Re: [PATCH 1/1 V2] workqueue: remove the del_timer_sync()s in maybe_create_worker()

From: Tejun Heo
Date: Mon Jul 14 2014 - 10:27:35 EST


On Mon, Jul 14, 2014 at 04:13:21PM +0800, Lai Jiangshan wrote:
> It is said in the document that the timer which is being
> deleted by del_timer_sync() should not be restarted:
> Synchronization rules: Callers must prevent restarting of
> the timer, otherwise this function is meaningless.
> Repeating timer may cause the del_timer_sync() spin longer,
> or even spin forever in very very very very extreme condition.

I'm fairly sure del_timer_sync() can delete self-requeueing timers.
The implementation busy-waits if the queued timer is the currently
executing one and dequeues only while the timer isn't running which
should be able to handle self-requeueing ones just fine. Thomas,
del_timer_sync() can reliably delete self-requeueing ones, right?


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