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Fix a deadlock between a route update and lltable

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It happens because rtalloc1 is called from lltable with holding
IF_AFDATA_WLOCK.

If a route update is in action, rtalloc1 would wait for its completion with
holding IF_AFDATA_WLOCK. At the same moment, a softint (e.g., arpintr) may try
to take IF_AFDATA_WLOCK and get stuck on it. Unfortunately the stuck softint
prevents the route update from progressing because the route update calls
psref_target_destroy that needs the softint to complete.

A resource allocation graph of the senario looks like this:
    route update =(psref_target_destroy)=> softint => IF_AFDATA_WLOCK
    =(rt_update_wait)=> route update

Fix the deadlock by pulling rtalloc1 out of the lltable codes inside
IF_AFDATA_WLOCK.

Note that the deadlock happens only if NET_MPSAFE is enabled.
This commit is contained in:
ozaki-r 2017-11-10 07:24:28 +00:00
parent faf7d24046
commit 1c27f64d6f
6 changed files with 55 additions and 39 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

21
sys/net/if_llatbl.c
View File

@ -1,4 +1,4 @@
/* $NetBSD: if_llatbl.c,v 1.21 2017/06/28 04:14:53 ozaki-r Exp $ */ /* $NetBSD: if_llatbl.c,v 1.22 2017/11/10 07:24:28 ozaki-r Exp $ */
/* /*
* Copyright (c) 2004 Luigi Rizzo, Alessandro Cerri. All rights reserved. * Copyright (c) 2004 Luigi Rizzo, Alessandro Cerri. All rights reserved.
* Copyright (c) 2004-2008 Qing Li. All rights reserved. * Copyright (c) 2004-2008 Qing Li. All rights reserved.
@ -386,7 +386,7 @@ llentry_alloc(struct ifnet *ifp, struct lltable *lt,
(ifp->if_flags & IFF_NOARP) == 0) { (ifp->if_flags & IFF_NOARP) == 0) {
#endif #endif
IF_AFDATA_WLOCK(ifp); IF_AFDATA_WLOCK(ifp);
la = lla_create(lt, 0, (struct sockaddr *)dst); la = lla_create(lt, 0, (struct sockaddr *)dst, NULL /* XXX */);
IF_AFDATA_WUNLOCK(ifp); IF_AFDATA_WUNLOCK(ifp);
} }
@ -656,7 +656,12 @@ lla_rt_output(const u_char rtm_type, const int rtm_flags, const time_t rtm_expir
error = 0; error = 0;
switch (rtm_type) { switch (rtm_type) {
case RTM_ADD: case RTM_ADD: {
struct rtentry *rt;
/* Never call rtalloc1 with IF_AFDATA_WLOCK */
rt = rtalloc1(dst, 0);
/* Add static LLE */ /* Add static LLE */
IF_AFDATA_WLOCK(ifp); IF_AFDATA_WLOCK(ifp);
lle = lla_lookup(llt, 0, dst); lle = lla_lookup(llt, 0, dst);
@ -666,15 +671,19 @@ lla_rt_output(const u_char rtm_type, const int rtm_flags, const time_t rtm_expir
(lle->la_flags & LLE_STATIC || lle->la_expire == 0)) { (lle->la_flags & LLE_STATIC || lle->la_expire == 0)) {
LLE_RUNLOCK(lle); LLE_RUNLOCK(lle);
IF_AFDATA_WUNLOCK(ifp); IF_AFDATA_WUNLOCK(ifp);
if (rt != NULL)
rt_unref(rt);
error = EEXIST; error = EEXIST;
goto out; goto out;
} }
if (lle != NULL) if (lle != NULL)
LLE_RUNLOCK(lle); LLE_RUNLOCK(lle);
lle = lla_create(llt, 0, dst); lle = lla_create(llt, 0, dst, rt);
if (lle == NULL) { if (lle == NULL) {
IF_AFDATA_WUNLOCK(ifp); IF_AFDATA_WUNLOCK(ifp);
if (rt != NULL)
rt_unref(rt);
error = ENOMEM; error = ENOMEM;
goto out; goto out;
} }
@ -703,6 +712,8 @@ lla_rt_output(const u_char rtm_type, const int rtm_flags, const time_t rtm_expir
laflags = lle->la_flags; laflags = lle->la_flags;
LLE_WUNLOCK(lle); LLE_WUNLOCK(lle);
IF_AFDATA_WUNLOCK(ifp); IF_AFDATA_WUNLOCK(ifp);
if (rt != NULL)
rt_unref(rt);
#if defined(INET) && NARP > 0 #if defined(INET) && NARP > 0
/* gratuitous ARP */ /* gratuitous ARP */
if ((laflags & LLE_PUB) && dst->sa_family == AF_INET) { if ((laflags & LLE_PUB) && dst->sa_family == AF_INET) {
@ -721,8 +732,8 @@ lla_rt_output(const u_char rtm_type, const int rtm_flags, const time_t rtm_expir
#else #else
(void)laflags; (void)laflags;
#endif #endif
break; break;
}
case RTM_DELETE: case RTM_DELETE:
IF_AFDATA_WLOCK(ifp); IF_AFDATA_WLOCK(ifp);

9
sys/net/if_llatbl.h
View File

@ -1,4 +1,4 @@
/* $NetBSD: if_llatbl.h,v 1.12 2017/06/23 05:46:10 ozaki-r Exp $ */ /* $NetBSD: if_llatbl.h,v 1.13 2017/11/10 07:24:28 ozaki-r Exp $ */
/* /*
* Copyright (c) 2004 Luigi Rizzo, Alessandro Cerri. All rights reserved. * Copyright (c) 2004 Luigi Rizzo, Alessandro Cerri. All rights reserved.
* Copyright (c) 2004-2008 Qing Li. All rights reserved. * Copyright (c) 2004-2008 Qing Li. All rights reserved.
@ -190,7 +190,7 @@ struct llentry {
typedef struct llentry *(llt_lookup_t)(struct lltable *, u_int flags, typedef struct llentry *(llt_lookup_t)(struct lltable *, u_int flags,
const struct sockaddr *l3addr); const struct sockaddr *l3addr);
typedef struct llentry *(llt_create_t)(struct lltable *, u_int flags, typedef struct llentry *(llt_create_t)(struct lltable *, u_int flags,
const struct sockaddr *l3addr); const struct sockaddr *l3addr, const struct rtentry *);
typedef int (llt_delete_t)(struct lltable *, u_int flags, typedef int (llt_delete_t)(struct lltable *, u_int flags,
const struct sockaddr *l3addr); const struct sockaddr *l3addr);
typedef void (llt_prefix_free_t)(struct lltable *, typedef void (llt_prefix_free_t)(struct lltable *,
@ -297,10 +297,11 @@ lla_lookup(struct lltable *llt, u_int flags, const struct sockaddr *l3addr)
} }
static __inline struct llentry * static __inline struct llentry *
lla_create(struct lltable *llt, u_int flags, const struct sockaddr *l3addr) lla_create(struct lltable *llt, u_int flags, const struct sockaddr *l3addr,
const struct rtentry *rt)
{ {
return (llt->llt_create(llt, flags, l3addr)); return (llt->llt_create(llt, flags, l3addr, rt));
} }
static __inline int static __inline int

18
sys/netinet/if_arp.c
View File

@ -1,4 +1,4 @@
/* $NetBSD: if_arp.c,v 1.253 2017/06/27 12:21:54 roy Exp $ */ /* $NetBSD: if_arp.c,v 1.254 2017/11/10 07:24:28 ozaki-r Exp $ */
/*- /*-
* Copyright (c) 1998, 2000, 2008 The NetBSD Foundation, Inc. * Copyright (c) 1998, 2000, 2008 The NetBSD Foundation, Inc.
@ -68,7 +68,7 @@
*/ */
#include <sys/cdefs.h> #include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: if_arp.c,v 1.253 2017/06/27 12:21:54 roy Exp $"); __KERNEL_RCSID(0, "$NetBSD: if_arp.c,v 1.254 2017/11/10 07:24:28 ozaki-r Exp $");
#ifdef _KERNEL_OPT #ifdef _KERNEL_OPT
#include "opt_ddb.h" #include "opt_ddb.h"
@ -754,10 +754,15 @@ notfound:
} }
#undef _IFF_NOARP #undef _IFF_NOARP
if (la == NULL) { if (la == NULL) {
struct rtentry *_rt;
create_lookup = "create"; create_lookup = "create";
_rt = rtalloc1(dst, 0);
IF_AFDATA_WLOCK(ifp); IF_AFDATA_WLOCK(ifp);
la = lla_create(LLTABLE(ifp), LLE_EXCLUSIVE, dst); la = lla_create(LLTABLE(ifp), LLE_EXCLUSIVE, dst, _rt);
IF_AFDATA_WUNLOCK(ifp); IF_AFDATA_WUNLOCK(ifp);
if (_rt != NULL)
rt_unref(_rt);
if (la == NULL) if (la == NULL)
ARP_STATINC(ARP_STAT_ALLOCFAIL); ARP_STATINC(ARP_STAT_ALLOCFAIL);
else { else {
@ -1452,9 +1457,14 @@ arpcreate(struct ifnet *ifp, struct mbuf *m, const struct in_addr *addr,
la = arplookup(ifp, m, addr, sa, wlock); la = arplookup(ifp, m, addr, sa, wlock);
if (la == NULL) { if (la == NULL) {
struct rtentry *rt;
rt = rtalloc1(sa, 0);
IF_AFDATA_WLOCK(ifp); IF_AFDATA_WLOCK(ifp);
la = lla_create(LLTABLE(ifp), flags, sa); la = lla_create(LLTABLE(ifp), flags, sa, rt);
IF_AFDATA_WUNLOCK(ifp); IF_AFDATA_WUNLOCK(ifp);
if (rt != NULL)
rt_unref(rt);
if (la != NULL) if (la != NULL)
arp_init_llentry(ifp, la); arp_init_llentry(ifp, la);

15
sys/netinet/in.c
View File

@ -1,4 +1,4 @@
/* $NetBSD: in.c,v 1.208 2017/11/10 07:15:32 ozaki-r Exp $ */ /* $NetBSD: in.c,v 1.209 2017/11/10 07:24:28 ozaki-r Exp $ */
/* /*
* Copyright (C) 1995, 1996, 1997, and 1998 WIDE Project. * Copyright (C) 1995, 1996, 1997, and 1998 WIDE Project.
@ -91,7 +91,7 @@
*/ */
#include <sys/cdefs.h> #include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: in.c,v 1.208 2017/11/10 07:15:32 ozaki-r Exp $"); __KERNEL_RCSID(0, "$NetBSD: in.c,v 1.209 2017/11/10 07:24:28 ozaki-r Exp $");
#include "arp.h" #include "arp.h"
@ -1975,12 +1975,11 @@ in_lltable_free_entry(struct lltable *llt, struct llentry *lle)
} }
static int static int
in_lltable_rtcheck(struct ifnet *ifp, u_int flags, const struct sockaddr *l3addr) in_lltable_rtcheck(struct ifnet *ifp, u_int flags, const struct sockaddr *l3addr,
const struct rtentry *rt)
{ {
struct rtentry *rt;
int error = EINVAL; int error = EINVAL;
rt = rtalloc1(l3addr, 0);
if (rt == NULL) if (rt == NULL)
return error; return error;
@ -2041,7 +2040,6 @@ in_lltable_rtcheck(struct ifnet *ifp, u_int flags, const struct sockaddr *l3addr
error = 0; error = 0;
error: error:
rt_unref(rt);
return error; return error;
} }
@ -2132,7 +2130,8 @@ in_lltable_delete(struct lltable *llt, u_int flags,
} }
static struct llentry * static struct llentry *
in_lltable_create(struct lltable *llt, u_int flags, const struct sockaddr *l3addr) in_lltable_create(struct lltable *llt, u_int flags, const struct sockaddr *l3addr,
const struct rtentry *rt)
{ {
const struct sockaddr_in *sin = (const struct sockaddr_in *)l3addr; const struct sockaddr_in *sin = (const struct sockaddr_in *)l3addr;
struct ifnet *ifp = llt->llt_ifp; struct ifnet *ifp = llt->llt_ifp;
@ -2157,7 +2156,7 @@ in_lltable_create(struct lltable *llt, u_int flags, const struct sockaddr *l3add
* verify this. * verify this.
*/ */
if (!(flags & LLE_IFADDR) && if (!(flags & LLE_IFADDR) &&
in_lltable_rtcheck(ifp, flags, l3addr) != 0) in_lltable_rtcheck(ifp, flags, l3addr, rt) != 0)
return (NULL); return (NULL);
lle = in_lltable_new(sin->sin_addr, flags); lle = in_lltable_new(sin->sin_addr, flags);

20
sys/netinet6/in6.c
View File

@ -1,4 +1,4 @@
/* $NetBSD: in6.c,v 1.249 2017/11/10 07:15:32 ozaki-r Exp $ */ /* $NetBSD: in6.c,v 1.250 2017/11/10 07:24:28 ozaki-r Exp $ */
/* $KAME: in6.c,v 1.198 2001/07/18 09:12:38 itojun Exp $ */ /* $KAME: in6.c,v 1.198 2001/07/18 09:12:38 itojun Exp $ */
/* /*
@ -62,7 +62,7 @@
*/ */
#include <sys/cdefs.h> #include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: in6.c,v 1.249 2017/11/10 07:15:32 ozaki-r Exp $"); __KERNEL_RCSID(0, "$NetBSD: in6.c,v 1.250 2017/11/10 07:24:28 ozaki-r Exp $");
#ifdef _KERNEL_OPT #ifdef _KERNEL_OPT
#include "opt_inet.h" #include "opt_inet.h"
@ -2458,14 +2458,11 @@ in6_lltable_free_entry(struct lltable *llt, struct llentry *lle)
} }
static int static int
in6_lltable_rtcheck(struct ifnet *ifp, in6_lltable_rtcheck(struct ifnet *ifp, u_int flags,
u_int flags, const struct sockaddr *l3addr, const struct rtentry *rt)
const struct sockaddr *l3addr)
{ {
struct rtentry *rt;
char ip6buf[INET6_ADDRSTRLEN]; char ip6buf[INET6_ADDRSTRLEN];
rt = rtalloc1(l3addr, 0);
if (rt == NULL || (rt->rt_flags & RTF_GATEWAY) || rt->rt_ifp != ifp) { if (rt == NULL || (rt->rt_flags & RTF_GATEWAY) || rt->rt_ifp != ifp) {
int s; int s;
struct ifaddr *ifa; struct ifaddr *ifa;
@ -2478,19 +2475,14 @@ in6_lltable_rtcheck(struct ifnet *ifp,
ifa = ifaof_ifpforaddr(l3addr, ifp); ifa = ifaof_ifpforaddr(l3addr, ifp);
if (ifa != NULL) { if (ifa != NULL) {
pserialize_read_exit(s); pserialize_read_exit(s);
if (rt != NULL)
rt_unref(rt);
return 0; return 0;
} }
pserialize_read_exit(s); pserialize_read_exit(s);
log(LOG_INFO, "IPv6 address: \"%s\" is not on the network\n", log(LOG_INFO, "IPv6 address: \"%s\" is not on the network\n",
IN6_PRINT(ip6buf, IN6_PRINT(ip6buf,
&((const struct sockaddr_in6 *)l3addr)->sin6_addr)); &((const struct sockaddr_in6 *)l3addr)->sin6_addr));
if (rt != NULL)
rt_unref(rt);
return EINVAL; return EINVAL;
} }
rt_unref(rt);
return 0; return 0;
} }
@ -2582,7 +2574,7 @@ in6_lltable_delete(struct lltable *llt, u_int flags,
static struct llentry * static struct llentry *
in6_lltable_create(struct lltable *llt, u_int flags, in6_lltable_create(struct lltable *llt, u_int flags,
const struct sockaddr *l3addr) const struct sockaddr *l3addr, const struct rtentry *rt)
{ {
const struct sockaddr_in6 *sin6 = (const struct sockaddr_in6 *)l3addr; const struct sockaddr_in6 *sin6 = (const struct sockaddr_in6 *)l3addr;
struct ifnet *ifp = llt->llt_ifp; struct ifnet *ifp = llt->llt_ifp;
@ -2605,7 +2597,7 @@ in6_lltable_create(struct lltable *llt, u_int flags,
* verify this. * verify this.
*/ */
if (!(flags & LLE_IFADDR) && if (!(flags & LLE_IFADDR) &&
in6_lltable_rtcheck(ifp, flags, l3addr) != 0) in6_lltable_rtcheck(ifp, flags, l3addr, rt) != 0)
return NULL; return NULL;
lle = in6_lltable_new(&sin6->sin6_addr, flags); lle = in6_lltable_new(&sin6->sin6_addr, flags);

11
sys/netinet6/nd6.c
View File

@ -1,4 +1,4 @@
/* $NetBSD: nd6.c,v 1.236 2017/10/05 03:42:14 ozaki-r Exp $ */ /* $NetBSD: nd6.c,v 1.237 2017/11/10 07:24:28 ozaki-r Exp $ */
/* $KAME: nd6.c,v 1.279 2002/06/08 11:16:51 itojun Exp $ */ /* $KAME: nd6.c,v 1.279 2002/06/08 11:16:51 itojun Exp $ */
/* /*
@ -31,7 +31,7 @@
*/ */
#include <sys/cdefs.h> #include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: nd6.c,v 1.236 2017/10/05 03:42:14 ozaki-r Exp $"); __KERNEL_RCSID(0, "$NetBSD: nd6.c,v 1.237 2017/11/10 07:24:28 ozaki-r Exp $");
#ifdef _KERNEL_OPT #ifdef _KERNEL_OPT
#include "opt_net_mpsafe.h" #include "opt_net_mpsafe.h"
@ -950,14 +950,17 @@ nd6_create(const struct in6_addr *addr6, const struct ifnet *ifp)
{ {
struct sockaddr_in6 sin6; struct sockaddr_in6 sin6;
struct llentry *ln; struct llentry *ln;
struct rtentry *rt;
sockaddr_in6_init(&sin6, addr6, 0, 0, 0); sockaddr_in6_init(&sin6, addr6, 0, 0, 0);
rt = rtalloc1(sin6tosa(&sin6), 0);
IF_AFDATA_WLOCK(ifp); IF_AFDATA_WLOCK(ifp);
ln = lla_create(LLTABLE6(ifp), LLE_EXCLUSIVE, ln = lla_create(LLTABLE6(ifp), LLE_EXCLUSIVE, sin6tosa(&sin6), rt);
sin6tosa(&sin6));
IF_AFDATA_WUNLOCK(ifp); IF_AFDATA_WUNLOCK(ifp);
if (rt != NULL)
rt_unref(rt);
if (ln != NULL) if (ln != NULL)
ln->ln_state = ND6_LLINFO_NOSTATE; ln->ln_state = ND6_LLINFO_NOSTATE;