Author: glebius
Date: Thu Dec 13 11:11:15 2012
New Revision: 244183
URL: http://svnweb.freebsd.org/changeset/base/244183
Log:
Fix problem in r238990. The LLE_LINKED flag should be tested prior to
entering llentry_free(), and in case if we lose the race, we should simply
perform LLE_FREE_LOCKED(). Otherwise, if the race is lost by the thread
performing arptimer(), it will remove two references from the lle instead
of one.
Reported by: Ian FREISLICH <ianf clue.co.za>
Modified:
head/sys/net/if_llatbl.c
head/sys/netinet/if_ether.c
head/sys/netinet6/nd6.c
Modified: head/sys/net/if_llatbl.c
==============================================================================
--- head/sys/net/if_llatbl.c Thu Dec 13 09:55:26 2012 (r244182)
+++ head/sys/net/if_llatbl.c Thu Dec 13 11:11:15 2012 (r244183)
@@ -109,12 +109,6 @@ llentry_free(struct llentry *lle)
IF_AFDATA_WLOCK_ASSERT(lle->lle_tbl->llt_ifp);
LLE_WLOCK_ASSERT(lle);
- /* XXX: guard against race with other llentry_free(). */
- if (!(lle->la_flags & LLE_LINKED)) {
- LLE_FREE_LOCKED(lle);
- return (0);
- }
-
LIST_REMOVE(lle, lle_next);
lle->la_flags &= ~(LLE_VALID | LLE_LINKED);
Modified: head/sys/netinet/if_ether.c
==============================================================================
--- head/sys/netinet/if_ether.c Thu Dec 13 09:55:26 2012 (r244182)
+++ head/sys/netinet/if_ether.c Thu Dec 13 11:11:15 2012 (r244183)
@@ -165,7 +165,6 @@ arptimer(void *arg)
{
struct llentry *lle = (struct llentry *)arg;
struct ifnet *ifp;
- size_t pkts_dropped;
if (lle->la_flags & LLE_STATIC) {
LLE_WUNLOCK(lle);
@@ -192,11 +191,20 @@ arptimer(void *arg)
IF_AFDATA_LOCK(ifp);
LLE_WLOCK(lle);
- LLE_REMREF(lle);
- pkts_dropped = llentry_free(lle);
+ /* Guard against race with other llentry_free(). */
+ if (lle->la_flags & LLE_LINKED) {
+ size_t pkts_dropped;
+
+ LLE_REMREF(lle);
+ pkts_dropped = llentry_free(lle);
+ ARPSTAT_ADD(dropped, pkts_dropped);
+ } else
+ LLE_FREE_LOCKED(lle);
+
IF_AFDATA_UNLOCK(ifp);
- ARPSTAT_ADD(dropped, pkts_dropped);
+
ARPSTAT_INC(timeouts);
+
CURVNET_RESTORE();
}
Modified: head/sys/netinet6/nd6.c
==============================================================================
--- head/sys/netinet6/nd6.c Thu Dec 13 09:55:26 2012 (r244182)
+++ head/sys/netinet6/nd6.c Thu Dec 13 11:11:15 2012 (r244183)
@@ -1108,8 +1108,14 @@ nd6_free(struct llentry *ln, int gc)
LLE_WUNLOCK(ln);
IF_AFDATA_LOCK(ifp);
LLE_WLOCK(ln);
- LLE_REMREF(ln);
- llentry_free(ln);
+
+ /* Guard against race with other llentry_free(). */
+ if (ln->la_flags & LLE_LINKED) {
+ LLE_REMREF(ln);
+ llentry_free(ln);
+ } else
+ LLE_FREE_LOCKED(ln);
+
IF_AFDATA_UNLOCK(ifp);
return (next);
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