svn commit: r286955 - in head/sys: net netinet netinet6

George Neville-Neil gnn at neville-neil.com
Thu Aug 20 13:13:45 UTC 2015


Why was this work not in Phabricator?  This is a large change that has 
not been reviewed,
as far as I can tell, by anyone else on the project.  I am tempted to 
ask that this be backed out
and reviewed BEFORE it goes into the tree.

Best,
George


On 20 Aug 2015, at 13:05, Alexander V. Chernikov wrote:

> Author: melifaro
> Date: Thu Aug 20 12:05:17 2015
> New Revision: 286955
> URL: https://svnweb.freebsd.org/changeset/base/286955
>
> Log:
> * Split allocation and table linking for lle's.
>  Before that, the logic besides lle_create() was the following:
>  return existing if found, create if not. This behaviour was 
> error-prone
>  since we had to deal with 'sudden' static<>dynamic lle changes.
>  This commit fixes bunch of different issues like:
>  - refcount leak when lle is converted to static.
>    Simple check case:
>    console 1:
>    while true;
>      do for i in `arp -an|awk '$4~/incomp/{print$2}'|tr -d '()'`;
>        do arp -s $i 00:22:44:66:88:00 ; arp -d $i;
>      done;
>    done
>   console 2:
>    ping -f any-dead-host-in-L2
>   console 3:
>    # watch for memory consumption:
>    vmstat -m | awk '$1~/lltable/{print$2}'
>  - possible problems in arptimer() / nd6_timer() when 
> dropping/reacquiring
>   lock.
>  New logic explicitly handles use-or-create cases in every lla_create
>  user. Basically, most of the changes are purely mechanical. However,
>  we explicitly avoid using existing lle's for interface/static LLE 
> records.
> * While here, call lle_event handlers on all real table lle change.
> * Create lltable_free_entry() calling existing per-lltable
>  lle_free_t callback for entry deletion
>
> Modified:
> head/sys/net/if_llatbl.c
> head/sys/net/if_llatbl.h
> head/sys/netinet/if_ether.c
> head/sys/netinet/in.c
> head/sys/netinet/toecore.c
> head/sys/netinet6/in6.c
> head/sys/netinet6/nd6.c
> head/sys/netinet6/nd6.h
>
> Modified: head/sys/net/if_llatbl.c
> ==============================================================================
> --- head/sys/net/if_llatbl.c	Thu Aug 20 11:26:26 2015	(r286954)
> +++ head/sys/net/if_llatbl.c	Thu Aug 20 12:05:17 2015	(r286955)
> @@ -228,7 +228,7 @@ htable_prefix_free(struct lltable *llt,
> 	IF_AFDATA_WUNLOCK(llt->llt_ifp);
>
> 	LIST_FOREACH_SAFE(lle, &pmd.dchain, lle_chain, next)
> -		llt->llt_free_entry(llt, lle);
> +		lltable_free_entry(llt, lle);
> }
>
> static void
> @@ -278,10 +278,13 @@ lltable_drop_entry_queue(struct llentry
> }
>
> /*
> - * Deletes an address from the address table.
> - * This function is called by the timer functions
> - * such as arptimer() and nd6_llinfo_timer(), and
> - * the caller does the locking.
> + *
> + * Performes generic cleanup routines and frees lle.
> + *
> + * Called for non-linked entries, with callouts and
> + * other AF-specific cleanups performed.
> + *
> + * @lle must be passed WLOCK'ed
> *
> * Returns the number of held packets, if any, that were dropped.
> */
> @@ -316,21 +319,35 @@ struct llentry *
> llentry_alloc(struct ifnet *ifp, struct lltable *lt,
>   struct sockaddr_storage *dst)
> {
> -	struct llentry *la;
> +	struct llentry *la, *la_tmp;
>
> 	IF_AFDATA_RLOCK(ifp);
> 	la = lla_lookup(lt, LLE_EXCLUSIVE, (struct sockaddr *)dst);
> 	IF_AFDATA_RUNLOCK(ifp);
> -	if ((la == NULL) &&
> -	    (ifp->if_flags & (IFF_NOARP | IFF_STATICARP)) == 0) {
> -		IF_AFDATA_WLOCK(ifp);
> -		la = lla_create(lt, 0, (struct sockaddr *)dst);
> -		IF_AFDATA_WUNLOCK(ifp);
> -	}
>
> 	if (la != NULL) {
> 		LLE_ADDREF(la);
> 		LLE_WUNLOCK(la);
> +		return (la);
> +	}
> +
> +	if ((ifp->if_flags & (IFF_NOARP | IFF_STATICARP)) == 0) {
> +		la = lltable_alloc_entry(lt, 0, (struct sockaddr *)dst);
> +		if (la == NULL)
> +			return (NULL);
> +		IF_AFDATA_WLOCK(ifp);
> +		LLE_WLOCK(la);
> +		/* Prefer any existing LLE over newly-created one */
> +		la_tmp = lla_lookup(lt, LLE_EXCLUSIVE, (struct sockaddr *)dst);
> +		if (la_tmp == NULL)
> +			lltable_link_entry(lt, la);
> +		IF_AFDATA_WUNLOCK(ifp);
> +		if (la_tmp != NULL) {
> +			lltable_free_entry(lt, la);
> +			la = la_tmp;
> +		}
> +		LLE_ADDREF(la);
> +		LLE_WUNLOCK(la);
> 	}
>
> 	return (la);
> @@ -483,6 +500,21 @@ lltable_foreach_lle(struct lltable *llt,
> 	return (llt->llt_foreach_entry(llt, f, farg));
> }
>
> +struct llentry *
> +lltable_alloc_entry(struct lltable *llt, u_int flags,
> +    const struct sockaddr *l3addr)
> +{
> +
> +	return (llt->llt_alloc_entry(llt, flags, l3addr));
> +}
> +
> +void
> +lltable_free_entry(struct lltable *llt, struct llentry *lle)
> +{
> +
> +	llt->llt_free_entry(llt, lle);
> +}
> +
> void
> lltable_link_entry(struct lltable *llt, struct llentry *lle)
> {
> @@ -531,7 +563,7 @@ lla_rt_output(struct rt_msghdr *rtm, str
> 	struct sockaddr *dst = (struct sockaddr *)info->rti_info[RTAX_DST];
> 	struct ifnet *ifp;
> 	struct lltable *llt;
> -	struct llentry *lle;
> +	struct llentry *lle, *lle_tmp;
> 	u_int laflags = 0;
> 	int error;
>
> @@ -560,13 +592,9 @@ lla_rt_output(struct rt_msghdr *rtm, str
> 	switch (rtm->rtm_type) {
> 	case RTM_ADD:
> 		/* Add static LLE */
> -		IF_AFDATA_WLOCK(ifp);
> -		lle = lla_create(llt, 0, dst);
> -		if (lle == NULL) {
> -			IF_AFDATA_WUNLOCK(ifp);
> +		lle = lltable_alloc_entry(llt, 0, dst);
> +		if (lle == NULL)
> 			return (ENOMEM);
> -		}
> -
>
> 		bcopy(LLADDR(dl), &lle->ll_addr, ifp->if_addrlen);
> 		if ((rtm->rtm_flags & RTF_ANNOUNCE))
> @@ -589,8 +617,39 @@ lla_rt_output(struct rt_msghdr *rtm, str
> 		} else
> 			lle->la_expire = rtm->rtm_rmx.rmx_expire;
> 		laflags = lle->la_flags;
> -		LLE_WUNLOCK(lle);
> +
> +		/* Try to link new entry */
> +		lle_tmp = NULL;
> +		IF_AFDATA_WLOCK(ifp);
> +		LLE_WLOCK(lle);
> +		lle_tmp = lla_lookup(llt, LLE_EXCLUSIVE, dst);
> +		if (lle_tmp != NULL) {
> +			/* Check if we are trying to replace immutable entry */
> +			if ((lle_tmp->la_flags & LLE_IFADDR) != 0) {
> +				IF_AFDATA_WUNLOCK(ifp);
> +				LLE_WUNLOCK(lle_tmp);
> +				lltable_free_entry(llt, lle);
> +				return (EPERM);
> +			}
> +			/* Unlink existing entry from table */
> +			lltable_unlink_entry(llt, lle_tmp);
> +		}
> +		lltable_link_entry(llt, lle);
> 		IF_AFDATA_WUNLOCK(ifp);
> +
> +		if (lle_tmp != NULL) {
> +			EVENTHANDLER_INVOKE(lle_event, lle_tmp,LLENTRY_EXPIRED);
> +			lltable_free_entry(llt, lle_tmp);
> +		}
> +
> +		/*
> +		 * By invoking LLE handler here we might get
> +		 * two events on static LLE entry insertion
> +		 * in routing socket. However, since we might have
> +		 * other subscribers we need to generate this event.
> +		 */
> +		EVENTHANDLER_INVOKE(lle_event, lle, LLENTRY_RESOLVED);
> +		LLE_WUNLOCK(lle);
> #ifdef INET
> 		/* gratuitous ARP */
> 		if ((laflags & LLE_PUB) && dst->sa_family == AF_INET)
>
> Modified: head/sys/net/if_llatbl.h
> ==============================================================================
> --- head/sys/net/if_llatbl.h	Thu Aug 20 11:26:26 2015	(r286954)
> +++ head/sys/net/if_llatbl.h	Thu Aug 20 12:05:17 2015	(r286955)
> @@ -133,7 +133,7 @@ struct llentry {
>
> typedef	struct llentry *(llt_lookup_t)(struct lltable *, u_int flags,
>   const struct sockaddr *l3addr);
> -typedef	struct llentry *(llt_create_t)(struct lltable *, u_int flags,
> +typedef	struct llentry *(llt_alloc_t)(struct lltable *, u_int flags,
>   const struct sockaddr *l3addr);
> typedef	int (llt_delete_t)(struct lltable *, u_int flags,
>   const struct sockaddr *l3addr);
> @@ -161,7 +161,7 @@ struct lltable {
> 	struct ifnet		*llt_ifp;
>
> 	llt_lookup_t		*llt_lookup;
> -	llt_create_t		*llt_create;
> +	llt_alloc_t		*llt_alloc_entry;
> 	llt_delete_t		*llt_delete;
> 	llt_prefix_free_t	*llt_prefix_free;
> 	llt_dump_entry_t	*llt_dump_entry;
> @@ -209,8 +209,9 @@ struct llentry  *llentry_alloc(struct if
> /* helper functions */
> size_t lltable_drop_entry_queue(struct llentry *);
>
> -struct llentry *lltable_create_lle(struct lltable *llt, u_int flags,
> -    const void *paddr);
> +struct llentry *lltable_alloc_entry(struct lltable *llt, u_int flags,
> +    const struct sockaddr *l4addr);
> +void lltable_free_entry(struct lltable *llt, struct llentry *lle);
> void lltable_link_entry(struct lltable *llt, struct llentry *lle);
> void lltable_unlink_entry(struct lltable *llt, struct llentry *lle);
> void lltable_fill_sa_entry(const struct llentry *lle, struct sockaddr 
> *sa);
> @@ -229,13 +230,6 @@ lla_lookup(struct lltable *llt, u_int fl
> 	return (llt->llt_lookup(llt, flags, l3addr));
> }
>
> -static __inline struct llentry *
> -lla_create(struct lltable *llt, u_int flags, const struct sockaddr 
> *l3addr)
> -{
> -
> -	return (llt->llt_create(llt, flags, l3addr));
> -}
> -
> static __inline int
> lla_delete(struct lltable *llt, u_int flags, const struct sockaddr 
> *l3addr)
> {
>
> Modified: head/sys/netinet/if_ether.c
> ==============================================================================
> --- head/sys/netinet/if_ether.c	Thu Aug 20 11:26:26 2015	(r286954)
> +++ head/sys/netinet/if_ether.c	Thu Aug 20 12:05:17 2015	(r286955)
> @@ -218,8 +218,8 @@ arptimer(void *arg)
>
> 	/* Guard against race with other llentry_free(). */
> 	if (lle->la_flags & LLE_LINKED) {
> -		size_t pkts_dropped;
>
> +		size_t pkts_dropped;
> 		LLE_REMREF(lle);
> 		pkts_dropped = llentry_free(lle);
> 		ARPSTAT_ADD(dropped, pkts_dropped);
> @@ -323,7 +323,7 @@ static int
> arpresolve_full(struct ifnet *ifp, int is_gw, int create, struct mbuf 
> *m,
> 	const struct sockaddr *dst, u_char *desten, uint32_t *pflags)
> {
> -	struct llentry *la = NULL;
> +	struct llentry *la = NULL, *la_tmp;
> 	struct mbuf *curr = NULL;
> 	struct mbuf *next = NULL;
> 	int error, renew;
> @@ -337,16 +337,28 @@ arpresolve_full(struct ifnet *ifp, int i
> 		IF_AFDATA_RUNLOCK(ifp);
> 	}
> 	if (la == NULL && (ifp->if_flags & (IFF_NOARP | IFF_STATICARP)) == 0) 
> {
> -		create = 1;
> +		la = lltable_alloc_entry(LLTABLE(ifp), 0, dst);
> +		if (la == NULL) {
> +			log(LOG_DEBUG,
> +			    "arpresolve: can't allocate llinfo for %s on %s\n",
> +			    inet_ntoa(SIN(dst)->sin_addr), if_name(ifp));
> +			m_freem(m);
> +			return (EINVAL);
> +		}
> +
> 		IF_AFDATA_WLOCK(ifp);
> -		la = lla_create(LLTABLE(ifp), 0, dst);
> +		LLE_WLOCK(la);
> +		la_tmp = lla_lookup(LLTABLE(ifp), LLE_EXCLUSIVE, dst);
> +		/* Prefer ANY existing lle over newly-created one */
> +		if (la_tmp == NULL)
> +			lltable_link_entry(LLTABLE(ifp), la);
> 		IF_AFDATA_WUNLOCK(ifp);
> +		if (la_tmp != NULL) {
> +			lltable_free_entry(LLTABLE(ifp), la);
> +			la = la_tmp;
> +		}
> 	}
> 	if (la == NULL) {
> -		if (create != 0)
> -			log(LOG_DEBUG,
> -			    "arpresolve: can't allocate llinfo for %s on %s\n",
> -			    inet_ntoa(SIN(dst)->sin_addr), ifp->if_xname);
> 		m_freem(m);
> 		return (EINVAL);
> 	}
> @@ -608,7 +620,7 @@ in_arpinput(struct mbuf *m)
> 	struct rm_priotracker in_ifa_tracker;
> 	struct arphdr *ah;
> 	struct ifnet *ifp = m->m_pkthdr.rcvif;
> -	struct llentry *la = NULL;
> +	struct llentry *la = NULL, *la_tmp;
> 	struct rtentry *rt;
> 	struct ifaddr *ifa;
> 	struct in_ifaddr *ia;
> @@ -620,6 +632,7 @@ in_arpinput(struct mbuf *m)
> 	int bridged = 0, is_bridge = 0;
> 	int carped;
> 	struct sockaddr_in sin;
> +	struct sockaddr *dst;
> 	sin.sin_len = sizeof(struct sockaddr_in);
> 	sin.sin_family = AF_INET;
> 	sin.sin_addr.s_addr = 0;
> @@ -778,8 +791,9 @@ match:
> 	sin.sin_len = sizeof(struct sockaddr_in);
> 	sin.sin_family = AF_INET;
> 	sin.sin_addr = isaddr;
> +	dst = (struct sockaddr *)&sin;
> 	IF_AFDATA_RLOCK(ifp);
> -	la = lla_lookup(LLTABLE(ifp), LLE_EXCLUSIVE, (struct sockaddr 
> *)&sin);
> +	la = lla_lookup(LLTABLE(ifp), LLE_EXCLUSIVE, dst);
> 	IF_AFDATA_RUNLOCK(ifp);
> 	if (la != NULL)
> 		arp_check_update_lle(ah, isaddr, ifp, bridged, la);
> @@ -788,15 +802,47 @@ match:
> 		 * Reply to our address, but no lle exists yet.
> 		 * do we really have to create an entry?
> 		 */
> +		la = lltable_alloc_entry(LLTABLE(ifp), 0, dst);
> +		if (la == NULL)
> +			goto drop;
> +		arp_update_lle(ah, ifp, la);
> +
> 		IF_AFDATA_WLOCK(ifp);
> -		la = lla_create(LLTABLE(ifp), 0, (struct sockaddr *)&sin);
> -		if (la != NULL)
> -			arp_update_lle(ah, ifp, la);
> +		LLE_WLOCK(la);
> +		la_tmp = lla_lookup(LLTABLE(ifp), LLE_EXCLUSIVE, dst);
> +
> +		/*
> +		 * Check if lle still does not exists.
> +		 * If it does, that means that we either
> +		 * 1) have configured it explicitly, via
> +		 * 1a) 'arp -s' static entry or
> +		 * 1b) interface address static record
> +		 * or
> +		 * 2) it was the result of sending first packet to-host
> +		 * or
> +		 * 3) it was another arp reply packet we handled in
> +		 * different thread.
> +		 *
> +		 * In all cases except 3) we definitely need to prefer
> +		 * existing lle. For the sake of simplicity, prefer any
> +		 * existing lle over newly-create one.
> +		 */
> +		if (la_tmp == NULL)
> +			lltable_link_entry(LLTABLE(ifp), la);
> 		IF_AFDATA_WUNLOCK(ifp);
> -		if (la != NULL) {
> +
> +		if (la_tmp == NULL) {
> 			arp_mark_lle_reachable(la);
> 			LLE_WUNLOCK(la);
> +		} else {
> +			/* Free newly-create entry and handle packet */
> +			lltable_free_entry(LLTABLE(ifp), la);
> +			la = la_tmp;
> +			la_tmp = NULL;
> +			arp_check_update_lle(ah, isaddr, ifp, bridged, la);
> +			/* arp_check_update_lle() returns @la unlocked */
> 		}
> +		la = NULL;
> 	}
> reply:
> 	if (op != ARPOP_REQUEST)
> @@ -1044,30 +1090,53 @@ arp_mark_lle_reachable(struct llentry *l
> void
> arp_ifinit(struct ifnet *ifp, struct ifaddr *ifa)
> {
> -	struct llentry *lle;
> +	struct llentry *lle, *lle_tmp;
> +	struct sockaddr_in *dst_in;
> +	struct sockaddr *dst;
>
> 	if (ifa->ifa_carp != NULL)
> 		return;
>
> -	if (ntohl(IA_SIN(ifa)->sin_addr.s_addr) != INADDR_ANY) {
> -		arprequest(ifp, &IA_SIN(ifa)->sin_addr,
> -				&IA_SIN(ifa)->sin_addr, IF_LLADDR(ifp));
> -		/*
> -		 * interface address is considered static entry
> -		 * because the output of the arp utility shows
> -		 * that L2 entry as permanent
> -		 */
> -		IF_AFDATA_LOCK(ifp);
> -		lle = lla_create(LLTABLE(ifp), LLE_IFADDR | LLE_STATIC,
> -				 (struct sockaddr *)IA_SIN(ifa));
> -		IF_AFDATA_UNLOCK(ifp);
> -		if (lle == NULL)
> -			log(LOG_INFO, "arp_ifinit: cannot create arp "
> -			    "entry for interface address\n");
> -		else
> -			LLE_WUNLOCK(lle);
> -	}
> 	ifa->ifa_rtrequest = NULL;
> +
> +	dst_in = IA_SIN(ifa);
> +	dst = (struct sockaddr *)dst_in;
> +
> +	if (ntohl(IA_SIN(ifa)->sin_addr.s_addr) == INADDR_ANY)
> +		return;
> +
> +	arprequest(ifp, &IA_SIN(ifa)->sin_addr,
> +			&IA_SIN(ifa)->sin_addr, IF_LLADDR(ifp));
> +
> +	/*
> +	 * Interface address LLE record is considered static
> +	 * because kernel code relies on LLE_STATIC flag to check
> +	 * if these entries can be rewriten by arp updates.
> +	 */
> +	lle = lltable_alloc_entry(LLTABLE(ifp), LLE_IFADDR | LLE_STATIC, 
> dst);
> +	if (lle == NULL) {
> +		log(LOG_INFO, "arp_ifinit: cannot create arp "
> +		    "entry for interface address\n");
> +		return;
> +	}
> +
> +	IF_AFDATA_WLOCK(ifp);
> +	LLE_WLOCK(lle);
> +	/* Unlink any entry if exists */
> +	lle_tmp = lla_lookup(LLTABLE(ifp), LLE_EXCLUSIVE, dst);
> +	if (lle_tmp != NULL)
> +		lltable_unlink_entry(LLTABLE(ifp), lle_tmp);
> +
> +	lltable_link_entry(LLTABLE(ifp), lle);
> +	IF_AFDATA_WUNLOCK(ifp);
> +
> +	if (lle_tmp != NULL)
> +		EVENTHANDLER_INVOKE(lle_event, lle_tmp, LLENTRY_EXPIRED);
> +
> +	EVENTHANDLER_INVOKE(lle_event, lle, LLENTRY_RESOLVED);
> +	LLE_WUNLOCK(lle);
> +	if (lle_tmp != NULL)
> +		lltable_free_entry(LLTABLE(ifp), lle_tmp);
> }
>
> void
>
> Modified: head/sys/netinet/in.c
> ==============================================================================
> --- head/sys/netinet/in.c	Thu Aug 20 11:26:26 2015	(r286954)
> +++ head/sys/netinet/in.c	Thu Aug 20 12:05:17 2015	(r286955)
> @@ -1202,25 +1202,15 @@ in_lltable_delete(struct lltable *llt, u
> }
>
> static struct llentry *
> -in_lltable_create(struct lltable *llt, u_int flags, const struct 
> sockaddr *l3addr)
> +in_lltable_alloc(struct lltable *llt, u_int flags, const struct 
> sockaddr *l3addr)
> {
> 	const struct sockaddr_in *sin = (const struct sockaddr_in *)l3addr;
> 	struct ifnet *ifp = llt->llt_ifp;
> 	struct llentry *lle;
>
> -	IF_AFDATA_WLOCK_ASSERT(ifp);
> 	KASSERT(l3addr->sa_family == AF_INET,
> 	    ("sin_family %d", l3addr->sa_family));
>
> -	lle = in_lltable_find_dst(llt, sin->sin_addr);
> -
> -	if (lle != NULL) {
> -		LLE_WLOCK(lle);
> -		return (lle);
> -	}
> -
> -	/* no existing record, we need to create new one */
> -
> 	/*
> 	 * A route that covers the given address must have
> 	 * been installed 1st because we are doing a resolution,
> @@ -1241,9 +1231,6 @@ in_lltable_create(struct lltable *llt, u
> 		lle->la_flags |= (LLE_VALID | LLE_STATIC);
> 	}
>
> -	lltable_link_entry(llt, lle);
> -	LLE_WLOCK(lle);
> -
> 	return (lle);
> }
>
> @@ -1346,7 +1333,7 @@ in_lltattach(struct ifnet *ifp)
> 	llt->llt_ifp = ifp;
>
> 	llt->llt_lookup = in_lltable_lookup;
> -	llt->llt_create = in_lltable_create;
> +	llt->llt_alloc_entry = in_lltable_alloc;
> 	llt->llt_delete = in_lltable_delete;
> 	llt->llt_dump_entry = in_lltable_dump_entry;
> 	llt->llt_hash = in_lltable_hash;
>
> Modified: head/sys/netinet/toecore.c
> ==============================================================================
> --- head/sys/netinet/toecore.c	Thu Aug 20 11:26:26 2015	(r286954)
> +++ head/sys/netinet/toecore.c	Thu Aug 20 12:05:17 2015	(r286955)
> @@ -456,7 +456,7 @@ toe_route_redirect_event(void *arg __unu
> static int
> toe_nd6_resolve(struct ifnet *ifp, struct sockaddr *sa, uint8_t 
> *lladdr)
> {
> -	struct llentry *lle;
> +	struct llentry *lle, *lle_tmp;
> 	struct sockaddr_in6 *sin6 = (void *)sa;
> 	int rc, flags = 0;
>
> @@ -465,19 +465,32 @@ restart:
> 	lle = lla_lookup(LLTABLE6(ifp), flags, sa);
> 	IF_AFDATA_RUNLOCK(ifp);
> 	if (lle == NULL) {
> -		IF_AFDATA_LOCK(ifp);
> -		lle = nd6_create(&sin6->sin6_addr, 0, ifp);
> -		IF_AFDATA_UNLOCK(ifp);
> +		lle = nd6_alloc(&sin6->sin6_addr, 0, ifp);
> 		if (lle == NULL)
> 			return (ENOMEM); /* Couldn't create entry in cache. */
> 		lle->ln_state = ND6_LLINFO_INCOMPLETE;
> -		nd6_llinfo_settimer_locked(lle,
> -		    (long)ND_IFINFO(ifp)->retrans * hz / 1000);
> -		LLE_WUNLOCK(lle);
> +		IF_AFDATA_WLOCK(ifp);
> +		LLE_WLOCK(lle);
> +		lle_tmp = nd6_lookup(&sin6->sin6_addr, ND6_EXCLUSIVE, ifp);
> +		/* Prefer any existing lle over newly-created one */
> +		if (lle_tmp == NULL)
> +			lltable_link_entry(LLTABLE6(ifp), lle);
> +		IF_AFDATA_WUNLOCK(ifp);
> +		if (lle_tmp == NULL) {
> +			/* Arm timer for newly-created entry and send NS */
> +			nd6_llinfo_settimer_locked(lle,
> +			    (long)ND_IFINFO(ifp)->retrans * hz / 1000);
> +			LLE_WUNLOCK(lle);
>
> -		nd6_ns_output(ifp, NULL, &sin6->sin6_addr, NULL, 0);
> +			nd6_ns_output(ifp, NULL, &sin6->sin6_addr, NULL, 0);
>
> -		return (EWOULDBLOCK);
> +			return (EWOULDBLOCK);
> +		} else {
> +			/* Drop newly-created lle and switch to existing one */
> +			lltable_free_entry(LLTABLE6(ifp), lle);
> +			lle = lle_tmp;
> +			lle_tmp = NULL;
> +		}
> 	}
>
> 	if (lle->ln_state == ND6_LLINFO_STALE) {
>
> Modified: head/sys/netinet6/in6.c
> ==============================================================================
> --- head/sys/netinet6/in6.c	Thu Aug 20 11:26:26 2015	(r286954)
> +++ head/sys/netinet6/in6.c	Thu Aug 20 12:05:17 2015	(r286955)
> @@ -2239,24 +2239,16 @@ in6_lltable_delete(struct lltable *llt,
> }
>
> static struct llentry *
> -in6_lltable_create(struct lltable *llt, u_int flags,
> +in6_lltable_alloc(struct lltable *llt, u_int flags,
> 	const struct sockaddr *l3addr)
> {
> 	const struct sockaddr_in6 *sin6 = (const struct sockaddr_in6 
> *)l3addr;
> 	struct ifnet *ifp = llt->llt_ifp;
> 	struct llentry *lle;
>
> -	IF_AFDATA_WLOCK_ASSERT(ifp);
> 	KASSERT(l3addr->sa_family == AF_INET6,
> 	    ("sin_family %d", l3addr->sa_family));
>
> -	lle = in6_lltable_find_dst(llt, &sin6->sin6_addr);
> -
> -	if (lle != NULL) {
> -		LLE_WLOCK(lle);
> -		return (lle);
> -	}
> -
> 	/*
> 	 * A route that covers the given address must have
> 	 * been installed 1st because we are doing a resolution,
> @@ -2277,9 +2269,6 @@ in6_lltable_create(struct lltable *llt,
> 		lle->la_flags |= (LLE_VALID | LLE_STATIC);
> 	}
>
> -	lltable_link_entry(llt, lle);
> -	LLE_WLOCK(lle);
> -
> 	return (lle);
> }
>
> @@ -2382,7 +2371,7 @@ in6_lltattach(struct ifnet *ifp)
> 	llt->llt_ifp = ifp;
>
> 	llt->llt_lookup = in6_lltable_lookup;
> -	llt->llt_create = in6_lltable_create;
> +	llt->llt_alloc_entry = in6_lltable_alloc;
> 	llt->llt_delete = in6_lltable_delete;
> 	llt->llt_dump_entry = in6_lltable_dump_entry;
> 	llt->llt_hash = in6_lltable_hash;
>
> Modified: head/sys/netinet6/nd6.c
> ==============================================================================
> --- head/sys/netinet6/nd6.c	Thu Aug 20 11:26:26 2015	(r286954)
> +++ head/sys/netinet6/nd6.c	Thu Aug 20 12:05:17 2015	(r286955)
> @@ -939,12 +939,8 @@ nd6_lookup(struct in6_addr *addr6, int f
> 	return (ln);
> }
>
> -/*
> - * the caller acquires and releases the lock on the lltbls
> - * Returns the llentry wlocked
> - */
> struct llentry *
> -nd6_create(struct in6_addr *addr6, int flags, struct ifnet *ifp)
> +nd6_alloc(struct in6_addr *addr6, int flags, struct ifnet *ifp)
> {
> 	struct sockaddr_in6 sin6;
> 	struct llentry *ln;
> @@ -954,9 +950,7 @@ nd6_create(struct in6_addr *addr6, int f
> 	sin6.sin6_family = AF_INET6;
> 	sin6.sin6_addr = *addr6;
>
> -	IF_AFDATA_WLOCK_ASSERT(ifp);
> -
> -	ln = lla_create(LLTABLE6(ifp), 0, (struct sockaddr *)&sin6);
> +	ln = lltable_alloc_entry(LLTABLE6(ifp), 0, (struct sockaddr 
> *)&sin6);
> 	if (ln != NULL)
> 		ln->ln_state = ND6_LLINFO_NOSTATE;
>
> @@ -1640,7 +1634,7 @@ struct llentry *
> nd6_cache_lladdr(struct ifnet *ifp, struct in6_addr *from, char 
> *lladdr,
>   int lladdrlen, int type, int code)
> {
> -	struct llentry *ln = NULL;
> +	struct llentry *ln = NULL, *ln_tmp;
> 	int is_newentry;
> 	int do_update;
> 	int olladdr;
> @@ -1674,22 +1668,33 @@ nd6_cache_lladdr(struct ifnet *ifp, stru
> 	IF_AFDATA_RLOCK(ifp);
> 	ln = nd6_lookup(from, flags, ifp);
> 	IF_AFDATA_RUNLOCK(ifp);
> +	is_newentry = 0;
> 	if (ln == NULL) {
> 		flags |= ND6_EXCLUSIVE;
> -		IF_AFDATA_LOCK(ifp);
> -		ln = nd6_create(from, 0, ifp);
> -		IF_AFDATA_UNLOCK(ifp);
> -		is_newentry = 1;
> -	} else {
> -		/* do nothing if static ndp is set */
> -		if (ln->la_flags & LLE_STATIC) {
> +		ln = nd6_alloc(from, 0, ifp);
> +		if (ln == NULL)
> +			return (NULL);
> +		IF_AFDATA_WLOCK(ifp);
> +		LLE_WLOCK(ln);
> +		/* Prefer any existing lle over newly-created one */
> +		ln_tmp = nd6_lookup(from, ND6_EXCLUSIVE, ifp);
> +		if (ln_tmp == NULL)
> +			lltable_link_entry(LLTABLE6(ifp), ln);
> +		IF_AFDATA_WUNLOCK(ifp);
> +		if (ln_tmp == NULL)
> +			/* No existing lle, mark as new entry */
> +			is_newentry = 1;
> +		else {
> +			lltable_free_entry(LLTABLE6(ifp), ln);
> +			ln = ln_tmp;
> +			ln_tmp = NULL;
> +		}
> +	}
> +	/* do nothing if static ndp is set */
> +	if ((ln->la_flags & LLE_STATIC)) {
> 			static_route = 1;
> 			goto done;
> -		}
> -		is_newentry = 0;
> 	}
> -	if (ln == NULL)
> -		return (NULL);
>
> 	olladdr = (ln->la_flags & LLE_VALID) ? 1 : 0;
> 	if (olladdr && lladdr) {
> @@ -2032,7 +2037,7 @@ static int
> nd6_output_lle(struct ifnet *ifp, struct ifnet *origifp, struct mbuf 
> *m,
>   struct sockaddr_in6 *dst)
> {
> -	struct llentry *lle = NULL;
> +	struct llentry *lle = NULL, *lle_tmp;
>
> 	KASSERT(m != NULL, ("NULL mbuf, nothing to send"));
> 	/* discard the packet if IPv6 operation is disabled on the interface 
> */
> @@ -2063,19 +2068,35 @@ nd6_output_lle(struct ifnet *ifp, struct
> 			 * the condition below is not very efficient.  But we believe
> 			 * it is tolerable, because this should be a rare case.
> 			 */
> -			IF_AFDATA_LOCK(ifp);
> -			lle = nd6_create(&dst->sin6_addr, 0, ifp);
> -			IF_AFDATA_UNLOCK(ifp);
> +			lle = nd6_alloc(&dst->sin6_addr, 0, ifp);
> +			if (lle == NULL) {
> +				char ip6buf[INET6_ADDRSTRLEN];
> +				log(LOG_DEBUG,
> +				    "nd6_output: can't allocate llinfo for %s "
> +				    "(ln=%p)\n",
> +				    ip6_sprintf(ip6buf, &dst->sin6_addr), lle);
> +				m_freem(m);
> +				return (ENOBUFS);
> +			}
> +			lle->ln_state = ND6_LLINFO_NOSTATE;
> +
> +			IF_AFDATA_WLOCK(ifp);
> +			LLE_WLOCK(lle);
> +			/* Prefer any existing entry over newly-created one */
> +			lle_tmp = nd6_lookup(&dst->sin6_addr, ND6_EXCLUSIVE, ifp);
> +			if (lle_tmp == NULL)
> +				lltable_link_entry(LLTABLE6(ifp), lle);
> +			IF_AFDATA_WUNLOCK(ifp);
> +			if (lle_tmp != NULL) {
> +				lltable_free_entry(LLTABLE6(ifp), lle);
> +				lle = lle_tmp;
> +				lle_tmp = NULL;
> +			}
> 		}
> 	}
> 	if (lle == NULL) {
> 		if ((ifp->if_flags & IFF_POINTOPOINT) == 0 &&
> 		    !(ND_IFINFO(ifp)->flags & ND6_IFF_PERFORMNUD)) {
> -			char ip6buf[INET6_ADDRSTRLEN];
> -			log(LOG_DEBUG,
> -			    "nd6_output: can't allocate llinfo for %s "
> -			    "(ln=%p)\n",
> -			    ip6_sprintf(ip6buf, &dst->sin6_addr), lle);
> 			m_freem(m);
> 			return (ENOBUFS);
> 		}
> @@ -2241,24 +2262,40 @@ int
> nd6_add_ifa_lle(struct in6_ifaddr *ia)
> {
> 	struct ifnet *ifp;
> -	struct llentry *ln;
> +	struct llentry *ln, *ln_tmp;
> +	struct sockaddr *dst;
>
> 	ifp = ia->ia_ifa.ifa_ifp;
> 	if (nd6_need_cache(ifp) == 0)
> 		return (0);
> -	IF_AFDATA_LOCK(ifp);
> +
> 	ia->ia_ifa.ifa_rtrequest = nd6_rtrequest;
> -	ln = lla_create(LLTABLE6(ifp), LLE_IFADDR,
> -	    (struct sockaddr *)&ia->ia_addr);
> -	IF_AFDATA_UNLOCK(ifp);
> -	if (ln != NULL) {
> -		ln->la_expire = 0;  /* for IPv6 this means permanent */
> -		ln->ln_state = ND6_LLINFO_REACHABLE;
> -		LLE_WUNLOCK(ln);
> -		return (0);
> -	}
> +	dst = (struct sockaddr *)&ia->ia_addr;
> +	ln = lltable_alloc_entry(LLTABLE6(ifp), LLE_IFADDR, dst);
> +	if (ln == NULL)
> +		return (ENOBUFS);
>
> -	return (ENOBUFS);
> +	ln->la_expire = 0;  /* for IPv6 this means permanent */
> +	ln->ln_state = ND6_LLINFO_REACHABLE;
> +
> +	IF_AFDATA_WLOCK(ifp);
> +	LLE_WLOCK(ln);
> +	/* Unlink any entry if exists */
> +	ln_tmp = lla_lookup(LLTABLE6(ifp), LLE_EXCLUSIVE, dst);
> +	if (ln_tmp != NULL)
> +		lltable_unlink_entry(LLTABLE6(ifp), ln_tmp);
> +	lltable_link_entry(LLTABLE6(ifp), ln);
> +	IF_AFDATA_WUNLOCK(ifp);
> +
> +	if (ln_tmp != NULL)
> +		EVENTHANDLER_INVOKE(lle_event, ln_tmp, LLENTRY_EXPIRED);
> +	EVENTHANDLER_INVOKE(lle_event, ln, LLENTRY_RESOLVED);
> +
> +	LLE_WUNLOCK(ln);
> +	if (ln_tmp != NULL)
> +		llentry_free(ln_tmp);
> +
> +	return (0);
> }
>
> /*
>
> Modified: head/sys/netinet6/nd6.h
> ==============================================================================
> --- head/sys/netinet6/nd6.h	Thu Aug 20 11:26:26 2015	(r286954)
> +++ head/sys/netinet6/nd6.h	Thu Aug 20 12:05:17 2015	(r286955)
> @@ -407,7 +407,7 @@ void nd6_option_init(void *, int, union
> struct nd_opt_hdr *nd6_option(union nd_opts *);
> int nd6_options(union nd_opts *);
> struct llentry *nd6_lookup(struct in6_addr *, int, struct ifnet *);
> -struct llentry *nd6_create(struct in6_addr *, int, struct ifnet *);
> +struct llentry *nd6_alloc(struct in6_addr *, int, struct ifnet *);
> void nd6_setmtu(struct ifnet *);
> void nd6_llinfo_settimer(struct llentry *, long);
> void nd6_llinfo_settimer_locked(struct llentry *, long);


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