Re: [PATCH liburing] Fix hang in in io_uring_get_cqe() with iopoll

[Jens Axboe <axboe@kernel.dk>]

On 6/21/20 4:30 AM, Pavel Begunkov wrote:
> Because of need_resched() check, io_uring_enter() -> io_iopoll_check()
> can return 0 even if @min_complete wasn't satisfied. If that's the
> case, __io_uring_get_cqe() sets submit=0 and wait_nr=0, disabling
> setting IORING_ENTER_GETEVENTS as well. So, it goes crazy calling
> io_uring_enter() in a loop, not actually submitting nor polling.
> 
> Set @wait_nr based on actual number of CQEs ready.
> BTW, atomic_load_acquire() in io_uring_cq_ready() can be replaced
> with a relaxed one for this particular place.

Can you preface this with an addition of __io_uring_cqe_ready() that
doesn't include the load acquire?

Also, s/io_adjut_wait_nr/io_adjust_wait_nr for the patch.

-- 
Jens Axboe