From: Pavel Begunkov <asml.silence@gmail.com>
To: Jens Axboe <axboe@kernel.dk>, io-uring@vger.kernel.org
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: <4f4d9d3f-64cf-dd02-4e7f-364a9c04012b@gmail.com> (raw)
In-Reply-To: <f61f129e-8709-1b40-86eb-42cb672fe74f@kernel.dk>
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
next prev parent 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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