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

[Jens Axboe <axboe@kernel.dk>]

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);
+
 	/* always use real head, to avoid losing sync for short submit */
-	return ring->sq.sqe_tail - io_uring_load_sq_head(ring);
+	return ring->sq.sqe_tail - head;
 }
 
 /*
@@ -2063,7 +2068,7 @@ IOURINGINLINE struct io_uring_sqe *io_uring_get_sqe128(struct io_uring *ring)
 	LIBURING_NOEXCEPT
 {
 	struct io_uring_sq *sq = &ring->sq;
-	unsigned head = io_uring_load_sq_head(ring), tail = sq->sqe_tail;
+	unsigned head = 0, tail = sq->sqe_tail;
 	struct io_uring_sqe *sqe;
 
 	if (ring->flags & IORING_SETUP_SQE128)
@@ -2071,6 +2076,9 @@ IOURINGINLINE struct io_uring_sqe *io_uring_get_sqe128(struct io_uring *ring)
 	if (!(ring->flags & IORING_SETUP_SQE_MIXED))
 		return NULL;
 
+	if (!(ring->flags & IORING_SETUP_SQ_REWIND))
+		head = io_uring_load_sq_head(ring);
+
 	if (((tail + 1) & sq->ring_mask) == 0) {
 		if ((tail + 2) - head >= sq->ring_entries)
 			return NULL;

-- 
Jens Axboe