[src/trunk]: src/sys/netinet6 Stop using callout randomly

[ozaki-r <ozaki-r%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/8662c4ce1552
branches:  trunk
changeset: 330249:8662c4ce1552
user:      ozaki-r <ozaki-r%NetBSD.org@localhost>
date:      Tue Jul 01 07:51:29 2014 +0000

description:
Stop using callout randomly

nd6_dad_start uses callout when xtick > 0 while doesn't when
xtick == 0. So if we pass a random value ranging from 0 to N,
nd6_dad_start uses callout randomly. This behavior makes
debugging difficult.

Discussed in http://mail-index.netbsd.org/tech-kern/2014/06/25/msg017278.html

diffstat:

 sys/netinet6/in6.c     |  15 +++++++++------
 sys/netinet6/nd6_nbr.c |   6 ++++--
 2 files changed, 13 insertions(+), 8 deletions(-)

diffs (76 lines):

diff -r aa0b62c32342 -r 8662c4ce1552 sys/netinet6/in6.c
--- a/sys/netinet6/in6.c        Tue Jul 01 05:49:18 2014 +0000
+++ b/sys/netinet6/in6.c        Tue Jul 01 07:51:29 2014 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: in6.c,v 1.172 2014/07/01 05:49:19 rtr Exp $    */
+/*     $NetBSD: in6.c,v 1.173 2014/07/01 07:51:29 ozaki-r Exp $        */
 /*     $KAME: in6.c,v 1.198 2001/07/18 09:12:38 itojun Exp $   */
 
 /*
@@ -62,7 +62,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: in6.c,v 1.172 2014/07/01 05:49:19 rtr Exp $");
+__KERNEL_RCSID(0, "$NetBSD: in6.c,v 1.173 2014/07/01 07:51:29 ozaki-r Exp $");
 
 #include "opt_inet.h"
 #include "opt_compat_netbsd.h"
@@ -1331,7 +1331,8 @@
                                    mindelay;
                        }
                }
-               nd6_dad_start(&ia->ia_ifa, dad_delay);
+               /* +1 ensures callout is always used */
+               nd6_dad_start(&ia->ia_ifa, dad_delay + 1);
        }
 
        return error;
@@ -2155,15 +2156,17 @@
                }
 
                if (ia->ia6_flags & IN6_IFF_TENTATIVE) {
+                       int delay;
                        /*
                         * The TENTATIVE flag was likely set by hand
                         * beforehand, implicitly indicating the need for DAD.
                         * We may be able to skip the random delay in this
                         * case, but we impose delays just in case.
                         */
-                       nd6_dad_start(ifa,
-                           cprng_fast32() %
-                               (MAX_RTR_SOLICITATION_DELAY * hz));
+                       delay = cprng_fast32() %
+                           (MAX_RTR_SOLICITATION_DELAY * hz);
+                       /* +1 ensures callout is always used */
+                       nd6_dad_start(ifa, delay + 1);
                }
        }
 
diff -r aa0b62c32342 -r 8662c4ce1552 sys/netinet6/nd6_nbr.c
--- a/sys/netinet6/nd6_nbr.c    Tue Jul 01 05:49:18 2014 +0000
+++ b/sys/netinet6/nd6_nbr.c    Tue Jul 01 07:51:29 2014 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: nd6_nbr.c,v 1.99 2014/01/13 18:23:36 roy Exp $ */
+/*     $NetBSD: nd6_nbr.c,v 1.100 2014/07/01 07:51:29 ozaki-r Exp $    */
 /*     $KAME: nd6_nbr.c,v 1.61 2001/02/10 16:06:14 jinmei Exp $        */
 
 /*
@@ -31,7 +31,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: nd6_nbr.c,v 1.99 2014/01/13 18:23:36 roy Exp $");
+__KERNEL_RCSID(0, "$NetBSD: nd6_nbr.c,v 1.100 2014/07/01 07:51:29 ozaki-r Exp $");
 
 #include "opt_inet.h"
 #include "opt_ipsec.h"
@@ -1097,6 +1097,8 @@
 /*
  * Start Duplicate Address Detection (DAD) for specified interface address.
  *
+ * Note that callout is used when xtick > 0 and not when xtick == 0.
+ *
  * xtick: minimum delay ticks for IFF_UP event
  */
 void