Messages in this thread | | | Date | Mon, 18 Dec 2006 16:27:01 -0800 | From | Andrew Morton <> | Subject | Re: [PATCH, RFC] reimplement flush_workqueue() |
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On Mon, 18 Dec 2006 01:34:16 +0300 Oleg Nesterov <oleg@tv-sign.ru> wrote:
> Remove ->remove_sequence, ->insert_sequence, and ->work_done from > struct cpu_workqueue_struct. To implement flush_workqueue() we can > queue a barrier work on each CPU and wait for its completition.
Seems sensible. I seem to recall considering doing it that way when I initially implemeted flush_workqueue(), but I don't recall why I didn't do this. hmm.
> We don't need to worry about CPU going down while we are are sleeping > on the completition. take_over_work() will move this work on another > CPU, and the handler will wake up us eventually. > > NOTE: I removed 'int cpu' parameter, flush_workqueue() locks/unlocks > workqueue_mutex unconditionally. It may be restored, but I think it > doesn't make much sense, we take the mutex for the very short time, > and the code becomes simpler. >
Taking workqueue_mutex() unconditionally in flush_workqueue() means that we'll deadlock if a single-threaded workqueue callback handler calls flush_workqueue().
It's an idiotic thing to do, but I think I spotted a site last week which does this. scsi? Not sure.. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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