Re: [PATCH 1/2] io_uring: wait potential ->release() on resurrect

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On 2/19/21 8:47 PM, Pavel Begunkov wrote:
> On 20/02/2021 03:40, Jens Axboe wrote:
>> On 2/19/21 6:39 PM, Pavel Begunkov wrote:
>>> There is a short window where percpu_refs are already turned zero, but
>>> we try to do resurrect(). Play nicer and wait for all users to leave RCU
>>> section.
>>
>> We need to do something better than synchronize_rcu() here, that can
>> take a long time on a loaded box. I'll try and think about this one.
> 
> It only happens when it can't be drained and there are task_works or
> signals. I have another patch, doing it via tryget, but it's uglier and
> I'd rather prefer synchronize_rcu for stable.

Right, but the task_work coming in may not be unlikely. So it's not
strictly an error path.

-- 
Jens Axboe




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