tcp: fix corner case issue in segmentation during rexmitting

If cur_mss grew very recently so that the previously G/TSOed skb
now fits well into a single segment it would get send up in
parts unless we calculate # of segments again. This corner-case
could happen eg. after mtu probe completes or less than
previously sack blocks are required for the opposite direction.

Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@helsinki.fi>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
index 3feab4d..77af7fa 100644 (file)
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c
@@ -1921,6 +1921,8 @@ int tcp_retransmit_skb(struct sock *sk, struct sk_buff *skb)
        if (skb->len > cur_mss) {
                if (tcp_fragment(sk, skb, cur_mss, cur_mss))
                        return -ENOMEM; /* We'll try again later. */
+       } else {
+               tcp_init_tso_segs(sk, skb, cur_mss);
        }
 
        tcp_retrans_try_collapse(sk, skb, cur_mss);