Re: [PATCH net 4/4] virito-net: fix leaking page for gso packet during mergeable XDP

On 2018年05月21日 23:01, Michael S. Tsirkin wrote:

On Mon, May 21, 2018 at 04:35:06PM +0800, Jason Wang wrote:

quoted

We need to drop refcnt to xdp_page if we see a gso packet. Otherwise
it will be leaked. Fixing this by moving the check of gso packet above
the linearizing logic.

Cc: John Fastabend <john.fastabend@gmail.com>
Fixes: 72979a6c3590 ("virtio_net: xdp, add slowpath case for non contiguous buffers")
Signed-off-by: Jason Wang <redacted>

typo in subject

Let me fix it in V2.

quoted

---
  drivers/net/virtio_net.c | 16 ++++++++--------
  1 file changed, 8 insertions(+), 8 deletions(-)

diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index 165a922..f8db809 100644
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c

@@ -707,6 +707,14 @@ static struct sk_buff *receive_mergeable(struct net_device *dev,
  		void *data;
  		u32 act;
  
+		/* Transient failure which in theory could occur if
+		 * in-flight packets from before XDP was enabled reach
+		 * the receive path after XDP is loaded. In practice I
+		 * was not able to create this condition.

BTW we should probably drop the last sentence. It says in theory, should be enough.

Ok.

Thanks

quoted

+		 */
+		if (unlikely(hdr->hdr.gso_type))
+			goto err_xdp;
+
  		/* This happens when rx buffer size is underestimated
  		 * or headroom is not enough because of the buffer
  		 * was refilled before XDP is set. This should only

@@ -728,14 +736,6 @@ static struct sk_buff *receive_mergeable(struct net_device *dev,
  			xdp_page = page;
  		}
  
-		/* Transient failure which in theory could occur if
-		 * in-flight packets from before XDP was enabled reach
-		 * the receive path after XDP is loaded. In practice I
-		 * was not able to create this condition.
-		 */
-		if (unlikely(hdr->hdr.gso_type))
-			goto err_xdp;
-
  		/* Allow consuming headroom but reserve enough space to push
  		 * the descriptor on if we get an XDP_TX return code.
  		 */

-- 
2.7.4