From dc6ce4bc2b355a47f225a0205046b3ebf29a7f72 Mon Sep 17 00:00:00 2001
From: Jackie Liu <liuyun01@kylinos.cn>
Date: Thu, 16 May 2019 11:46:30 +0800
Subject: [PATCH] io_uring: adjust smp_rmb inside io_cqring_events
Whenever smp_rmb is required to use io_cqring_events,
keep smp_rmb inside the function io_cqring_events.
Signed-off-by: Jackie Liu <liuyun01@kylinos.cn>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
---
fs/io_uring.c | 6 ++----
1 file changed, 2 insertions(+), 4 deletions(-)
diff --git a/fs/io_uring.c b/fs/io_uring.c
index 67d1aae349d7d..9cc7a101ef2a6 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -2167,6 +2167,8 @@ static int io_ring_submit(struct io_ring_ctx *ctx, unsigned int to_submit)
static unsigned io_cqring_events(struct io_cq_ring *ring)
{
+ /* See comment at the top of this file */
+ smp_rmb();
return READ_ONCE(ring->r.tail) - READ_ONCE(ring->r.head);
}
@@ -2182,8 +2184,6 @@ static int io_cqring_wait(struct io_ring_ctx *ctx, int min_events,
DEFINE_WAIT(wait);
int ret;
- /* See comment at the top of this file */
- smp_rmb();
if (io_cqring_events(ring) >= min_events)
return 0;
@@ -2205,8 +2205,6 @@ static int io_cqring_wait(struct io_ring_ctx *ctx, int min_events,
prepare_to_wait(&ctx->wait, &wait, TASK_INTERRUPTIBLE);
ret = 0;
- /* See comment at the top of this file */
- smp_rmb();
if (io_cqring_events(ring) >= min_events)
break;
--
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