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- /*
- * RT-Mutexes: blocking mutual exclusion locks with PI support
- *
- * started by Ingo Molnar and Thomas Gleixner:
- *
- * Copyright (C) 2004-2006 Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
- * Copyright (C) 2006 Timesys Corp., Thomas Gleixner <tglx@timesys.com>
- *
- * This code is based on the rt.c implementation in the preempt-rt tree.
- * Portions of said code are
- *
- * Copyright (C) 2004 LynuxWorks, Inc., Igor Manyilov, Bill Huey
- * Copyright (C) 2006 Esben Nielsen
- * Copyright (C) 2006 Kihon Technologies Inc.,
- * Steven Rostedt <rostedt@goodmis.org>
- *
- * See rt.c in preempt-rt for proper credits and further information
- */
- #include <linux/sched.h>
- #include <linux/delay.h>
- #include <linux/module.h>
- #include <linux/spinlock.h>
- #include <linux/kallsyms.h>
- #include <linux/syscalls.h>
- #include <linux/interrupt.h>
- #include <linux/plist.h>
- #include <linux/fs.h>
- #include <linux/debug_locks.h>
- #include "rtmutex_common.h"
- #ifdef CONFIG_DEBUG_RT_MUTEXES
- # include "rtmutex-debug.h"
- #else
- # include "rtmutex.h"
- #endif
- # define TRACE_WARN_ON(x) WARN_ON(x)
- # define TRACE_BUG_ON(x) BUG_ON(x)
- # define TRACE_OFF() \
- do { \
- if (rt_trace_on) { \
- rt_trace_on = 0; \
- console_verbose(); \
- if (spin_is_locked(¤t->pi_lock)) \
- spin_unlock(¤t->pi_lock); \
- } \
- } while (0)
- # define TRACE_OFF_NOLOCK() \
- do { \
- if (rt_trace_on) { \
- rt_trace_on = 0; \
- console_verbose(); \
- } \
- } while (0)
- # define TRACE_BUG_LOCKED() \
- do { \
- TRACE_OFF(); \
- BUG(); \
- } while (0)
- # define TRACE_WARN_ON_LOCKED(c) \
- do { \
- if (unlikely(c)) { \
- TRACE_OFF(); \
- WARN_ON(1); \
- } \
- } while (0)
- # define TRACE_BUG_ON_LOCKED(c) \
- do { \
- if (unlikely(c)) \
- TRACE_BUG_LOCKED(); \
- } while (0)
- #ifdef CONFIG_SMP
- # define SMP_TRACE_BUG_ON_LOCKED(c) TRACE_BUG_ON_LOCKED(c)
- #else
- # define SMP_TRACE_BUG_ON_LOCKED(c) do { } while (0)
- #endif
- /*
- * deadlock detection flag. We turn it off when we detect
- * the first problem because we dont want to recurse back
- * into the tracing code when doing error printk or
- * executing a BUG():
- */
- int rt_trace_on = 1;
- void deadlock_trace_off(void)
- {
- rt_trace_on = 0;
- }
- static void printk_task(struct task_struct *p)
- {
- if (p)
- printk("%16s:%5d [%p, %3d]", p->comm, p->pid, p, p->prio);
- else
- printk("<none>");
- }
- static void printk_lock(struct rt_mutex *lock, int print_owner)
- {
- if (lock->name)
- printk(" [%p] {%s}\n",
- lock, lock->name);
- else
- printk(" [%p] {%s:%d}\n",
- lock, lock->file, lock->line);
- if (print_owner && rt_mutex_owner(lock)) {
- printk(".. ->owner: %p\n", lock->owner);
- printk(".. held by: ");
- printk_task(rt_mutex_owner(lock));
- printk("\n");
- }
- }
- void rt_mutex_debug_task_free(struct task_struct *task)
- {
- WARN_ON(!plist_head_empty(&task->pi_waiters));
- WARN_ON(task->pi_blocked_on);
- }
- /*
- * We fill out the fields in the waiter to store the information about
- * the deadlock. We print when we return. act_waiter can be NULL in
- * case of a remove waiter operation.
- */
- void debug_rt_mutex_deadlock(int detect, struct rt_mutex_waiter *act_waiter,
- struct rt_mutex *lock)
- {
- struct task_struct *task;
- if (!rt_trace_on || detect || !act_waiter)
- return;
- task = rt_mutex_owner(act_waiter->lock);
- if (task && task != current) {
- act_waiter->deadlock_task_pid = task->pid;
- act_waiter->deadlock_lock = lock;
- }
- }
- void debug_rt_mutex_print_deadlock(struct rt_mutex_waiter *waiter)
- {
- struct task_struct *task;
- if (!waiter->deadlock_lock || !rt_trace_on)
- return;
- task = find_task_by_pid(waiter->deadlock_task_pid);
- if (!task)
- return;
- TRACE_OFF_NOLOCK();
- printk("\n============================================\n");
- printk( "[ BUG: circular locking deadlock detected! ]\n");
- printk( "--------------------------------------------\n");
- printk("%s/%d is deadlocking current task %s/%d\n\n",
- task->comm, task->pid, current->comm, current->pid);
- printk("\n1) %s/%d is trying to acquire this lock:\n",
- current->comm, current->pid);
- printk_lock(waiter->lock, 1);
- printk("\n2) %s/%d is blocked on this lock:\n", task->comm, task->pid);
- printk_lock(waiter->deadlock_lock, 1);
- debug_show_held_locks(current);
- debug_show_held_locks(task);
- printk("\n%s/%d's [blocked] stackdump:\n\n", task->comm, task->pid);
- show_stack(task, NULL);
- printk("\n%s/%d's [current] stackdump:\n\n",
- current->comm, current->pid);
- dump_stack();
- debug_show_all_locks();
- printk("[ turning off deadlock detection."
- "Please report this trace. ]\n\n");
- local_irq_disable();
- }
- void debug_rt_mutex_lock(struct rt_mutex *lock)
- {
- }
- void debug_rt_mutex_unlock(struct rt_mutex *lock)
- {
- TRACE_WARN_ON_LOCKED(rt_mutex_owner(lock) != current);
- }
- void
- debug_rt_mutex_proxy_lock(struct rt_mutex *lock, struct task_struct *powner)
- {
- }
- void debug_rt_mutex_proxy_unlock(struct rt_mutex *lock)
- {
- TRACE_WARN_ON_LOCKED(!rt_mutex_owner(lock));
- }
- void debug_rt_mutex_init_waiter(struct rt_mutex_waiter *waiter)
- {
- memset(waiter, 0x11, sizeof(*waiter));
- plist_node_init(&waiter->list_entry, MAX_PRIO);
- plist_node_init(&waiter->pi_list_entry, MAX_PRIO);
- }
- void debug_rt_mutex_free_waiter(struct rt_mutex_waiter *waiter)
- {
- TRACE_WARN_ON(!plist_node_empty(&waiter->list_entry));
- TRACE_WARN_ON(!plist_node_empty(&waiter->pi_list_entry));
- TRACE_WARN_ON(waiter->task);
- memset(waiter, 0x22, sizeof(*waiter));
- }
- void debug_rt_mutex_init(struct rt_mutex *lock, const char *name)
- {
- /*
- * Make sure we are not reinitializing a held lock:
- */
- debug_check_no_locks_freed((void *)lock, sizeof(*lock));
- lock->name = name;
- }
- void
- rt_mutex_deadlock_account_lock(struct rt_mutex *lock, struct task_struct *task)
- {
- }
- void rt_mutex_deadlock_account_unlock(struct task_struct *task)
- {
- }
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