Messages in this thread Patch in this message | | | Date | Tue, 11 Aug 2009 17:06:17 -0400 (EDT) | From | Alan Stern <> | Subject | [PATCH] Add kerneldoc for flush_scheduled_work() |
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This patch (as1279) adds kerneldoc for flush_scheduled_work() containing a stern warning that the function should be avoided.
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
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Index: usb-2.6/kernel/workqueue.c =================================================================== --- usb-2.6.orig/kernel/workqueue.c +++ usb-2.6/kernel/workqueue.c @@ -739,6 +739,24 @@ int schedule_on_each_cpu(work_func_t fun return 0; } +/** + * flush_scheduled_work - ensure that all work scheduled on keventd_wq has run to completion. + * + * Blocks until all works on the keventd_wq global workqueue have completed. + * We sleep until all works present upon entry have been handled, but we + * are not livelocked by new incoming ones. + * + * Use of this function is discouraged, as it is highly prone to deadlock. + * It should never be called from within a work routine on the global + * queue, and it should never be called while holding a mutex required + * by one of the works on the global queue. But the fact that keventd_wq + * _is_ global means that it can contain works requiring practically any + * mutex. Hence this routine shouldn't be called while holding any mutex. + * + * Consider using cancel_work_sync() or cancel_delayed_work_sync() instead. + * They don't do the same thing (they cancel the work instead of waiting + * for it to complete), but in most cases they will suffice. + */ void flush_scheduled_work(void) { flush_workqueue(keventd_wq);
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