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From: Pavel Begunkov <[email protected]>
To: Jens Axboe <[email protected]>, [email protected]
Subject: Re: io_uring: io_fail_links() should only consider first linked timeout
Date: Wed, 20 Nov 2019 18:02:12 +0300	[thread overview]
Message-ID: <[email protected]> (raw)
In-Reply-To: <[email protected]>

On 11/20/2019 5:22 PM, Jens Axboe wrote:
>> However, this is only true if linked timeout isn't fired. Otherwise,
>> there is another bug, which isn't fixed by either of the patches. We
>> need to clear REQ_F_LINK_TIMEOUT in io_link_timeout_fn() as well.
>>
>> Let: REQ -> L_TIMEOUT1 -> L_TIMEOUT2
>> 1. L_TIMEOUT1 fired before REQ is completed
>>
>> 2. io_link_timeout_fn() removes L_TIMEOUT1 from the list:
>> REQ|REQ_F_LINK_TIMEOUT -> L_TIMEOUT2
>>
>> 3. free_req(REQ) then call io_link_cancel_timeout(L_TIMEOUT2)
>> leaking it (as described in my patch).
>>
>> P.S. haven't tried to test nor reproduce it yet.
> 
> That's exactly the case I was worried about. In any case, it seems
> prudent to handle it defensively.
> 
Yeah, I've got from the patch that may have missed something.

Will you add this "should clear REQ_F_LINK_TIMEOUT in
io_link_timeout_fn()" (e.g. in v2), or should I?

-- 
Pavel Begunkov

  reply	other threads:[~2019-11-20 15:02 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-11-19 22:33 io_uring: io_fail_links() should only consider first linked timeout Jens Axboe
2019-11-20  8:44 ` Pavel Begunkov
2019-11-20 10:22   ` Bob Liu
2019-11-20 11:07     ` Pavel Begunkov
2019-11-20 14:03       ` Bob Liu
2019-11-20 14:23         ` Jens Axboe
2019-11-20 14:28         ` Pavel Begunkov
2019-11-20 14:22   ` Jens Axboe
2019-11-20 15:02     ` Pavel Begunkov [this message]
2019-11-20 15:06       ` Jens Axboe

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