net: Fix possible wrong checksum generation.

Patch cef401de7be8c4e (net: fix possible wrong checksum
generation) fixed wrong checksum calculation but it broke TSO by
defining new GSO type but not a netdev feature for that type.
net_gso_ok() would not allow hardware checksum/segmentation
offload of such packets without the feature.

Following patch fixes TSO and wrong checksum. This patch uses
same logic that Eric Dumazet used. Patch introduces new flag
SKBTX_SHARED_FRAG if at least one frag can be modified by
the user. but SKBTX_SHARED_FRAG flag is kept in skb shared
info tx_flags rather than gso_type.

tx_flags is better compared to gso_type since we can have skb with
shared frag without gso packet. It does not link SHARED_FRAG to
GSO, So there is no need to define netdev feature for this.

Signed-off-by: Pravin B Shelar <pshelar@nicira.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 2 insertions, 2 deletions

diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
index 564bf89d9fd3..6182d90e97b0 100644
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c
@@ -1133,7 +1133,6 @@ static void tcp_queue_skb(struct sock *sk, struct sk_buff *skb)
 static void tcp_set_skb_tso_segs(const struct sock *sk, struct sk_buff *skb,
                                  unsigned int mss_now)
 {
-        skb_shinfo(skb)->gso_type &= SKB_GSO_SHARED_FRAG;
         if (skb->len <= mss_now || !sk_can_gso(sk) ||
             skb->ip_summed == CHECKSUM_NONE) {
                 /* Avoid the costly divide in the normal
@@ -1141,10 +1140,11 @@ static void tcp_set_skb_tso_segs(const struct sock *sk, struct sk_buff *skb,
                  */
                 skb_shinfo(skb)->gso_segs = 1;
                 skb_shinfo(skb)->gso_size = 0;
+                skb_shinfo(skb)->gso_type = 0;
         } else {
                 skb_shinfo(skb)->gso_segs = DIV_ROUND_UP(skb->len, mss_now);
                 skb_shinfo(skb)->gso_size = mss_now;
-                skb_shinfo(skb)->gso_type |= sk->sk_gso_type;
+                skb_shinfo(skb)->gso_type = sk->sk_gso_type;
         }
 }