gro: fix aggregation for skb using frag_list

In commit 8a29111c7ca6 ("net: gro: allow to build full sized skb")
I added a regression for linear skb that traditionally force GRO
to use the frag_list fallback.

Erez Shitrit found that at most two segments were aggregated and
the "if (skb_gro_len(p) != pinfo->gso_size)" test was failing.

This is because pinfo at this spot still points to the last skb in the
chain, instead of the first one, where we find the correct gso_size
information.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Fixes: 8a29111c7ca6 ("net: gro: allow to build full sized skb")
Reported-by: Erez Shitrit <erezsh@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 3 insertions, 0 deletions

diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index da1378a3e2c7..8d289697cc7a 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -3152,6 +3152,9 @@ int skb_gro_receive(struct sk_buff **head, struct sk_buff *skb)
                 NAPI_GRO_CB(skb)->free = NAPI_GRO_FREE_STOLEN_HEAD;
                 goto done;
         }
+        /* switch back to head shinfo */
+        pinfo = skb_shinfo(p);
+
         if (pinfo->frag_list)
                 goto merge;
         if (skb_gro_len(p) != pinfo->gso_size)