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>

1 files changed, 2 insertions, 4 deletions

diff --git a/fs/io_uring.c b/fs/io_uring.c
index 67d1aae349d7..9cc7a101ef2a 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;