Fix a deadlock between a route update and lltable
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
parent
faf7d24046
commit
1c27f64d6f
@ -1,4 +1,4 @@
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/* $NetBSD: if_llatbl.c,v 1.21 2017/06/28 04:14:53 ozaki-r Exp $ */
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/* $NetBSD: if_llatbl.c,v 1.22 2017/11/10 07:24:28 ozaki-r Exp $ */
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/*
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* Copyright (c) 2004 Luigi Rizzo, Alessandro Cerri. All rights reserved.
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* Copyright (c) 2004-2008 Qing Li. All rights reserved.
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@ -386,7 +386,7 @@ llentry_alloc(struct ifnet *ifp, struct lltable *lt,
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(ifp->if_flags & IFF_NOARP) == 0) {
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#endif
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IF_AFDATA_WLOCK(ifp);
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la = lla_create(lt, 0, (struct sockaddr *)dst);
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la = lla_create(lt, 0, (struct sockaddr *)dst, NULL /* XXX */);
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IF_AFDATA_WUNLOCK(ifp);
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}
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@ -656,7 +656,12 @@ lla_rt_output(const u_char rtm_type, const int rtm_flags, const time_t rtm_expir
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error = 0;
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switch (rtm_type) {
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case RTM_ADD:
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case RTM_ADD: {
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struct rtentry *rt;
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/* Never call rtalloc1 with IF_AFDATA_WLOCK */
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rt = rtalloc1(dst, 0);
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/* Add static LLE */
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IF_AFDATA_WLOCK(ifp);
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lle = lla_lookup(llt, 0, dst);
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@ -666,15 +671,19 @@ lla_rt_output(const u_char rtm_type, const int rtm_flags, const time_t rtm_expir
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(lle->la_flags & LLE_STATIC || lle->la_expire == 0)) {
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LLE_RUNLOCK(lle);
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IF_AFDATA_WUNLOCK(ifp);
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if (rt != NULL)
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rt_unref(rt);
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error = EEXIST;
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goto out;
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}
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if (lle != NULL)
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LLE_RUNLOCK(lle);
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lle = lla_create(llt, 0, dst);
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lle = lla_create(llt, 0, dst, rt);
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if (lle == NULL) {
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IF_AFDATA_WUNLOCK(ifp);
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if (rt != NULL)
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rt_unref(rt);
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error = ENOMEM;
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goto out;
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}
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@ -703,6 +712,8 @@ lla_rt_output(const u_char rtm_type, const int rtm_flags, const time_t rtm_expir
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laflags = lle->la_flags;
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LLE_WUNLOCK(lle);
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IF_AFDATA_WUNLOCK(ifp);
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if (rt != NULL)
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rt_unref(rt);
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#if defined(INET) && NARP > 0
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/* gratuitous ARP */
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if ((laflags & LLE_PUB) && dst->sa_family == AF_INET) {
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@ -721,8 +732,8 @@ lla_rt_output(const u_char rtm_type, const int rtm_flags, const time_t rtm_expir
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#else
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(void)laflags;
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#endif
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break;
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}
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case RTM_DELETE:
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IF_AFDATA_WLOCK(ifp);
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@ -1,4 +1,4 @@
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/* $NetBSD: if_llatbl.h,v 1.12 2017/06/23 05:46:10 ozaki-r Exp $ */
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/* $NetBSD: if_llatbl.h,v 1.13 2017/11/10 07:24:28 ozaki-r Exp $ */
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/*
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* Copyright (c) 2004 Luigi Rizzo, Alessandro Cerri. All rights reserved.
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* Copyright (c) 2004-2008 Qing Li. All rights reserved.
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@ -190,7 +190,7 @@ struct llentry {
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typedef struct llentry *(llt_lookup_t)(struct lltable *, u_int flags,
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const struct sockaddr *l3addr);
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typedef struct llentry *(llt_create_t)(struct lltable *, u_int flags,
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const struct sockaddr *l3addr);
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const struct sockaddr *l3addr, const struct rtentry *);
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typedef int (llt_delete_t)(struct lltable *, u_int flags,
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const struct sockaddr *l3addr);
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typedef void (llt_prefix_free_t)(struct lltable *,
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@ -297,10 +297,11 @@ lla_lookup(struct lltable *llt, u_int flags, const struct sockaddr *l3addr)
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}
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static __inline struct llentry *
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lla_create(struct lltable *llt, u_int flags, const struct sockaddr *l3addr)
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lla_create(struct lltable *llt, u_int flags, const struct sockaddr *l3addr,
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const struct rtentry *rt)
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{
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return (llt->llt_create(llt, flags, l3addr));
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return (llt->llt_create(llt, flags, l3addr, rt));
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}
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static __inline int
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@ -1,4 +1,4 @@
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/* $NetBSD: if_arp.c,v 1.253 2017/06/27 12:21:54 roy Exp $ */
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/* $NetBSD: if_arp.c,v 1.254 2017/11/10 07:24:28 ozaki-r Exp $ */
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/*-
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* Copyright (c) 1998, 2000, 2008 The NetBSD Foundation, Inc.
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@ -68,7 +68,7 @@
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*/
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#include <sys/cdefs.h>
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__KERNEL_RCSID(0, "$NetBSD: if_arp.c,v 1.253 2017/06/27 12:21:54 roy Exp $");
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__KERNEL_RCSID(0, "$NetBSD: if_arp.c,v 1.254 2017/11/10 07:24:28 ozaki-r Exp $");
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#ifdef _KERNEL_OPT
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#include "opt_ddb.h"
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@ -754,10 +754,15 @@ notfound:
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}
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#undef _IFF_NOARP
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if (la == NULL) {
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struct rtentry *_rt;
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create_lookup = "create";
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_rt = rtalloc1(dst, 0);
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IF_AFDATA_WLOCK(ifp);
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la = lla_create(LLTABLE(ifp), LLE_EXCLUSIVE, dst);
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la = lla_create(LLTABLE(ifp), LLE_EXCLUSIVE, dst, _rt);
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IF_AFDATA_WUNLOCK(ifp);
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if (_rt != NULL)
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rt_unref(_rt);
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if (la == NULL)
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ARP_STATINC(ARP_STAT_ALLOCFAIL);
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else {
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@ -1452,9 +1457,14 @@ arpcreate(struct ifnet *ifp, struct mbuf *m, const struct in_addr *addr,
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la = arplookup(ifp, m, addr, sa, wlock);
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if (la == NULL) {
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struct rtentry *rt;
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rt = rtalloc1(sa, 0);
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IF_AFDATA_WLOCK(ifp);
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la = lla_create(LLTABLE(ifp), flags, sa);
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la = lla_create(LLTABLE(ifp), flags, sa, rt);
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IF_AFDATA_WUNLOCK(ifp);
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if (rt != NULL)
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rt_unref(rt);
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if (la != NULL)
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arp_init_llentry(ifp, la);
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@ -1,4 +1,4 @@
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/* $NetBSD: in.c,v 1.208 2017/11/10 07:15:32 ozaki-r Exp $ */
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/* $NetBSD: in.c,v 1.209 2017/11/10 07:24:28 ozaki-r Exp $ */
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/*
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* Copyright (C) 1995, 1996, 1997, and 1998 WIDE Project.
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@ -91,7 +91,7 @@
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*/
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#include <sys/cdefs.h>
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__KERNEL_RCSID(0, "$NetBSD: in.c,v 1.208 2017/11/10 07:15:32 ozaki-r Exp $");
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__KERNEL_RCSID(0, "$NetBSD: in.c,v 1.209 2017/11/10 07:24:28 ozaki-r Exp $");
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#include "arp.h"
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@ -1975,12 +1975,11 @@ in_lltable_free_entry(struct lltable *llt, struct llentry *lle)
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}
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static int
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in_lltable_rtcheck(struct ifnet *ifp, u_int flags, const struct sockaddr *l3addr)
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in_lltable_rtcheck(struct ifnet *ifp, u_int flags, const struct sockaddr *l3addr,
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const struct rtentry *rt)
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{
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struct rtentry *rt;
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int error = EINVAL;
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rt = rtalloc1(l3addr, 0);
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if (rt == NULL)
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return error;
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@ -2041,7 +2040,6 @@ in_lltable_rtcheck(struct ifnet *ifp, u_int flags, const struct sockaddr *l3addr
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error = 0;
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error:
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rt_unref(rt);
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return error;
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}
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@ -2132,7 +2130,8 @@ in_lltable_delete(struct lltable *llt, u_int flags,
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}
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static struct llentry *
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in_lltable_create(struct lltable *llt, u_int flags, const struct sockaddr *l3addr)
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in_lltable_create(struct lltable *llt, u_int flags, const struct sockaddr *l3addr,
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const struct rtentry *rt)
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{
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const struct sockaddr_in *sin = (const struct sockaddr_in *)l3addr;
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struct ifnet *ifp = llt->llt_ifp;
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@ -2157,7 +2156,7 @@ in_lltable_create(struct lltable *llt, u_int flags, const struct sockaddr *l3add
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* verify this.
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*/
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if (!(flags & LLE_IFADDR) &&
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in_lltable_rtcheck(ifp, flags, l3addr) != 0)
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in_lltable_rtcheck(ifp, flags, l3addr, rt) != 0)
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return (NULL);
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lle = in_lltable_new(sin->sin_addr, flags);
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@ -1,4 +1,4 @@
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/* $NetBSD: in6.c,v 1.249 2017/11/10 07:15:32 ozaki-r Exp $ */
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/* $NetBSD: in6.c,v 1.250 2017/11/10 07:24:28 ozaki-r Exp $ */
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/* $KAME: in6.c,v 1.198 2001/07/18 09:12:38 itojun Exp $ */
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/*
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@ -62,7 +62,7 @@
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*/
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#include <sys/cdefs.h>
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__KERNEL_RCSID(0, "$NetBSD: in6.c,v 1.249 2017/11/10 07:15:32 ozaki-r Exp $");
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__KERNEL_RCSID(0, "$NetBSD: in6.c,v 1.250 2017/11/10 07:24:28 ozaki-r Exp $");
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#ifdef _KERNEL_OPT
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#include "opt_inet.h"
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@ -2458,14 +2458,11 @@ in6_lltable_free_entry(struct lltable *llt, struct llentry *lle)
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}
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static int
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in6_lltable_rtcheck(struct ifnet *ifp,
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u_int flags,
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const struct sockaddr *l3addr)
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in6_lltable_rtcheck(struct ifnet *ifp, u_int flags,
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const struct sockaddr *l3addr, const struct rtentry *rt)
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{
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struct rtentry *rt;
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char ip6buf[INET6_ADDRSTRLEN];
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rt = rtalloc1(l3addr, 0);
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if (rt == NULL || (rt->rt_flags & RTF_GATEWAY) || rt->rt_ifp != ifp) {
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int s;
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struct ifaddr *ifa;
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@ -2478,19 +2475,14 @@ in6_lltable_rtcheck(struct ifnet *ifp,
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ifa = ifaof_ifpforaddr(l3addr, ifp);
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if (ifa != NULL) {
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pserialize_read_exit(s);
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if (rt != NULL)
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rt_unref(rt);
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return 0;
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}
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pserialize_read_exit(s);
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log(LOG_INFO, "IPv6 address: \"%s\" is not on the network\n",
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IN6_PRINT(ip6buf,
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&((const struct sockaddr_in6 *)l3addr)->sin6_addr));
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if (rt != NULL)
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rt_unref(rt);
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return EINVAL;
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}
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rt_unref(rt);
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return 0;
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}
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@ -2582,7 +2574,7 @@ in6_lltable_delete(struct lltable *llt, u_int flags,
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static struct llentry *
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in6_lltable_create(struct lltable *llt, u_int flags,
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const struct sockaddr *l3addr)
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const struct sockaddr *l3addr, const struct rtentry *rt)
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{
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const struct sockaddr_in6 *sin6 = (const struct sockaddr_in6 *)l3addr;
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struct ifnet *ifp = llt->llt_ifp;
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@ -2605,7 +2597,7 @@ in6_lltable_create(struct lltable *llt, u_int flags,
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* verify this.
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*/
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if (!(flags & LLE_IFADDR) &&
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in6_lltable_rtcheck(ifp, flags, l3addr) != 0)
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in6_lltable_rtcheck(ifp, flags, l3addr, rt) != 0)
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return NULL;
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lle = in6_lltable_new(&sin6->sin6_addr, flags);
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@ -1,4 +1,4 @@
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/* $NetBSD: nd6.c,v 1.236 2017/10/05 03:42:14 ozaki-r Exp $ */
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/* $NetBSD: nd6.c,v 1.237 2017/11/10 07:24:28 ozaki-r Exp $ */
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/* $KAME: nd6.c,v 1.279 2002/06/08 11:16:51 itojun Exp $ */
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/*
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@ -31,7 +31,7 @@
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*/
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#include <sys/cdefs.h>
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__KERNEL_RCSID(0, "$NetBSD: nd6.c,v 1.236 2017/10/05 03:42:14 ozaki-r Exp $");
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__KERNEL_RCSID(0, "$NetBSD: nd6.c,v 1.237 2017/11/10 07:24:28 ozaki-r Exp $");
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#ifdef _KERNEL_OPT
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#include "opt_net_mpsafe.h"
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@ -950,14 +950,17 @@ nd6_create(const struct in6_addr *addr6, const struct ifnet *ifp)
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{
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struct sockaddr_in6 sin6;
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struct llentry *ln;
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struct rtentry *rt;
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sockaddr_in6_init(&sin6, addr6, 0, 0, 0);
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rt = rtalloc1(sin6tosa(&sin6), 0);
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IF_AFDATA_WLOCK(ifp);
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ln = lla_create(LLTABLE6(ifp), LLE_EXCLUSIVE,
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sin6tosa(&sin6));
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ln = lla_create(LLTABLE6(ifp), LLE_EXCLUSIVE, sin6tosa(&sin6), rt);
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IF_AFDATA_WUNLOCK(ifp);
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if (rt != NULL)
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rt_unref(rt);
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if (ln != NULL)
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ln->ln_state = ND6_LLINFO_NOSTATE;
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