Merge branch 'writeback-for-2.6.34' into nfs-for-2.6.34

1 files changed, 14 insertions, 4 deletions

diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index 28e02963249..788851ca8c5 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -89,6 +89,8 @@ int sysctl_tcp_frto __read_mostly = 2;
 int sysctl_tcp_frto_response __read_mostly;
 int sysctl_tcp_nometrics_save __read_mostly;
 
+int sysctl_tcp_thin_dupack __read_mostly;
+
 int sysctl_tcp_moderate_rcvbuf __read_mostly = 1;
 int sysctl_tcp_abc __read_mostly;
 
@@ -2447,6 +2449,16 @@ static int tcp_time_to_recover(struct sock *sk)
 		return 1;
 	}
 
+	/* If a thin stream is detected, retransmit after first
+	 * received dupack. Employ only if SACK is supported in order
+	 * to avoid possible corner-case series of spurious retransmissions
+	 * Use only if there are no unsent data.
+	 */
+	if ((tp->thin_dupack || sysctl_tcp_thin_dupack) &&
+	    tcp_stream_is_thin(tp) && tcp_dupack_heuristics(tp) > 1 &&
+	    tcp_is_sack(tp) && !tcp_send_head(sk))
+		return 1;
+
 	return 0;
 }
 
@@ -5783,11 +5795,9 @@ int tcp_rcv_state_process(struct sock *sk, struct sk_buff *skb,
 
 				/* tcp_ack considers this ACK as duplicate
 				 * and does not calculate rtt.
-				 * Fix it at least with timestamps.
+				 * Force it here.
 				 */
-				if (tp->rx_opt.saw_tstamp &&
-				    tp->rx_opt.rcv_tsecr && !tp->srtt)
-					tcp_ack_saw_tstamp(sk, 0);
+				tcp_ack_update_rtt(sk, 0, 0);
 
 				if (tp->rx_opt.tstamp_ok)
 					tp->advmss -= TCPOLEN_TSTAMP_ALIGNED;