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io_uring: refactor io_get_sqe() 

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>
Link: https://lore.kernel.org/r/866ad6e4ef4851c7c61f6b0e08dbd0a8d1abce84.1623709150.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Pavel Begunkov 2021-06-14 23:37:23 +01:00 committed by Jens Axboe
parent 7f1129d227
commit 17d3aeb33c
1 changed files with 2 additions and 2 deletions
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4
fs/io_uring.c
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@ -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];