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Commit eef6a7d5 authored by Alan Stern's avatar Alan Stern Committed by Tejun Heo
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workqueue: warn about flush_scheduled_work()



This patch (as1319) adds kerneldoc and a pointed warning to
flush_scheduled_work().

Signed-off-by: default avatarAlan Stern <stern@rowland.harvard.edu>
Signed-off-by: default avatarTejun Heo <tj@kernel.org>
parent 47dd5be2
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+24 −0
Original line number Diff line number Diff line
@@ -845,6 +845,30 @@ int schedule_on_each_cpu(work_func_t func)
	return 0;
}

/**
 * flush_scheduled_work - ensure that any scheduled work has run to completion.
 *
 * Forces execution of the kernel-global workqueue and blocks until its
 * completion.
 *
 * Think twice before calling this function!  It's very easy to get into
 * trouble if you don't take great care.  Either of the following situations
 * will lead to deadlock:
 *
 *	One of the work items currently on the workqueue needs to acquire
 *	a lock held by your code or its caller.
 *
 *	Your code is running in the context of a work routine.
 *
 * They will be detected by lockdep when they occur, but the first might not
 * occur very often.  It depends on what work items are on the workqueue and
 * what locks they need, which you have no control over.
 *
 * In most situations flushing the entire workqueue is overkill; you merely
 * need to know that a particular work item isn't queued and isn't running.
 * In such cases you should use cancel_delayed_work_sync() or
 * cancel_work_sync() instead.
 */
void flush_scheduled_work(void)
{
	flush_workqueue(keventd_wq);