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Modify nd6_llinfo_timer() to acquire the nd6 lock before the LLE lock.

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When expiring a neighbour cache entry we may need to look up the associated
default router, which requires the nd6 read lock. To avoid an LOR, the nd6
lock should be acquired first.

X-MFC-With:	r296063
Tested by:	Larry Rosenman <ler@lerctr.org> (previous revision)
This commit is contained in:
markj 2016-03-29 19:23:00 +00:00
parent 50470342d9
commit db6b45eb6c
1 changed files with 32 additions and 24 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

56
sys/netinet6/nd6.c
View File

@ -127,7 +127,7 @@ static int nd6_is_new_addr_neighbor(const struct sockaddr_in6 *,
static void nd6_setmtu0(struct ifnet *, struct nd_ifinfo *);
static void nd6_slowtimo(void *);
static int regen_tmpaddr(struct in6_ifaddr *);
static void nd6_free(struct llentry *, int);
static void nd6_free(struct llentry **, int);
static void nd6_free_redirect(const struct llentry *);
static void nd6_llinfo_timer(void *);
static void nd6_llinfo_settimer_locked(struct llentry *, long);
@ -727,12 +727,16 @@ nd6_llinfo_timer(void *arg)
struct llentry *ln;
struct in6_addr *dst, *pdst, *psrc, src;
struct ifnet *ifp;
struct nd_ifinfo *ndi = NULL;
struct nd_ifinfo *ndi;
int do_switch, send_ns;
long delay;
KASSERT(arg != NULL, ("%s: arg NULL", __func__));
ln = (struct llentry *)arg;
ifp = lltable_get_ifp(ln->lle_tbl);
CURVNET_SET(ifp->if_vnet);
ND6_RLOCK();
LLE_WLOCK(ln);
if (callout_pending(&ln->lle_timer)) {
/*
@ -752,10 +756,10 @@ nd6_llinfo_timer(void *arg)
* would have been 1.
*/
LLE_WUNLOCK(ln);
ND6_RUNLOCK();
CURVNET_RESTORE();
return;
}
ifp = ln->lle_tbl->llt_ifp;
CURVNET_SET(ifp->if_vnet);
ndi = ND_IFINFO(ifp);
send_ns = 0;
dst = &ln->r_l3addr.addr6;
@ -777,8 +781,7 @@ nd6_llinfo_timer(void *arg)
}
if (ln->la_flags & LLE_DELETED) {
nd6_free(ln, 0);
ln = NULL;
nd6_free(&ln, 0);
goto done;
}
@ -803,9 +806,7 @@ nd6_llinfo_timer(void *arg)
ln->la_hold = m0;
clear_llinfo_pqueue(ln);
}
EVENTHANDLER_INVOKE(lle_event, ln, LLENTRY_TIMEDOUT);
nd6_free(ln, 0);
ln = NULL;
nd6_free(&ln, 0);
if (m != NULL)
icmp6_error2(m, ICMP6_DST_UNREACH,
ICMP6_DST_UNREACH_ADDR, 0, ifp);
@ -834,12 +835,8 @@ nd6_llinfo_timer(void *arg)
* GC timer has ended and entry hasn't been used.
* Run Garbage collector (RFC 4861, 5.3)
*/
if (!ND6_LLINFO_PERMANENT(ln)) {
EVENTHANDLER_INVOKE(lle_event, ln,
LLENTRY_EXPIRED);
nd6_free(ln, 1);
ln = NULL;
}
if (!ND6_LLINFO_PERMANENT(ln))
nd6_free(&ln, 1);
break;
}
@ -861,9 +858,7 @@ nd6_llinfo_timer(void *arg)
ln->la_asked++;
send_ns = 1;
} else {
EVENTHANDLER_INVOKE(lle_event, ln, LLENTRY_EXPIRED);
nd6_free(ln, 0);
ln = NULL;
nd6_free(&ln, 0);
}
break;
default:
@ -871,6 +866,8 @@ nd6_llinfo_timer(void *arg)
__func__, ln->ln_state);
}
done:
if (ln != NULL)
ND6_RUNLOCK();
if (send_ns != 0) {
nd6_llinfo_settimer_locked(ln, (long)ndi->retrans * hz / 1000);
psrc = nd6_llinfo_get_holdsrc(ln, &src);
@ -1367,12 +1364,27 @@ nd6_is_addr_neighbor(const struct sockaddr_in6 *addr, struct ifnet *ifp)
* Set noinline to be dtrace-friendly
*/
static __noinline void
nd6_free(struct llentry *ln, int gc)
nd6_free(struct llentry **lnp, int gc)
{
struct nd_defrouter *dr;
struct ifnet *ifp;
struct llentry *ln;
struct nd_defrouter *dr;
ln = *lnp;
*lnp = NULL;
LLE_WLOCK_ASSERT(ln);
ND6_RLOCK_ASSERT();
ifp = lltable_get_ifp(ln->lle_tbl);
if ((ND_IFINFO(ifp)->flags & ND6_IFF_ACCEPT_RTADV) != 0)
dr = defrouter_lookup_locked(&ln->r_l3addr.addr6, ifp);
else
dr = NULL;
ND6_RUNLOCK();
if ((ln->la_flags & LLE_DELETED) == 0)
EVENTHANDLER_INVOKE(lle_event, ln, LLENTRY_EXPIRED);
/*
* we used to have pfctlinput(PRC_HOSTDEAD) here.
@ -1382,11 +1394,7 @@ nd6_free(struct llentry *ln, int gc)
/* cancel timer */
nd6_llinfo_settimer_locked(ln, -1);
dr = NULL;
ifp = ln->lle_tbl->llt_ifp;
if (ND_IFINFO(ifp)->flags & ND6_IFF_ACCEPT_RTADV) {
dr = defrouter_lookup(&ln->r_l3addr.addr6, ifp);
if (dr != NULL && dr->expire &&
ln->ln_state == ND6_LLINFO_STALE && gc) {
/*