netdev - [PATCHv5 net-next 02/16] udp6: move the mss check after udp gso tunnel processing

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Message-Id: <4f439ed717442a649ba78dc0efc6f121208a9995.1603955040.git.lucien.xin@gmail.com>
Date:   Thu, 29 Oct 2020 15:04:56 +0800
From:   Xin Long <lucien.xin@...il.com>
To:     network dev <netdev@...r.kernel.org>, linux-sctp@...r.kernel.org
Cc:     Marcelo Ricardo Leitner <marcelo.leitner@...il.com>,
        Neil Horman <nhorman@...driver.com>,
        Michael Tuexen <tuexen@...muenster.de>, davem@...emloft.net,
        Jakub Kicinski <kuba@...nel.org>, gnault@...hat.com,
        pabeni@...hat.com, willemdebruijn.kernel@...il.com
Subject: [PATCHv5 net-next 02/16] udp6: move the mss check after udp gso tunnel processing

For some protocol's gso, like SCTP, it's using GSO_BY_FRAGS for
gso_size. When using UDP to encapsulate its packet, it will
return error in udp6_ufo_fragment() as skb->len < gso_size,
and it will never go to the gso tunnel processing.

So we should move this check after udp gso tunnel processing,
the same as udp4_ufo_fragment() does.

v1->v2:
  - no change.
v2->v3:
  - not do any cleanup.

Signed-off-by: Xin Long <lucien.xin@...il.com>
---
 net/ipv6/udp_offload.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/net/ipv6/udp_offload.c b/net/ipv6/udp_offload.c
index 584157a..aa602af 100644
--- a/net/ipv6/udp_offload.c
+++ b/net/ipv6/udp_offload.c
@@ -28,10 +28,6 @@ static struct sk_buff *udp6_ufo_fragment(struct sk_buff *skb,
 	int tnl_hlen;
 	int err;
 
-	mss = skb_shinfo(skb)->gso_size;
-	if (unlikely(skb->len <= mss))
-		goto out;
-
 	if (skb->encapsulation && skb_shinfo(skb)->gso_type &
 	    (SKB_GSO_UDP_TUNNEL|SKB_GSO_UDP_TUNNEL_CSUM))
 		segs = skb_udp_tunnel_segment(skb, features, true);
@@ -48,6 +44,10 @@ static struct sk_buff *udp6_ufo_fragment(struct sk_buff *skb,
 		if (skb_shinfo(skb)->gso_type & SKB_GSO_UDP_L4)
 			return __udp_gso_segment(skb, features);
 
+		mss = skb_shinfo(skb)->gso_size;
+		if (unlikely(skb->len <= mss))
+			goto out;
+
 		/* Do software UFO. Complete and fill in the UDP checksum as HW cannot
 		 * do checksum of UDP packets sent as multiple IP fragments.
 		 */
-- 
2.1.0