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From: Hiren Panchasara <hiren@FreeBSD.org>
Date: Tue, 6 Oct 2015 07:46:20 +0000 (UTC)
To: src-committers@freebsd.org, svn-src-all@freebsd.org,
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Subject: svn commit: r288914 - head/sys/netinet
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Author: hiren
Date: Tue Oct  6 07:46:19 2015
New Revision: 288914
URL: https://svnweb.freebsd.org/changeset/base/288914

Log:
  Add a comment specifying how we implement rfc3042.
  
  Differential Revision:	D3746
  MFC after:	    1 week
  Sponsored by:	    Limelight Networks

Modified:
  head/sys/netinet/tcp_input.c

Modified: head/sys/netinet/tcp_input.c
==============================================================================
--- head/sys/netinet/tcp_input.c	Tue Oct  6 07:28:54 2015	(r288913)
+++ head/sys/netinet/tcp_input.c	Tue Oct  6 07:46:19 2015	(r288914)
@@ -2536,6 +2536,16 @@ tcp_do_segment(struct mbuf *m, struct tc
 						tp->snd_nxt = onxt;
 					goto drop;
 				} else if (V_tcp_do_rfc3042) {
+					/*
+					 * Process first and second duplicate
+					 * ACKs. Each indicates a segment
+					 * leaving the network, creating room
+					 * for more. Make sure we can send a
+					 * packet on reception of each duplicate
+					 * ACK by increasing snd_cwnd by one
+					 * segment. Restore the original
+					 * snd_cwnd after packet transmission.
+					 */
 					cc_ack_received(tp, th, CC_DUPACK);
 					u_long oldcwnd = tp->snd_cwnd;
 					tcp_seq oldsndmax = tp->snd_max;