Re: [PATCH net] virtio-net: don't free skb immediately on kick failure
From: "Michael S. Tsirkin" <mst@redhat.com>
Date: 2014-03-23 11:27:19
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On Fri, Mar 21, 2014 at 04:30:01PM +0800, Jason Wang wrote:
We free the skb immediately on kick failure during xmit without detaching it
from the virtqueue. This may lead double free for the skb during
free_unused_bufs(). This patch fixes this by not freeing it on kick failure and
let it to be freed through free_unused_bufs().
Fixes 67975901183799af8e93ec60e322f9e2a1940b9b
("virtio_net: verify if virtqueue_kick() succeeded").It's not even obvious we want to increment fifo errors counter. So basically we want to ignore these errors. In that case how about just reverting this chunk of the patch? Seems cleaner than adding more code. The chunk filling in RX also seems inappropriate: it will cause RX work to be requeued which isn't what we wanted. Also, what happens with virtnet_send_command? Looks like that patch is completely wrong.
quoted hunk ↗ jump to hunk
Cc: Rusty Russell <redacted> Cc: Michael S. Tsirkin <mst@redhat.com> Cc: Heinz Graalfs <redacted> Signed-off-by: Jason Wang <jasowang@redhat.com> --- drivers/net/virtio_net.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-)diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c index 5632a99..d833d38 100644 --- a/drivers/net/virtio_net.c +++ b/drivers/net/virtio_net.c@@ -882,8 +882,10 @@ static netdev_tx_t start_xmit(struct sk_buff *skb, struct net_device *dev) if (net_ratelimit()) dev_warn(&dev->dev, "Unexpected TXQ (%d) queue failure: %d\n", qnum, err); - dev->stats.tx_dropped++; - kfree_skb(skb); + if (err) { + dev->stats.tx_dropped++; + kfree_skb(skb); + } return NETDEV_TX_OK; }-- 1.8.3.2