IP_GRE: Fix GRE_CSUM case.

commit "ip_gre: allow CSUM capable devices to handle packets"
aa0e51cdda005cd37e2, broke GRE_CSUM case.
GRE_CSUM needs checksum computed for inner packet. Therefore
csum-calculation can not be offloaded if tunnel device requires
GRE_CSUM.  Following patch fixes it by computing inner packet checksum
for GRE_CSUM type, for all other type of GRE devices csum is offloaded.

CC: Dmitry Kravkov <dmitry@broadcom.com>
Signed-off-by: Pravin B Shelar <pshelar@nicira.com>
Acked-by: Dmitry Kravkov <dmitry@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 8 insertions, 4 deletions

diff --git a/net/ipv4/ip_gre.c b/net/ipv4/ip_gre.c
index b8bada00d516..406512934507 100644
--- a/net/ipv4/ip_gre.c
+++ b/net/ipv4/ip_gre.c
@@ -735,7 +735,7 @@ drop:
         return 0;
 }
 
-static struct sk_buff *handle_offloads(struct sk_buff *skb)
+static struct sk_buff *handle_offloads(struct ip_tunnel *tunnel, struct sk_buff *skb)
 {
         int err;
 
@@ -745,8 +745,12 @@ static struct sk_buff *handle_offloads(struct sk_buff *skb)
                         goto error;
                 skb_shinfo(skb)->gso_type |= SKB_GSO_GRE;
                 return skb;
-        }
-        if (skb->ip_summed != CHECKSUM_PARTIAL)
+        } else if (skb->ip_summed == CHECKSUM_PARTIAL &&
+                   tunnel->parms.o_flags&GRE_CSUM) {
+                err = skb_checksum_help(skb);
+                if (unlikely(err))
+                        goto error;
+        } else if (skb->ip_summed != CHECKSUM_PARTIAL)
                 skb->ip_summed = CHECKSUM_NONE;
 
         return skb;
@@ -776,7 +780,7 @@ static netdev_tx_t ipgre_tunnel_xmit(struct sk_buff *skb, struct net_device *dev
         int    err;
         int    pkt_len;
 
-        skb = handle_offloads(skb);
+        skb = handle_offloads(tunnel, skb);
         if (IS_ERR(skb)) {
                 dev->stats.tx_dropped++;
                 return NETDEV_TX_OK;