From: Jens Axboe <[email protected]>
To: Pavel Begunkov <[email protected]>, [email protected]
Subject: Re: [PATCH 1/1] io_uring: fix racy REQ_F_LINK_TIMEOUT clearing
Date: Tue, 20 Oct 2020 08:10:39 -0600 [thread overview]
Message-ID: <[email protected]> (raw)
In-Reply-To: <5a8d5c3e3445a2f06070d827f15b4a04fac82076.1603120597.git.asml.silence@gmail.com>
On 10/19/20 9:39 AM, Pavel Begunkov wrote:
> io_link_timeout_fn() removes REQ_F_LINK_TIMEOUT from the link head's
> flags, it's not atomic and may race with what the head is doing.
>
> If io_link_timeout_fn() doesn't clear the flag, as forced by this patch,
> then it may happen that for "req -> link_timeout1 -> link_timeout2",
> __io_kill_linked_timeout() would find link_timeout2 and try to cancel
> it, so miscounting references. Teach it to ignore such double timeouts
> by marking the active one with a new flag in io_prep_linked_timeout().
Applied, thanks.
--
Jens Axboe
prev parent reply other threads:[~2020-10-20 14:10 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-19 15:39 [PATCH 1/1] io_uring: fix racy REQ_F_LINK_TIMEOUT clearing Pavel Begunkov
2020-10-20 14:10 ` Jens Axboe [this message]
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