[PATCH] udp: let rx-udp-gro-forwarding aggregate under encapsulation

[PATCH] udp: let rx-udp-gro-forwarding aggregate under encapsulation

[Eva Kurchatova]

The rx-udp-gro-forwarding checks of the veth kselftest fail with "got
10 packets, expected 1" on a host where something uses UDP
encapsulation, a vxlan say, and pass on a host where nothing does.

Since commit f2e9de210d50 ("udp: gro behind static key") the receiving
socket is looked up only once a tunnel socket exists, and commit
36707061d6ba ("udp: allow forwarding of plain (non-fraglisted) UDP GRO
packets") takes "no socket found" for "forwarded" and aggregates only
then. So the device setting works on a host without a tunnel and stops
working with one.

Aggregate whenever the device asks, socket found or not. That is what
every host without a tunnel has done all along: a local socket without
UDP_GRO gets the packets resegmented on delivery, and a tunnel socket
keeps its own receive path.

Fixes: 36707061d6ba ("udp: allow forwarding of plain (non-fraglisted) UDP GRO packets")
Signed-off-by: Eva Kurchatova <eva.kurchatova@virtuozzo.com>
---
 net/ipv4/udp_offload.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/ipv4/udp_offload.c b/net/ipv4/udp_offload.c
index cf07c3c6611a..d4e0e6bb9959 100644
--- a/net/ipv4/udp_offload.c
+++ b/net/ipv4/udp_offload.c
@@ -804,7 +804,7 @@ struct sk_buff *udp_gro_receive(struct list_head *head, struct sk_buff *skb,
 		if (skb->dev->features & NETIF_F_GRO_FRAGLIST)
 			NAPI_GRO_CB(skb)->is_flist = sk ? !udp_test_bit(GRO_ENABLED, sk) : 1;
 
-		if ((!sk && (skb->dev->features & NETIF_F_GRO_UDP_FWD)) ||
+		if ((skb->dev->features & NETIF_F_GRO_UDP_FWD) ||
 		    (sk && udp_test_bit(GRO_ENABLED, sk)) || NAPI_GRO_CB(skb)->is_flist)
 			return call_gro_receive(udp_gro_receive_segment, head, skb);
 
-- 
2.56.0