[TCP]: Receive buffer moderation fixes.

1) Make window clamp follow receive buffer growth so it
   does not limit window advertisements.  Noticed by John
   Heffner and Stephen Hemminger.
2) Fix rcvmem calculation such that tcp_adv_win_scale is
   taken into account.

diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index 708005f0d0b0c324354ea46ffc68db3edd0ac838..c0a0b65f5066f4dd88c673b4e6be4d89ce5519b5 100644 (file)
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -463,6 +463,8 @@ void tcp_rcv_space_adjust(struct sock *sk)
                tp->rcvq_space.space = space;
 
                if (sysctl_tcp_moderate_rcvbuf) {
+                       int new_clamp = space;
+
                        /* Receive space grows, normalize in order to
                         * take into account packet headers and sk_buff
                         * structure overhead.
@@ -472,10 +474,16 @@ void tcp_rcv_space_adjust(struct sock *sk)
                                space = 1;
                        rcvmem = (tp->advmss + MAX_TCP_HEADER +
                                  16 + sizeof(struct sk_buff));
+                       while (tcp_win_from_space(rcvmem) < tp->advmss)
+                               rcvmem += 128;
                        space *= rcvmem;
                        space = min(space, sysctl_tcp_rmem[2]);
-                       if (space > sk->sk_rcvbuf)
+                       if (space > sk->sk_rcvbuf) {
                                sk->sk_rcvbuf = space;
+
+                               /* Make the window clamp follow along.  */
+                               tp->window_clamp = new_clamp;
+                       }
                }
        }