Author: glebius
Date: Thu Aug 2 13:57:49 2012
New Revision: 238990
URL: http://svn.freebsd.org/changeset/base/238990
Log:
Fix races between in_lltable_prefix_free(), lla_lookup(),
llentry_free() and arptimer():
o Use callout_init_rw() for lle timeout, this allows us safely
disestablish them.
- This allows us to simplify the arptimer() and make it
race safe.
o Consistently use ifp->if_afdata_lock to lock access to
linked lists in the lle hashes.
o Introduce new lle flag LLE_LINKED, which marks an entry that
is attached to the hash.
- Use LLE_LINKED to avoid double unlinking via consequent
calls to llentry_free().
- Mark lle with LLE_DELETED via |= operation istead of =,
so that other flags won't be lost.
o Make LLE_ADDREF(), LLE_REMREF() and LLE_FREE_LOCKED() more
consistent and provide more informative KASSERTs.
The patch is a collaborative work of all submitters and myself.
PR: kern/165863
Submitted by: Andrey Zonov <andrey zonov.org>
Submitted by: Ryan Stone <rysto32 gmail.com>
Submitted by: Eric van Gyzen <eric_van_gyzen dell.com>
Modified:
head/sys/net/if_llatbl.c
head/sys/net/if_llatbl.h
head/sys/net/if_var.h
head/sys/netinet/if_ether.c
head/sys/netinet/in.c
head/sys/netinet6/in6.c
Modified: head/sys/net/if_llatbl.c
==============================================================================
--- head/sys/net/if_llatbl.c Thu Aug 2 13:20:44 2012 (r238989)
+++ head/sys/net/if_llatbl.c Thu Aug 2 13:57:49 2012 (r238990)
@@ -106,10 +106,19 @@ llentry_free(struct llentry *lle)
size_t pkts_dropped;
struct mbuf *next;
- pkts_dropped = 0;
+ 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);
+ pkts_dropped = 0;
while ((lle->la_numheld > 0) && (lle->la_hold != NULL)) {
next = lle->la_hold->m_nextpkt;
m_freem(lle->la_hold);
@@ -122,7 +131,6 @@ llentry_free(struct llentry *lle)
("%s: la_numheld %d > 0, pkts_droped %zd", __func__,
lle->la_numheld, pkts_dropped));
- lle->la_flags &= ~LLE_VALID;
LLE_FREE_LOCKED(lle);
return (pkts_dropped);
@@ -173,17 +181,16 @@ lltable_free(struct lltable *llt)
SLIST_REMOVE(&V_lltables, llt, lltable, llt_link);
LLTABLE_WUNLOCK();
+ IF_AFDATA_WLOCK(llt->llt_ifp);
for (i = 0; i < LLTBL_HASHTBL_SIZE; i++) {
LIST_FOREACH_SAFE(lle, &llt->lle_head[i], lle_next, next) {
- int canceled;
-
- canceled = callout_drain(&lle->la_timer);
LLE_WLOCK(lle);
- if (canceled)
+ if (callout_stop(&lle->la_timer))
LLE_REMREF(lle);
llentry_free(lle);
}
}
+ IF_AFDATA_WUNLOCK(llt->llt_ifp);
free(llt, M_LLTABLE);
}
Modified: head/sys/net/if_llatbl.h
==============================================================================
--- head/sys/net/if_llatbl.h Thu Aug 2 13:20:44 2012 (r238989)
+++ head/sys/net/if_llatbl.h Thu Aug 2 13:57:49 2012 (r238990)
@@ -103,26 +103,28 @@ struct llentry {
#define LLE_ADDREF(lle) do { \
LLE_WLOCK_ASSERT(lle); \
KASSERT((lle)->lle_refcnt >= 0, \
- ("negative refcnt %d", (lle)->lle_refcnt)); \
+ ("negative refcnt %d on lle %p", \
+ (lle)->lle_refcnt, (lle))); \
(lle)->lle_refcnt++; \
} while (0)
#define LLE_REMREF(lle) do { \
LLE_WLOCK_ASSERT(lle); \
- KASSERT((lle)->lle_refcnt > 1, \
- ("bogus refcnt %d", (lle)->lle_refcnt)); \
+ KASSERT((lle)->lle_refcnt > 0, \
+ ("bogus refcnt %d on lle %p", \
+ (lle)->lle_refcnt, (lle))); \
(lle)->lle_refcnt--; \
} while (0)
#define LLE_FREE_LOCKED(lle) do { \
- if ((lle)->lle_refcnt <= 1) \
- (lle)->lle_free((lle)->lle_tbl, (lle));\
+ if ((lle)->lle_refcnt == 1) \
+ (lle)->lle_free((lle)->lle_tbl, (lle)); \
else { \
- (lle)->lle_refcnt--; \
+ LLE_REMREF(lle); \
LLE_WUNLOCK(lle); \
} \
/* guard against invalid refs */ \
- lle = NULL; \
+ (lle) = NULL; \
} while (0)
#define LLE_FREE(lle) do { \
@@ -172,6 +174,7 @@ MALLOC_DECLARE(M_LLTABLE);
#define LLE_VALID 0x0008 /* ll_addr is valid */
#define LLE_PROXY 0x0010 /* proxy entry ??? */
#define LLE_PUB 0x0020 /* publish entry ??? */
+#define LLE_LINKED 0x0040 /* linked to lookup structure */
#define LLE_EXCLUSIVE 0x2000 /* return lle xlocked */
#define LLE_DELETE 0x4000 /* delete on a lookup - match
LLE_IFADDR */
#define LLE_CREATE 0x8000 /* create on a lookup miss */
Modified: head/sys/net/if_var.h
==============================================================================
--- head/sys/net/if_var.h Thu Aug 2 13:20:44 2012 (r238989)
+++ head/sys/net/if_var.h Thu Aug 2 13:57:49 2012 (r238990)
@@ -415,6 +415,8 @@ EVENTHANDLER_DECLARE(group_change_event,
#define IF_AFDATA_DESTROY(ifp) rw_destroy(&(ifp)->if_afdata_lock)
#define IF_AFDATA_LOCK_ASSERT(ifp)
rw_assert(&(ifp)->if_afdata_lock, RA_LOCKED)
+#define IF_AFDATA_RLOCK_ASSERT(ifp)
rw_assert(&(ifp)->if_afdata_lock, RA_RLOCKED)
+#define IF_AFDATA_WLOCK_ASSERT(ifp)
rw_assert(&(ifp)->if_afdata_lock, RA_WLOCKED)
#define IF_AFDATA_UNLOCK_ASSERT(ifp)
rw_assert(&(ifp)->if_afdata_lock, RA_UNLOCKED)
int if_handoff(struct ifqueue *ifq, struct mbuf *m, struct ifnet *ifp,
Modified: head/sys/netinet/if_ether.c
==============================================================================
--- head/sys/netinet/if_ether.c Thu Aug 2 13:20:44 2012 (r238989)
+++ head/sys/netinet/if_ether.c Thu Aug 2 13:57:49 2012 (r238990)
@@ -163,49 +163,40 @@ arp_ifscrub(struct ifnet *ifp, uint32_t
static void
arptimer(void *arg)
{
+ struct llentry *lle = (struct llentry *)arg;
struct ifnet *ifp;
- struct llentry *lle;
- int pkts_dropped;
+ size_t pkts_dropped;
+
+ if (lle->la_flags & LLE_STATIC) {
+ LLE_WUNLOCK(lle);
+ return;
+ }
- KASSERT(arg != NULL, ("%s: arg NULL", __func__));
- lle = (struct llentry *)arg;
ifp = lle->lle_tbl->llt_ifp;
CURVNET_SET(ifp->if_vnet);
+
+ if (lle->la_flags != LLE_DELETED) {
+ int evt;
+
+ if (lle->la_flags & LLE_VALID)
+ evt = LLENTRY_EXPIRED;
+ else
+ evt = LLENTRY_TIMEDOUT;
+ EVENTHANDLER_INVOKE(lle_event, lle, evt);
+ }
+
+ callout_stop(&lle->la_timer);
+
+ /* XXX: LOR avoidance. We still have ref on lle. */
+ LLE_WUNLOCK(lle);
IF_AFDATA_LOCK(ifp);
LLE_WLOCK(lle);
- if (lle->la_flags & LLE_STATIC)
- LLE_WUNLOCK(lle);
- else {
- if (!callout_pending(&lle->la_timer) &&
- callout_active(&lle->la_timer)) {
- callout_stop(&lle->la_timer);
- LLE_REMREF(lle);
-
- if (lle->la_flags != LLE_DELETED) {
- int evt;
-
- if (lle->la_flags & LLE_VALID)
- evt = LLENTRY_EXPIRED;
- else
- evt = LLENTRY_TIMEDOUT;
- EVENTHANDLER_INVOKE(lle_event, lle, evt);
- }
- pkts_dropped = llentry_free(lle);
- ARPSTAT_ADD(dropped, pkts_dropped);
- ARPSTAT_INC(timeouts);
- } else {
-#ifdef DIAGNOSTIC
- struct sockaddr *l3addr = L3_ADDR(lle);
- log(LOG_INFO,
- "arptimer issue: %p, IPv4 address: \"%s\"\n", lle,
- inet_ntoa(
- ((const struct sockaddr_in
*)l3addr)->sin_addr));
-#endif
- LLE_WUNLOCK(lle);
- }
- }
+ LLE_REMREF(lle);
+ pkts_dropped = llentry_free(lle);
IF_AFDATA_UNLOCK(ifp);
+ ARPSTAT_ADD(dropped, pkts_dropped);
+ ARPSTAT_INC(timeouts);
CURVNET_RESTORE();
}
Modified: head/sys/netinet/in.c
==============================================================================
--- head/sys/netinet/in.c Thu Aug 2 13:20:44 2012 (r238989)
+++ head/sys/netinet/in.c Thu Aug 2 13:57:49 2012 (r238990)
@@ -1280,7 +1280,6 @@ in_lltable_new(const struct sockaddr *l3
if (lle == NULL) /* NB: caller generates msg */
return NULL;
- callout_init(&lle->base.la_timer, CALLOUT_MPSAFE);
/*
* For IPv4 this will trigger "arpresolve" to generate
* an ARP request.
@@ -1290,7 +1289,10 @@ in_lltable_new(const struct sockaddr *l3
lle->base.lle_refcnt = 1;
lle->base.lle_free = in_lltable_free;
LLE_LOCK_INIT(&lle->base);
- return &lle->base;
+ callout_init_rw(&lle->base.la_timer, &lle->base.lle_lock,
+ CALLOUT_RETURNUNLOCKED);
+
+ return (&lle->base);
}
#define IN_ARE_MASKED_ADDR_EQUAL(d, a, m) ( \
@@ -1306,6 +1308,7 @@ in_lltable_prefix_free(struct lltable *l
int i;
size_t pkts_dropped;
+ IF_AFDATA_WLOCK(llt->llt_ifp);
for (i = 0; i < LLTBL_HASHTBL_SIZE; i++) {
LIST_FOREACH_SAFE(lle, &llt->lle_head[i], lle_next, next) {
/*
@@ -1315,17 +1318,15 @@ in_lltable_prefix_free(struct lltable *l
if (IN_ARE_MASKED_ADDR_EQUAL(satosin(L3_ADDR(lle)),
pfx, msk) && ((flags & LLE_STATIC) ||
!(lle->la_flags & LLE_STATIC))) {
- int canceled;
-
- canceled = callout_drain(&lle->la_timer);
LLE_WLOCK(lle);
- if (canceled)
+ if (callout_stop(&lle->la_timer))
LLE_REMREF(lle);
pkts_dropped = llentry_free(lle);
ARPSTAT_ADD(dropped, pkts_dropped);
}
}
}
+ IF_AFDATA_WUNLOCK(llt->llt_ifp);
}
@@ -1457,11 +1458,12 @@ in_lltable_lookup(struct lltable *llt, u
lle->lle_tbl = llt;
lle->lle_head = lleh;
+ lle->la_flags |= LLE_LINKED;
LIST_INSERT_HEAD(lleh, lle, lle_next);
} else if (flags & LLE_DELETE) {
if (!(lle->la_flags & LLE_IFADDR) || (flags & LLE_IFADDR)) {
LLE_WLOCK(lle);
- lle->la_flags = LLE_DELETED;
+ lle->la_flags |= LLE_DELETED;
EVENTHANDLER_INVOKE(lle_event, lle, LLENTRY_DELETED);
LLE_WUNLOCK(lle);
#ifdef DIAGNOSTIC
Modified: head/sys/netinet6/in6.c
==============================================================================
--- head/sys/netinet6/in6.c Thu Aug 2 13:20:44 2012 (r238989)
+++ head/sys/netinet6/in6.c Thu Aug 2 13:57:49 2012 (r238990)
@@ -2497,23 +2497,22 @@ in6_lltable_prefix_free(struct lltable *
* (flags & LLE_STATIC) means deleting all entries
* including static ND6 entries.
*/
+ IF_AFDATA_WLOCK(llt->llt_ifp);
for (i = 0; i < LLTBL_HASHTBL_SIZE; i++) {
LIST_FOREACH_SAFE(lle, &llt->lle_head[i], lle_next, next) {
if (IN6_ARE_MASKED_ADDR_EQUAL(
- &((struct sockaddr_in6
*)L3_ADDR(lle))->sin6_addr,
- &pfx->sin6_addr,
- &msk->sin6_addr) &&
- ((flags & LLE_STATIC) || !(lle->la_flags &
LLE_STATIC))) {
- int canceled;
-
- canceled = callout_drain(&lle->la_timer);
+ &satosin6(L3_ADDR(lle))->sin6_addr,
+ &pfx->sin6_addr, &msk->sin6_addr) &&
+ ((flags & LLE_STATIC) ||
+ !(lle->la_flags & LLE_STATIC))) {
LLE_WLOCK(lle);
- if (canceled)
+ if (callout_stop(&lle->la_timer))
LLE_REMREF(lle);
llentry_free(lle);
}
}
}
+ IF_AFDATA_WUNLOCK(llt->llt_ifp);
}
static int
@@ -2605,11 +2604,12 @@ in6_lltable_lookup(struct lltable *llt,
lle->lle_tbl = llt;
lle->lle_head = lleh;
+ lle->la_flags |= LLE_LINKED;
LIST_INSERT_HEAD(lleh, lle, lle_next);
} else if (flags & LLE_DELETE) {
if (!(lle->la_flags & LLE_IFADDR) || (flags & LLE_IFADDR)) {
LLE_WLOCK(lle);
- lle->la_flags = LLE_DELETED;
+ lle->la_flags |= LLE_DELETED;
LLE_WUNLOCK(lle);
#ifdef DIAGNOSTIC
log(LOG_INFO, "ifaddr cache = %p is deleted\n", lle);
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