Hi,
On Thu, 3 Nov 2016 09:06:27 -0400 (EDT) Lance Richardson <[email protected]>
wrote:
> I'm not sure what could be added that would help, was there something
> specific you had in mind?
How about something like this (preliminary, feel free to massage):
@@ -248,10 +248,16 @@ static int ip_finish_output_gso(struct net *net, struct
sock *sk,
/* Slowpath - GSO segment length is exceeding the dst MTU.
*
- * This can happen in two cases:
- * 1) TCP GRO packet, DF bit not set
- * 2) skb arrived via virtio-net, we thus get TSO/GSO skbs directly
- * from host network stack.
+ * This can happen in several cases:
+ * - Forwarding of TCP GRO packet, DF bit not set
+ * - Forwarding of skb arrived in a virtualization environment (from
+ * virtio-net/vhost/tap) with TSO/GSO size set by other's network
+ * stack
+ * - Local GSO skb xmitted on an NETIF_F_TSO tunnel stacked over an
+ * interface with a smaller mtu
+ * - Arriving GRO skb (or GSO skb in a virtualized env) that gets L2
+ * bridged to a NETIF_F_TSO tunnel stacked over an interface with an
+ * insufficent mtu
*/
features = netif_skb_features(skb);
BUILD_BUG_ON(sizeof(*IPCB(skb)) > SKB_SGO_CB_OFFSET);
