[PATCH 1/2] io_uring: adjust smp_rmb inside io_cqring_events

[Jackie Liu]

Whenever smp_rmb is required to use io_cqring_events,
keep smp_rmb inside the function io_cqring_events.

Signed-off-by: Jackie Liu <liuyu...@kylinos.cn>
---
 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 84efb89..516f036 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -2044,6 +2044,8 @@ 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);
 }
 
@@ -2059,8 +2061,6 @@ 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;
 
@@ -2082,8 +2082,6 @@ 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;
 
-- 
2.7.4