#undef DEBUG
#include <linux/interrupt.h>
+#include <linux/oom.h>
#include <linux/suspend.h>
#include <linux/module.h>
#include <linux/syscalls.h>
#include <linux/freezer.h>
+#include <linux/delay.h>
+#include <linux/workqueue.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)
+static inline int freezable(struct task_struct * p)
{
if ((p == current) ||
(p->flags & PF_NOFREEZE) ||
return 1;
}
-/*
- * freezing is complete, mark current process as frozen
- */
-static inline void frozen_process(void)
-{
- if (!unlikely(current->flags & PF_NOFREEZE)) {
- current->flags |= PF_FROZEN;
- wmb();
- }
- clear_freeze_flag(current);
-}
-
-/* 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;
-
- task_lock(current);
- if (freezing(current)) {
- frozen_process();
- task_unlock(current);
- } else {
- task_unlock(current);
- return;
- }
- save = current->state;
- pr_debug("%s entered refrigerator\n", current->comm);
-
- spin_lock_irq(¤t->sighand->siglock);
- recalc_sigpending(); /* We sent fake signal, clean it up */
- spin_unlock_irq(¤t->sighand->siglock);
-
- for (;;) {
- set_current_state(TASK_UNINTERRUPTIBLE);
- if (!frozen(current))
- break;
- schedule();
- }
- pr_debug("%s left refrigerator\n", current->comm);
- current->state = save;
-}
-
-static void freeze_task(struct task_struct *p)
-{
- unsigned long flags;
-
- if (!freezing(p)) {
- rmb();
- if (!frozen(p)) {
- set_freeze_flag(p);
- if (p->state == TASK_STOPPED)
- force_sig_specific(SIGSTOP, 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);
- clear_freeze_flag(p);
- spin_lock_irqsave(&p->sighand->siglock, flags);
- recalc_sigpending_and_wake(p);
- spin_unlock_irqrestore(&p->sighand->siglock, flags);
- }
-}
-
-static unsigned int try_to_freeze_tasks(int freeze_user_space)
+static int try_to_freeze_tasks(bool sig_only)
{
struct task_struct *g, *p;
unsigned long end_time;
unsigned int todo;
+ bool wq_busy = false;
+ struct timeval start, end;
+ u64 elapsed_csecs64;
+ unsigned int elapsed_csecs;
+ bool wakeup = false;
+
+ do_gettimeofday(&start);
end_time = jiffies + TIMEOUT;
- do {
+
+ if (!sig_only)
+ freeze_workqueues_begin();
+
+ while (true) {
todo = 0;
read_lock(&tasklist_lock);
do_each_thread(g, p) {
- if (frozen(p) || !freezeable(p))
+ if (frozen(p) || !freezable(p))
continue;
- if (freeze_user_space) {
- if (p->state == TASK_TRACED &&
- frozen(p->parent)) {
- cancel_freezing(p);
- continue;
- }
- /*
- * Kernel threads should not have TIF_FREEZE set
- * at this point, so we must ensure that either
- * p->mm is not NULL *and* PF_BORROWED_MM is
- * unset, or TIF_FRREZE is left unset.
- * The task_lock() is necessary to prevent races
- * with exit_mm() or use_mm()/unuse_mm() from
- * occuring.
- */
- task_lock(p);
- if (!p->mm || (p->flags & PF_BORROWED_MM)) {
- task_unlock(p);
- continue;
- }
- freeze_task(p);
- task_unlock(p);
- } else {
- freeze_task(p);
- }
- if (!freezer_should_skip(p))
+ if (!freeze_task(p, sig_only))
+ continue;
+
+ /*
+ * Now that we've done set_freeze_flag, don't
+ * perturb a task in TASK_STOPPED or TASK_TRACED.
+ * It is "frozen enough". If the task does wake
+ * up, it will immediately call try_to_freeze.
+ *
+ * Because freeze_task() goes through p's
+ * scheduler lock after setting TIF_FREEZE, it's
+ * guaranteed that either we see TASK_RUNNING or
+ * try_to_stop() after schedule() in ptrace/signal
+ * stop sees TIF_FREEZE.
+ */
+ if (!task_is_stopped_or_traced(p) &&
+ !freezer_should_skip(p))
todo++;
} while_each_thread(g, p);
read_unlock(&tasklist_lock);
- yield(); /* Yield is okay here */
- if (todo && time_after(jiffies, end_time))
+
+ if (!sig_only) {
+ wq_busy = freeze_workqueues_busy();
+ todo += wq_busy;
+ }
+
+ if (!todo || time_after(jiffies, end_time))
+ break;
+
+ if (pm_wakeup_pending()) {
+ wakeup = true;
break;
- } while (todo);
+ }
+
+ /*
+ * We need to retry, but first give the freezing tasks some
+ * time to enter the regrigerator.
+ */
+ msleep(10);
+ }
+
+ do_gettimeofday(&end);
+ elapsed_csecs64 = timeval_to_ns(&end) - timeval_to_ns(&start);
+ do_div(elapsed_csecs64, NSEC_PER_SEC / 100);
+ elapsed_csecs = elapsed_csecs64;
if (todo) {
/* This does not unfreeze processes that are already frozen
* but it cleans up leftover PF_FREEZE requests.
*/
printk("\n");
- printk(KERN_ERR "Freezing of %s timed out after %d seconds "
- "(%d tasks refusing to freeze):\n",
- freeze_user_space ? "user space " : "tasks ",
- TIMEOUT / HZ, todo);
- show_state();
+ printk(KERN_ERR "Freezing of tasks %s after %d.%02d seconds "
+ "(%d tasks refusing to freeze, wq_busy=%d):\n",
+ wakeup ? "aborted" : "failed",
+ elapsed_csecs / 100, elapsed_csecs % 100,
+ todo - wq_busy, wq_busy);
+
+ thaw_workqueues();
+
read_lock(&tasklist_lock);
do_each_thread(g, p) {
task_lock(p);
- if (freezing(p) && !freezer_should_skip(p))
- printk(KERN_ERR " %s\n", p->comm);
+ if (!wakeup && freezing(p) && !freezer_should_skip(p))
+ sched_show_task(p);
cancel_freezing(p);
task_unlock(p);
} while_each_thread(g, p);
read_unlock(&tasklist_lock);
+ } else {
+ printk("(elapsed %d.%02d seconds) ", elapsed_csecs / 100,
+ elapsed_csecs % 100);
}
- return todo;
+ return todo ? -EBUSY : 0;
}
/**
* 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;
+ int error;
- printk("Stopping tasks ... ");
- nr_unfrozen = try_to_freeze_tasks(FREEZER_USER_SPACE);
- if (nr_unfrozen)
- return nr_unfrozen;
+ printk("Freezing user space processes ... ");
+ error = try_to_freeze_tasks(true);
+ if (error)
+ goto Exit;
+ printk("done.\n");
- sys_sync();
- nr_unfrozen = try_to_freeze_tasks(FREEZER_KERNEL_THREADS);
- if (nr_unfrozen)
- return nr_unfrozen;
+ printk("Freezing remaining freezable tasks ... ");
+ error = try_to_freeze_tasks(false);
+ if (error)
+ goto Exit;
+ printk("done.");
- printk("done.\n");
+ oom_killer_disable();
+ Exit:
BUG_ON(in_atomic());
- return 0;
+ printk("\n");
+
+ return error;
}
-static void thaw_tasks(int thaw_user_space)
+static void thaw_tasks(bool nosig_only)
{
struct task_struct *g, *p;
read_lock(&tasklist_lock);
do_each_thread(g, p) {
- if (!freezeable(p))
+ if (!freezable(p))
continue;
- if (!p->mm == thaw_user_space)
+ if (nosig_only && should_send_signal(p))
+ continue;
+
+ if (cgroup_freezing_or_frozen(p))
continue;
thaw_process(p);
void thaw_processes(void)
{
+ oom_killer_enable();
+
printk("Restarting tasks ... ");
- thaw_tasks(FREEZER_KERNEL_THREADS);
- thaw_tasks(FREEZER_USER_SPACE);
+ thaw_workqueues();
+ thaw_tasks(true);
+ thaw_tasks(false);
schedule();
printk("done.\n");
}
-EXPORT_SYMBOL(refrigerator);