_base_stat_cputime_show(seq);
- #ifdef CONFIG_CGROUP_SCHED
- ret = cgroup_extra_stat_show(seq, cgrp, cpu_cgrp_id);
- #endif
- return ret;
- }
- #ifdef CONFIG_PSI
- static int cgroup_io_pressure_show(struct seq_file *seq, void *v)
- {
- struct cgroup *cgrp = seq_css(seq)->cgroup;
- struct psi_group *psi = cgroup_ino(cgrp) == 1 ? &psi_system : &cgrp->psi;
- return psi_show(seq, psi, PSI_IO);
- }
- static int cgroup_memory_pressure_show(struct seq_file *seq, void *v)
- {
- struct cgroup *cgrp = seq_css(seq)->cgroup;
- struct psi_group *psi = cgroup_ino(cgrp) == 1 ? &psi_system : &cgrp->psi;
- return psi_show(seq, psi, PSI_MEM);
- }
- static int cgroup_cpu_pressure_show(struct seq_file *seq, void *v)
- {
- struct cgroup *cgrp = seq_css(seq)->cgroup;
- struct psi_group *psi = cgroup_ino(cgrp) == 1 ? &psi_system : &cgrp->psi;
- return psi_show(seq, psi, PSI_CPU);
- }
- static ssize_t cgroup_pressure_write(struct kernfs_open_file *of, char *buf,
- size_t nbytes, enum psi_res res)
- {
- struct cgroup_file_ctx *ctx = of->priv;
- struct psi_trigger *new;
- struct cgroup *cgrp;
- struct psi_group *psi;
- cgrp = cgroup_kn_lock_live(of->kn, false);
- if (!cgrp)
- return -ENODEV;
- cgroup_get(cgrp);
- cgroup_kn_unlock(of->kn);
- /* Allow only one trigger per file descriptor */
- if (ctx->psi.trigger) {
- cgroup_put(cgrp);
- return -EBUSY;
- }
- psi = cgroup_ino(cgrp) == 1 ? &psi_system : &cgrp->psi;
- new = psi_trigger_create(psi, buf, nbytes, res);
- if (IS_ERR(new)) {
- cgroup_put(cgrp);
- return PTR_ERR(new);
- }
- smp_store_release(&ctx->psi.trigger, new);
- cgroup_put(cgrp);
- return nbytes;
- }
- static ssize_t cgroup_io_pressure_write(struct kernfs_open_file *of,
- char *buf, size_t nbytes,
- loff_t off)
- {
- return cgroup_pressure_write(of, buf, nbytes, PSI_IO);
- }
- static ssize_t cgroup_memory_pressure_write(struct kernfs_open_file *of,
- char *buf, size_t nbytes,
- loff_t off)
- {
- return cgroup_pressure_write(of, buf, nbytes, PSI_MEM);
- }
- static ssize_t cgroup_cpu_pressure_write(struct kernfs_open_file *of,
- char *buf, size_t nbytes,
- loff_t off)
- {
- return cgroup_pressure_write(of, buf, nbytes, PSI_CPU);
- }
- static __poll_t cgroup_pressure_poll(struct kernfs_open_file *of,
- poll_table *pt)
- {
- struct cgroup_file_ctx *ctx = of->priv;
- return psi_trigger_poll(&ctx->psi.trigger, of->file, pt);
- }
- static void cgroup_pressure_release(struct kernfs_open_file *of)
- {
- struct cgroup_file_ctx *ctx = of->priv;
- psi_trigger_destroy(ctx->psi.trigger);
- }
- bool cgroup_psi_enabled(void)
- {
- return (cgroup_feature_disable_mask & (1 << OPT_FEATURE_PRESSURE)) == 0;
- }
- #else /* CONFIG_PSI */
- bool cgroup_psi_enabled(void)
- {
- return false;
- }
- #endif /* CONFIG_PSI */
- static int cgroup_freeze_show(struct seq_file *seq, void *v)
- {
- struct cgroup *cgrp = seq_css(seq)->cgroup;
- seq_printf(seq, "%d\n", cgrp->freezer.freeze);
- return 0;
- }
- static ssize_t cgroup_freeze_write(struct kernfs_open_file *of,
- char *buf, size_t nbytes, loff_t off)
- {
- struct cgroup *cgrp;
- ssize_t ret;
- int freeze;
- ret = kstrtoint(strstrip(buf), 0, &freeze);
- if (ret)
- return ret;
- if (freeze < 0 || freeze > 1)
- return -ERANGE;
- cgrp = cgroup_kn_lock_live(of->kn, false);
- if (!cgrp)
- return -ENOENT;
- cgroup_freeze(cgrp, freeze);
- cgroup_kn_unlock(of->kn);
- return nbytes;
- }
- static int cgroup_file_open(struct kernfs_open_file *of)
- {
- struct cftype *cft = of->kn->priv;
- struct cgroup_file_ctx *ctx;
- int ret;
- ctx = kzalloc(sizeof(*ctx), GFP_KERNEL);
- if (!ctx)
- return -ENOMEM;
- ctx->ns = current->nsproxy->cgroup_ns;
- get_cgroup_ns(ctx->ns);
- of->priv = ctx;
- if (!cft->open)
- return 0;
- ret = cft->open(of);
- if (ret) {
- put_cgroup_ns(ctx->ns);
- kfree(ctx);
- }
- return ret;
- }
- static void cgroup_file_release(struct kernfs_open_file *of)
- {
- struct cftype *cft = of->kn->priv;
- struct cgroup_file_ctx *ctx = of->priv;
- if (cft->release)
- cft->release(of);
- put_cgroup_ns(ctx->ns);
- kfree(ctx);
- }
- static ssize_t cgroup_file_write(struct kernfs_open_file *of, char *buf,
- size_t nbytes, loff_t off)
- {
- struct cgroup_file_ctx *ctx = of->priv;
- struct cgroup *cgrp = of->kn->parent->priv;
- struct cftype *cft = of->kn->priv;
- struct cgroup_subsys_state *css;
- int ret;
- if (!nbytes)
- return 0;
- /*
- * If namespaces are delegation boundaries, disallow writes to
- * files in an non-init namespace root from inside the namespace
- * except for the files explicitly marked delegatable -
- * cgroup.procs and cgroup.subtree_control.
- */
- if ((cgrp->root->flags & CGRP_ROOT_NS_DELEGATE) &&
- !(cft->flags & CFTYPE_NS_DELEGATABLE) &&
- ctx->ns != &init_cgroup_ns && ctx->ns->root_cset->dfl_cgrp == cgrp)
- return -EPERM;
- if (cft->write)
- return cft->write(of, buf, nbytes, off);
- /*
- * kernfs guarantees that a file isn't deleted with operations in
- * flight, which means that the matching css is and stays alive and
- * doesn't need to be pinned. The RCU locking is not necessary
- * either. It's just for the convenience of using cgroup_css().
- */
- rcu_read_lock();
- css = cgroup_css(cgrp, cft->ss);
- rcu_read_unlock();
- if (cft->write_u64) {
- unsigned long long v;
- ret = kstrtoull(buf, 0, &v);
- if (!ret)
- ret = cft->write_u64(css, cft, v);
- } else if (cft->write_s64) {
- long long v;
- ret = kstrtoll(buf, 0, &v);
- if (!ret)
- ret = cft->write_s64(css, cft, v);
- } else {
- ret = -EINVAL;
- }
- return ret ?: nbytes;
- }
- static __poll_t cgroup_file_poll(struct kernfs_open_file *of, poll_table *pt)
- {
- struct cftype *cft = of->kn->priv;
- if (cft->poll)
- return cft->poll(of, pt);
- return kernfs_generic_poll(of, pt);
- }
- static void *cgroup_seqfile_start(struct seq_file *seq, loff_t *ppos)
- {
- return seq_cft(seq)->seq_start(seq, ppos);
- }
- static void *cgroup_seqfile_next(struct seq_file *seq, void *v, loff_t *ppos)
- {
- return seq_cft(seq)->seq_next(seq, v, ppos);
- }
- static void cgroup_seqfile_stop(struct seq_file *seq, void *v)
- {
- if (seq_cft(seq)->seq_stop)
- seq_cft(seq)->seq_stop(seq, v);
- }
- static int cgroup_seqfile_show(struct seq_file *m, void *arg)
- {
- struct cftype *cft = seq_cft(m);
- struct cgroup_subsys_state *css = seq_css(m);
- if (cft->seq_show)
- return cft->seq_show(m, arg);
- if (cft->read_u64)
- seq_printf(m, "%llu\n", cft->read_u64(css, cft));
- else if (cft->read_s64)
- seq_printf(m, "%lld\n", cft->read_s64(css, cft));
- else
- return -EINVAL;
- return 0;
- }
- static struct kernfs_ops cgroup_kf_single_ops = {
- .atomic_write_len = PAGE_SIZE,
- .open = cgroup_file_open,
- .release = cgroup_file_release,
- .write = cgroup_file_write,
- .poll = cgroup_file_poll,
- .seq_show = cgroup_seqfile_show,
- };
- static struct kernfs_ops cgroup_kf_ops = {
- .atomic_write_len = PAGE_SIZE,
- .open = cgroup_file_open,
- .release = cgroup_file_release,
- .write = cgroup_file_write,
- .poll = cgroup_file_poll,
- .seq_start = cgroup_seqfile_start,
- .seq_next = cgroup_seqfile_next,
- .seq_stop = cgroup_seqfile_stop,
- .seq_show = cgroup_seqfile_show,
- };
- /* set uid and gid of cgroup dirs and files to that of the creator */
- static int cgroup_kn_set_ugid(struct kernfs_node *kn)
- {
- struct iattr iattr = { .ia_valid = ATTR_UID | ATTR_GID,
- .ia_uid = current_fsuid(),
- .ia_gid = current_fsgid(), };
- if (uid_eq(iattr.ia_uid, GLOBAL_ROOT_UID) &&
- gid_eq(iattr.ia_gid, GLOBAL_ROOT_GID))
- return 0;
- return kernfs_setattr(kn, &iattr);
- }
- static void cgroup_file_notify_timer(struct timer_list *timer)
- {
- cgroup_file_notify(container_of(timer, struct cgroup_file,
- notify_timer));
- }
- static int cgroup_add_file(struct cgroup_subsys_state *css, struct cgroup *cgrp,
- struct cftype *cft)
- {
- char name[CGROUP_FILE_NAME_MAX];
- struct kernfs_node *kn;
- struct lock_class_key *key = NULL;
- int ret;
- #ifdef CONFIG_DEBUG_LOCK_ALLOC
- key = &cft->lockdep_key;
- #endif
- kn = __kernfs_create_file(cgrp->kn, cgroup_file_name(cgrp, cft, name),
- cgroup_file_mode(cft),
- GLOBAL_ROOT_UID, GLOBAL_ROOT_GID,
- 0, cft->kf_ops, cft,
- NULL, key);
- if (IS_ERR(kn))
- return PTR_ERR(kn);
- ret = cgroup_kn_set_ugid(kn);
- if (ret) {
- kernfs_remove(kn);
- return ret;
- }
- if (cft->file_offset) {
- struct cgroup_file *cfile = (void *)css + cft->file_offset;
- timer_setup(&cfile->notify_timer, cgroup_file_notify_timer, 0);
- spin_lock_irq(&cgroup_file_kn_lock);
- cfile->kn = kn;
- spin_unlock_irq(&cgroup_file_kn_lock);
- }
- return 0;
- }
- /**
- * cgroup_addrm_files - add or remove files to a cgroup directory
- * @css: the target css
- * @cgrp: the target cgroup (usually css->cgroup)
- * @cfts: array of cftypes to be added
- * @is_add: whether to add or remove
- *
- * Depending on @is_add, add or remove files defined by @cfts on @cgrp.
- * For removals, this function never fails.
- */
- static int cgroup_addrm_files(struct cgroup_subsys_state *css,
- struct cgroup *cgrp, struct cftype cfts[],
- bool is_add)
- {
- struct cftype *cft, *cft_end = NULL;
- int ret = 0;
- lockdep_assert_held(&cgroup_mutex);
- restart:
- for (cft = cfts; cft != cft_end && cft->name[0] != '\0'; cft++) {
- /* does cft->flags tell us to skip this file on @cgrp? */
- if ((cft->flags & CFTYPE_PRESSURE) && !cgroup_psi_enabled())
- continue;
- if ((cft->flags & __CFTYPE_ONLY_ON_DFL) && !cgroup_on_dfl(cgrp))
- continue;
- if ((cft->flags & __CFTYPE_NOT_ON_DFL) && cgroup_on_dfl(cgrp))
- continue;
- if ((cft->flags & CFTYPE_NOT_ON_ROOT) && !cgroup_parent(cgrp))
- continue;
- if ((cft->flags & CFTYPE_ONLY_ON_ROOT) && cgroup_parent(cgrp))
- continue;
- if ((cft->flags & CFTYPE_DEBUG) && !cgroup_debug)
- continue;
- if (is_add) {
- ret = cgroup_add_file(css, cgrp, cft);
- if (ret) {
- pr_warn("%s: failed to add %s, err=%d\n",
- __func__, cft->name, ret);
- cft_end = cft;
- is_add = false;
- goto restart;
- }
- } else {
- cgroup_rm_file(cgrp, cft);
- }
- }
- return ret;
- }
- static int cgroup_apply_cftypes(struct cftype *cfts, bool is_add)
- {
- struct cgroup_subsys *ss = cfts[0].ss;
- struct cgroup *root = &ss->root->cgrp;
- struct cgroup_subsys_state *css;
- int ret = 0;
- lockdep_assert_held(&cgroup_mutex);
- /* add/rm files for all cgroups created before */
- css_for_each_descendant_pre(css, cgroup_css(root, ss)) {
- struct cgroup *cgrp = css->cgroup;
- if (!(css->flags & CSS_VISIBLE))
- continue;
- ret = cgroup_addrm_files(css, cgrp, cfts, is_add);
- if (ret)
- break;
- }
- if (is_add && !ret)
- kernfs_activate(root->kn);
- return ret;
- }
- static void cgroup_exit_cftypes(struct cftype *cfts)
- {
- struct cftype *cft;
- for (cft = cfts; cft->name[0] != '\0'; cft++) {
- /* free copy for custom atomic_write_len, see init_cftypes() */
- if (cft->max_write_len && cft->max_write_len != PAGE_SIZE)
- kfree(cft->kf_ops);
- cft->kf_ops = NULL;
- cft->ss = NULL;
- /* revert flags set by cgroup core while adding @cfts */
- cft->flags &= ~(__CFTYPE_ONLY_ON_DFL | __CFTYPE_NOT_ON_DFL);
- }
- }
- static int cgroup_init_cftypes(struct cgroup_subsys *ss, struct cftype *cfts)
- {
- struct cftype *cft;
- for (cft = cfts; cft->name[0] != '\0'; cft++) {
- struct kernfs_ops *kf_ops;
- WARN_ON(cft->ss || cft->kf_ops);
- if ((cft->flags & CFTYPE_PRESSURE) && !cgroup_psi_enabled())
- continue;
- if (cft->seq_start)
- kf_ops = &cgroup_kf_ops;
- else
- kf_ops = &cgroup_kf_single_ops;
- /*
- * Ugh... if @cft wants a custom max_write_len, we need to
- * make a copy of kf_ops to set its atomic_write_len.
- */
- if (cft->max_write_len && cft->max_write_len != PAGE_SIZE) {
- kf_ops = kmemdup(kf_ops, sizeof(*kf_ops), GFP_KERNEL);
- if (!kf_ops) {
- cgroup_exit_cftypes(cfts);
- return -ENOMEM;
- }
- kf_ops->atomic_write_len = cft->max_write_len;
- }
- cft->kf_ops = kf_ops;
- cft->ss = ss;
- }
- return 0;
- }
- static int cgroup_rm_cftypes_locked(struct cftype *cfts)
- {
- lockdep_assert_held(&cgroup_mutex);
- if (!cfts || !cfts[0].ss)
- return -ENOENT;
- list_del(&cfts->node);
- cgroup_apply_cftypes(cfts, false);
- cgroup_exit_cftypes(cfts);
- return 0;
- }
- /**
- * cgroup_rm_cftypes - remove an array of cftypes from a subsystem
- * @cfts: zero-length name terminated array of cftypes
- *
- * Unregister @cfts. Files described by @cfts are removed from all
- * existing cgroups and all future cgroups won't have them either. This
- * function can be called anytime whether @cfts' subsys is attached or not.
- *
- * Returns 0 on successful unregistration, -ENOENT if @cfts is not
- * registered.
- */
- int cgroup_rm_cftypes(struct cftype *cfts)
- {
- int ret;
- mutex_lock(&cgroup_mutex);
- ret = cgroup_rm_cftypes_locked(cfts);
- mutex_unlock(&cgroup_mutex);
- return ret;
- }
- /**
- * cgroup_add_cftypes - add an array of cftypes to a subsystem
- * @ss: target cgroup subsystem
- * @cfts: zero-length name terminated array of cftypes
- *
- * Register @cfts to @ss. Files described by @cfts are created for all
- * existing cgroups to which @ss is attached and all future cgroups will
- * have them too. This function can be called anytime whether @ss is
- * attached or not.
- *
- * Returns 0 on successful registration, -errno on failure. Note that this
- * function currently returns 0 as long as @cfts registration is successful
- * even if some file creation attempts on existing cgroups fail.
- */
- static int cgroup_add_cftypes(struct cgroup_subsys *ss, struct cftype *cfts)
- {
- int ret;
- if (!cgroup_ssid_enabled(ss->id))
- return 0;
- if (!cfts || cfts[0].name[0] == '\0')
- return 0;
- ret = cgroup_init_cftypes(ss, cfts);
- if (ret)
- return ret;
- mutex_lock(&cgroup_mutex);
- list_add_tail(&cfts->node, &ss->cfts);
- ret = cgroup_apply_cftypes(cfts, true);
- if (ret)
- cgroup_rm_cftypes_locked(cfts);
- mutex_unlock(&cgroup_mutex);
- return ret;
- }
- /**
- * cgroup_add_dfl_cftypes - add an array of cftypes for default hierarchy
- * @ss: target cgroup subsystem
- * @cfts: zero-length name terminated array of cftypes
- *
- * Similar to cgroup_add_cftypes() but the added files are only used for
- * the default hierarchy.
- */
- int cgroup_add_dfl_cftypes(struct cgroup_subsys *ss, struct cftype *cfts)
- {
- struct cftype *cft;
- for (cft = cfts; cft && cft->name[0] != '\0'; cft++)
- cft->flags |= __CFTYPE_ONLY_ON_DFL;
- return cgroup_add_cftypes(ss, cfts);
- }
- /**
- * cgroup_add_legacy_cftypes - add an array of cftypes for legacy hierarchies
- * @ss: target cgroup subsystem
- * @cfts: zero-length name terminated array of cftypes
- *
- * Similar to cgroup_add_cftypes() but the added files are only used for
- * the legacy hierarchies.
- */
- int cgroup_add_legacy_cftypes(struct cgroup_subsys *ss, struct cftype *cfts)
- {
- struct cftype *cft;
- for (cft = cfts; cft && cft->name[0] != '\0'; cft++)
- cft->flags |= __CFTYPE_NOT_ON_DFL;
- return cgroup_add_cftypes(ss, cfts);
- }
- EXPORT_SYMBOL_GPL(cgroup_add_legacy_cftypes);
- /**
- * cgroup_file_notify - generate a file modified event for a cgroup_file
- * @cfile: target cgroup_file
- *
- * @cfile must have been obtained by setting cftype->file_offset.
- */
- void cgroup_file_notify(struct cgroup_file *cfile)
- {
- unsigned long flags;
- spin_lock_irqsave(&cgroup_file_kn_lock, flags);
- if (cfile->kn) {
- unsigned long last = cfile->notified_at;
- unsigned long next = last + CGROUP_FILE_NOTIFY_MIN_INTV;
- if (time_in_range(jiffies, last, next)) {
- timer_reduce(&cfile->notify_timer, next);
- } else {
- kernfs_notify(cfile->kn);
- cfile->notified_at = jiffies;
- }
- }
- spin_unlock_irqrestore(&cgroup_file_kn_lock, flags);
- }
- /**
- * css_next_child - find the next child of a given css
- * @pos: the current position (%NULL to initiate traversal)
- * @parent: css whose children to walk
- *
- * This function returns the next child of @parent and should be called
- * under either cgroup_mutex or RCU read lock. The only requirement is
- * that @parent and @pos are accessible. The next sibling is guaranteed to
- * be returned regardless of their states.
- *
- * If a subsystem synchronizes ->css_online() and the start of iteration, a
- * css which finished ->css_online() is guaranteed to be visible in the
- * future iterations and will stay visible until the last reference is put.
- * A css which hasn't finished ->css_online() or already finished
- * ->css_offline() may show up during traversal. It's each subsystem's
- * responsibility to synchronize against on/offlining.
- */
- struct cgroup_subsys_state *css_next_child(struct cgroup_subsys_state *pos,
- struct cgroup_subsys_state *parent)
- {
- struct cgroup_subsys_state *next;
- cgroup_assert_mutex_or_rcu_locked();
- /*
- * @pos could already have been unlinked from the sibling list.
- * Once a cgroup is removed, its ->sibling.next is no longer
- * updated when its next sibling changes. CSS_RELEASED is set when
- * @pos is taken off list, at which time its next pointer is valid,
- * and, as releases are serialized, the one pointed to by the next
- * pointer is guaranteed to not have started release yet. This
- * implies that if we observe !CSS_RELEASED on @pos in this RCU
- * critical section, the one pointed to by its next pointer is
- * guaranteed to not have finished its RCU grace period even if we
- * have dropped rcu_read_lock() inbetween iterations.
- *
- * If @pos has CSS_RELEASED set, its next pointer can't be
- * dereferenced; however, as each css is given a monotonically
- * increasing unique serial number and always appended to the
- * sibling list, the next one can be found by walking the parent's
- * children until the first css with higher serial number than
- * @pos's. While this path can be slower, it happens iff iteration
- * races against release and the race window is very small.
- */
- if (!pos) {
- next = list_entry_rcu(parent->children.next, struct cgroup_subsys_state, sibling);
- } else if (likely(!(pos->flags & CSS_RELEASED))) {
- next = list_entry_rcu(pos->sibling.next, struct cgroup_subsys_state, sibling);
- } else {
- list_for_each_entry_rcu(next, &parent->children, sibling,
- lockdep_is_held(&cgroup_mutex))
- if (next->serial_nr > pos->serial_nr)
- break;
- }
- /*
- * @next, if not pointing to the head, can be dereferenced and is
- * the next sibling.
- */
- if (&next->sibling != &parent->children)
- return next;
- return NULL;
- }
- EXPORT_SYMBOL_GPL(css_next_child);
- /**
- * css_next_descendant_pre - find the next descendant for pre-order walk
- * @pos: the current position (%NULL to initiate traversal)
- * @root: css whose descendants to walk
- *
- * To be used by css_for_each_descendant_pre(). Find the next descendant
- * to visit for pre-order traversal of @root's descendants. @root is
- * included in the iteration and the first node to be visited.
- *
- * While this function requires cgroup_mutex or RCU read locking, it
- * doesn't require the whole traversal to be contained in a single critical
- * section. This function will return the correct next descendant as long
- * as both @pos and @root are accessible and @pos is a descendant of @root.
- *
- * If a subsystem synchronizes ->css_online() and the start of iteration, a
- * css which finished ->css_online() is guaranteed to be visible in the
- * future iterations and will stay visible until the last reference is put.
- * A css which hasn't finished ->css_online() or already finished
- * ->css_offline() may show up during traversal. It's each subsystem's
- * responsibility to synchronize against on/offlining.
- */
- struct cgroup_subsys_state *
- css_next_descendant_pre(struct cgroup_subsys_state *pos,
- struct cgroup_subsys_state *root)
- {
- struct cgroup_subsys_state *next;
- cgroup_assert_mutex_or_rcu_locked();
- /* if first iteration, visit @root */
- if (!pos)
- return root;
- /* visit the first child if exists */
- next = css_next_child(NULL, pos);
- if (next)
- return next;
- /* no child, visit my or the closest ancestor's next sibling */
- while (pos != root) {
- next = css_next_child(pos, pos->parent);
- if (next)
- return next;
- pos = pos->parent;
- }
- return NULL;
- }
- EXPORT_SYMBOL_GPL(css_next_descendant_pre);
- /**
- * css_rightmost_descendant - return the rightmost descendant of a css
- * @pos: css of interest
- *
- * Return the rightmost descendant of @pos. If there's no descendant, @pos
- * is returned. This can be used during pre-order traversal to skip
- * subtree of @pos.
- *
- * While this function requires cgroup_mutex or RCU read locking, it
- * doesn't require the whole traversal to be contained in a single critical
- * section. This function will return the correct rightmost descendant as
- * long as @pos is accessible.
- */
- struct cgroup_subsys_state *
- css_rightmost_descendant(struct cgroup_subsys_state *pos)
- {
- struct cgroup_subsys_state *last, *tmp;
- cgroup_assert_mutex_or_rcu_locked();
- do {
- last = pos;
- /* ->prev isn't RCU safe, walk ->next till the end */
- pos = NULL;
- css_for_each_child(tmp, last)
- pos = tmp;
- } while (pos);
- return last;
- }
- static struct cgroup_subsys_state *
- css_leftmost_descendant(struct cgroup_subsys_state *pos)
- {
- struct cgroup_subsys_state *last;
- do {
- last = pos;
- pos = css_next_child(NULL, pos);
- } while (pos);
- return last;
- }
- /**
- * css_next_descendant_post - find the next descendant for post-order walk
- * @pos: the current position (%NULL to initiate traversal)
- * @root: css whose descendants to walk
- *
- * To be used by css_for_each_descendant_post(). Find the next descendant
- * to visit for post-order traversal of @root's descendants. @root is
- * included in the iteration and the last node to be visited.
- *
- * While this function requires cgroup_mutex or RCU read locking, it
- * doesn't require the whole traversal to be contained in a single critical
- * section. This function will return the correct next descendant as long
- * as both @pos and @cgroup are accessible and @pos is a descendant of
- * @cgroup.
- *
- * If a subsystem synchronizes ->css_online() and the start of iteration, a
- * css which finished ->css_online() is guaranteed to be visible in the
- * future iterations and will stay visible until the last reference is put.
- * A css which hasn't finished ->css_online() or already finished
- * ->css_offline() may show up during traversal. It's each subsystem's
- * responsibility to synchronize against on/offlining.
- */
- struct cgroup_subsys_state *
- css_next_descendant_post(struct cgroup_subsys_state *pos,
- struct cgroup_subsys_state *root)
- {
- struct cgroup_subsys_state *next;
- cgroup_assert_mutex_or_rcu_locked();
- /* if first iteration, visit leftmost descendant which may be @root */
- if (!pos)
- return css_leftmost_descendant(root);
- /* if we visited @root, we're done */
- if (pos == root)
- return NULL;
- /* if there's an unvisited sibling, visit its leftmost descendant */
- next = css_next_child(pos, pos->parent);
- if (next)
- return css_leftmost_descendant(next);
- /* no sibling left, visit parent */
- return pos->parent;
- }
- /**
- * css_has_online_children - does a css have online children
- * @css: the target css
- *
- * Returns %true if @css has any online children; otherwise, %false. This
- * function can be called from any context but the caller is responsible
- * for synchronizing against on/offlining as necessary.
- */
- bool css_has_online_children(struct cgroup_subsys_state *css)
- {
- struct cgroup_subsys_state *child;
- bool ret = false;
- rcu_read_lock();
- css_for_each_child(child, css) {
- if (child->flags & CSS_ONLINE) {
- ret = true;
- break;
- }
- }
- rcu_read_unlock();
- return ret;
- }
- static struct css_set *css_task_iter_next_css_set(struct css_task_iter *it)
- {
- struct list_head *l;
- struct cgrp_cset_link *link;
- struct css_set *cset;
- lockdep_assert_held(&css_set_lock);
- /* find the next threaded cset */
- if (it->tcset_pos) {
- l = it->tcset_pos->next;
- if (l != it->tcset_head) {
- it->tcset_pos = l;
- return container_of(l, struct css_set,
- threaded_csets_node);
- }
- it->tcset_pos = NULL;
- }
- /* find the next cset */
- l = it->cset_pos;
- l = l->next;
- if (l == it->cset_head) {
- it->cset_pos = NULL;
- return NULL;
- }
- if (it->ss) {
- cset = container_of(l, struct css_set, e_cset_node[it->ss->id]);
- } else {
- link = list_entry(l, struct cgrp_cset_link, cset_link);
- cset = link->cset;
- }
- it->cset_pos = l;
- /* initialize threaded css_set walking */
- if (it->flags & CSS_TASK_ITER_THREADED) {
- if (it->cur_dcset)
- put_css_set_locked(it->cur_dcset);
- it->cur_dcset = cset;
- get_css_set(cset);
- it->tcset_head = &cset->threaded_csets;
- it->tcset_pos = &cset->threaded_csets;
- }
- return cset;
- }
- /**
- * css_task_iter_advance_css_set - advance a task itererator to the next css_set
- * @it: the iterator to advance
- *
- * Advance @it to the next css_set to walk.
- */
- static void css_task_iter_advance_css_set(struct css_task_iter *it)
- {
- struct css_set *cset;
- lockdep_assert_held(&css_set_lock);
- /* Advance to the next non-empty css_set and find first non-empty tasks list*/
- while ((cset = css_task_iter_next_css_set(it))) {
- if (!list_empty(&cset->tasks)) {
- it->cur_tasks_head = &cset->tasks;
- break;
- } else if (!list_empty(&cset->mg_tasks)) {
- it->cur_tasks_head = &cset->mg_tasks;
- break;
- } else if (!list_empty(&cset->dying_tasks)) {
- it->cur_tasks_head = &cset->dying_tasks;
- break;
- }
- }
- if (!cset) {
- it->task_pos = NULL;
- return;
- }
- it->task_pos = it->cur_tasks_head->next;
- /*
- * We don't keep css_sets locked across iteration steps and thus
- * need to take steps to ensure that iteration can be resumed after
- * the lock is re-acquired. Iteration is performed at two levels -
- * css_sets and tasks in them.
- *
- * Once created, a css_set never leaves its cgroup lists, so a
- * pinned css_set is guaranteed to stay put and we can resume
- * iteration afterwards.
- *
- * Tasks may leave @cset across iteration steps. This is resolved
- * by registering each iterator with the css_set currently being
- * walked and making css_set_move_task() advance iterators whose
- * next task is leaving.
- */
- if (it->cur_cset) {
- list_del(&it->iters_node);
- put_css_set_locked(it->cur_cset);
- }
- get_css_set(cset);
- it->cur_cset = cset;
- list_add(&it->iters_node, &cset->task_iters);
- }
- static void css_task_iter_skip(struct css_task_iter *it,
- struct task_struct *task)
- {
- lockdep_assert_held(&css_set_lock);
- if (it->task_pos == &task->cg_list) {
- it->task_pos = it->task_pos->next;
- it->flags |= CSS_TASK_ITER_SKIPPED;
- }
- }
- static void css_task_iter_advance(struct css_task_iter *it)
- {
- struct task_struct *task;
- lockdep_assert_held(&css_set_lock);
- repeat:
- if (it->task_pos) {
- /*
- * Advance iterator to find next entry. We go through cset
- * tasks, mg_tasks and dying_tasks, when consumed we move onto
- * the next cset.
- */
- if (it->flags & CSS_TASK_ITER_SKIPPED)
- it->flags &= ~CSS_TASK_ITER_SKIPPED;
- else
- it->task_pos = it->task_pos->next;
- if (it->task_pos == &it->cur_cset->tasks) {
- it->cur_tasks_head = &it->cur_cset->mg_tasks;
- it->task_pos = it->cur_tasks_head->next;
- }
- if (it->task_pos == &it->cur_cset->mg_tasks) {
- it->cur_tasks_head = &it->cur_cset->dying_tasks;
- it->task_pos = it->cur_tasks_head->next;
- }
- if (it->task_pos == &it->cur_cset->dying_tasks)
- css_task_iter_advance_css_set(it);
- } else {
- /* called from start, proceed to the first cset */
- css_task_iter_advance_css_set(it);
- }
- if (!it->task_pos)
- return;
- task = list_entry(it->task_pos, struct task_struct, cg_list);
- if (it->flags & CSS_TASK_ITER_PROCS) {
- /* if PROCS, skip over tasks which aren't group leaders */
- if (!thread_group_leader(task))
- goto repeat;
- /* and dying leaders w/o live member threads */
- if (it->cur_tasks_head == &it->cur_cset->dying_tasks &&
- !atomic_read(&task->signal->live))
- goto repeat;
- } else {
- /* skip all dying ones */
- if (it->cur_tasks_head == &it->cur_cset->dying_tasks)
- goto repeat;
- }
- }
- /**
- * css_task_iter_start - initiate task iteration
- * @css: the css to walk tasks of
- * @flags: CSS_TASK_ITER_* flags
- * @it: the task iterator to use
- *
- * Initiate iteration through the tasks of @css. The caller can call
- * css_task_iter_next() to walk through the tasks until the function
- * returns NULL. On completion of iteration, css_task_iter_end() must be
- * called.
- */
- void css_task_iter_start(struct cgroup_subsys_state *css, unsigned int flags,
- struct css_task_iter *it)
- {
- memset(it, 0, sizeof(*it));
- spin_lock_irq(&css_set_lock);
- it->ss = css->ss;
- it->flags = flags;
- if (it->ss)
- it->cset_pos = &css->cgroup->e_csets[css->ss->id];
- else
- it->cset_pos = &css->cgroup->cset_links;
- it->cset_head = it->cset_pos;
- css_task_iter_advance(it);
- spin_unlock_irq(&css_set_lock);
- }
- /**
- * css_task_iter_next - return the next task for the iterator
- * @it: the task iterator being iterated
- *
- * The "next" function for task iteration. @it should have been
- * initialized via css_task_iter_start(). Returns NULL when the iteration
- * reaches the end.
- */
- struct task_struct *css_task_iter_next(struct css_task_iter *it)
- {
- if (it->cur_task) {
- put_task_struct(it->cur_task);
- it->cur_task = NULL;
- }
- spin_lock_irq(&css_set_lock);
- /* @it may be half-advanced by skips, finish advancing */
- if (it->flags & CSS_TASK_ITER_SKIPPED)
- css_task_iter_advance(it);
- if (it->task_pos) {
- it->cur_task = list_entry(it->task_pos, struct task_struct,
- cg_list);
- get_task_struct(it->cur_task);
- css_task_iter_advance(it);
- }
- spin_unlock_irq(&css_set_lock);
- return it->cur_task;
- }
- /**
- * css_task_iter_end - finish task iteration
- * @it: the task iterator to finish
- *
- * Finish task iteration started by css_task_iter_start().
- */
- void css_task_iter_end(struct css_task_iter *it)
- {
- if (it->cur_cset) {
- spin_lock_irq(&css_set_lock);
- list_del(&it->iters_node);
- put_css_set_locked(it->cur_cset);
- spin_unlock_irq(&css_set_lock);
- }
- if (it->cur_dcset)
- put_css_set(it->cur_dcset);
- if (it->cur_task)
- put_task_struct(it->cur_task);
- }
- static void cgroup_procs_release(struct kernfs_open_file *of)
- {
- struct cgroup_file_ctx *ctx = of->priv;
- if (ctx->procs.started)
- css_task_iter_end(&ctx->procs.iter);
- }
- static void *cgroup_procs_next(struct seq_file *s, void *v, loff_t *pos)
- {
- struct kernfs_open_file *of = s->private;
- struct cgroup_file_ctx *ctx = of->priv;
- if (pos)
- (*pos)++;
- return css_task_iter_next(&ctx->procs.iter);
- }
- static void *__cgroup_procs_start(struct seq_file *s, loff_t *pos,
- unsigned int iter_flags)
- {
- struct kernfs_open_file *of = s->private;
- struct cgroup *cgrp = seq_css(s)->cgroup;
- struct cgroup_file_ctx *ctx = of->priv;
- struct css_task_iter *it = &ctx->procs.iter;
- /*
- * When a seq_file is seeked, it's always traversed sequentially
- * from position 0, so we can simply keep iterating on !0 *pos.
- */
- if (!ctx->procs.started) {
- if (WARN_ON_ONCE((*pos)))
- return ERR_PTR(-EINVAL);
- css_task_iter_start(&cgrp->self, iter_flags, it);
- ctx->procs.started = true;
- } else if (!(*pos)) {
- css_task_iter_end(it);
- css_task_iter_start(&cgrp->self, iter_flags, it);
- } else
- return it->cur_task;
- return cgroup_procs_next(s, NULL, NULL);
- }
- static void *cgroup_procs_start(struct seq_file *s, loff_t *pos)
- {
- struct cgroup *cgrp = seq_css(s)->cgroup;
- /*
- * All processes of a threaded subtree belong to the domain cgroup
- * of the subtree. Only threads can be distributed across the
- * subtree. Reject reads on cgroup.procs in the subtree proper.
- * They're always empty anyway.
- */
- if (cgroup_is_threaded(cgrp))
- return ERR_PTR(-EOPNOTSUPP);
- return __cgroup_procs_start(s, pos, CSS_TASK_ITER_PROCS |
- CSS_TASK_ITER_THREADED);
- }
- static int cgroup_procs_show(struct seq_file *s, void *v)
- {
- seq_printf(s, "%d\n", task_pid_vnr(v));
- return 0;
- }
- static int cgroup_may_write(const struct cgroup *cgrp, struct super_block *sb)
- {
- int ret;
- struct inode *inode;
- lockdep_assert_held(&cgroup_mutex);
- inode = kernfs_get_inode(sb, cgrp->procs_file.kn);
- if (!inode)
- return -ENOMEM;
- ret = inode_permission(inode, MAY_WRITE);
- iput(inode);
- return ret;
- }
- static int cgroup_procs_write_permission(struct cgroup *src_cgrp,
- struct cgroup *dst_cgrp,
- struct super_block *sb,
- struct cgroup_namespace *ns)
- {
- struct cgroup *com_cgrp = src_cgrp;
- int ret;
- lockdep_assert_held(&cgroup_mutex);
- /* find the common ancestor */
- while (!cgroup_is_descendant(dst_cgrp, com_cgrp))
- com_cgrp = cgroup_parent(com_cgrp);
- /* %current should be authorized to migrate to the common ancestor */
- ret = cgroup_may_write(com_cgrp, sb);
- if (ret)
- return ret;
- /*
- * If namespaces are delegation boundaries, %current must be able
- * to see both source and destination cgroups from its namespace.
- */
- if ((cgrp_dfl_root.flags & CGRP_ROOT_NS_DELEGATE) &&
- (!cgroup_is_descendant(src_cgrp, ns->root_cset->dfl_cgrp) ||
- !cgroup_is_descendant(dst_cgrp, ns->root_cset->dfl_cgrp)))
- return -ENOENT;
- return 0;
- }
- static int cgroup_attach_permissions(struct cgroup *src_cgrp,
- struct cgroup *dst_cgrp,
- struct super_block *sb, bool threadgroup,
- struct cgroup_namespace *ns)
- {
- int ret = 0;
- ret = cgroup_procs_write_permission(src_cgrp, dst_cgrp, sb, ns);
- if (ret)
- return ret;
- ret = cgroup_migrate_vet_dst(dst_cgrp);
- if (ret)
- return ret;
- if (!threadgroup && (src_cgrp->dom_cgrp != dst_cgrp->dom_cgrp))
- ret = -EOPNOTSUPP;
- return ret;
- }
- static ssize_t cgroup_procs_write(struct kernfs_open_file *of,
- char *buf, size_t nbytes, loff_t off)
- {
- struct cgroup_file_ctx *ctx = of->priv;
- struct cgroup *src_cgrp, *dst_cgrp;
- struct task_struct *task;
- const struct cred *saved_cred;
- ssize_t ret;
- bool locked;
- dst_cgrp = cgroup_kn_lock_live(of->kn, false);
- if (!dst_cgrp)
- return -ENODEV;
- task = cgroup_procs_write_start(buf, true, &locked, dst_cgrp);
- ret = PTR_ERR_OR_ZERO(task);
- if (ret)
- goto out_unlock;
- /* find the source cgroup */
- spin_lock_irq(&css_set_lock);
- src_cgrp = task_cgroup_from_root(task, &cgrp_dfl_root);
- spin_unlock_irq(&css_set_lock);
- /*
- * Process and thread migrations follow same delegation rule. Check
- * permissions using the credentials from file open to protect against
- * inherited fd attacks.
- */
- saved_cred = override_creds(of->file->f_cred);
- ret = cgroup_attach_permissions(src_cgrp, dst_cgrp,
- of->file->f_path.dentry->d_sb, true,
- ctx->ns);
- revert_creds(saved_cred);
- if (ret)
- goto out_finish;
- ret = cgroup_attach_task(dst_cgrp, task, true);
- out_finish:
- cgroup_procs_write_finish(task, locked);
- out_unlock:
- cgroup_kn_unlock(of->kn);
- return ret ?: nbytes;
- }
- static void *cgroup_threads_start(struct seq_file *s, loff_t *pos)
- {
- return __cgroup_procs_start(s, pos, 0);
- }
- static ssize_t cgroup_threads_write(struct kernfs_open_file *of,
- char *buf, size_t nbytes, loff_t off)
- {
- struct cgroup_file_ctx *ctx = of->priv;
- struct cgroup *src_cgrp, *dst_cgrp;
- struct task_struct *task;
- const struct cred *saved_cred;
- ssize_t ret;
- bool locked;
- buf = strstrip(buf);
- dst_cgrp = cgroup_kn_lock_live(of->kn, false);
- if (!dst_cgrp)
- return -ENODEV;
- task = cgroup_procs_write_start(buf, false, &locked, dst_cgrp);
- ret = PTR_ERR_OR_ZERO(task);
- if (ret)
- goto out_unlock;
- /* find the source cgroup */
- spin_lock_irq(&css_set_lock);
- src_cgrp = task_cgroup_from_root(task, &cgrp_dfl_root);
- spin_unlock_irq(&css_set_lock);
- /*
- * Process and thread migrations follow same delegation rule. Check
- * permissions using the credentials from file open to protect against
- * inherited fd attacks.
- */
- saved_cred = override_creds(of->file->f_cred);
- ret = cgroup_attach_permissions(src_cgrp, dst_cgrp,
- of->file->f_path.dentry->d_sb, false,
- ctx->ns);
- revert_creds(saved_cred);
- if (ret)
- goto out_finish;
- ret = cgroup_attach_task(dst_cgrp, task, false);
- out_finish:
- cgroup_procs_write_finish(task, locked);
- out_unlock:
- cgroup_kn_unlock(of->kn);
- return ret ?: nbytes;
- }
- /* cgroup core interface files for the default hierarchy */
- static struct cftype cgroup_base_files[] = {
- {
- .name = "cgroup.type",
- .flags = CFTYPE_NOT_ON_ROOT,
- .seq_show = cgroup_type_show,
- .write = cgroup_type_write,
- },
- {
- .name = "cgroup.procs",
- .flags = CFTYPE_NS_DELEGATABLE,
- .file_offset = offsetof(struct cgroup, procs_file),
- .release = cgroup_procs_release,
- .seq_start = cgroup_procs_start,
- .seq_next = cgroup_procs_next,
- .seq_show = cgroup_procs_show,
- .write = cgroup_procs_write,
- },
- {
- .name = "cgroup.threads",
- .flags = CFTYPE_NS_DELEGATABLE,
- .release = cgroup_procs_release,
- .seq_start = cgroup_threads_start,
- .seq_next = cgroup_procs_next,
- .seq_show = cgroup_procs_show,
- .write = cgroup_threads_write,
- },
- {
- .name = "cgroup.controllers",
- .seq_show = cgroup_controllers_show,
- },
- {
- .name = "cgroup.subtree_control",
- .flags = CFTYPE_NS_DELEGATABLE,
- .seq_show = cgroup_subtree_control_show,
- .write = cgroup_subtree_control_write,
- },
- {
- .name = "cgroup.events",
- .flags = CFTYPE_NOT_ON_ROOT,
- .file_offset = offsetof(struct cgroup, events_file),
- .seq_show = cgroup_events_show,
- },
- {
- .name = "cgroup.max.descendants",
- .seq_show = cgroup_max_descendants_show,
- .write = cgroup_max_descendants_write,
- },
- {
- .name = "cgroup.max.depth",
- .seq_show = cgroup_max_depth_show,
- .write = cgroup_max_depth_write,
- },
- {
- .name = "cgroup.stat",
- .seq_show = cgroup_stat_show,
- },
- {
- .name = "cgroup.freeze",
- .flags = CFTYPE_NOT_ON_ROOT,
- .seq_show = cgroup_freeze_show,
- .write = cgroup_freeze_write,
- },
- {
- .name = "cpu.stat",
- .seq_show = cpu_stat_show,
- },
- #ifdef CONFIG_PSI
- {
- .name = "io.pressure",
- .flags = CFTYPE_PRESSURE,
- .seq_show = cgroup_io_pressure_show,
- .write = cgroup_io_pressure_write,
- .poll = cgroup_pressure_poll,
- .release = cgroup_pressure_release,
- },
- {
- .name = "memory.pressure",
- .flags = CFTYPE_PRESSURE,
- .seq_show = cgroup_memory_pressure_show,
- .write = cgroup_memory_pressure_write,
- .poll = cgroup_pressure_poll,
- .release = cgroup_pressure_release,
- },
- {
- .name = "cpu.pressure",
- .flags = CFTYPE_PRESSURE,
- .seq_show = cgroup_cpu_pressure_show,
- .write = cgroup_cpu_pressure_write,
- .poll = cgroup_pressure_poll,
- .release = cgroup_pressure_release,
- },
- #endif /* CONFIG_PSI */
- { } /* terminate */
- };
- /*
- * css destruction is four-stage process.
- *
- * 1. Destruction starts. Killing of the percpu_ref is initiated.
- * Implemented in kill_css().
- *
- * 2. When the percpu_ref is confirmed to be visible as killed on all CPUs
- * and thus css_tryget_online() is guaranteed to fail, the css can be
- * offlined by invoking offline_css(). After offlining, the base ref is
- * put. Implemented in css_killed_work_fn().
- *
- * 3. When the percpu_ref reaches zero, the only possible remaining
- * accessors are inside RCU read sections. css_release() schedules the
- * RCU callback.
- *
- * 4. After the grace period, the css can be freed. Implemented in
- * css_free_work_fn().
- *
- * It is actually hairier because both step 2 and 4 require process context
- * and thus involve punting to css->destroy_work adding two additional
- * steps to the already complex sequence.
- */
- static void css_free_rwork_fn(struct work_struct *work)
- {
- struct cgroup_subsys_state *css = container_of(to_rcu_work(work),
- struct cgroup_subsys_state, destroy_rwork);
- struct cgroup_subsys *ss = css->ss;
- struct cgroup *cgrp = css->cgroup;
- percpu_ref_exit(&css->refcnt);
- if (ss) {
- /* css free path */
- struct cgroup_subsys_state *parent = css->parent;
- int id = css->id;
- ss->css_free(css);
- cgroup_idr_remove(&ss->css_idr, id);
- cgroup_put(cgrp);
- if (parent)
- css_put(parent);
- } else {
- /* cgroup free path */
- atomic_dec(&cgrp->root->nr_cgrps);
- cgroup1_pidlist_destroy_all(cgrp);
- cancel_work_sync(&cgrp->release_agent_work);
- if (cgroup_parent(cgrp)) {
- /*
- * We get a ref to the parent, and put the ref when
- * this cgroup is being freed, so it's guaranteed
- * that the parent won't be destroyed before its
- * children.
- */
- cgroup_put(cgroup_parent(cgrp));
- kernfs_put(cgrp->kn);
- psi_cgroup_free(cgrp);
- if (cgroup_on_dfl(cgrp))
- cgroup_rstat_exit(cgrp);
- kfree(cgrp);
- } else {
- /*
- * This is root cgroup's refcnt reaching zero,
- * which indicates that the root should be
- * released.
- */
- cgroup_destroy_root(cgrp->root);
- }
- }
- }
- static void css_release_work_fn(struct work_struct *work)
- {
- struct cgroup_subsys_state *css =
- container_of(work, struct cgroup_subsys_state, destroy_work);
- struct cgroup_subsys *ss = css->ss;
- struct cgroup *cgrp = css->cgroup;
- mutex_lock(&cgroup_mutex);
- css->flags |= CSS_RELEASED;
- list_del_rcu(&css->sibling);
- if (ss) {
- /* css release path */
- if (!list_empty(&css->rstat_css_node)) {
- cgroup_rstat_flush(cgrp);
- list_del_rcu(&css->rstat_css_node);
- }
- cgroup_idr_replace(&ss->css_idr, NULL, css->id);
- if (ss->css_released)
- ss->css_released(css);
- } else {
- struct cgroup *tcgrp;
- /* cgroup release path */
- TRACE_CGROUP_PATH(release, cgrp);
- if (cgroup_on_dfl(cgrp))
- cgroup_rstat_flush(cgrp);
- spin_lock_irq(&css_set_lock);
- for (tcgrp = cgroup_parent(cgrp); tcgrp;
- tcgrp = cgroup_parent(tcgrp))
- tcgrp->nr_dying_descendants--;
- spin_unlock_irq(&css_set_lock);
- /*
- * There are two control paths which try to determine
- * cgroup from dentry without going through kernfs -
- * cgroupstats_build() and css_tryget_online_from_dir().
- * Those are supported by RCU protecting clearing of
- * cgrp->kn->priv backpointer.
- */
- if (cgrp->kn)
- RCU_INIT_POINTER(*(void __rcu __force **)&cgrp->kn->priv,
- NULL);
- }
- mutex_unlock(&cgroup_mutex);
- INIT_RCU_WORK(&css->destroy_rwork, css_free_rwork_fn);
- queue_rcu_work(cgroup_destroy_wq, &css->destroy_rwork);
- }
- static void css_release(struct percpu_ref *ref)
- {
- struct cgroup_subsys_state *css =
- container_of(ref, struct cgroup_subsys_state, refcnt);
- INIT_WORK(&css->destroy_work, css_release_work_fn);
- queue_work(cgroup_destroy_wq, &css->destroy_work);
- }
- static void init_and_link_css(struct cgroup_subsys_state *css,
- struct cgroup_subsys *ss, struct cgroup *cgrp)
- {
- lockdep_assert_held(&cgroup_mutex);
- cgroup_get_live(cgrp);
- memset(css, 0, sizeof(*css));
- css->cgroup = cgrp;
- css->ss = ss;
- css->id = -1;
- INIT_LIST_HEAD(&css->sibling);
- INIT_LIST_HEAD(&css->children);
- INIT_LIST_HEAD(&css->rstat_css_node);
- css->serial_nr = css_serial_nr_next++;
- atomic_set(&css->online_cnt, 0);
- if (cgroup_parent(cgrp)) {
- css->parent = cgroup_css(cgroup_parent(cgrp), ss);
- css_get(css->parent);
- }
- if (cgroup_on_dfl(cgrp) && ss->css_rstat_flush)
- list_add_rcu(&css->rstat_css_node, &cgrp->rstat_css_list);
- BUG_ON(cgroup_css(cgrp, ss));
- }
- /* invoke ->css_online() on a new CSS and mark it online if successful */
- static int online_css(struct cgroup_subsys_state *css)
- {
- struct cgroup_subsys *ss = css->ss;
- int ret = 0;
- lockdep_assert_held(&cgroup_mutex);
- if (ss->css_online)
- ret = ss->css_online(css);
- if (!ret) {
- css->flags |= CSS_ONLINE;
- rcu_assign_pointer(css->cgroup->subsys[ss->id], css);
- atomic_inc(&css->online_cnt);
- if (css->parent)
- atomic_inc(&css->parent->online_cnt);
- }
- return ret;
- }
- /* if the CSS is online, invoke ->css_offline() on it and mark it offline */
- static void offline_css(struct cgroup_subsys_state *css)
- {
- struct cgroup_subsys *ss = css->ss;
- lockdep_assert_held(&cgroup_mutex);
- if (!(css->flags & CSS_ONLINE))
- return;
- if (ss->css_offline)
- ss->css_offline(css);
- css->flags &= ~CSS_ONLINE;
- RCU_INIT_POINTER(css->cgroup->subsys[ss->id], NULL);
- wake_up_all(&css->cgroup->offline_waitq);
- }
- /**
- * css_create - create a cgroup_subsys_state
- * @cgrp: the cgroup new css will be associated with
- * @ss: the subsys of new css
- *
- * Create a new css associated with @cgrp - @ss pair. On success, the new
- * css is online and installed in @cgrp. This function doesn't create the
- * interface files. Returns 0 on success, -errno on failure.
- */
- static struct cgroup_subsys_state *css_create(struct cgroup *cgrp,
- struct cgroup_subsys *ss)
- {
- struct cgroup *parent = cgroup_parent(cgrp);
- struct cgroup_subsys_state *parent_css = cgroup_css(parent, ss);
- struct cgroup_subsys_state *css;
- int err;
- lockdep_assert_held(&cgroup_mutex);
- css = ss->css_alloc(parent_css);
- if (!css)
- css = ERR_PTR(-ENOMEM);
- if (IS_ERR(css))
- return css;
- init_and_link_css(css, ss, cgrp);
- err = percpu_ref_init(&css->refcnt, css_release, 0, GFP_KERNEL);
- if (err)
- goto err_free_css;
- err = cgroup_idr_alloc(&ss->css_idr, NULL, 2, 0, GFP_KERNEL);
- if (err < 0)
- goto err_free_css;
- css->id = err;
- /* @css is ready to be brought online now, make it visible */
- list_add_tail_rcu(&css->sibling, &parent_css->children);
- cgroup_idr_replace(&ss->css_idr, css, css->id);
- err = online_css(css);
- if (err)
- goto err_list_del;
- if (ss->broken_hierarchy && !ss->warned_broken_hierarchy &&
- cgroup_parent(parent)) {
- pr_warn("%s (%d) created nested cgroup for controller \"%s\" which has incomplete hierarchy support. Nested cgroups may change behavior in the future.\n",
- current->comm, current->pid, ss->name);
- if (!strcmp(ss->name, "memory"))
- pr_warn("\"memory\" requires setting use_hierarchy to 1 on the root\n");
- ss->warned_broken_hierarchy = true;
- }
- return css;
- err_list_del:
- list_del_rcu(&css->sibling);
- err_free_css:
- list_del_rcu(&css->rstat_css_node);
- INIT_RCU_WORK(&css->destroy_rwork, css_free_rwork_fn);
- queue_rcu_work(cgroup_destroy_wq, &css->destroy_rwork);
- return ERR_PTR(err);
- }
- /*
- * The returned cgroup is fully initialized including its control mask, but
- * it isn't associated with its kernfs_node and doesn't have the control
- * mask applied.
- */
- static struct cgroup *cgroup_create(struct cgroup *parent, const char *name,
- umode_t mode)
- {
- struct cgroup_root *root = parent->root;
- struct cgroup *cgrp, *tcgrp;
- struct kernfs_node *kn;
- int level = parent->level + 1;
- int ret;
- /* allocate the cgroup and its ID, 0 is reserved for the root */
- cgrp = kzalloc(struct_size(cgrp, ancestor_ids, (level + 1)),
- GFP_KERNEL);
- if (!cgrp)
- return ERR_PTR(-ENOMEM);
- ret = percpu_ref_init(&cgrp->self.refcnt, css_release, 0, GFP_KERNEL);
- if (ret)
- goto out_free_cgrp;
- if (cgroup_on_dfl(parent)) {
- ret = cgroup_rstat_init(cgrp);
- if (ret)
- goto out_cancel_ref;
- }
- /* create the directory */
- kn = kernfs_create_dir(parent->kn, name, mode, cgrp);
- if (IS_ERR(kn)) {
- ret = PTR_ERR(kn);
- goto out_stat_exit;
- }
- cgrp->kn = kn;
- init_cgroup_housekeeping(cgrp);
- cgrp->self.parent = &parent->self;
- cgrp->root = root;
- cgrp->level = level;
- ret = psi_cgroup_alloc(cgrp);
- if (ret)
- goto out_kernfs_remove;
- ret = cgroup_bpf_inherit(cgrp);
- if (ret)
- goto out_psi_free;
- /*
- * New cgroup inherits effective freeze counter, and
- * if the parent has to be frozen, the child has too.
- */
- cgrp->freezer.e_freeze = parent->freezer.e_freeze;
- if (cgrp->freezer.e_freeze) {
- /*
- * Set the CGRP_FREEZE flag, so when a process will be
- * attached to the child cgroup, it will become frozen.
- * At this point the new cgroup is unpopulated, so we can
- * consider it frozen immediately.
- */
- set_bit(CGRP_FREEZE, &cgrp->flags);
- set_bit(CGRP_FROZEN, &cgrp->flags);
- }
- spin_lock_irq(&css_set_lock);
- for (tcgrp = cgrp; tcgrp; tcgrp = cgroup_parent(tcgrp)) {
- cgrp->ancestor_ids[tcgrp->level] = cgroup_id(tcgrp);
- if (tcgrp != cgrp) {
- tcgrp->nr_descendants++;
- /*
- * If the new cgroup is frozen, all ancestor cgroups
- * get a new frozen descendant, but their state can't
- * change because of this.
- */
- if (cgrp->freezer.e_freeze)
- tcgrp->freezer.nr_frozen_descendants++;
- }
- }
- spin_unlock_irq(&css_set_lock);
- if (notify_on_release(parent))
- set_bit(CGRP_NOTIFY_ON_RELEASE, &cgrp->flags);
- if (test_bit(CGRP_CPUSET_CLONE_CHILDREN, &parent->flags))
- set_bit(CGRP_CPUSET_CLONE_CHILDREN, &cgrp->flags);
- cgrp->self.serial_nr = css_serial_nr_next++;
- /* allocation complete, commit to creation */
- list_add_tail_rcu(&cgrp->self.sibling, &cgroup_parent(cgrp)->self.children);
- atomic_inc(&root->nr_cgrps);
- cgroup_get_live(parent);
- /*
- * On the default hierarchy, a child doesn't automatically inherit
- * subtree_control from the parent. Each is configured manually.
- */
- if (!cgroup_on_dfl(cgrp))
- cgrp->subtree_control = cgroup_control(cgrp);
- cgroup_propagate_control(cgrp);
- return cgrp;
- out_psi_free:
- psi_cgroup_free(cgrp);
- out_kernfs_remove:
- kernfs_remove(cgrp->kn);
- out_stat_exit:
- if (cgroup_on_dfl(parent))
- cgroup_rstat_exit(cgrp);
- out_cancel_ref:
- percpu_ref_exit(&cgrp->self.refcnt);
- out_free_cgrp:
- kfree(cgrp);
- return ERR_PTR(ret);
- }
- static bool cgroup_check_hierarchy_limits(struct cgroup *parent)
- {
- struct cgroup *cgroup;
- int ret = false;
- int level = 1;
- lockdep_assert_held(&cgroup_mutex);
- for (cgroup = parent; cgroup; cgroup = cgroup_parent(cgroup)) {
- if (cgroup->nr_descendants >= cgroup->max_descendants)
- goto fail;
- if (level > cgroup->max_depth)
- goto fail;
- level++;
- }
- ret = true;
- fail:
- return ret;
- }
- int cgroup_mkdir(struct kernfs_node *parent_kn, const char *name, umode_t mode)
- {
- struct cgroup *parent, *cgrp;
- int ret;
- /* do not accept '\n' to prevent making /proc/<pid>/cgroup unparsable */
- if (strchr(name, '\n'))
- return -EINVAL;
- parent = cgroup_kn_lock_live(parent_kn, false);
- if (!parent)
- return -ENODEV;
- if (!cgroup_check_hierarchy_limits(parent)) {
- ret = -EAGAIN;
- goto out_unlock;
- }
- cgrp = cgroup_create(parent, name, mode);
- if (IS_ERR(cgrp)) {
- ret = PTR_ERR(cgrp);
- goto out_unlock;
- }
- /*
- * This extra ref will be put in cgroup_free_fn() and guarantees
- * that @cgrp->kn is always accessible.
- */
- kernfs_get(cgrp->kn);
- ret = cgroup_kn_set_ugid(cgrp->kn);
- if (ret)
- goto out_destroy;
- ret = css_populate_dir(&cgrp->self);
- if (ret)
- goto out_destroy;
- ret = cgroup_apply_control_enable(cgrp);
- if (ret)
- goto out_destroy;
- TRACE_CGROUP_PATH(mkdir, cgrp);
- /* let's create and online css's */
- kernfs_activate(cgrp->kn);
- ret = 0;
- goto out_unlock;
- out_destroy:
- cgroup_destroy_locked(cgrp);
- out_unlock:
- cgroup_kn_unlock(parent_kn);
- return ret;
- }
- /*
- * This is called when the refcnt of a css is confirmed to be killed.
- * css_tryget_online() is now guaranteed to fail. Tell the subsystem to
- * initate destruction and put the css ref from kill_css().
- */
- static void css_killed_work_fn(struct work_struct *work)
- {
- struct cgroup_subsys_state *css =
- container_of(work, struct cgroup_subsys_state, destroy_work);
- mutex_lock(&cgroup_mutex);
- do {
- offline_css(css);
- css_put(css);
- /* @css can't go away while we're holding cgroup_mutex */
- css = css->parent;
- } while (css && atomic_dec_and_test(&css->online_cnt));
- mutex_unlock(&cgroup_mutex);
- }
- /* css kill confirmation processing requires process context, bounce */
- static void css_killed_ref_fn(struct percpu_ref *ref)
- {
- struct cgroup_subsys_state *css =
- container_of(ref, struct cgroup_subsys_state, refcnt);
- if (atomic_dec_and_test(&css->online_cnt)) {
- INIT_WORK(&css->destroy_work, css_killed_work_fn);
- queue_work(cgroup_destroy_wq, &css->destroy_work);
- }
- }
- /**
- * kill_css - destroy a css
- * @css: css to destroy
- *
- * This function initiates destruction of @css by removing cgroup interface
- * files and putting its base reference. ->css_offline() will be invoked
- * asynchronously once css_tryget_online() is guaranteed to fail and when
- * the reference count reaches zero, @css will be released.
- */
- static void kill_css(struct cgroup_subsys_state *css)
- {
- lockdep_assert_held(&cgroup_mutex);
- if (css->flags & CSS_DYING)
- return;
- css->flags |= CSS_DYING;
- /*
- * This must happen before css is disassociated with its cgroup.
- * See seq_css() for details.
- */
- css_clear_dir(css);
- /*
- * Killing would put the base ref, but we need to keep it alive
- * until after ->css_offline().
- */
- css_get(css);
- /*
- * cgroup core guarantees that, by the time ->css_offline() is
- * invoked, no new css reference will be given out via
- * css_tryget_online(). We can't simply call percpu_ref_kill() and
- * proceed to offlining css's because percpu_ref_kill() doesn't
- * guarantee that the ref is seen as killed on all CPUs on return.
- *
- * Use percpu_ref_kill_and_confirm() to get notifications as each
- * css is confirmed to be seen as killed on all CPUs.
- */
- percpu_ref_kill_and_confirm(&css->refcnt, css_killed_ref_fn);
- }
- /**
- * cgroup_destroy_locked - the first stage of cgroup destruction
- * @cgrp: cgroup to be destroyed
- *
- * css's make use of percpu refcnts whose killing latency shouldn't be
- * exposed to userland and are RCU protected. Also, cgroup core needs to
- * guarantee that css_tryget_online() won't succeed by the time
- * ->css_offline() is invoked. To satisfy all the requirements,
- * destruction is implemented in the following two steps.
- *
- * s1. Verify @cgrp can be destroyed and mark it dying. Remove all
- * userland visible parts and start killing the percpu refcnts of
- * css's. Set up so that the next stage will be kicked off once all
- * the percpu refcnts are confirmed to be killed.
- *
- * s2. Invoke ->css_offline(), mark the cgroup dead and proceed with the
- * rest of destruction. Once all cgroup references are gone, the
- * cgroup is RCU-freed.
- *
- * This function implements s1. After this step, @cgrp is gone as far as
- * the userland is concerned and a new cgroup with the same name may be
- * created. As cgroup doesn't care about the names internally, this
- * doesn't cause any problem.
- */
- static int cgroup_destroy_locked(struct cgroup *cgrp)
- __releases(&cgroup_mutex) __acquires(&cgroup_mutex)
- {
- struct cgroup *tcgrp, *parent = cgroup_parent(cgrp);
- struct cgroup_subsys_state *css;
- struct cgrp_cset_link *link;
- int ssid;
- lockdep_assert_held(&cgroup_mutex);
- /*
- * Only migration can raise populated from zero and we're already
- * holding cgroup_mutex.
- */
- if (cgroup_is_populated(cgrp))
- return -EBUSY;
- /*
- * Make sure there's no live children. We can't test emptiness of
- * ->self.children as dead children linger on it while being
- * drained; otherwise, "rmdir parent/child parent" may fail.
- */
- if (css_has_online_children(&cgrp->self))
- return -EBUSY;
- /*
- * Mark @cgrp and the associated csets dead. The former prevents
- * further task migration and child creation by disabling
- * cgroup_lock_live_group(). The latter makes the csets ignored by
- * the migration path.
- */
- cgrp->self.flags &= ~CSS_ONLINE;
- spin_lock_irq(&css_set_lock);
- list_for_each_entry(link, &cgrp->cset_links, cset_link)
- link->cset->dead = true;
- spin_unlock_irq(&css_set_lock);
- /* initiate massacre of all css's */
- for_each_css(css, ssid, cgrp)
- kill_css(css);
- /* clear and remove @cgrp dir, @cgrp has an extra ref on its kn */
- css_clear_dir(&cgrp->self);
- kernfs_remove(cgrp->kn);
- if (parent && cgroup_is_threaded(cgrp))
- parent->nr_threaded_children--;
- spin_lock_irq(&css_set_lock);
- for (tcgrp = cgroup_parent(cgrp); tcgrp; tcgrp = cgroup_parent(tcgrp)) {
- tcgrp->nr_descendants--;
- tcgrp->nr_dying_descendants++;
- /*
- * If the dying cgroup is frozen, decrease frozen descendants
- * counters of ancestor cgroups.
- */
- if (test_bit(CGRP_FROZEN, &cgrp->flags))
- tcgrp->freezer.nr_frozen_descendants--;
- }
- spin_unlock_irq(&css_set_lock);
- cgroup1_check_for_release(parent);
- cgroup_bpf_offline(cgrp);
- /* put the base reference */
- percpu_ref_kill(&cgrp->self.refcnt);
- return 0;
- };
- int cgroup_rmdir(struct kernfs_node *kn)
- {
- struct cgroup *cgrp;
- int ret = 0;
- cgrp = cgroup_kn_lock_live(kn, false);
- if (!cgrp)
- return 0;
- ret = cgroup_destroy_locked(cgrp);
- if (!ret)
- TRACE_CGROUP_PATH(rmdir, cgrp);
- cgroup_kn_unlock(kn);
- return ret;
- }
- static struct kernfs_syscall_ops cgroup_kf_syscall_ops = {
- .show_options = cgroup_show_options,
- .mkdir = cgroup_mkdir,
- .rmdir = cgroup_rmdir,
- .show_path = cgroup_show_path,
- };
- static void __init cgroup_init_subsys(struct cgroup_subsys *ss, bool early)
- {
- struct cgroup_subsys_state *css;
- pr_debug("Initializing cgroup subsys %s\n", ss->name);
- mutex_lock(&cgroup_mutex);
- idr_init(&ss->css_idr);
- INIT_LIST_HEAD(&ss->cfts);
- /* Create the root cgroup state for this subsystem */
- ss->root = &cgrp_dfl_root;
- css = ss->css_alloc(cgroup_css(&cgrp_dfl_root.cgrp, ss));
- /* We don't handle early failures gracefully */
- BUG_ON(IS_ERR(css));
- init_and_link_css(css, ss, &cgrp_dfl_root.cgrp);
- /*
- * Root csses are never destroyed and we can't initialize
- * percpu_ref during early init. Disable refcnting.
- */
- css->flags |= CSS_NO_REF;
- if (early) {
- /* allocation can't be done safely during early init */
- css->id = 1;
- } else {
- css->id = cgroup_idr_alloc(&ss->css_idr, css, 1, 2, GFP_KERNEL);
- BUG_ON(css->id < 0);
- }
- /* Update the init_css_set to contain a subsys
- * pointer to this state - since the subsystem is
- * newly registered, all tasks and hence the
- * init_css_set is in the subsystem's root cgroup. */
- init_css_set.subsys[ss->id] = css;
- have_fork_callback |= (bool)ss->fork << ss->id;
- have_exit_callback |= (bool)ss->exit << ss->id;
- have_release_callback |= (bool)ss->release << ss->id;
- have_canfork_callback |= (bool)ss->can_fork << ss->id;
- /* At system boot, before all subsystems have been
- * registered, no tasks have been forked, so we don't
- * need to invoke fork callbacks here. */
- BUG_ON(!list_empty(&init_task.tasks));
- BUG_ON(online_css(css));
- mutex_unlock(&cgroup_mutex);
- }
- /**
- * cgroup_init_early - cgroup initialization at system boot
- *
- * Initialize cgroups at system boot, and initialize any
- * subsystems that request early init.
- */
- int __init cgroup_init_early(void)
- {
- static struct cgroup_fs_context __initdata ctx;
- struct cgroup_subsys *ss;
- int i;
- ctx.root = &cgrp_dfl_root;
- init_cgroup_root(&ctx);
- cgrp_dfl_root.cgrp.self.flags |= CSS_NO_REF;
- RCU_INIT_POINTER(init_task.cgroups, &init_css_set);
- for_each_subsys(ss, i) {
- WARN(!ss->css_alloc || !ss->css_free || ss->name || ss->id,
- "invalid cgroup_subsys %d:%s css_alloc=%p css_free=%p id:name=%d:%s\n",
- i, cgroup_subsys_name[i], ss->css_alloc, ss->css_free,
- ss->id, ss->name);
- WARN(strlen(cgroup_subsys_name[i]) > MAX_CGROUP_TYPE_NAMELEN,
- "cgroup_subsys_name %s too long\n", cgroup_subsys_name[i]);
- ss->id = i;
- ss->name = cgroup_subsys_name[i];
- if (!ss->legacy_name)
- ss->legacy_name = cgroup_subsys_name[i];
- if (ss->early_init)
- cgroup_init_subsys(ss, true);
- }
- return 0;
- }
- /**
- * cgroup_init - cgroup initialization
- *
- * Register cgroup filesystem and /proc file, and initialize
- * any subsystems that didn't request early init.
- */
- int __init cgroup_init(void)
- {
- struct cgroup_subsys *ss;
- int ssid;
- BUILD_BUG_ON(CGROUP_SUBSYS_COUNT > 16);
- BUG_ON(cgroup_init_cftypes(NULL, cgroup_base_files));
- BUG_ON(cgroup_init_cftypes(NULL, cgroup1_base_files));
- cgroup_rstat_boot();
- /*
- * The latency of the synchronize_rcu() is too high for cgroups,
- * avoid it at the cost of forcing all readers into the slow path.
- */
- rcu_sync_enter_start(&cgroup_threadgroup_rwsem.rss);
- get_user_ns(init_cgroup_ns.user_ns);
- mutex_lock(&cgroup_mutex);
- /*
- * Add init_css_set to the hash table so that dfl_root can link to
- * it during init.
- */
- hash_add(css_set_table, &init_css_set.hlist,
- css_set_hash(init_css_set.subsys));
- BUG_ON(cgroup_setup_root(&cgrp_dfl_root, 0));
- mutex_unlock(&cgroup_mutex);
- for_each_subsys(ss, ssid) {
- if (ss->early_init) {
- struct cgroup_subsys_state *css =
- init_css_set.subsys[ss->id];
- css->id = cgroup_idr_alloc(&ss->css_idr, css, 1, 2,
- GFP_KERNEL);
- BUG_ON(css->id < 0);
- } else {
- cgroup_init_subsys(ss, false);
- }
- list_add_tail(&init_css_set.e_cset_node[ssid],
- &cgrp_dfl_root.cgrp.e_csets[ssid]);
- /*
- * Setting dfl_root subsys_mask needs to consider the
- * disabled flag and cftype registration needs kmalloc,
- * both of which aren't available during early_init.
- */
- if (!cgroup_ssid_enabled(ssid))
- continue;
- if (cgroup1_ssid_disabled(ssid))
- printk(KERN_INFO "Disabling %s control group subsystem in v1 mounts\n",
- ss->name);
- cgrp_dfl_root.subsys_mask |= 1 << ss->id;
- /* implicit controllers must be threaded too */
- WARN_ON(ss->implicit_on_dfl && !ss->threaded);
- if (ss->implicit_on_dfl)
- cgrp_dfl_implicit_ss_mask |= 1 << ss->id;
- else if (!ss->dfl_cftypes)
- cgrp_dfl_inhibit_ss_mask |= 1 << ss->id;
- if (ss->threaded)
- cgrp_dfl_threaded_ss_mask |= 1 << ss->id;
- if (ss->dfl_cftypes == ss->legacy_cftypes) {
- WARN_ON(cgroup_add_cftypes(ss, ss->dfl_cftypes));
- } else {
- WARN_ON(cgroup_add_dfl_cftypes(ss, ss->dfl_cftypes));
- WARN_ON(cgroup_add_legacy_cftypes(ss, ss->legacy_cftypes));
- }
- if (ss->bind)
- ss->bind(init_css_set.subsys[ssid]);
- mutex_lock(&cgroup_mutex);
- css_populate_dir(init_css_set.subsys[ssid]);
- mutex_unlock(&cgroup_mutex);
- }
- /* init_css_set.subsys[] has been updated, re-hash */
- hash_del(&init_css_set.hlist);
- hash_add(css_set_table, &init_css_set.hlist,
- css_set_hash(init_css_set.subsys));
- WARN_ON(sysfs_create_mount_point(fs_kobj, "cgroup"));
- WARN_ON(register_filesystem(&cgroup_fs_type));
- WARN_ON(register_filesystem(&cgroup2_fs_type));
- WARN_ON(!proc_create_single("cgroups", 0, NULL, proc_cgroupstats_show));
- #ifdef CONFIG_CPUSETS
- WARN_ON(register_filesystem(&cpuset_fs_type));
- #endif
- return 0;
- }
- static int __init cgroup_wq_init(void)
- {
- /*
- * There isn't much point in executing destruction path in
- * parallel. Good chunk is serialized with cgroup_mutex anyway.
- * Use 1 for @max_active.
- *
- * We would prefer to do this in cgroup_init() above, but that
- * is called before init_workqueues(): so leave this until after.
- */
- cgroup_destroy_wq = alloc_workqueue("cgroup_destroy", 0, 1);
- BUG_ON(!cgroup_destroy_wq);
- return 0;
- }
- core_initcall(cgroup_wq_init);
- void cgroup_path_from_kernfs_id(u64 id, char *buf, size_t buflen)
- {
- struct kernfs_node *kn;
- kn = kernfs_find_and_get_node_by_id(cgrp_dfl_root.kf_root, id);
- if (!kn)
- return;
- kernfs_path(kn, buf, buflen);
- kernfs_put(kn);
- }
- /*
- * proc_cgroup_show()
- * - Print task's cgroup paths into seq_file, one line for each hierarchy
- * - Used for /proc/<pid>/cgroup.
- */
- int proc_cgroup_show(struct seq_file *m, struct pid_namespace *ns,
- struct pid *pid, struct task_struct *tsk)
- {
- char *buf;
- int retval;
- struct cgroup_root *root;
- retval = -ENOMEM;
- buf = kmalloc(PATH_MAX, GFP_KERNEL);
- if (!buf)
- goto out;
- mutex_lock(&cgroup_mutex);
- spin_lock_irq(&css_set_lock);
- for_each_root(root) {
- struct cgroup_subsys *ss;
- struct cgroup *cgrp;
- int ssid, count = 0;
- if (root == &cgrp_dfl_root && !cgrp_dfl_visible)
- continue;
- seq_printf(m, "%d:", root->hierarchy_id);
- if (root != &cgrp_dfl_root)
- for_each_subsys(ss, ssid)
- if (root->subsys_mask & (1 << ssid))
- seq_printf(m, "%s%s", count++ ? "," : "",
- ss->legacy_name);
- if (strlen(root->name))
- seq_printf(m, "%sname=%s", count ? "," : "",
- root->name);
- seq_putc(m, ':');
- cgrp = task_cgroup_from_root(tsk, root);
- /*
- * On traditional hierarchies, all zombie tasks show up as
- * belonging to the root cgroup. On the default hierarchy,
- * while a zombie doesn't show up in "cgroup.procs" and
- * thus can't be migrated, its /proc/PID/cgroup keeps
- * reporting the cgroup it belonged to before exiting. If
- * the cgroup is removed before the zombie is reaped,
- * " (deleted)" is appended to the cgroup path.
- */
- if (cgroup_on_dfl(cgrp) || !(tsk->flags & PF_EXITING)) {
- retval = cgroup_path_ns_locked(cgrp, buf, PATH_MAX,
- current->nsproxy->cgroup_ns);
- if (retval >= PATH_MAX)
- retval = -ENAMETOOLONG;
- if (retval < 0)
- goto out_unlock;
- seq_puts(m, buf);
- } else {
- seq_puts(m, "/");
- }
- if (cgroup_on_dfl(cgrp) && cgroup_is_dead(cgrp))
- seq_puts(m, " (deleted)\n");
- else
- seq_putc(m, '\n');
- }
- retval = 0;
- out_unlock:
- spin_unlock_irq(&css_set_lock);
- mutex_unlock(&cgroup_mutex);
- kfree(buf);
- out:
- return retval;
- }
- /**
- * cgroup_fork - initialize cgroup related fields during copy_process()
- * @child: pointer to task_struct of forking parent process.
- *
- * A task is associated with the init_css_set until cgroup_post_fork()
- * attaches it to the target css_set.
- */
- void cgroup_fork(struct task_struct *child)
- {
- RCU_INIT_POINTER(child->cgroups, &init_css_set);
- INIT_LIST_HEAD(&child->cg_list);
- }
- static struct cgroup *cgroup_get_from_file(struct file *f)
- {
- struct cgroup_subsys_state *css;
- struct cgroup *cgrp;
- css = css_tryget_online_from_dir(f->f_path.dentry, NULL);
- if (IS_ERR(css))
- return ERR_CAST(css);
- cgrp = css->cgroup;
- if (!cgroup_on_dfl(cgrp)) {
- cgroup_put(cgrp);
- return ERR_PTR(-EBADF);
- }
- return cgrp;
- }
- /**
- * cgroup_css_set_fork - find or create a css_set for a child process
- * @kargs: the arguments passed to create the child process
- *
- * This functions finds or creates a new css_set which the child
- * process will be attached to in cgroup_post_fork(). By default,
- * the child process will be given the same css_set as its parent.
- *
- * If CLONE_INTO_CGROUP is specified this function will try to find an
- * existing css_set which includes the requested cgroup and if not create
- * a new css_set that the child will be attached to later. If this function
- * succeeds it will hold cgroup_threadgroup_rwsem on return. If
- * CLONE_INTO_CGROUP is requested this function will grab cgroup mutex
- * before grabbing cgroup_threadgroup_rwsem and will hold a reference
- * to the target cgroup.
- */
- static int cgroup_css_set_fork(struct kernel_clone_args *kargs)
- __acquires(&cgroup_mutex) __acquires(&cgroup_threadgroup_rwsem)
- {
- int ret;
- struct cgroup *dst_cgrp = NULL;
- struct css_set *cset;
- struct super_block *sb;
- struct file *f;
- if (kargs->flags & CLONE_INTO_CGROUP)
- mutex_lock(&cgroup_mutex);
- cgroup_threadgroup_change_begin(current);
- spin_lock_irq(&css_set_lock);
- cset = task_css_set(current);
- get_css_set(cset);
- spin_unlock_irq(&css_set_lock);
- if (!(kargs->flags & CLONE_INTO_CGROUP)) {
- kargs->cset = cset;
- return 0;
- }
- f = fget_raw(kargs->cgroup);
- if (!f) {
- ret = -EBADF;
- goto err;
- }
- sb = f->f_path.dentry->d_sb;
- dst_cgrp = cgroup_get_from_file(f);
- if (IS_ERR(dst_cgrp)) {
- ret = PTR_ERR(dst_cgrp);
- dst_cgrp = NULL;
- goto err;
- }
- if (cgroup_is_dead(dst_cgrp)) {
- ret = -ENODEV;
- goto err;
- }
- /*
- * Verify that we the target cgroup is writable for us. This is
- * usually done by the vfs layer but since we're not going through
- * the vfs layer here we need to do it "manually".
- */
- ret = cgroup_may_write(dst_cgrp, sb);
- if (ret)
- goto err;
- ret = cgroup_attach_permissions(cset->dfl_cgrp, dst_cgrp, sb,
- !(kargs->flags & CLONE_THREAD),
- current->nsproxy->cgroup_ns);
- if (ret)
- goto err;
- kargs->cset = find_css_set(cset, dst_cgrp);
- if (!kargs->cset) {
- ret = -ENOMEM;
- goto err;
- }
- put_css_set(cset);
- fput(f);
- kargs->cgrp = dst_cgrp;
- return ret;
- err:
- cgroup_threadgroup_change_end(current);
- mutex_unlock(&cgroup_mutex);
- if (f)
- fput(f);
- if (dst_cgrp)
- cgroup_put(dst_cgrp);
- put_css_set(cset);
- if (kargs->cset)
- put_css_set(kargs->cset);
- return ret;
- }
- /**
- * cgroup_css_set_put_fork - drop references we took during fork
- * @kargs: the arguments passed to create the child process
- *
- * Drop references to the prepared css_set and target cgroup if
- * CLONE_INTO_CGROUP was requested.
- */
- static void cgroup_css_set_put_fork(struct kernel_clone_args *kargs)
- __releases(&cgroup_threadgroup_rwsem) __releases(&cgroup_mutex)
- {
- cgroup_threadgroup_change_end(current);
- if (kargs->flags & CLONE_INTO_CGROUP) {
- struct cgroup *cgrp = kargs->cgrp;
- struct css_set *cset = kargs->cset;
- mutex_unlock(&cgroup_mutex);
- if (cset) {
- put_css_set(cset);
- kargs->cset = NULL;
- }
- if (cgrp) {
- cgroup_put(cgrp);
- kargs->cgrp = NULL;
- }
- }
- }
- /**
- * cgroup_can_fork - called on a new task before the process is exposed
- * @child: the child process
- *
- * This prepares a new css_set for the child process which the child will
- * be attached to in cgroup_post_fork().
- * This calls the subsystem can_fork() callbacks. If the cgroup_can_fork()
- * callback returns an error, the fork aborts with that error code. This
- * allows for a cgroup subsystem to conditionally allow or deny new forks.
- */
- int cgroup_can_fork(struct task_struct *child, struct kernel_clone_args *kargs)
- {
- struct cgroup_subsys *ss;
- int i, j, ret;
- ret = cgroup_css_set_fork(kargs);
- if (ret)
- return ret;
- do_each_subsys_mask(ss, i, have_canfork_callback) {
- ret = ss->can_fork(child, kargs->cset);
- if (ret)
- goto out_revert;
- } while_each_subsys_mask();
- return 0;
- out_revert:
- for_each_subsys(ss, j) {
- if (j >= i)
- break;
- if (ss->cancel_fork)
- ss->cancel_fork(child, kargs->cset);
- }
- cgroup_css_set_put_fork(kargs);
- return ret;
- }
- /**
- * cgroup_cancel_fork - called if a fork failed after cgroup_can_fork()
- * @child: the child process
- * @kargs: the arguments passed to create the child process
- *
- * This calls the cancel_fork() callbacks if a fork failed *after*
- * cgroup_can_fork() succeded and cleans up references we took to
- * prepare a new css_set for the child process in cgroup_can_fork().
- */
- void cgroup_cancel_fork(struct task_struct *child,
- struct kernel_clone_args *kargs)
- {
- struct cgroup_subsys *ss;
- int i;
- for_each_subsys(ss, i)
- if (ss->cancel_fork)
- ss->cancel_fork(child, kargs->cset);
- cgroup_css_set_put_fork(kargs);
- }
- /**
- * cgroup_post_fork - finalize cgroup setup for the child process
- * @child: the child process
- *
- * Attach the child process to its css_set calling the subsystem fork()
- * callbacks.
- */
- void cgroup_post_fork(struct task_struct *child,
- struct kernel_clone_args *kargs)
- __releases(&cgroup_threadgroup_rwsem) __releases(&cgroup_mutex)
- {
- struct cgroup_subsys *ss;
- struct css_set *cset;
- int i;
- cset = kargs->cset;
- kargs->cset = NULL;
- spin_lock_irq(&css_set_lock);
- /* init tasks are special, only link regular threads */
- if (likely(child->pid)) {
- WARN_ON_ONCE(!list_empty(&child->cg_list));
- cset->nr_tasks++;
- css_set_move_task(child, NULL, cset, false);
- } else {
- put_css_set(cset);
- cset = NULL;
- }
- /*
- * If the cgroup has to be frozen, the new task has too. Let's set
- * the JOBCTL_TRAP_FREEZE jobctl bit to get the task into the
- * frozen state.
- */
- if (unlikely(cgroup_task_freeze(child))) {
- spin_lock(&child->sighand->siglock);
- WARN_ON_ONCE(child->frozen);
- child->jobctl |= JOBCTL_TRAP_FREEZE;
- spin_unlock(&child->sighand->siglock);
- /*
- * Calling cgroup_update_frozen() isn't required here,
- * because it will be called anyway a bit later from
- * do_freezer_trap(). So we avoid cgroup's transient switch
- * from the frozen state and back.
- */
- }
- spin_unlock_irq(&css_set_lock);
- /*
- * Call ss->fork(). This must happen after @child is linked on
- * css_set; otherwise, @child might change state between ->fork()
- * and addition to css_set.
- */
- do_each_subsys_mask(ss, i, have_fork_callback) {
- ss->fork(child);
- } while_each_subsys_mask();
- /* Make the new cset the root_cset of the new cgroup namespace. */
- if (kargs->flags & CLONE_NEWCGROUP) {
- struct css_set *rcset = child->nsproxy->cgroup_ns->root_cset;
- get_css_set(cset);
- child->nsproxy->cgroup_ns->root_cset = cset;
- put_css_set(rcset);
- }
- cgroup_css_set_put_fork(kargs);
- }
- /**
- * cgroup_exit - detach cgroup from exiting task
- * @tsk: pointer to task_struct of exiting process
- *
- * Description: Detach cgroup from @tsk.
- *
- */
- void cgroup_exit(struct task_struct *tsk)
- {
- struct cgroup_subsys *ss;
- struct css_set *cset;
- int i;
- spin_lock_irq(&css_set_lock);
- WARN_ON_ONCE(list_empty(&tsk->cg_list));
- cset = task_css_set(tsk);
- css_set_move_task(tsk, cset, NULL, false);
- list_add_tail(&tsk->cg_list, &cset->dying_tasks);
- cset->nr_tasks--;
- WARN_ON_ONCE(cgroup_task_frozen(tsk));
- if (unlikely(cgroup_task_freeze(tsk)))
- cgroup_update_frozen(task_dfl_cgroup(tsk));
- spin_unlock_irq(&css_set_lock);
- /* see cgroup_post_fork() for details */
- do_each_subsys_mask(ss, i, have_exit_callback) {
- ss->exit(tsk);
- } while_each_subsys_mask();
- }
- void cgroup_release(struct task_struct *task)
- {
- struct cgroup_subsys *ss;
- int ssid;
- do_each_subsys_mask(ss, ssid, have_release_callback) {
- ss->release(task);
- } while_each_subsys_mask();
- spin_lock_irq(&css_set_lock);
- css_set_skip_task_iters(task_css_set(task), task);
- list_del_init(&task->cg_list);
- spin_unlock_irq(&css_set_lock);
- }
- void cgroup_free(struct task_struct *task)
- {
- struct css_set *cset = task_css_set(task);
- put_css_set(cset);
- }
- static int __init cgroup_disable(char *str)
- {
- struct cgroup_subsys *ss;
- char *token;
- int i;
- while ((token = strsep(&str, ",")) != NULL) {
- if (!*token)
- continue;
- for_each_subsys(ss, i) {
- if (strcmp(token, ss->name) &&
- strcmp(token, ss->legacy_name))
- continue;
- static_branch_disable(cgroup_subsys_enabled_key[i]);
- pr_info("Disabling %s control group subsystem\n",
- ss->name);
- }
- for (i = 0; i < OPT_FEATURE_COUNT; i++) {
- if (strcmp(token, cgroup_opt_feature_names[i]))
- continue;
- cgroup_feature_disable_mask |= 1 << i;
- pr_info("Disabling %s control group feature\n",
- cgroup_opt_feature_names[i]);
- break;
- }
- }
- return 1;
- }
- __setup("cgroup_disable=", cgroup_disable);
- void __init __weak enable_debug_cgroup(void) { }
- static int __init enable_cgroup_debug(char *str)
- {
- cgroup_debug = true;
- enable_debug_cgroup();
- return 1;
- }
- __setup("cgroup_debug", enable_cgroup_debug);
- /**
- * css_tryget_online_from_dir - get corresponding css from a cgroup dentry
- * @dentry: directory dentry of interest
- * @ss: subsystem of interest
- *
- * If @dentry is a directory for a cgroup which has @ss enabled on it, try
- * to get the corresponding css and return it. If such css doesn't exist
- * or can't be pinned, an ERR_PTR value is returned.
- */
- struct cgroup_subsys_state *css_tryget_online_from_dir(struct dentry *dentry,
- struct cgroup_subsys *ss)
- {
- struct kernfs_node *kn = kernfs_node_from_dentry(dentry);
- struct file_system_type *s_type = dentry->d_sb->s_type;
- struct cgroup_subsys_state *css = NULL;
- struct cgroup *cgrp;
- /* is @dentry a cgroup dir? */
- if ((s_type != &cgroup_fs_type && s_type != &cgroup2_fs_type) ||
- !kn || kernfs_type(kn) != KERNFS_DIR)
- return ERR_PTR(-EBADF);
- rcu_read_lock();
- /*
- * This path doesn't originate from kernfs and @kn could already
- * have been or be removed at any point. @kn->priv is RCU
- * protected for this access. See css_release_work_fn() for details.
- */
- cgrp = rcu_dereference(*(void __rcu __force **)&kn->priv);
- if (cgrp)
- css = cgroup_css(cgrp, ss);
- if (!css || !css_tryget_online(css))
- css = ERR_PTR(-ENOENT);
- rcu_read_unlock();
- return css;
- }
- /**
- * css_from_id - lookup css by id
- * @id: the cgroup id
- * @ss: cgroup subsys to be looked into
- *
- * Returns the css if there's valid one with @id, otherwise returns NULL.
- * Should be called under rcu_read_lock().
- */
- struct cgroup_subsys_state *css_from_id(int id, struct cgroup_subsys *ss)
- {
- WARN_ON_ONCE(!rcu_read_lock_held());
- return idr_find(&ss->css_idr, id);
- }
- /**
- * cgroup_get_from_path - lookup and get a cgroup from its default hierarchy path
- * @path: path on the default hierarchy
- *
- * Find the cgroup at @path on the default hierarchy, increment its
- * reference count and return it. Returns pointer to the found cgroup on
- * success, ERR_PTR(-ENOENT) if @path doens't exist and ERR_PTR(-ENOTDIR)
- * if @path points to a non-directory.
- */
- struct cgroup *cgroup_get_from_path(const char *path)
- {
- struct kernfs_node *kn;
- struct cgroup *cgrp;
- mutex_lock(&cgroup_mutex);
- kn = kernfs_walk_and_get(cgrp_dfl_root.cgrp.kn, path);
- if (kn) {
- if (kernfs_type(kn) == KERNFS_DIR) {
- cgrp = kn->priv;
- cgroup_get_live(cgrp);
- } else {
- cgrp = ERR_PTR(-ENOTDIR);
- }
- kernfs_put(kn);
- } else {
- cgrp = ERR_PTR(-ENOENT);
- }
- mutex_unlock(&cgroup_mutex);
- return cgrp;
- }
- EXPORT_SYMBOL_GPL(cgroup_get_from_path);
- /**
- * cgroup_get_from_fd - get a cgroup pointer from a fd
- * @fd: fd obtained by open(cgroup2_dir)
- *
- * Find the cgroup from a fd which should be obtained
- * by opening a cgroup directory. Returns a pointer to the
- * cgroup on success. ERR_PTR is returned if the cgroup
- * cannot be found.
- */
- struct cgroup *cgroup_get_from_fd(int fd)
- {
- struct cgroup *cgrp;
- struct file *f;
- f = fget_raw(fd);
- if (!f)
- return ERR_PTR(-EBADF);
- cgrp = cgroup_get_from_file(f);
- fput(f);
- return cgrp;
- }
- EXPORT_SYMBOL_GPL(cgroup_get_from_fd);
- static u64 power_of_ten(int power)
- {
- u64 v = 1;
- while (power--)
- v *= 10;
- return v;
- }
- /**
- * cgroup_parse_float - parse a floating number
- * @input: input string
- * @dec_shift: number of decimal digits to shift
- * @v: output
- *
- * Parse a decimal floating point number in @input and store the result in
- * @v with decimal point right shifted @dec_shift times. For example, if
- * @input is "12.3456" and @dec_shift is 3, *@v will be set to 12345.
- * Returns 0 on success, -errno otherwise.
- *
- * There's nothing cgroup specific about this function except that it's
- * currently the only user.
- */
- int cgroup_parse_float(const char *input, unsigned dec_shift, s64 *v)
- {
- s64 whole, frac = 0;
- int fstart = 0, fend = 0, flen;
- if (!sscanf(input, "%lld.%n%lld%n", &whole, &fstart, &frac, &fend))
- return -EINVAL;
- if (frac < 0)
- return -EINVAL;
- flen = fend > fstart ? fend - fstart : 0;
- if (flen < dec_shift)
- frac *= power_of_ten(dec_shift - flen);
- else
- frac = DIV_ROUND_CLOSEST_ULL(frac, power_of_ten(flen - dec_shift));
- *v = whole * power_of_ten(dec_shift) + frac;
- return 0;
- }
- /*
- * sock->sk_cgrp_data handling. For more info, see sock_cgroup_data
- * definition in cgroup-defs.h.
- */
- #ifdef CONFIG_SOCK_CGROUP_DATA
- #if defined(CONFIG_CGROUP_NET_PRIO) || defined(CONFIG_CGROUP_NET_CLASSID)
- DEFINE_SPINLOCK(cgroup_sk_update_lock);
- static bool cgroup_sk_alloc_disabled __read_mostly;
- void cgroup_sk_alloc_disable(void)
- {
- if (cgroup_sk_alloc_disabled)
- return;
- pr_info("cgroup: disabling cgroup2 socket matching due to net_prio or net_cls activation\n");
- cgroup_sk_alloc_disabled = true;
- }
- #else
- #define cgroup_sk_alloc_disabled false
- #endif
- void cgroup_sk_alloc(struct sock_cgroup_data *skcd)
- {
- if (cgroup_sk_alloc_disabled) {
- skcd->no_refcnt = 1;
- return;
- }
- /* Don't associate the sock with unrelated interrupted task's cgroup. */
- if (in_interrupt())
- return;
- rcu_read_lock();
- while (true) {
- struct css_set *cset;
- cset = task_css_set(current);
- if (likely(cgroup_tryget(cset->dfl_cgrp))) {
- skcd->val = (unsigned long)cset->dfl_cgrp;
- cgroup_bpf_get(cset->dfl_cgrp);
- break;
- }
- cpu_relax();
- }
- rcu_read_unlock();
- }
- void cgroup_sk_clone(struct sock_cgroup_data *skcd)
- {
- if (skcd->val) {
- if (skcd->no_refcnt)
- return;
- /*
- * We might be cloning a socket which is left in an empty
- * cgroup and the cgroup might have already been rmdir'd.
- * Don't use cgroup_get_live().
- */
- cgroup_get(sock_cgroup_ptr(skcd));
- cgroup_bpf_get(sock_cgroup_ptr(skcd));
- }
- }
- void cgroup_sk_free(struct sock_cgroup_data *skcd)
- {
- struct cgroup *cgrp = sock_cgroup_ptr(skcd);
- if (skcd->no_refcnt)
- return;
- cgroup_bpf_put(cgrp);
- cgroup_put(cgrp);
- }
- #endif /* CONFIG_SOCK_CGROUP_DATA */
- #ifdef CONFIG_CGROUP_BPF
- int cgroup_bpf_attach(struct cgroup *cgrp,
- struct bpf_prog *prog, struct bpf_prog *replace_prog,
- struct bpf_cgroup_link *link,
- enum bpf_attach_type type,
- u32 flags)
- {
- int ret;
- mutex_lock(&cgroup_mutex);
- ret = __cgroup_bpf_attach(cgrp, prog, replace_prog, link, type, flags);
- mutex_unlock(&cgroup_mutex);
- return ret;
- }
- int cgroup_bpf_detach(struct cgroup *cgrp, struct bpf_prog *prog,
- enum bpf_attach_type type)
- {
- int ret;
- mutex_lock(&cgroup_mutex);
- ret = __cgroup_bpf_detach(cgrp, prog, NULL, type);
- mutex_unlock(&cgroup_mutex);
- return ret;
- }
- int cgroup_bpf_query(struct cgroup *cgrp, const union bpf_attr *attr,
- union bpf_attr __user *uattr)
- {
- int ret;
- mutex_lock(&cgroup_mutex);
- ret = __cgroup_bpf_query(cgrp, attr, uattr);
- mutex_unlock(&cgroup_mutex);
- return ret;
- }
- #endif /* CONFIG_CGROUP_BPF */
- #ifdef CONFIG_SYSFS
- static ssize_t show_delegatable_files(struct cftype *files, char *buf,
- ssize_t size, const char *prefix)
- {
- struct cftype *cft;
- ssize_t ret = 0;
- for (cft = files; cft && cft->name[0] != '\0'; cft++) {
- if (!(cft->flags & CFTYPE_NS_DELEGATABLE))
- continue;
- if ((cft->flags & CFTYPE_PRESSURE) && !cgroup_psi_enabled())
- continue;
- if (prefix)
- ret += snprintf(buf + ret, size - ret, "%s.", prefix);
- ret += snprintf(buf + ret, size - ret, "%s\n", cft->name);
- if (WARN_ON(ret >= size))
- break;
- }
- return ret;
- }
- static ssize_t delegate_show(struct kobject *kobj, struct kobj_attribute *attr,
- char *buf)
- {
- struct cgroup_subsys *ss;
- int ssid;
- ssize_t ret = 0;
- ret = show_delegatable_files(cgroup_base_files, buf, PAGE_SIZE - ret,
- NULL);
- for_each_subsys(ss, ssid)
- ret += show_delegatable_files(ss->dfl_cftypes, buf + ret,
- PAGE_SIZE - ret,
- cgroup_subsys_name[ssid]);
- return ret;
- }
- static struct kobj_attribute cgroup_delegate_attr = __ATTR_RO(delegate);
- static ssize_t features_show(struct kobject *kobj, struct kobj_attribute *attr,
- char *buf)
- {
- return snprintf(buf, PAGE_SIZE,
- "nsdelegate\n"
- "memory_localevents\n"
- "memory_recursiveprot\n");
- }
- static struct kobj_attribute cgroup_features_attr = __ATTR_RO(features);
- static struct attribute *cgroup_sysfs_attrs[] = {
- &cgroup_delegate_attr.attr,
- &cgroup_features_attr.attr,
- NULL,
- };
- static const struct attribute_group cgroup_sysfs_attr_group = {
- .attrs = cgroup_sysfs_attrs,
- .name = "cgroup",
- };
- static int __init cgroup_sysfs_init(void)
- {
- return sysfs_create_group(kernel_kobj, &cgroup_sysfs_attr_group);
- }
- subsys_initcall(cgroup_sysfs_init);
- #endif /* CONFIG_SYSFS */
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