[lltable] Add per-family lltable getters.

Introduce a new function, lltable_get(), to retrieve lltable pointer
 for the specified interface and family.
Use it to avoid all-iftable list traversal when adding or deleting
 ARP/ND records.

Differential Revision: https://reviews.freebsd.org/D33660
Approved by:    re(gjb)
MFC after:	2 weeks

(cherry picked from commit ff3a85d32411cdd7894f932b1d3d7ce01ec7a648)
(cherry picked from commit ffcca53561ed0b3d4755dbd2ce1d9942ea4a468e)

4 files changed, 44 insertions, 8 deletions

diff --git a/sys/net/if_llatbl.c b/sys/net/if_llatbl.c
index e4dfc45705a8..10d555b1bd86 100644
--- a/sys/net/if_llatbl.c
+++ b/sys/net/if_llatbl.c
@@ -713,6 +713,22 @@ lltable_unlink(struct lltable *llt)
 }
 
 /*
+ * Gets interface @ifp lltable for the specified @family
+ */
+struct lltable *
+lltable_get(struct ifnet *ifp, int family)
+{
+	switch (family) {
+	case AF_INET:
+		return (in_lltable_get(ifp));
+	case AF_INET6:
+		return (in6_lltable_get(ifp));
+	}
+
+	return (NULL);
+}
+
+/*
  * External methods used by lltable consumers
  */
 
@@ -823,14 +839,8 @@ lla_rt_output(struct rt_msghdr *rtm, struct rt_addrinfo *info)
 		return EINVAL;
 	}
 
-	/* XXX linked list may be too expensive */
-	LLTABLE_LIST_RLOCK();
-	SLIST_FOREACH(llt, &V_lltables, llt_link) {
-		if (llt->llt_af == dst->sa_family &&
-		    llt->llt_ifp == ifp)
-			break;
-	}
-	LLTABLE_LIST_RUNLOCK();
+	llt = lltable_get(ifp, dst->sa_family);
+
 	if (llt == NULL)
 		return (ESRCH);
 
diff --git a/sys/net/if_llatbl.h b/sys/net/if_llatbl.h
index 7ad9d59a1a0e..dfb5e13a9436 100644
--- a/sys/net/if_llatbl.h
+++ b/sys/net/if_llatbl.h
@@ -222,6 +222,10 @@ void		lltable_prefix_free(int, struct sockaddr *,
 		    struct sockaddr *, u_int);
 int		lltable_sysctl_dumparp(int, struct sysctl_req *);
 
+struct lltable *in_lltable_get(struct ifnet *ifp);
+struct lltable *in6_lltable_get(struct ifnet *ifp);
+struct lltable *lltable_get(struct ifnet *ifp, int family);
+
 size_t		llentry_free(struct llentry *);
 
 /* helper functions */
diff --git a/sys/netinet/in.c b/sys/netinet/in.c
index 5448c3b5fccd..2303a8f10aa4 100644
--- a/sys/netinet/in.c
+++ b/sys/netinet/in.c
@@ -1695,6 +1695,17 @@ in_lltattach(struct ifnet *ifp)
 	return (llt);
 }
 
+struct lltable *
+in_lltable_get(struct ifnet *ifp)
+{
+	struct lltable *llt = NULL;
+
+	void *afdata_ptr = ifp->if_afdata[AF_INET];
+	if (afdata_ptr != NULL)
+		llt = ((struct in_ifinfo *)afdata_ptr)->ii_llt;
+	return (llt);
+}
+
 void *
 in_domifattach(struct ifnet *ifp)
 {
diff --git a/sys/netinet6/in6.c b/sys/netinet6/in6.c
index d54aba58edb6..41b05ae2ca53 100644
--- a/sys/netinet6/in6.c
+++ b/sys/netinet6/in6.c
@@ -2462,6 +2462,17 @@ in6_lltattach(struct ifnet *ifp)
 	return (llt);
 }
 
+struct lltable *
+in6_lltable_get(struct ifnet *ifp)
+{
+	struct lltable *llt = NULL;
+
+	void *afdata_ptr = ifp->if_afdata[AF_INET6];
+	if (afdata_ptr != NULL)
+		llt = ((struct in6_ifextra *)afdata_ptr)->lltable;
+	return (llt);
+}
+
 void *
 in6_domifattach(struct ifnet *ifp)
 {