On Wed, Mar 26, 2014 at 01:03:00PM +0800, Jason Wang wrote:
> 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
> 67975901183799af8e93ec60e322f9e2a1940b9b.
>
> Fixes 67975901183799af8e93ec60e322f9e2a1940b9b
> (virtio_net: verify if virtqueue_kick() succeeded).
>
> Cc: Heinz Graalfs <graalfs@xxxxxxxxxxxxxxxxxx>
> Cc: Rusty Russell <rusty@xxxxxxxxxxxxxxx>
> Cc: Michael S. Tsirkin <mst@xxxxxxxxxx>
> Signed-off-by: Jason Wang <jasowang@xxxxxxxxxx>
Acked-by: Michael S. Tsirkin <mst@xxxxxxxxxx>
> ---
> drivers/net/virtio_net.c | 6 +++---
> 1 files changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
> index 5632a99..841b608 100644
> --- 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);
> --
> 1.7.1
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