svn commit: r334497 - head/sys/netinet

[Michael Tuexen]

Author: tuexen
Date: Fri Jun  1 21:24:27 2018
New Revision: 334497
URL: https://svnweb.freebsd.org/changeset/base/334497

Log:
  Limit the retransmission timer for SYN-ACKs by TCPTV_REXMTMAX.
  
  Use the same logic to handle the SYN-ACK retransmission when sent from
  the syn cache code as when sent from the main code.
  
  MFC after:	3 days
  Sponsored by:	Netflix, Inc.

Modified:
  head/sys/netinet/tcp_syncache.c

Modified: head/sys/netinet/tcp_syncache.c
==============================================================================
--- head/sys/netinet/tcp_syncache.c	Fri Jun  1 21:24:10 2018	(r334496)
+++ head/sys/netinet/tcp_syncache.c	Fri Jun  1 21:24:27 2018	(r334497)
@@ -415,8 +415,14 @@ syncache_drop(struct syncache *sc, struct syncache_hea
 static void
 syncache_timeout(struct syncache *sc, struct syncache_head *sch, int docallout)
 {
-	sc->sc_rxttime = ticks +
-		TCPTV_RTOBASE * (tcp_syn_backoff[sc->sc_rxmits]);
+	int rexmt;
+
+	if (sc->sc_rxmits == 0)
+		rexmt = TCPTV_RTOBASE;
+	else
+		TCPT_RANGESET(rexmt, TCPTV_RTOBASE * tcp_syn_backoff[sc->sc_rxmits],
+		    tcp_rexmit_min, TCPTV_REXMTMAX);
+	sc->sc_rxttime = ticks + rexmt;
 	sc->sc_rxmits++;
 	if (TSTMP_LT(sc->sc_rxttime, sch->sch_nextc)) {
 		sch->sch_nextc = sc->sc_rxttime;