[PATCH 04/12] io_uring: refactor io_get_sqe()

Pavel Begunkov
2021-06-14T22:39:05Z

The line of io_get_sqe() evaluating @head consists of too many
operations including READ_ONCE(), it's not convenient for probing.
Refactor it also improving readability.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
---
fs/io_uring.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/fs/io_uring.c b/fs/io_uring.c
index 5cc0c4dd2709..3baacfe2c9b7 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -6685,8 +6685,8 @@ static void io_commit_sqring(struct io_ring_ctx *ctx)
*/
static const struct io_uring_sqe *io_get_sqe(struct io_ring_ctx *ctx)
{
- u32 *sq_array = ctx->sq_array;
unsigned head, mask = ctx->sq_entries - 1;
+ unsigned sq_idx = ctx->cached_sq_head++ & mask;

/*
* The cached sq head (or cq tail) serves two purposes:
@@ -6696,7 +6696,7 @@ static const struct io_uring_sqe *io_get_sqe(struct io_ring_ctx *ctx)
* 2) allows the kernel side to track the head on its own, even
* though the application is the one updating it.
*/
- head = READ_ONCE(sq_array[ctx->cached_sq_head++ & mask]);
+ head = READ_ONCE(ctx->sq_array[sq_idx]);
if (likely(head < ctx->sq_entries))
return &ctx->sq_sqes[head];

--
2.31.1