From ab5c14d828c4bf6c3cd195d0ef6a44a29d4885fa Mon Sep 17 00:00:00 2001
From: Robert Watson <rwatson@FreeBSD.org>
Date: Sat, 30 Oct 2004 12:02:50 +0000
Subject: [PATCH] Correct a bug in TCP SACK that could result in wedging of the
 TCP stack under high load: only set function state to loop and continuing
 sending if there is no data left to send.

RELENG_5_3 candidate.

Feet provided:	Peter Losher <Peter underscore Losher at isc dot org>
Diagnosed by:	Aniel Hartmeier <daniel at benzedrine dot cx>
Submitted by:	mohan <mohans at yahoo-inc dot com>
---
 sys/netinet/tcp_output.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/sys/netinet/tcp_output.c b/sys/netinet/tcp_output.c
index 15bf0c0122a..2ad8ccb9438 100644
--- a/sys/netinet/tcp_output.c
+++ b/sys/netinet/tcp_output.c
@@ -231,12 +231,12 @@ again:
 						   tp->snd_recover - p->rxmit));
 		} else
 			len = ((long)ulmin(cwin, p->end - p->rxmit));
-		sack_rxmit = 1;
-		sendalot = 1;
 		off = p->rxmit - tp->snd_una;
 		KASSERT(off >= 0,("%s: sack block to the left of una : %d",
 		    __func__, off));
 		if (len > 0) {
+			sack_rxmit = 1;
+			sendalot = 1;
 			tcpstat.tcps_sack_rexmits++;
 			tcpstat.tcps_sack_rexmit_bytes +=
 			    min(len, tp->t_maxseg);