diff options
Diffstat (limited to 'drivers/virtio/virtio_ring.c')
| -rw-r--r-- | drivers/virtio/virtio_ring.c | 20 |
1 files changed, 14 insertions, 6 deletions
diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c index 99dc9480f3fe..36bb6a613728 100644 --- a/drivers/virtio/virtio_ring.c +++ b/drivers/virtio/virtio_ring.c @@ -251,9 +251,20 @@ add_head: /* Put entry in available array (but don't update avail->idx until they * do sync). */ - avail = ((vq->vring.avail->idx + vq->num_added++) & (vq->vring.num-1)); + avail = (vq->vring.avail->idx & (vq->vring.num-1)); vq->vring.avail->ring[avail] = head; + /* Descriptors and available array need to be set before we expose the + * new available array entries. */ + virtio_wmb(vq); + vq->vring.avail->idx++; + vq->num_added++; + + /* This is very unlikely, but theoretically possible. Kick + * just in case. */ + if (unlikely(vq->num_added == (1 << 16) - 1)) + virtqueue_kick(_vq); + pr_debug("Added buffer head %i to %p\n", head, vq); END_USE(vq); @@ -283,13 +294,10 @@ bool virtqueue_kick_prepare(struct virtqueue *_vq) * new available array entries. */ virtio_wmb(vq); - old = vq->vring.avail->idx; - new = vq->vring.avail->idx = old + vq->num_added; + old = vq->vring.avail->idx - vq->num_added; + new = vq->vring.avail->idx; vq->num_added = 0; - /* Need to update avail index before checking if we should notify */ - virtio_mb(vq); - if (vq->event) { needs_kick = vring_need_event(vring_avail_event(&vq->vring), new, old); |