netinet6: use in6_ifmtu() instead of IN6_LINKMTU() macro

There should be no functional change.  If there are any performance
concerns with a function call, with the future changes, that would move
ND6 bits into in6_ifextra, this function would be easily inline-able.

Reviewed by:		tuexen
Differential Revision:	https://reviews.freebsd.org/D54724

sys/netinet6/in6.c

@@ -2627,9 +2627,14 @@ EVENTHANDLER_DEFINE(ifnet_arrival_event, in6_ifarrival, NULL,
     EVENTHANDLER_PRI_ANY);
 
 uint32_t
-in6_ifmtu(struct ifnet *ifp)
+in6_ifmtu(const struct ifnet *ifp)
 {
-	return (IN6_LINKMTU(ifp));
+	struct nd_ifinfo *ndi = ND_IFINFO(ifp);
+
+	return (
+	    (ndi->linkmtu > 0 && ndi->linkmtu < ifp->if_mtu) ? ndi->linkmtu :
+	    ((ndi->maxmtu > 0 && ndi->maxmtu < ifp->if_mtu) ? ndi->maxmtu :
+	    ifp->if_mtu));
 }
 
 /*

sys/netinet6/in6_rmx.c

@@ -114,10 +114,8 @@ rib6_augment_nh(u_int fibnum, struct nhop_object *nh)
 	 * inherit interface MTU if not set or
 	 * check if MTU is too large.
 	 */
-	if (nh->nh_mtu == 0) {
+	if (nh->nh_mtu == 0 || nh->nh_mtu > in6_ifmtu(nh->nh_ifp))
-		nh->nh_mtu = IN6_LINKMTU(nh->nh_ifp);
+		nh->nh_mtu = in6_ifmtu(nh->nh_ifp);
-	} else if (nh->nh_mtu > IN6_LINKMTU(nh->nh_ifp))
-		nh->nh_mtu = IN6_LINKMTU(nh->nh_ifp);
 
 	/* Set nexthop type */
 	if (nhop_get_type(nh) == 0) {

sys/netinet6/in6_var.h

@@ -861,7 +861,7 @@ void	in6_purgeaddr(struct ifaddr *);
 void	in6_purgeifaddr(struct in6_ifaddr *);
 int	in6if_do_dad(struct ifnet *);
 void	in6_savemkludge(struct in6_ifaddr *);
-uint32_t in6_ifmtu(struct ifnet *);
+uint32_t in6_ifmtu(const struct ifnet *);
 struct rib_head *in6_inithead(uint32_t fibnum);
 void	in6_detachhead(struct rib_head *rh);
 int	in6_if2idlen(struct ifnet *);

sys/netinet6/ip6_forward.c

@@ -384,11 +384,11 @@ ip6_forward(struct mbuf *m, int srcrt)
 pass:
 	/* See if the size was changed by the packet filter. */
 	/* TODO: change to nh->nh_mtu */
-	if (m->m_pkthdr.len > IN6_LINKMTU(nh->nh_ifp)) {
+	if (m->m_pkthdr.len > in6_ifmtu(nh->nh_ifp)) {
 		in6_ifstat_inc(nh->nh_ifp, ifs6_in_toobig);
 		if (mcopy)
 			icmp6_error(mcopy, ICMP6_PACKET_TOO_BIG, 0,
-			    IN6_LINKMTU(nh->nh_ifp));
+			    in6_ifmtu(nh->nh_ifp));
 		goto bad;
 	}
 

sys/netinet6/ip6_mroute.c

@@ -1582,7 +1582,7 @@ phyint_send(struct ip6_hdr *ip6, struct mif6 *mifp, struct mbuf *m)
 	 * Put the packet into the sending queue of the outgoing interface
 	 * if it would fit in the MTU of the interface.
 	 */
-	linkmtu = IN6_LINKMTU(ifp);
+	linkmtu = in6_ifmtu(ifp);
 	if (mb_copy->m_pkthdr.len <= linkmtu || linkmtu < IPV6_MMTU) {
 		struct sockaddr_in6 dst6;
 

sys/netinet6/ip6_output.c

@@ -1147,7 +1147,7 @@ ip6_output(struct mbuf *m0, struct ip6_pktopts *opt,
 		dontfrag = 1;
 	else
 		dontfrag = 0;
-	if (dontfrag && tlen > IN6_LINKMTU(ifp) && !tso) {	/* Case 2-b. */
+	if (dontfrag && tlen > in6_ifmtu(ifp) && !tso) {	/* Case 2-b. */
 		/*
 		 * If the DONTFRAG option is specified, we cannot send the
 		 * packet when the data length is larger than the MTU of the
@@ -1561,7 +1561,7 @@ ip6_calcmtu(struct ifnet *ifp, const struct in6_addr *dst, u_long rt_mtu,
 	}
 
 	if (mtu == 0)
-		mtu = IN6_LINKMTU(ifp);
+		mtu = in6_ifmtu(ifp);
 
 	*mtup = mtu;
 }

sys/netinet6/nd6.c

@@ -1662,7 +1662,7 @@ nd6_ioctl(u_long cmd, caddr_t data, struct ifnet *ifp)
 		/* 0 means 'unspecified' */
 		if (ND.linkmtu != 0) {
 			if (ND.linkmtu < IPV6_MMTU ||
-			    ND.linkmtu > IN6_LINKMTU(ifp)) {
+			    ND.linkmtu > in6_ifmtu(ifp)) {
 				error = EINVAL;
 				break;
 			}

sys/netinet6/nd6.h

@@ -83,11 +83,6 @@ struct llentry;
 
 #ifdef _KERNEL
 #define ND_IFINFO(ifp)	((if_getinet6(ifp))->nd_ifinfo)
-#define IN6_LINKMTU(ifp) \
-	((ND_IFINFO(ifp)->linkmtu && ND_IFINFO(ifp)->linkmtu < (ifp)->if_mtu) \
-	    ? ND_IFINFO(ifp)->linkmtu \
-	    : ((ND_IFINFO(ifp)->maxmtu && ND_IFINFO(ifp)->maxmtu < (ifp)->if_mtu) \
-		? ND_IFINFO(ifp)->maxmtu : (ifp)->if_mtu))
 #endif
 
 struct in6_nbrinfo {

sys/netpfil/pf/pf.c

@@ -11708,9 +11708,9 @@ pf_test(sa_family_t af, int dir, int pflags, struct ifnet *ifp, struct mbuf **m0
 	 * it here, before we do any NAT.
 	 */
 	if (af == AF_INET6 && dir == PF_OUT && pflags & PFIL_FWD &&
-	    IN6_LINKMTU(ifp) < pf_max_frag_size(*m0)) {
+	    in6_ifmtu(ifp) < pf_max_frag_size(*m0)) {
 		PF_RULES_RUNLOCK();
-		icmp6_error(*m0, ICMP6_PACKET_TOO_BIG, 0, IN6_LINKMTU(ifp));
+		icmp6_error(*m0, ICMP6_PACKET_TOO_BIG, 0, in6_ifmtu(ifp));
 		*m0 = NULL;
 		return (PF_DROP);
 	}