Re: [PATCH] slow_work_execute() needs mb() before test_bit(SLOW_WORK_PENDING)

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From: Oleg Nesterov

Subject: Re: [PATCH] slow_work_execute() needs mb() before test_bit(SLOW_WORK_PENDING)

Date: Thursday, April 16, 2009 - 7:15 am

On 04/16, David Howells wrote:
quoted text>
> Oleg Nesterov <oleg@redhat.com> wrote:
>
> > But why do we need the barrier before clear_bit(SLOW_WORK_EXECUTING) ?
> > We do have one after test_and_clear_bit(SLOW_WORK_PENDING) above, and it
> > should be enough, no?
>
> No.  There lock is covering work->ops->execute(work) too, and that is after
> the clearance of SLOW_WORK_PENDING.  The UNLOCK-class barrier must go between
> execution and clearance of the execution lock bit.

Ah. Now I see.

It is still not clear to me whether we need a barrier after clear_bit_unlock.

Thanks David!

Oleg.

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Messages in current thread:

[PATCH] slow_work_execute() needs mb() before test_bit(SLO ..., Oleg Nesterov, (Mon Apr 13, 1:13 pm)

Re: [PATCH] slow_work_execute() needs mb() before test_bit ..., Oleg Nesterov, (Mon Apr 13, 1:13 pm)

Re: [PATCH] slow_work_execute() needs mb() before test_bit ..., David Howells, (Mon Apr 13, 2:47 pm)

Re: [PATCH] slow_work_execute() needs mb() before test_bit ..., Oleg Nesterov, (Mon Apr 13, 3:02 pm)

Re: [PATCH] slow_work_execute() needs mb() before test_bit ..., David Howells, (Thu Apr 16, 2:43 am)

Re: [PATCH] slow_work_execute() needs mb() before test_bit ..., Oleg Nesterov, (Thu Apr 16, 7:15 am)

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