svn commit: r301601 - projects/vnet/sys/netinet

[Bjoern A. Zeeb]

Author: bz
Date: Wed Jun  8 11:24:01 2016
New Revision: 301601
URL: https://svnweb.freebsd.org/changeset/base/301601

Log:
  Replace the DELAY with a more sophisticated check to make sure
  the inps are all gone before doing the cleanup.  We might decide
  to do a partial cleanup before polling, but for now bail on the
  safe side.
  
  Also use pause instead of DELAY [1].
  
  Suggested by:	rwatson [1]
  Sponsored by:	The FreeBSD Foundation

Modified:
  projects/vnet/sys/netinet/tcp_subr.c

Modified: projects/vnet/sys/netinet/tcp_subr.c
==============================================================================
--- projects/vnet/sys/netinet/tcp_subr.c	Wed Jun  8 11:18:49 2016	(r301600)
+++ projects/vnet/sys/netinet/tcp_subr.c	Wed Jun  8 11:24:01 2016	(r301601)
@@ -731,18 +731,19 @@ tcp_init(void)
 static void
 tcp_destroy(void *unused __unused)
 {
-	int error;
+	int error, n;
 
 	/*
 	 * All our processes are gone, all our sockets should be cleaned
 	 * up, which means, we should be past the tcp_discardcb() calls.
-	 * Sleep to let all tcpcb timers really disappear and then cleanup.
-	 * Timewait will cleanup its queue and will be ready to go.
-	 * XXX-BZ In theory a few ticks should be good enough to make sure
-	 * the timers are all really gone.  We should see if we could use a
-	 * better metric here and, e.g., check a tcbcb count as an optimization?
+	 * Sleep to let all tcpcb timers really disappear and cleanup.
 	 */
-	DELAY(1000000 / hz);
+	do {
+		pause("tcpdes", hz/10);
+		INP_LIST_RLOCK(&V_tcbinfo);
+		n = V_tcbinfo.ipi_count;
+		INP_LIST_RUNLOCK(&V_tcbinfo);
+	} while (n != 0);
 	tcp_hc_destroy();
 	syncache_destroy();
 	tcp_tw_destroy();