Re: [PATCH net 3/4] virtio-net: reset num_buf to 1 after linearizing packet
From: "Michael S. Tsirkin" <mst@redhat.com>
Date: 2018-05-21 14:59:14
On Mon, May 21, 2018 at 04:35:05PM +0800, Jason Wang wrote:
quoted hunk
If we successfully linearize the packets, num_buf were set to zero which was wrong since we now have only 1 buffer to be used for e.g in the error path of receive_mergeable(). Zero num_buf will lead the code try to pop the buffers of next packet and drop it. Fixing this by set num_buf to 1 if we successfully linearize the packet. Fixes: 4941d472bf95 ("virtio-net: do not reset during XDP set") Signed-off-by: Jason Wang <redacted> --- drivers/net/virtio_net.c | 1 + 1 file changed, 1 insertion(+)diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c index 6260d65..165a922 100644 --- a/drivers/net/virtio_net.c +++ b/drivers/net/virtio_net.c@@ -722,6 +722,7 @@ static struct sk_buff *receive_mergeable(struct net_device *dev, &len); if (!xdp_page) goto err_xdp; + num_buf = 1;
So this is tweaked here for the benefit of err_skb below.
That's confusing and we won't remember to change it
if we change the error handling.
How about fixing the error path?
- while (--num_buf) {
+ while (num_buf-- > 1) {
Seems more robust to me.
offset = VIRTIO_XDP_HEADROOM;
} else {
xdp_page = page;
--
2.7.4