virtio: correct the memory barrier in virtqueue_kick_prepare()

[cascardo/linux.git] / drivers / virtio / virtio_ring.c

diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
index 79e1b29..5aa43c3 100644 (file)
--- a/drivers/virtio/virtio_ring.c
+++ b/drivers/virtio/virtio_ring.c
@@ -35,7 +35,7 @@
 #define virtio_rmb(vq) \
        do { if ((vq)->weak_barriers) smp_rmb(); else rmb(); } while(0)
 #define virtio_wmb(vq) \
-       do { if ((vq)->weak_barriers) smp_rmb(); else rmb(); } while(0)
+       do { if ((vq)->weak_barriers) smp_wmb(); else wmb(); } while(0)
 #else
 /* We must force memory ordering even if guest is UP since host could be
  * running on another CPU, but SMP barriers are defined to barrier() in that
@@ -308,9 +308,9 @@ bool virtqueue_kick_prepare(struct virtqueue *_vq)
        bool needs_kick;
 
        START_USE(vq);
-       /* Descriptors and available array need to be set before we expose the
-        * new available array entries. */
-       virtio_wmb(vq);
+       /* We need to expose available array entries before checking avail
+        * event. */
+       virtio_mb(vq);
 
        old = vq->vring.avail->idx - vq->num_added;
        new = vq->vring.avail->idx;