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Merge branch 'for-3.15-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq

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Pull workqueue fixes from Tejun Heo:
 "Fixes for two bugs in workqueue.

  One is exiting with internal mutex held in a failure path of
  wq_update_unbound_numa().  The other is a subtle and unlikely
  use-after-possible-last-put in the rescuer logic.  Both have been
  around for quite some time now and are unlikely to have triggered
  noticeably often.  All patches are marked for -stable backport"

* 'for-3.15-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq:
  workqueue: fix a possible race condition between rescuer and pwq-release
  workqueue: make rescuer_thread() empty wq->maydays list before exiting
  workqueue: fix bugs in wq_update_unbound_numa() failure path
This commit is contained in:
Linus Torvalds 2014-05-13 11:24:07 +09:00
commit efb2b1d5fd
1 changed files with 30 additions and 6 deletions
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36
kernel/workqueue.c
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@ -1916,6 +1916,12 @@ static void send_mayday(struct work_struct *work)
/* mayday mayday mayday */ /* mayday mayday mayday */
if (list_empty(&pwq->mayday_node)) { if (list_empty(&pwq->mayday_node)) {
/*
* If @pwq is for an unbound wq, its base ref may be put at
* any time due to an attribute change. Pin @pwq until the
* rescuer is done with it.
*/
get_pwq(pwq);
list_add_tail(&pwq->mayday_node, &wq->maydays); list_add_tail(&pwq->mayday_node, &wq->maydays);
wake_up_process(wq->rescuer->task); wake_up_process(wq->rescuer->task);
} }
@ -2398,6 +2404,7 @@ static int rescuer_thread(void *__rescuer)
struct worker *rescuer = __rescuer; struct worker *rescuer = __rescuer;
struct workqueue_struct *wq = rescuer->rescue_wq; struct workqueue_struct *wq = rescuer->rescue_wq;
struct list_head *scheduled = &rescuer->scheduled; struct list_head *scheduled = &rescuer->scheduled;
bool should_stop;
set_user_nice(current, RESCUER_NICE_LEVEL); set_user_nice(current, RESCUER_NICE_LEVEL);
@ -2409,11 +2416,15 @@ static int rescuer_thread(void *__rescuer)
repeat: repeat:
set_current_state(TASK_INTERRUPTIBLE); set_current_state(TASK_INTERRUPTIBLE);
if (kthread_should_stop()) { /*
__set_current_state(TASK_RUNNING); * By the time the rescuer is requested to stop, the workqueue
rescuer->task->flags &= ~PF_WQ_WORKER; * shouldn't have any work pending, but @wq->maydays may still have
return 0; * pwq(s) queued. This can happen by non-rescuer workers consuming
} * all the work items before the rescuer got to them. Go through
* @wq->maydays processing before acting on should_stop so that the
* list is always empty on exit.
*/
should_stop = kthread_should_stop();
/* see whether any pwq is asking for help */ /* see whether any pwq is asking for help */
spin_lock_irq(&wq_mayday_lock); spin_lock_irq(&wq_mayday_lock);
@ -2444,6 +2455,12 @@ repeat:
process_scheduled_works(rescuer); process_scheduled_works(rescuer);
/*
* Put the reference grabbed by send_mayday(). @pool won't
* go away while we're holding its lock.
*/
put_pwq(pwq);
/* /*
* Leave this pool. If keep_working() is %true, notify a * Leave this pool. If keep_working() is %true, notify a
* regular worker; otherwise, we end up with 0 concurrency * regular worker; otherwise, we end up with 0 concurrency
@ -2459,6 +2476,12 @@ repeat:
spin_unlock_irq(&wq_mayday_lock); spin_unlock_irq(&wq_mayday_lock);
if (should_stop) {
__set_current_state(TASK_RUNNING);
rescuer->task->flags &= ~PF_WQ_WORKER;
return 0;
}
/* rescuers should never participate in concurrency management */ /* rescuers should never participate in concurrency management */
WARN_ON_ONCE(!(rescuer->flags & WORKER_NOT_RUNNING)); WARN_ON_ONCE(!(rescuer->flags & WORKER_NOT_RUNNING));
schedule(); schedule();
@ -4100,7 +4123,8 @@ static void wq_update_unbound_numa(struct workqueue_struct *wq, int cpu,
if (!pwq) { if (!pwq) {
pr_warning("workqueue: allocation failed while updating NUMA affinity of \"%s\"\n", pr_warning("workqueue: allocation failed while updating NUMA affinity of \"%s\"\n",
wq->name); wq->name);
goto out_unlock; mutex_lock(&wq->mutex);
goto use_dfl_pwq;
} }
/* /*