svn commit: r306768 - head/sys/netinet

[Jonathan T. Looney]

Author: jtl
Date: Thu Oct  6 16:09:45 2016
New Revision: 306768
URL: https://svnweb.freebsd.org/changeset/base/306768

Log:
  If the new window size is less than the old window size, skip the
  calculations to check if we should advertise a larger window.
  
  Reviewed by:	gnn
  MFC after:	2 weeks
  Sponsored by:	Juniper Networks, Netflix
  Differential Revision:	https://reviews.freebsd.org/D7076
  Tested by:	Limelight, Netflix

Modified:
  head/sys/netinet/tcp_output.c

Modified: head/sys/netinet/tcp_output.c
==============================================================================
--- head/sys/netinet/tcp_output.c	Thu Oct  6 16:00:48 2016	(r306767)
+++ head/sys/netinet/tcp_output.c	Thu Oct  6 16:09:45 2016	(r306768)
@@ -654,10 +654,11 @@ after_sack_rexmit:
 			oldwin = 0;
 
 		/* 
-		 * If the new window size ends up being the same as the old
-		 * size when it is scaled, then don't force a window update.
+		 * If the new window size ends up being the same as or less
+		 * than the old size when it is scaled, then don't force
+		 * a window update.
 		 */
-		if (oldwin >> tp->rcv_scale == (adv + oldwin) >> tp->rcv_scale)
+		if (oldwin >> tp->rcv_scale >= (adv + oldwin) >> tp->rcv_scale)
 			goto dontupdate;
 
 		if (adv >= (long)(2 * tp->t_maxseg) &&