tcp: tcp_disconnect() should clear window_clamp

NFS can reuse its TCP socket after calling tcp_disconnect().

We noticed window scaling was not negotiated in SYN packet of next
connection request.

Fix is to clear tp->window_clamp in tcp_disconnect().

Reported-by: Krzysztof Oledzki <ole@ans.pl>
Tested-by: Krzysztof Oledzki <ole@ans.pl>
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 1 insertions, 0 deletions

diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index f1813bc71088..d7a884c534a6 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -2059,6 +2059,7 @@ int tcp_disconnect(struct sock *sk, int flags)
         tp->snd_ssthresh = TCP_INFINITE_SSTHRESH;
         tp->snd_cwnd_cnt = 0;
         tp->bytes_acked = 0;
+        tp->window_clamp = 0;
         tcp_set_ca_state(sk, TCP_CA_Open);
         tcp_clear_retrans(tp);
         inet_csk_delack_init(sk);