From: Pavel Begunkov <asml.silence@gmail.com>
To: Ren Wei <n05ec@lzu.edu.cn>, io-uring@vger.kernel.org
Cc: axboe@kernel.dk, yifanwucs@gmail.com, tomapufckgml@gmail.com,
yuantan098@gmail.com, bird@lzu.edu.cn, zcliangcn@gmail.com,
ylong030@ucr.edu
Subject: Re: [PATCH 1/1] io_uring/poll: fix signed comparison in io_poll_get_ownership()
Date: Tue, 14 Apr 2026 11:50:29 +0100 [thread overview]
Message-ID: <703f88ff-5242-406c-87e2-8cf1a70bbf57@gmail.com> (raw)
In-Reply-To: <3a3508b08bcd7f1bc3beff848ae6e1d73d355043.1775965597.git.ylong030@ucr.edu>
On 4/12/26 09:38, Ren Wei wrote:
> From: Longxuan Yu <ylong030@ucr.edu>
>
> io_poll_get_ownership() uses a signed comparison to check whether
> poll_refs has reached the threshold for the slowpath:
>
> if (unlikely(atomic_read(&req->poll_refs) >= IO_POLL_REF_BIAS))
>
> atomic_read() returns int (signed). When IO_POLL_CANCEL_FLAG
> (BIT(31)) is set in poll_refs, the value becomes negative in
> signed arithmetic, so the >= 128 comparison always evaluates to
> false and the slowpath is never taken.
>
> Fix this by casting the atomic_read() result to unsigned int
> before the comparison, so that the cancel flag is treated as a
> large positive value and correctly triggers the slowpath.
Looks good, thanks for the patch
Reviewed-by: Pavel Begunkov <asml.silence@gmail.com>
--
Pavel Begunkov
next prev parent reply other threads:[~2026-04-14 10:50 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <cover.1775965597.git.ylong030@ucr.edu>
2026-04-12 8:38 ` [PATCH 1/1] io_uring/poll: fix signed comparison in io_poll_get_ownership() Ren Wei
2026-04-14 10:50 ` Pavel Begunkov [this message]
2026-04-15 20:08 ` Jens Axboe
2026-04-15 20:09 ` Jens Axboe
2026-04-16 1:50 ` Yuan Tan
2026-04-16 15:28 ` Jens Axboe
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