From 17d3aeb33cdae8c87a8ad97c4358a623a630e19a Mon Sep 17 00:00:00 2001
From: Pavel Begunkov <asml.silence@gmail.com>
Date: Mon, 14 Jun 2021 23:37:23 +0100
Subject: [PATCH] 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>
---
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 a0720fb2565c9..c74a84a2532b3 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];
--
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