Author: bz
Date: Sat Apr  9 12:05:23 2016
New Revision: 297742
URL: https://svnweb.freebsd.org/changeset/base/297742

Log:
  Mfp: r296310,r296343
  
  It looks like as with the safety belt of DELAY() fastened (*) we can
  completely tear down and free all memory for TCP (after r281599).
  
  (*) in theory a few ticks should be good enough to make sure the timers
  are all really gone. Could we use a better matric here and check a
  tcbcb count as an optimization?
  
  PR:           164763
  Reviewed by:  gnn, emaste
  MFC after:    2 weeks
  Sponsored by: The FreeBSD Foundation
  Differential Revision:        https://reviews.freebsd.org/D5734

Modified:
  head/sys/netinet/tcp_subr.c

Modified: head/sys/netinet/tcp_subr.c
==============================================================================
--- head/sys/netinet/tcp_subr.c Sat Apr  9 11:54:09 2016        (r297741)
+++ head/sys/netinet/tcp_subr.c Sat Apr  9 12:05:23 2016        (r297742)
@@ -660,7 +660,7 @@ tcp_init(void)
         * These have to be type stable for the benefit of the timers.
         */
        V_tcpcb_zone = uma_zcreate("tcpcb", sizeof(struct tcpcb_mem),
-           NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, UMA_ZONE_NOFREE);
+           NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, 0);
        uma_zone_set_max(V_tcpcb_zone, maxsockets);
        uma_zone_set_warning(V_tcpcb_zone, "kern.ipc.maxsockets limit reached");
 
@@ -670,7 +670,7 @@ tcp_init(void)
 
        TUNABLE_INT_FETCH("net.inet.tcp.sack.enable", &V_tcp_do_sack);
        V_sack_hole_zone = uma_zcreate("sackhole", sizeof(struct sackhole),
-           NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, UMA_ZONE_NOFREE);
+           NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, 0);
 
        /* Skip initialization of globals for non-default instances. */
        if (!IS_DEFAULT_VNET(curvnet))
@@ -737,10 +737,21 @@ tcp_destroy(void)
 {
        int error;
 
+       /*
+        * 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?
+        */
+       DELAY(1000000 / hz);
        tcp_hc_destroy();
        syncache_destroy();
        tcp_tw_destroy();
        in_pcbinfo_destroy(&V_tcbinfo);
+       /* tcp_discardcb() clears the sack_holes up. */
        uma_zdestroy(V_sack_hole_zone);
        uma_zdestroy(V_tcpcb_zone);
 
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