svn commit: r364378 - stable/12/sys/netinet/cc

[Richard Scheffenegger]

Author: rscheff
Date: Wed Aug 19 10:40:02 2020
New Revision: 364378
URL: https://svnweb.freebsd.org/changeset/base/364378

Log:
  MFC r363397: Fix style and comment around concave/convex regions in TCP cubic.
  
  In cubic, the concave region is when snd_cwnd starts growing slower
  towards max_cwnd (cwnd at the time of the congestion event), and
  the convex region is when snd_cwnd starts to grow faster and
  eventually appearing like slow-start like growth.
  
  PR:		238478
  Reviewed by:	tuexen (mentor), rgrimes (mentor)
  Sponsored by:	NetApp, Inc.
  Differential Revision:	https://reviews.freebsd.org/D24657

Modified:
  stable/12/sys/netinet/cc/cc_cubic.c
Directory Properties:
  stable/12/   (props changed)

Modified: stable/12/sys/netinet/cc/cc_cubic.c
==============================================================================
--- stable/12/sys/netinet/cc/cc_cubic.c	Wed Aug 19 10:36:16 2020	(r364377)
+++ stable/12/sys/netinet/cc/cc_cubic.c	Wed Aug 19 10:40:02 2020	(r364378)
@@ -185,12 +185,11 @@ cubic_ack_received(struct cc_var *ccv, uint16_t type)
 				 */
 				if (CCV(ccv, snd_cwnd) < w_tf)
 					CCV(ccv, snd_cwnd) = ulmin(w_tf, INT_MAX);
-			}
-
-			else if (CCV(ccv, snd_cwnd) < w_cubic_next) {
+			} else if (CCV(ccv, snd_cwnd) < w_cubic_next) {
 				/*
 				 * Concave or convex region, follow CUBIC
 				 * cwnd growth.
+				 * Only update snd_cwnd, if it doesn't shrink.
 				 */
 				if (V_tcp_do_rfc3465)
 					CCV(ccv, snd_cwnd) = ulmin(w_cubic_next,