[3.13.y-ckt stable] Patch "gre: fix the inner mac header in nbma tunnel xmit path" has been added to staging queue

[Kamal Mostafa]

This is a note to let you know that I have just added a patch titled

    gre: fix the inner mac header in nbma tunnel xmit path

to the linux-3.13.y-queue branch of the 3.13.y-ckt extended stable tree 
which can be found at:

 http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.13.y-queue

This patch is scheduled to be released in version 3.13.11-ckt15.

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.13.y-ckt tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Kamal

------

>From 646c38fb16913b76cafc84fcf40730c3601703df Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Timo=20Ter=C3=A4s?= <timo.teras at iki.fi>
Date: Mon, 15 Dec 2014 09:24:13 +0200
Subject: gre: fix the inner mac header in nbma tunnel xmit path
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

[ Upstream commit 8a0033a947403569caeca45fa5e6f7ba60d51974 ]

The NBMA GRE tunnels temporarily push GRE header that contain the
per-packet NBMA destination on the skb via header ops early in xmit
path. It is the later pulled before the real GRE header is constructed.

The inner mac was thus set differently in nbma case: the GRE header
has been pushed by neighbor layer, and mac header points to beginning
of the temporary gre header (set by dev_queue_xmit).

Now that the offloads expect mac header to point to the gre payload,
fix the xmit patch to:
 - pull first the temporary gre header away
 - and reset mac header to point to gre payload

This fixes tso to work again with nbma tunnels.

Fixes: 14051f0452a2 ("gre: Use inner mac length when computing tunnel length")
Signed-off-by: Timo Teräs <timo.teras at iki.fi>
Cc: Tom Herbert <therbert at google.com>
Cc: Alexander Duyck <alexander.h.duyck at redhat.com>
Signed-off-by: David S. Miller <davem at davemloft.net>
Signed-off-by: Kamal Mostafa <kamal at canonical.com>
---
 net/ipv4/ip_gre.c | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/net/ipv4/ip_gre.c b/net/ipv4/ip_gre.c
index b3becd0..b22c309 100644
--- a/net/ipv4/ip_gre.c
+++ b/net/ipv4/ip_gre.c
@@ -250,10 +250,6 @@ static netdev_tx_t ipgre_xmit(struct sk_buff *skb,
 	struct ip_tunnel *tunnel = netdev_priv(dev);
 	const struct iphdr *tnl_params;

-	skb = gre_handle_offloads(skb, !!(tunnel->parms.o_flags&TUNNEL_CSUM));
-	if (IS_ERR(skb))
-		goto out;
-
 	if (dev->header_ops) {
 		/* Need space for new headers */
 		if (skb_cow_head(skb, dev->needed_headroom -
@@ -266,6 +262,7 @@ static netdev_tx_t ipgre_xmit(struct sk_buff *skb,
 		 * to gre header.
 		 */
 		skb_pull(skb, tunnel->hlen + sizeof(struct iphdr));
+		skb_reset_mac_header(skb);
 	} else {
 		if (skb_cow_head(skb, dev->needed_headroom))
 			goto free_skb;
@@ -273,6 +270,10 @@ static netdev_tx_t ipgre_xmit(struct sk_buff *skb,
 		tnl_params = &tunnel->parms.iph;
 	}

+	skb = gre_handle_offloads(skb, !!(tunnel->parms.o_flags&TUNNEL_CSUM));
+	if (IS_ERR(skb))
+		goto out;
+
 	__gre_xmit(skb, dev, tnl_params, skb->protocol);

 	return NETDEV_TX_OK;
--
1.9.1