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- /*
- * drivers/power/process.c - Functions for starting/stopping processes on
- * suspend transitions.
- *
- * Originally from swsusp.
- */
- #undef DEBUG
- #include <linux/smp_lock.h>
- #include <linux/interrupt.h>
- #include <linux/suspend.h>
- #include <linux/module.h>
- #include <linux/syscalls.h>
- #include <linux/freezer.h>
- /*
- * Timeout for stopping processes
- */
- #define TIMEOUT (20 * HZ)
- #define FREEZER_KERNEL_THREADS 0
- #define FREEZER_USER_SPACE 1
- static inline int freezeable(struct task_struct * p)
- {
- if ((p == current) ||
- (p->flags & PF_NOFREEZE) ||
- (p->exit_state == EXIT_ZOMBIE) ||
- (p->exit_state == EXIT_DEAD))
- return 0;
- return 1;
- }
- /* Refrigerator is place where frozen processes are stored :-). */
- void refrigerator(void)
- {
- /* Hmm, should we be allowed to suspend when there are realtime
- processes around? */
- long save;
- save = current->state;
- pr_debug("%s entered refrigerator\n", current->comm);
- frozen_process(current);
- spin_lock_irq(¤t->sighand->siglock);
- recalc_sigpending(); /* We sent fake signal, clean it up */
- spin_unlock_irq(¤t->sighand->siglock);
- while (frozen(current)) {
- current->state = TASK_UNINTERRUPTIBLE;
- schedule();
- }
- pr_debug("%s left refrigerator\n", current->comm);
- current->state = save;
- }
- static inline void freeze_process(struct task_struct *p)
- {
- unsigned long flags;
- if (!freezing(p)) {
- rmb();
- if (!frozen(p)) {
- if (p->state == TASK_STOPPED)
- force_sig_specific(SIGSTOP, p);
- freeze(p);
- spin_lock_irqsave(&p->sighand->siglock, flags);
- signal_wake_up(p, p->state == TASK_STOPPED);
- spin_unlock_irqrestore(&p->sighand->siglock, flags);
- }
- }
- }
- static void cancel_freezing(struct task_struct *p)
- {
- unsigned long flags;
- if (freezing(p)) {
- pr_debug(" clean up: %s\n", p->comm);
- do_not_freeze(p);
- spin_lock_irqsave(&p->sighand->siglock, flags);
- recalc_sigpending_tsk(p);
- spin_unlock_irqrestore(&p->sighand->siglock, flags);
- }
- }
- static inline int is_user_space(struct task_struct *p)
- {
- return p->mm && !(p->flags & PF_BORROWED_MM);
- }
- static unsigned int try_to_freeze_tasks(int freeze_user_space)
- {
- struct task_struct *g, *p;
- unsigned long end_time;
- unsigned int todo;
- end_time = jiffies + TIMEOUT;
- do {
- todo = 0;
- read_lock(&tasklist_lock);
- do_each_thread(g, p) {
- if (!freezeable(p))
- continue;
- if (frozen(p))
- continue;
- if (p->state == TASK_TRACED && frozen(p->parent)) {
- cancel_freezing(p);
- continue;
- }
- if (is_user_space(p)) {
- if (!freeze_user_space)
- continue;
- /* Freeze the task unless there is a vfork
- * completion pending
- */
- if (!p->vfork_done)
- freeze_process(p);
- } else {
- if (freeze_user_space)
- continue;
- freeze_process(p);
- }
- todo++;
- } while_each_thread(g, p);
- read_unlock(&tasklist_lock);
- yield(); /* Yield is okay here */
- if (todo && time_after(jiffies, end_time))
- break;
- } while (todo);
- if (todo) {
- /* This does not unfreeze processes that are already frozen
- * (we have slightly ugly calling convention in that respect,
- * and caller must call thaw_processes() if something fails),
- * but it cleans up leftover PF_FREEZE requests.
- */
- printk("\n");
- printk(KERN_ERR "Stopping %s timed out after %d seconds "
- "(%d tasks refusing to freeze):\n",
- freeze_user_space ? "user space processes" :
- "kernel threads",
- TIMEOUT / HZ, todo);
- read_lock(&tasklist_lock);
- do_each_thread(g, p) {
- if (is_user_space(p) == !freeze_user_space)
- continue;
- if (freezeable(p) && !frozen(p))
- printk(KERN_ERR " %s\n", p->comm);
- cancel_freezing(p);
- } while_each_thread(g, p);
- read_unlock(&tasklist_lock);
- }
- return todo;
- }
- /**
- * freeze_processes - tell processes to enter the refrigerator
- *
- * Returns 0 on success, or the number of processes that didn't freeze,
- * although they were told to.
- */
- int freeze_processes(void)
- {
- unsigned int nr_unfrozen;
- printk("Stopping tasks ... ");
- nr_unfrozen = try_to_freeze_tasks(FREEZER_USER_SPACE);
- if (nr_unfrozen)
- return nr_unfrozen;
- sys_sync();
- nr_unfrozen = try_to_freeze_tasks(FREEZER_KERNEL_THREADS);
- if (nr_unfrozen)
- return nr_unfrozen;
- printk("done.\n");
- BUG_ON(in_atomic());
- return 0;
- }
- static void thaw_tasks(int thaw_user_space)
- {
- struct task_struct *g, *p;
- read_lock(&tasklist_lock);
- do_each_thread(g, p) {
- if (!freezeable(p))
- continue;
- if (is_user_space(p) == !thaw_user_space)
- continue;
- if (!thaw_process(p))
- printk(KERN_WARNING " Strange, %s not stopped\n",
- p->comm );
- } while_each_thread(g, p);
- read_unlock(&tasklist_lock);
- }
- void thaw_processes(void)
- {
- printk("Restarting tasks ... ");
- thaw_tasks(FREEZER_KERNEL_THREADS);
- thaw_tasks(FREEZER_USER_SPACE);
- schedule();
- printk("done.\n");
- }
- EXPORT_SYMBOL(refrigerator);
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