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Commit efb2b1d5 authored by Linus Torvalds's avatar Linus Torvalds
Browse files

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

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
parents 26a41cd1 77668c8b

kernel/workqueue.c

+30 −6
Original line number Diff line number Diff line
@@ -1916,6 +1916,12 @@ static void send_mayday(struct work_struct *work) 


	/* mayday mayday mayday */

	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);

		wake_up_process(wq->rescuer->task);

	}
@@ -2398,6 +2404,7 @@ static int rescuer_thread(void *__rescuer) 
	struct worker *rescuer = __rescuer;

	struct workqueue_struct *wq = rescuer->rescue_wq;

	struct list_head *scheduled = &rescuer->scheduled;

	bool should_stop;



	set_user_nice(current, RESCUER_NICE_LEVEL);
@@ -2409,11 +2416,15 @@ static int rescuer_thread(void *__rescuer) 
repeat:

	set_current_state(TASK_INTERRUPTIBLE);



	if (kthread_should_stop()) {

		__set_current_state(TASK_RUNNING);

		rescuer->task->flags &= ~PF_WQ_WORKER;

		return 0;

	}

	/*

	 * By the time the rescuer is requested to stop, the workqueue

	 * shouldn't have any work pending, but @wq->maydays may still have

	 * 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 */

	spin_lock_irq(&wq_mayday_lock);
@@ -2444,6 +2455,12 @@ static int rescuer_thread(void *__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

		 * regular worker; otherwise, we end up with 0 concurrency
@@ -2459,6 +2476,12 @@ static int rescuer_thread(void *__rescuer) 


	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 */

	WARN_ON_ONCE(!(rescuer->flags & WORKER_NOT_RUNNING));

	schedule();
@@ -4100,7 +4123,8 @@ static void wq_update_unbound_numa(struct workqueue_struct *wq, int cpu, 
	if (!pwq) {

		pr_warning("workqueue: allocation failed while updating NUMA affinity of \"%s\"\n",

			   wq->name);

		goto out_unlock;

		mutex_lock(&wq->mutex);

		goto use_dfl_pwq;

	}



	/*