Re: [PATCH for-next 1/7] io_uring: use user visible tail in io_uring_poll()

Jens Axboe
2023-01-23T21:09:47Z

On 1/23/23 1:56 PM, Pavel Begunkov wrote:
> On 1/23/23 18:25, Jens Axboe wrote:
>> On 1/23/23 7:37 AM, Pavel Begunkov wrote:
>>> We return POLLIN from io_uring_poll() depending on whether there are
>>> CQEs for the userspace, and so we should use the user visible tail
>>> pointer instead of a transient cached value.
>>
>> Should we mark this one for stable as well?
> Yeah, we can. It makes it to overestimate the number of ready CQEs
> and causes spurious POLLINs, but should be extremely rare and happen
> only on queue (but not wq wake up).

Right, it's not critical, but we may as well.

--
Jens Axboe