Re: [RFC,PATCH] workqueues: turn queue_work() into the "barrier" for work->func()

[David Howells]

Oleg Nesterov <oleg@xxxxxxxxxx> wrote:

> I think the caller of queue_work() has all rights to expect that
> the next invocation of work_func() must see "VAR == 1", but this
> is not true if the work is already pending.

As you said, queue_work() does test_and_set_bit() which implies smp_mb()
either side of the function, so you're half way there, and run_workqueue()
calls spin_unlock_irq() just before calling work_clear_pending()...  So might
it make sense to move the work_clear_pending() into locked section?  Or would
that require an smp_mb__before_clear_bit()?

David
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