svn commit: r363397 - head/sys/netinet/cc

[Richard Scheffenegger]

Author: rscheff
Date: Tue Jul 21 16:21:52 2020
New Revision: 363397
URL: https://svnweb.freebsd.org/changeset/base/363397

Log:
  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)
  Approved by:	tuexen (mentor), rgrimes (mentor)
  MFC after:	2 weeks
  Sponsored by:	NetApp, Inc.
  Differential Revision:	https://reviews.freebsd.org/D24657

Modified:
  head/sys/netinet/cc/cc_cubic.c

Modified: head/sys/netinet/cc/cc_cubic.c
==============================================================================
--- head/sys/netinet/cc/cc_cubic.c	Tue Jul 21 16:17:23 2020	(r363396)
+++ head/sys/netinet/cc/cc_cubic.c	Tue Jul 21 16:21:52 2020	(r363397)
@@ -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,