On Fri, 18 Nov 2022 20:20:29 +0000, Pavel Begunkov wrote:
> poll_refs carry two functions, the first is ownership over the request.
> The second is notifying the io_poll_check_events() that there was an
> event but wake up couldn't grab the ownership, so io_poll_check_events()
> should retry.
>
> We want to make poll_refs more robust against overflows. Instead of
> always incrementing it, which covers two purposes with one atomic, check
> if poll_refs is large and if so set a retry flag without attempts to
> grab ownership. The gap between the bias check and following atomics may
> seem racy, but we don't need it to be strict. Moreover there might only
> be maximum 4 parallel updates: by the first and the second poll entries,
> __io_arm_poll_handler() and cancellation. From those four, only poll wake
> ups may be executed multiple times, but they're protected by a spin.
>
> [...]
Applied, thanks!
[1/1] io_uring: make poll refs more robust
(no commit info)
Best regards,
--
Jens Axboe
