Commit 2a8ab0fb authored by Tejun Heo's avatar Tejun Heo
Browse files

Merge branch 'workqueue/for-5.16-fixes' into workqueue/for-5.17 

for-5.16-fixes contains two subtle race conditions which were introduced by
scheduler side code cleanups. The branch didn't get pushed out, so merge
into for-5.17.
parents 84f91c62 45c753f5

kernel/workqueue.c

+21 −1
Original line number Diff line number Diff line
@@ -864,8 +864,17 @@ void wq_worker_running(struct task_struct *task) 


	if (!worker->sleeping)

		return;



	/*

	 * If preempted by unbind_workers() between the WORKER_NOT_RUNNING check

	 * and the nr_running increment below, we may ruin the nr_running reset

	 * and leave with an unexpected pool->nr_running == 1 on the newly unbound

	 * pool. Protect against such race.

	 */

	preempt_disable();

	if (!(worker->flags & WORKER_NOT_RUNNING))

		atomic_inc(&worker->pool->nr_running);

	preempt_enable();

	worker->sleeping = 0;

}
@@ -898,6 +907,16 @@ void wq_worker_sleeping(struct task_struct *task) 
	worker->sleeping = 1;

	raw_spin_lock_irq(&pool->lock);



	/*

	 * Recheck in case unbind_workers() preempted us. We don't

	 * want to decrement nr_running after the worker is unbound

	 * and nr_running has been reset.

	 */

	if (worker->flags & WORKER_NOT_RUNNING) {

		raw_spin_unlock_irq(&pool->lock);

		return;

	}



	/*

	 * The counterpart of the following dec_and_test, implied mb,

	 * worklist not empty test sequence is in insert_work().
@@ -1526,7 +1545,8 @@ static void __queue_work(int cpu, struct workqueue_struct *wq, 
 * @work: work to queue

 *

 * We queue the work to a specific CPU, the caller must ensure it

 * can't go away.

 * can't go away.  Callers that fail to ensure that the specified

 * CPU cannot go away will execute on a randomly chosen CPU.

 *

 * Return: %false if @work was already on a queue, %true otherwise.

 */