Re: [PATCH liburing 0/2] Add support for IORING_SETUP_SQ_REWIND

[Jens Axboe <axboe@kernel.dk>]

On 1/23/26 7:14 AM, Pavel Begunkov wrote:
> On 1/22/26 23:05, Jens Axboe wrote:
>> On 1/22/26 3:59 PM, Jens Axboe wrote:
>>>
>>> On Wed, 21 Jan 2026 22:23:20 +0000, Pavel Begunkov wrote:
>>>> Add liburing support and tests for IORING_SETUP_SQ_REWIND.
>>>>
>>>> Pavel Begunkov (2):
>>>>    src/queue: Add support for non circular SQ
>>>>    tests: add SETUP_SQ_REWIND tests
>>>>
>>>> src/include/liburing.h          |  5 ++++-
>>>>   src/include/liburing/io_uring.h | 12 ++++++++++++
>>>>   src/queue.c                     |  5 +++++
>>>>   test/test.h                     |  2 ++
>>>>   4 files changed, 23 insertions(+), 1 deletion(-)
>>>>
>>>> [...]
>>>
>>> Applied, thanks!
>>>
>>> [1/2] src/queue: Add support for non circular SQ
>>>        commit: c22129cf0b8c936eb478d920ef84e53d89c6a5cc
>>> [2/2] tests: add SETUP_SQ_REWIND tests
>>>        commit: 346c063d16bda52f02d00feb744aafe35b4002a9
>>
>> Hmm I do think you're missing some spots though, no?
>>
>> diff --git a/src/include/liburing.h b/src/include/liburing.h
>> index 987b28aaf99e..016be1e80ef2 100644
>> --- a/src/include/liburing.h
>> +++ b/src/include/liburing.h
>> @@ -1702,8 +1702,13 @@ IOURINGINLINE unsigned io_uring_load_sq_head(const struct io_uring *ring)
>>   IOURINGINLINE unsigned io_uring_sq_ready(const struct io_uring *ring)
>>       LIBURING_NOEXCEPT
>>   {
>> +    unsigned head = 0;
>> +
>> +    if (!(ring->flags & IORING_SETUP_SQ_REWIND))
>> +        head = io_uring_load_sq_head(ring);
> 
> The head should already be zero. Actually, sounds like the get_sqe
> hunk from the patch is not needed either.

Yeah agree, I think they are both false alarms. Might warrant a comment
though. Or maybe we just fold it into io_uring_load_sq_head()?

-- 
Jens Axboe