bridge: store a bridge_iflist pointer in ifnet

currently, bridge stores a pointer to its softc in ifnet.  this means
that when processing a packet, it needs to walk the bridge's member list
to find the bridge_iflist for the interface the packet came from.

instead, store a pointer to the bridge_iflist in ifnet, and add a
pointer from bridge_iflist back to the bridge_softc.  this means given
an ifnet, we always have both the softc and the bridge_iflist without a
list walk.

there are two places outside if_bridge that treat ifnet->if_bridge as
something other than an opaque pointer: bridgestp, and netinet.  add two
function pointers exported from if_bridge to handle those cases.

bump __FreeBSD_version as this is technically a KABI break.

Reviewed by:	kp

sys/net/bridgestp.c

@@ -57,6 +57,7 @@
 #include <net/if_types.h>
 #include <net/if_llc.h>
 #include <net/if_media.h>
+#include <net/if_bridgevar.h>
 #include <net/vnet.h>
 
 #include <netinet/in.h>
@@ -2059,6 +2060,7 @@ bstp_reinit(struct bstp_state *bs)
 	mif = NULL;
 	bridgeptr = LIST_FIRST(&bs->bs_bplist)->bp_ifp->if_bridge;
 	KASSERT(bridgeptr != NULL, ("Invalid bridge pointer"));
+	KASSERT(bridge_same_p != NULL, ("if_bridge not loaded"));
 	/*
 	 * Search through the Ethernet adapters and find the one with the
 	 * lowest value. Make sure the adapter which we take the MAC address
@@ -2070,7 +2072,7 @@ bstp_reinit(struct bstp_state *bs)
 		if (ifp->if_type != IFT_ETHER && ifp->if_type != IFT_L2VLAN)
 			continue;	/* Not Ethernet */
 
-		if (ifp->if_bridge != bridgeptr)
+		if (!bridge_same_p(ifp->if_bridge, bridgeptr))
 			continue;	/* Not part of our bridge */
 
 		if (bstp_addr_cmp(IF_LLADDR(ifp), llzero) == 0)

sys/net/if_bridge.c

@@ -238,12 +238,15 @@
 #define BRIDGE_RT_LOCK_OR_NET_EPOCH_ASSERT(_sc)	\
 	    MPASS(in_epoch(net_epoch_preempt) || mtx_owned(&(_sc)->sc_rt_mtx))
 
+struct bridge_softc;
+
 /*
  * Bridge interface list entry.
  */
 struct bridge_iflist {
 	CK_LIST_ENTRY(bridge_iflist) bif_next;
 	struct ifnet		*bif_ifp;	/* member if */
+	struct bridge_softc	*bif_sc;	/* parent bridge */
 	struct bstp_port	bif_stp;	/* STP state */
 	uint32_t		bif_flags;	/* member if flags */
 	int			bif_savedcaps;	/* saved capabilities */
@@ -314,6 +317,8 @@ static void	bridge_set_ifcap(struct bridge_softc *, struct bridge_iflist *,
 static void	bridge_ifdetach(void *arg __unused, struct ifnet *);
 static void	bridge_init(void *);
 static void	bridge_dummynet(struct mbuf *, struct ifnet *);
+static bool	bridge_same(const void *, const void *);
+static void	*bridge_get_softc(struct ifnet *);
 static void	bridge_stop(struct ifnet *, int);
 static int	bridge_transmit(struct ifnet *, struct mbuf *);
 #ifdef ALTQ
@@ -658,6 +663,8 @@ bridge_modevent(module_t mod, int type, void *data)
 	switch (type) {
 	case MOD_LOAD:
 		bridge_dn_p = bridge_dummynet;
+		bridge_same_p = bridge_same;
+		bridge_get_softc_p = bridge_get_softc;
 		bridge_detach_cookie = EVENTHANDLER_REGISTER(
 		    ifnet_departure_event, bridge_ifdetach, NULL,
 		    EVENTHANDLER_PRI_ANY);
@@ -666,6 +673,8 @@ bridge_modevent(module_t mod, int type, void *data)
 		EVENTHANDLER_DEREGISTER(ifnet_departure_event,
 		    bridge_detach_cookie);
 		bridge_dn_p = NULL;
+		bridge_same_p = NULL;
+		bridge_get_softc_p = NULL;
 		break;
 	default:
 		return (EOPNOTSUPP);
@@ -740,6 +749,43 @@ bridge_reassign(struct ifnet *ifp, struct vnet *newvnet, char *arg)
 }
 #endif
 
+/*
+ * bridge_get_softc:
+ *
+ * Return the bridge softc for an ifnet.
+ */
+static void *
+bridge_get_softc(struct ifnet *ifp)
+{
+	struct bridge_iflist *bif;
+
+	NET_EPOCH_ASSERT();
+
+	bif = ifp->if_bridge;
+	if (bif == NULL)
+		return (NULL);
+	return (bif->bif_sc);
+}
+
+/*
+ * bridge_same:
+ *
+ * Return true if two interfaces are in the same bridge.  This is only used by
+ * bridgestp via bridge_same_p.
+ */
+static bool
+bridge_same(const void *bifap, const void *bifbp)
+{
+	const struct bridge_iflist *bifa = bifap, *bifb = bifbp;
+
+	NET_EPOCH_ASSERT();
+
+	if (bifa == NULL || bifb == NULL)
+		return (false);
+
+	return (bifa->bif_sc == bifb->bif_sc);
+}
+
 /*
  * bridge_clone_create:
  *
@@ -1116,16 +1162,8 @@ bridge_lookup_member(struct bridge_softc *sc, const char *name)
 static struct bridge_iflist *
 bridge_lookup_member_if(struct bridge_softc *sc, struct ifnet *member_ifp)
 {
-	struct bridge_iflist *bif;
-
 	BRIDGE_LOCK_OR_NET_EPOCH_ASSERT(sc);
-
+	return (member_ifp->if_bridge);
-	CK_LIST_FOREACH(bif, &sc->sc_iflist, bif_next) {
-		if (bif->bif_ifp == member_ifp)
-			return (bif);
-	}
-
-	return (NULL);
 }
 
 static void
@@ -1257,11 +1295,13 @@ bridge_ioctl_add(struct bridge_softc *sc, void *arg)
 		if (ifs == bif->bif_ifp)
 			return (EBUSY);
 
-	if (ifs->if_bridge == sc)
+	if (ifs->if_bridge) {
+		struct bridge_iflist *sbif = ifs->if_bridge;
+		if (sbif->bif_sc == sc)
 			return (EEXIST);
 
-	if (ifs->if_bridge != NULL)
 		return (EBUSY);
+	}
 
 	switch (ifs->if_type) {
 	case IFT_ETHER:
@@ -1336,6 +1376,7 @@ bridge_ioctl_add(struct bridge_softc *sc, void *arg)
 	if (bif == NULL)
 		return (ENOMEM);
 
+	bif->bif_sc = sc;
 	bif->bif_ifp = ifs;
 	bif->bif_flags = IFBIF_LEARNING | IFBIF_DISCOVER;
 	bif->bif_savedcaps = ifs->if_capenable;
@@ -1352,7 +1393,7 @@ bridge_ioctl_add(struct bridge_softc *sc, void *arg)
 		EVENTHANDLER_INVOKE(iflladdr_event, sc->sc_ifp);
 	}
 
-	ifs->if_bridge = sc;
+	ifs->if_bridge = bif;
 	ifs->if_bridge_output = bridge_output;
 	ifs->if_bridge_input = bridge_input;
 	ifs->if_bridge_linkstate = bridge_linkstate;
@@ -1979,8 +2020,11 @@ bridge_ioctl_stxhc(struct bridge_softc *sc, void *arg)
 static void
 bridge_ifdetach(void *arg __unused, struct ifnet *ifp)
 {
-	struct bridge_softc *sc = ifp->if_bridge;
+	struct bridge_iflist *bif = ifp->if_bridge;
-	struct bridge_iflist *bif;
+	struct bridge_softc *sc = NULL;
+
+	if (bif)
+		sc = bif->bif_sc;
 
 	if (ifp->if_flags & IFF_RENAMING)
 		return;
@@ -1994,11 +2038,7 @@ bridge_ifdetach(void *arg __unused, struct ifnet *ifp)
 	/* Check if the interface is a bridge member */
 	if (sc != NULL) {
 		BRIDGE_LOCK(sc);
-
-		bif = bridge_lookup_member_if(sc, ifp);
-		if (bif != NULL)
 		bridge_delete_member(sc, bif, 1);
-
 		BRIDGE_UNLOCK(sc);
 		return;
 	}
@@ -2136,9 +2176,11 @@ bridge_enqueue(struct bridge_softc *sc, struct ifnet *dst_ifp, struct mbuf *m)
 static void
 bridge_dummynet(struct mbuf *m, struct ifnet *ifp)
 {
-	struct bridge_softc *sc;
+	struct bridge_iflist *bif = ifp->if_bridge;
+	struct bridge_softc *sc = NULL;
 
-	sc = ifp->if_bridge;
+	if (bif)
+		sc = bif->bif_sc;
 
 	/*
 	 * The packet didnt originate from a member interface. This should only
@@ -2175,6 +2217,7 @@ bridge_output(struct ifnet *ifp, struct mbuf *m, struct sockaddr *sa,
     struct rtentry *rt)
 {
 	struct ether_header *eh;
+	struct bridge_iflist *sbif;
 	struct ifnet *bifp, *dst_if;
 	struct bridge_softc *sc;
 	uint16_t vlan;
@@ -2187,12 +2230,13 @@ bridge_output(struct ifnet *ifp, struct mbuf *m, struct sockaddr *sa,
 			return (0);
 	}
 
-	eh = mtod(m, struct ether_header *);
+	sbif = ifp->if_bridge;
-	sc = ifp->if_bridge;
+	sc = sbif->bif_sc;
-	vlan = VLANTAGOF(m);
-
 	bifp = sc->sc_ifp;
 
+	eh = mtod(m, struct ether_header *);
+	vlan = VLANTAGOF(m);
+
 	/*
 	 * If bridge is down, but the original output interface is up,
 	 * go ahead and send out that interface.  Otherwise, the packet
@@ -2503,7 +2547,7 @@ bridge_forward(struct bridge_softc *sc, struct bridge_iflist *sbif,
 static struct mbuf *
 bridge_input(struct ifnet *ifp, struct mbuf *m)
 {
-	struct bridge_softc *sc;
+	struct bridge_softc *sc = NULL;
 	struct bridge_iflist *bif, *bif2;
 	struct ifnet *bifp;
 	struct ether_header *eh;
@@ -2516,7 +2560,10 @@ bridge_input(struct ifnet *ifp, struct mbuf *m)
 	eh = mtod(m, struct ether_header *);
 	vlan = VLANTAGOF(m);
 
-	sc = ifp->if_bridge;
+	bif = ifp->if_bridge;
+	if (bif)
+		sc = bif->bif_sc;
+
 	if (sc == NULL) {
 		/*
 		 * This packet originated from the bridge itself, so it must
@@ -2553,10 +2600,6 @@ bridge_input(struct ifnet *ifp, struct mbuf *m)
 		m_freem(m);
 		return (NULL);
 	}
-	bif = bridge_lookup_member_if(sc, ifp);
-	if (bif == NULL) {
-		return (m);
-	}
 
 	bridge_span(sc, m);
 
@@ -3329,10 +3372,16 @@ bridge_rtnode_destroy(struct bridge_softc *sc, struct bridge_rtnode *brt)
 static void
 bridge_rtable_expire(struct ifnet *ifp, int age)
 {
-	struct bridge_softc *sc = ifp->if_bridge;
+	struct bridge_iflist *bif = NULL;
+	struct bridge_softc *sc = NULL;
 	struct bridge_rtnode *brt;
 
 	CURVNET_SET(ifp->if_vnet);
+
+	bif = ifp->if_bridge;
+	if (bif)
+		sc = bif->bif_sc;
+	MPASS(sc != NULL);
 	BRIDGE_RT_LOCK(sc);
 
 	/*
@@ -3362,7 +3411,8 @@ bridge_rtable_expire(struct ifnet *ifp, int age)
 static void
 bridge_state_change(struct ifnet *ifp, int state)
 {
-	struct bridge_softc *sc = ifp->if_bridge;
+	struct bridge_iflist *bif = ifp->if_bridge;
+	struct bridge_softc *sc = bif->bif_sc;
 	static const char *stpstates[] = {
 		"disabled",
 		"listening",
@@ -3877,20 +3927,20 @@ bridge_fragment(struct ifnet *ifp, struct mbuf **mp, struct ether_header *eh,
 static void
 bridge_linkstate(struct ifnet *ifp)
 {
-	struct bridge_softc *sc = ifp->if_bridge;
+	struct bridge_softc *sc = NULL;
 	struct bridge_iflist *bif;
 	struct epoch_tracker et;
 
 	NET_EPOCH_ENTER(et);
 
-	bif = bridge_lookup_member_if(sc, ifp);
+	bif = ifp->if_bridge;
-	if (bif == NULL) {
+	if (bif)
-		NET_EPOCH_EXIT(et);
+		sc = bif->bif_sc;
-		return;
-	}
-	bridge_linkcheck(sc);
 
+	if (sc != NULL) {
+		bridge_linkcheck(sc);
 		bstp_linkstate(&bif->bif_stp);
+	}
 
 	NET_EPOCH_EXIT(et);
 }

sys/net/if_bridgevar.h

@@ -320,5 +320,7 @@ struct ifbpstpconf {
 } while (0)
 
 extern	void (*bridge_dn_p)(struct mbuf *, struct ifnet *);
+extern	bool (*bridge_same_p)(const void *, const void *);
+extern	void *(*bridge_get_softc_p)(struct ifnet *);
 
 #endif /* _KERNEL */

sys/net/if_ethersubr.c

@@ -110,6 +110,8 @@ void	(*vlan_input_p)(struct ifnet *, struct mbuf *);
 
 /* if_bridge(4) support */
 void	(*bridge_dn_p)(struct mbuf *, struct ifnet *);
+bool	(*bridge_same_p)(const void *, const void *);
+void	*(*bridge_get_softc_p)(struct ifnet *);
 
 /* if_lagg(4) support */
 struct mbuf *(*lagg_input_ethernet_p)(struct ifnet *, struct mbuf *); 

sys/netinet/if_ether.c

@@ -56,6 +56,7 @@
 #include <net/if_dl.h>
 #include <net/if_private.h>
 #include <net/if_types.h>
+#include <net/if_bridgevar.h>
 #include <net/netisr.h>
 #include <net/ethernet.h>
 #include <net/route.h>
@@ -832,7 +833,7 @@ in_arpinput(struct mbuf *m)
 	 * when we have clusters of interfaces).
 	 */
 	CK_LIST_FOREACH(ia, INADDR_HASH(itaddr.s_addr), ia_hash) {
-		if (((bridged && ia->ia_ifp->if_bridge == ifp->if_bridge) ||
+		if (((bridged && bridge_same_p(ia->ia_ifp->if_bridge, ifp->if_bridge)) ||
 		    ia->ia_ifp == ifp) &&
 		    itaddr.s_addr == ia->ia_addr.sin_addr.s_addr &&
 		    (ia->ia_ifa.ifa_carp == NULL ||
@@ -842,7 +843,7 @@ in_arpinput(struct mbuf *m)
 		}
 	}
 	CK_LIST_FOREACH(ia, INADDR_HASH(isaddr.s_addr), ia_hash)
-		if (((bridged && ia->ia_ifp->if_bridge == ifp->if_bridge) ||
+		if (((bridged && bridge_same_p(ia->ia_ifp->if_bridge, ifp->if_bridge)) ||
 		    ia->ia_ifp == ifp) &&
 		    isaddr.s_addr == ia->ia_addr.sin_addr.s_addr) {
 			ifa_ref(&ia->ia_ifa);
@@ -850,7 +851,7 @@ in_arpinput(struct mbuf *m)
 		}
 
 #define BDG_MEMBER_MATCHES_ARP(addr, ifp, ia)				\
-  (ia->ia_ifp->if_bridge == ifp->if_softc &&				\
+  (bridge_get_softc_p(ia->ia_ifp) == ifp->if_softc &&			\
   !bcmp(IF_LLADDR(ia->ia_ifp), IF_LLADDR(ifp), ifp->if_addrlen) &&	\
   addr == ia->ia_addr.sin_addr.s_addr)
 	/*

sys/sys/param.h

@@ -73,7 +73,7 @@
  * cannot include sys/param.h and should only be updated here.
  */
 #undef __FreeBSD_version
-#define __FreeBSD_version 1500035
+#define __FreeBSD_version 1500036
 
 /*
  * __FreeBSD_kernel__ indicates that this system uses the kernel of FreeBSD,