From: Pavel Begunkov <asml.silence@gmail.com>
To: Bui Quang Minh <minhquangbui99@gmail.com>, linux-kernel@vger.kernel.org
Cc: Jens Axboe <axboe@kernel.dk>,
io-uring@vger.kernel.org,
syzbot+3c750be01dab672c513d@syzkaller.appspotmail.com,
Li Zetao <lizetao1@huawei.com>
Subject: Re: [PATCH v2] io_uring: simplify the SQPOLL thread check when cancelling requests
Date: Mon, 13 Jan 2025 21:34:56 +0000 [thread overview]
Message-ID: <a5910007-017c-4b80-b0ae-e36569c88b15@gmail.com> (raw)
In-Reply-To: <20250113160331.44057-1-minhquangbui99@gmail.com>
On 1/13/25 16:03, Bui Quang Minh wrote:
> In io_uring_try_cancel_requests, we check whether sq_data->thread ==
> current to determine if the function is called by the SQPOLL thread to do
> iopoll when IORING_SETUP_SQPOLL is set. This check can race with the SQPOLL
> thread termination.
>
> io_uring_cancel_generic is used in 2 places: io_uring_cancel_generic and
> io_ring_exit_work. In io_uring_cancel_generic, we have the information
> whether the current is SQPOLL thread already. And the SQPOLL thread never
> reaches io_ring_exit_work.
>
> So to avoid the racy check, this commit adds a boolean flag to
> io_uring_try_cancel_requests to determine if the caller is SQPOLL thread.
I think the comment is excessive, but let's leave it at that if
you don't want to respin it.
Reviewed-by: Pavel Begunkov <asml.silence@gmail.com>
--
Pavel Begunkov
next prev parent reply other threads:[~2025-01-13 21:34 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-01-13 16:03 [PATCH v2] io_uring: simplify the SQPOLL thread check when cancelling requests Bui Quang Minh
2025-01-13 21:34 ` Pavel Begunkov [this message]
2025-01-13 22:30 ` Jens Axboe
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