Check the V_tcbinfo.ipi_count to hit 0 before doing the full TCP cleanup.

That way timers can finish cleanly and we do not gamble with a DELAY().

Reviewed by:		gnn, jtl
Approved by:		re (gjb)
Obtained from:		projects/vnet
MFC after:		2 weeks
Sponsored by:		The FreeBSD Foundation
Differential Revision:	https://reviews.freebsd.org/D6923

1 files changed, 8 insertions, 7 deletions

diff --git a/sys/netinet/tcp_subr.c b/sys/netinet/tcp_subr.c
index 7863f1c..f219e6b 100644
--- a/sys/netinet/tcp_subr.c
+++ b/sys/netinet/tcp_subr.c
@@ -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();