[TCP]: skb pcount with MTU discovery

The problem is that when doing MTU discovery, the too-large segments in
the write queue will be calculated as having a pcount of >1.  When
tcp_write_xmit() is trying to send, tcp_snd_test() fails the cwnd test
when pcount > cwnd.

The segments are eventually transmitted one at a time by keepalive, but
this can take a long time.

This patch checks if TSO is enabled when setting pcount.

Signed-off-by: John Heffner <jheffner@psc.edu>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 6 insertions, 5 deletions

diff --git a/include/net/tcp.h b/include/net/tcp.h
index 503810a70e21..9355ae5b1d75 100644
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -1417,19 +1417,20 @@ tcp_nagle_check(const struct tcp_sock *tp, const struct sk_buff *skb,
                   tcp_minshall_check(tp))));
 }
 
-extern void tcp_set_skb_tso_segs(struct sk_buff *, unsigned int);
+extern void tcp_set_skb_tso_segs(struct sock *, struct sk_buff *);
 
 /* This checks if the data bearing packet SKB (usually sk->sk_send_head)
  * should be put on the wire right now.
  */
-static __inline__ int tcp_snd_test(const struct tcp_sock *tp, 
+static __inline__ int tcp_snd_test(struct sock *sk,
                                    struct sk_buff *skb,
                                    unsigned cur_mss, int nonagle)
 {
+        struct tcp_sock *tp = tcp_sk(sk);
         int pkts = tcp_skb_pcount(skb);
 
         if (!pkts) {
-                tcp_set_skb_tso_segs(skb, tp->mss_cache_std);
+                tcp_set_skb_tso_segs(sk, skb);
                 pkts = tcp_skb_pcount(skb);
         }
 
@@ -1490,7 +1491,7 @@ static __inline__ void __tcp_push_pending_frames(struct sock *sk,
         if (skb) {
                 if (!tcp_skb_is_last(sk, skb))
                         nonagle = TCP_NAGLE_PUSH;
-                if (!tcp_snd_test(tp, skb, cur_mss, nonagle) ||
+                if (!tcp_snd_test(sk, skb, cur_mss, nonagle) ||
                     tcp_write_xmit(sk, nonagle))
                         tcp_check_probe_timer(sk, tp);
         }
@@ -1508,7 +1509,7 @@ static __inline__ int tcp_may_send_now(struct sock *sk, struct tcp_sock *tp)
         struct sk_buff *skb = sk->sk_send_head;
 
         return (skb &&
-                tcp_snd_test(tp, skb, tcp_current_mss(sk, 1),
+                tcp_snd_test(sk, skb, tcp_current_mss(sk, 1),
                              tcp_skb_is_last(sk, skb) ? TCP_NAGLE_PUSH : tp->nonagle));
 }