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

[David Howells]

Oleg Nesterov <oleg@xxxxxxxxxx> 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.

David
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