Re: [PATCH v2] io_uring: simplify the SQPOLL thread check when cancelling requests

[Pavel Begunkov]

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@xxxxxxxxx>

--
Pavel Begunkov