Messages in this thread | | | Date | Mon, 25 Apr 2016 13:51:15 -0400 | From | Tejun Heo <> | Subject | Re: [PATCH 1/1] [RFC] workqueue: fix ghost PENDING flag while doing MQ IO |
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Hello, Roman.
On Mon, Apr 25, 2016 at 07:39:52PM +0200, Roman Penyaev wrote: > Ok, that's clear now. Thanks. I was confused also by a spin lock, which > is being released just after clear pending: > > set_work_pool_and_clear_pending(work, pool->id); > spin_unlock_irq(&pool->lock); > ... > worker->current_func(work); > > But seems memory operations of execution can leak-in and appear before > pended bit is cleared and spin lock is released. > (according to Documentation/memory-barriers.txt, (6) RELEASE operations)
Yeap, release doesn't prevent following reads from creeping ahead of it.
> Tejun, do you need an updated patch for that? With a proper smp_mb()?
Yes, can you please also add comment explaining what the mb is interlocking?
Thanks a lot!
-- tejun
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