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Fix problem in r238990. The LLE_LINKED flag should be tested prior to

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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>
This commit is contained in:
Gleb Smirnoff 2012-12-13 11:11:15 +00:00
parent 01487e405c
commit b1ec2940af
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=244183
3 changed files with 20 additions and 12 deletions
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6
sys/net/if_llatbl.c
View File

@ -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);

16
sys/netinet/if_ether.c
View File

@ -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();
}

10
sys/netinet6/nd6.c
View File

@ -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);