MFC of r278472

This fixes a bug in the way that the LLE timers for nd6
and arp were being used. They basically would pass in the
mutex to the callout_init. Because they used this method
to the callout system, it was possible to "stop" the callout.
When flushing the table and you stopped the running callout, the
callout_stop code would return 1 indicating that it was going
to stop the callout (that was about to run on the callout_wheel blocked
by the function calling the stop). Now when 1 was returned, it would
lower the reference count one extra time for the stopped timer, then
a few lines later delete the memory. Of course the callout_wheel was
stuck in the lock code and would then crash since it was accessing
freed memory. By using callout_init(c, 1) we always get a 0 back
and the reference counting bug does not rear its head. We do have
to make a few adjustments to the callouts themselves though to make
sure it does the proper thing if rescheduled as well as gets the lock.

Sponsored by:	Netflix Inc.

2 files changed, 22 insertions, 4 deletions

diff --git a/sys/netinet6/in6.c b/sys/netinet6/in6.c
index 714e33f..6a8a155 100644
--- a/sys/netinet6/in6.c
+++ b/sys/netinet6/in6.c
@@ -2519,8 +2519,7 @@ in6_lltable_new(const struct sockaddr *l3addr, u_int flags)
 	lle->base.lle_refcnt = 1;
 	lle->base.lle_free = in6_lltable_free;
 	LLE_LOCK_INIT(&lle->base);
-	callout_init_rw(&lle->base.ln_timer_ch, &lle->base.lle_lock,
-	    CALLOUT_RETURNUNLOCKED);
+	callout_init(&lle->base.ln_timer_ch, 1);
 
 	return (&lle->base);
 }
diff --git a/sys/netinet6/nd6.c b/sys/netinet6/nd6.c
index 53087f4..fb3c995 100644
--- a/sys/netinet6/nd6.c
+++ b/sys/netinet6/nd6.c
@@ -466,9 +466,28 @@ nd6_llinfo_timer(void *arg)
 
 	KASSERT(arg != NULL, ("%s: arg NULL", __func__));
 	ln = (struct llentry *)arg;
-	LLE_WLOCK_ASSERT(ln);
+	LLE_WLOCK(ln);
+	if (callout_pending(&ln->la_timer)) {
+		/*
+		 * Here we are a bit odd here in the treatment of 
+		 * active/pending. If the pending bit is set, it got
+		 * rescheduled before I ran. The active
+		 * bit we ignore, since if it was stopped
+		 * in ll_tablefree() and was currently running
+		 * it would have return 0 so the code would
+		 * not have deleted it since the callout could
+		 * not be stopped so we want to go through
+		 * with the delete here now. If the callout
+		 * was restarted, the pending bit will be back on and
+		 * we just want to bail since the callout_reset would
+		 * return 1 and our reference would have been removed
+		 * by nd6_llinfo_settimer_locked above since canceled
+		 * would have been 1.
+		 */
+		LLE_WUNLOCK(ln);
+		return;
+	}
 	ifp = ln->lle_tbl->llt_ifp;
-
 	CURVNET_SET(ifp->if_vnet);
 
 	if (ln->ln_ntick > 0) {