Commit 681daee2 authored Mar 26, 2014 by Jason Wang Committed by David S. Miller Mar 27, 2014

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
67975901.

Fixes 67975901
(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>

parent de144391

drivers/net/virtio_net.c

+3 −3

Original line number	Diff line number	Diff line
		@@ -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);

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