drivers/vhost: Remove now-redundant read_barrier_depends()

Because READ_ONCE() now implies read_barrier_depends(), the
read_barrier_depends() in next_desc() is now redundant.  This commit
therefore removes it and the related comments.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Jason Wang <jasowang@redhat.com>
Cc: <kvm@vger.kernel.org>
Cc: <virtualization@lists.linux-foundation.org>
Cc: <netdev@vger.kernel.org>

diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c
index 33ac2b1..78b5940 100644 (file)
--- a/drivers/vhost/vhost.c
+++ b/drivers/vhost/vhost.c
@@ -1877,12 +1877,7 @@ static unsigned next_desc(struct vhost_virtqueue *vq, struct vring_desc *desc)
                return -1U;
 
        /* Check they're not leading us off end of descriptors. */
-       next = vhost16_to_cpu(vq, desc->next);
-       /* Make sure compiler knows to grab that: we don't want it changing! */
-       /* We will use the result as an index in an array, so most
-        * architectures only need a compiler barrier here. */
-       read_barrier_depends();
-
+       next = vhost16_to_cpu(vq, READ_ONCE(desc->next));
        return next;
 }