virtio-net: correct error handling of virtqueue_kick()

Current error handling of virtqueue_kick() was wrong in two places:
- The skb were freed immediately when virtqueue_kick() fail during
  xmit. This may lead double free since the skb was not detached from
  the virtqueue.
- try_fill_recv() returns false when virtqueue_kick() fail. This will
  lead unnecessary rescheduling of refill work.

Actually, it's safe to just ignore the kick failure in those two
places. So this patch fixes this by partially revert commit
af005b45b1e88f7a4839aba0ba8425ba7e5a51f7.

Fixes af005b45b1e88f7a4839aba0ba8425ba7e5a51f7
(virtio_net: verify if virtqueue_kick() succeeded).

Cc: Heinz Graalfs <graalfs@linux.vnet.ibm.com>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Jason Wang <jasowang@redhat.com>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index 5632a99cbbd24fdd059c182e5b28d1d19b3ea4e9..841b60831df1b2e83c12f55ee5e8fc90874b9475 100644 (file)
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -671,8 +671,7 @@ static bool try_fill_recv(struct receive_queue *rq, gfp_t gfp)
                if (err)
                        break;
        } while (rq->vq->num_free);
-       if (unlikely(!virtqueue_kick(rq->vq)))
-               return false;
+       virtqueue_kick(rq->vq);
        return !oom;
 }
 
@@ -877,7 +876,7 @@ static netdev_tx_t start_xmit(struct sk_buff *skb, struct net_device *dev)
        err = xmit_skb(sq, skb);
 
        /* This should not happen! */
-       if (unlikely(err) || unlikely(!virtqueue_kick(sq->vq))) {
+       if (unlikely(err)) {
                dev->stats.tx_fifo_errors++;
                if (net_ratelimit())
                        dev_warn(&dev->dev,
@@ -886,6 +885,7 @@ static netdev_tx_t start_xmit(struct sk_buff *skb, struct net_device *dev)
                kfree_skb(skb);
                return NETDEV_TX_OK;
        }
+       virtqueue_kick(sq->vq);
 
        /* Don't wait up for transmitted skbs to be freed. */
        skb_orphan(skb);