Merge branch 'bridge-rx-simplify-fwd-consolidate'

Nikolay Aleksandrov says:

====================
net: bridge: simplify receive path and consolidate forwarding paths

This set tries to simplify the receive and forwarding paths. Patch 01 is
a trivial style adjustment, patch 02 removes one conditional from the
unicast fast path, patch 03 removes another conditional and more imporantly
removes the skb0/skb2 ambiguity about locally receiving the skb and
switches to a boolean called "local_rcv".
Patch 04 is the most important change which consolidates the forwarding
paths for locally originated and forwarded packets into __br_forward. This
allows us to remove the function pointers giving a minor performance boost,
more importantly it makes it much easier to reason about the forwarding
path and reduces the code duplication that was needed when making changes.
Also it allows the receive path to fully setup the environment prior to
calling any forwarding functions (i.e. to properly set unicast, local_rcv
and search for unicast/mcast dst).
Functionally everything should stay the same after this set.

I've done basic tests with unicast/multicast/broadcast Tx/Rx. Please
review carefully.
====================
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

net/bridge/br_device.c

@@ -61,11 +61,11 @@ netdev_tx_t br_dev_xmit(struct sk_buff *skb, struct net_device *dev)
 	if (!br_allowed_ingress(br, br_vlan_group_rcu(br), skb, &vid))
 		goto out;
 
-	if (is_broadcast_ether_addr(dest))
-		br_flood_deliver(br, skb, false);
-	else if (is_multicast_ether_addr(dest)) {
+	if (is_broadcast_ether_addr(dest)) {
+		br_flood(br, skb, false, false, true);
+	} else if (is_multicast_ether_addr(dest)) {
 		if (unlikely(netpoll_tx_running(dev))) {
-			br_flood_deliver(br, skb, false);
+			br_flood(br, skb, false, false, true);
 			goto out;
 		}
 		if (br_multicast_rcv(br, NULL, skb, vid)) {
@@ -76,14 +76,14 @@ netdev_tx_t br_dev_xmit(struct sk_buff *skb, struct net_device *dev)
 		mdst = br_mdb_get(br, skb, vid);
 		if ((mdst || BR_INPUT_SKB_CB_MROUTERS_ONLY(skb)) &&
 		    br_multicast_querier_exists(br, eth_hdr(skb)))
-			br_multicast_deliver(mdst, skb);
+			br_multicast_flood(mdst, skb, false, true);
 		else
-			br_flood_deliver(br, skb, false);
-	} else if ((dst = __br_fdb_get(br, dest, vid)) != NULL)
-		br_deliver(dst->dst, skb);
-	else
-		br_flood_deliver(br, skb, true);
-
+			br_flood(br, skb, false, false, true);
+	} else if ((dst = __br_fdb_get(br, dest, vid)) != NULL) {
+		br_forward(dst->dst, skb, false, true);
+	} else {
+		br_flood(br, skb, true, false, true);
+	}
 out:
 	rcu_read_unlock();
 	return NETDEV_TX_OK;

net/bridge/br_forward.c

@@ -21,11 +21,6 @@
 #include <linux/netfilter_bridge.h>
 #include "br_private.h"
 
-static int deliver_clone(const struct net_bridge_port *prev,
-			 struct sk_buff *skb,
-			 void (*__packet_hook)(const struct net_bridge_port *p,
-					       struct sk_buff *skb));
-
 /* Don't forward packets to originating port or forwarding disabled */
 static inline int should_deliver(const struct net_bridge_port *p,
 				 const struct sk_buff *skb)
@@ -75,105 +70,92 @@ int br_forward_finish(struct net *net, struct sock *sk, struct sk_buff *skb)
 }
 EXPORT_SYMBOL_GPL(br_forward_finish);
 
-static void __br_deliver(const struct net_bridge_port *to, struct sk_buff *skb)
+static void __br_forward(const struct net_bridge_port *to,
+			 struct sk_buff *skb, bool local_orig)
 {
 	struct net_bridge_vlan_group *vg;
+	struct net_device *indev;
+	struct net *net;
+	int br_hook;
 
 	vg = nbp_vlan_group_rcu(to);
 	skb = br_handle_vlan(to->br, vg, skb);
 	if (!skb)
 		return;
 
+	indev = skb->dev;
 	skb->dev = to->dev;
-
-	if (unlikely(netpoll_tx_running(to->br->dev))) {
-		if (!is_skb_forwardable(skb->dev, skb))
+	if (!local_orig) {
+		if (skb_warn_if_lro(skb)) {
 			kfree_skb(skb);
-		else {
-			skb_push(skb, ETH_HLEN);
-			br_netpoll_send_skb(to, skb);
+			return;
 		}
-		return;
+		br_hook = NF_BR_FORWARD;
+		skb_forward_csum(skb);
+		net = dev_net(indev);
+	} else {
+		if (unlikely(netpoll_tx_running(to->br->dev))) {
+			if (!is_skb_forwardable(skb->dev, skb)) {
+				kfree_skb(skb);
+			} else {
+				skb_push(skb, ETH_HLEN);
+				br_netpoll_send_skb(to, skb);
+			}
+			return;
+		}
+		br_hook = NF_BR_LOCAL_OUT;
+		net = dev_net(skb->dev);
+		indev = NULL;
 	}
 
-	NF_HOOK(NFPROTO_BRIDGE, NF_BR_LOCAL_OUT,
-		dev_net(skb->dev), NULL, skb,NULL, skb->dev,
+	NF_HOOK(NFPROTO_BRIDGE, br_hook,
+		net, NULL, skb, indev, skb->dev,
 		br_forward_finish);
 }
 
-static void __br_forward(const struct net_bridge_port *to, struct sk_buff *skb)
+static int deliver_clone(const struct net_bridge_port *prev,
+			 struct sk_buff *skb, bool local_orig)
 {
-	struct net_bridge_vlan_group *vg;
-	struct net_device *indev;
-
-	if (skb_warn_if_lro(skb)) {
-		kfree_skb(skb);
-		return;
-	}
-
-	vg = nbp_vlan_group_rcu(to);
-	skb = br_handle_vlan(to->br, vg, skb);
-	if (!skb)
-		return;
-
-	indev = skb->dev;
-	skb->dev = to->dev;
-	skb_forward_csum(skb);
-
-	NF_HOOK(NFPROTO_BRIDGE, NF_BR_FORWARD,
-		dev_net(indev), NULL, skb, indev, skb->dev,
-		br_forward_finish);
-}
+	struct net_device *dev = BR_INPUT_SKB_CB(skb)->brdev;
 
-/* called with rcu_read_lock */
-void br_deliver(const struct net_bridge_port *to, struct sk_buff *skb)
-{
-	if (to && should_deliver(to, skb)) {
-		__br_deliver(to, skb);
-		return;
+	skb = skb_clone(skb, GFP_ATOMIC);
+	if (!skb) {
+		dev->stats.tx_dropped++;
+		return -ENOMEM;
 	}
 
-	kfree_skb(skb);
+	__br_forward(prev, skb, local_orig);
+	return 0;
 }
-EXPORT_SYMBOL_GPL(br_deliver);
 
-/* called with rcu_read_lock */
-void br_forward(const struct net_bridge_port *to, struct sk_buff *skb, struct sk_buff *skb0)
+/**
+ * br_forward - forward a packet to a specific port
+ * @to: destination port
+ * @skb: packet being forwarded
+ * @local_rcv: packet will be received locally after forwarding
+ * @local_orig: packet is locally originated
+ *
+ * Should be called with rcu_read_lock.
+ */
+void br_forward(const struct net_bridge_port *to,
+		struct sk_buff *skb, bool local_rcv, bool local_orig)
 {
 	if (to && should_deliver(to, skb)) {
-		if (skb0)
-			deliver_clone(to, skb, __br_forward);
+		if (local_rcv)
+			deliver_clone(to, skb, local_orig);
 		else
-			__br_forward(to, skb);
+			__br_forward(to, skb, local_orig);
 		return;
 	}
 
-	if (!skb0)
+	if (!local_rcv)
 		kfree_skb(skb);
 }
-
-static int deliver_clone(const struct net_bridge_port *prev,
-			 struct sk_buff *skb,
-			 void (*__packet_hook)(const struct net_bridge_port *p,
-					       struct sk_buff *skb))
-{
-	struct net_device *dev = BR_INPUT_SKB_CB(skb)->brdev;
-
-	skb = skb_clone(skb, GFP_ATOMIC);
-	if (!skb) {
-		dev->stats.tx_dropped++;
-		return -ENOMEM;
-	}
-
-	__packet_hook(prev, skb);
-	return 0;
-}
+EXPORT_SYMBOL_GPL(br_forward);
 
 static struct net_bridge_port *maybe_deliver(
 	struct net_bridge_port *prev, struct net_bridge_port *p,
-	struct sk_buff *skb,
-	void (*__packet_hook)(const struct net_bridge_port *p,
-			      struct sk_buff *skb))
+	struct sk_buff *skb, bool local_orig)
 {
 	int err;
 
@@ -183,7 +165,7 @@ static struct net_bridge_port *maybe_deliver(
 	if (!prev)
 		goto out;
 
-	err = deliver_clone(prev, skb, __packet_hook);
+	err = deliver_clone(prev, skb, local_orig);
 	if (err)
 		return ERR_PTR(err);
 
@@ -191,19 +173,14 @@ static struct net_bridge_port *maybe_deliver(
 	return p;
 }
 
-/* called under bridge lock */
-static void br_flood(struct net_bridge *br, struct sk_buff *skb,
-		     struct sk_buff *skb0,
-		     void (*__packet_hook)(const struct net_bridge_port *p,
-					   struct sk_buff *skb),
-		     bool unicast)
+/* called under rcu_read_lock */
+void br_flood(struct net_bridge *br, struct sk_buff *skb,
+	      bool unicast, bool local_rcv, bool local_orig)
 {
 	u8 igmp_type = br_multicast_igmp_type(skb);
-	struct net_bridge_port *prev;
+	struct net_bridge_port *prev = NULL;
 	struct net_bridge_port *p;
 
-	prev = NULL;
-
 	list_for_each_entry_rcu(p, &br->port_list, list) {
 		/* Do not flood unicast traffic to ports that turn it off */
 		if (unicast && !(p->flags & BR_FLOOD))
@@ -216,7 +193,7 @@ static void br_flood(struct net_bridge *br, struct sk_buff *skb,
 		    BR_INPUT_SKB_CB(skb)->proxyarp_replied)
 			continue;
 
-		prev = maybe_deliver(prev, p, skb, __packet_hook);
+		prev = maybe_deliver(prev, p, skb, local_orig);
 		if (IS_ERR(prev))
 			goto out;
 		if (prev == p)
@@ -227,38 +204,22 @@ static void br_flood(struct net_bridge *br, struct sk_buff *skb,
 	if (!prev)
 		goto out;
 
-	if (skb0)
-		deliver_clone(prev, skb, __packet_hook);
+	if (local_rcv)
+		deliver_clone(prev, skb, local_orig);
 	else
-		__packet_hook(prev, skb);
+		__br_forward(prev, skb, local_orig);
 	return;
 
 out:
-	if (!skb0)
+	if (!local_rcv)
 		kfree_skb(skb);
 }
 
-
-/* called with rcu_read_lock */
-void br_flood_deliver(struct net_bridge *br, struct sk_buff *skb, bool unicast)
-{
-	br_flood(br, skb, NULL, __br_deliver, unicast);
-}
-
-/* called under bridge lock */
-void br_flood_forward(struct net_bridge *br, struct sk_buff *skb,
-		      struct sk_buff *skb2, bool unicast)
-{
-	br_flood(br, skb, skb2, __br_forward, unicast);
-}
-
 #ifdef CONFIG_BRIDGE_IGMP_SNOOPING
 /* called with rcu_read_lock */
-static void br_multicast_flood(struct net_bridge_mdb_entry *mdst,
-			       struct sk_buff *skb, struct sk_buff *skb0,
-			       void (*__packet_hook)(
-					const struct net_bridge_port *p,
-					struct sk_buff *skb))
+void br_multicast_flood(struct net_bridge_mdb_entry *mdst,
+			struct sk_buff *skb,
+			bool local_rcv, bool local_orig)
 {
 	struct net_device *dev = BR_INPUT_SKB_CB(skb)->brdev;
 	u8 igmp_type = br_multicast_igmp_type(skb);
@@ -279,7 +240,7 @@ static void br_multicast_flood(struct net_bridge_mdb_entry *mdst,
 		port = (unsigned long)lport > (unsigned long)rport ?
 		       lport : rport;
 
-		prev = maybe_deliver(prev, port, skb, __packet_hook);
+		prev = maybe_deliver(prev, port, skb, local_orig);
 		if (IS_ERR(prev))
 			goto out;
 		if (prev == port)
@@ -295,28 +256,14 @@ static void br_multicast_flood(struct net_bridge_mdb_entry *mdst,
 	if (!prev)
 		goto out;
 
-	if (skb0)
-		deliver_clone(prev, skb, __packet_hook);
+	if (local_rcv)
+		deliver_clone(prev, skb, local_orig);
 	else
-		__packet_hook(prev, skb);
+		__br_forward(prev, skb, local_orig);
 	return;
 
 out:
-	if (!skb0)
+	if (!local_rcv)
 		kfree_skb(skb);
 }
-
-/* called with rcu_read_lock */
-void br_multicast_deliver(struct net_bridge_mdb_entry *mdst,
-			  struct sk_buff *skb)
-{
-	br_multicast_flood(mdst, skb, NULL, __br_deliver);
-}
-
-/* called with rcu_read_lock */
-void br_multicast_forward(struct net_bridge_mdb_entry *mdst,
-			  struct sk_buff *skb, struct sk_buff *skb2)
-{
-	br_multicast_flood(mdst, skb, skb2, __br_forward);
-}
 #endif

net/bridge/br_input.c

@@ -131,13 +131,12 @@ static void br_do_proxy_arp(struct sk_buff *skb, struct net_bridge *br,
 /* note: already called with rcu_read_lock */
 int br_handle_frame_finish(struct net *net, struct sock *sk, struct sk_buff *skb)
 {
-	const unsigned char *dest = eth_hdr(skb)->h_dest;
+	bool local_rcv = false, mcast_hit = false, unicast = true;
 	struct net_bridge_port *p = br_port_get_rcu(skb->dev);
-	struct net_bridge *br;
-	struct net_bridge_fdb_entry *dst;
+	const unsigned char *dest = eth_hdr(skb)->h_dest;
+	struct net_bridge_fdb_entry *dst = NULL;
 	struct net_bridge_mdb_entry *mdst;
-	struct sk_buff *skb2;
-	bool unicast = true;
+	struct net_bridge *br;
 	u16 vid = 0;
 
 	if (!p || p->state == BR_STATE_DISABLED)
@@ -160,53 +159,46 @@ int br_handle_frame_finish(struct net *net, struct sock *sk, struct sk_buff *skb
 
 	BR_INPUT_SKB_CB(skb)->brdev = br->dev;
 
-	/* The packet skb2 goes to the local host (NULL to skip). */
-	skb2 = NULL;
-
-	if (br->dev->flags & IFF_PROMISC)
-		skb2 = skb;
-
-	dst = NULL;
+	local_rcv = !!(br->dev->flags & IFF_PROMISC);
 
 	if (IS_ENABLED(CONFIG_INET) && skb->protocol == htons(ETH_P_ARP))
 		br_do_proxy_arp(skb, br, vid, p);
 
 	if (is_broadcast_ether_addr(dest)) {
-		skb2 = skb;
+		local_rcv = true;
 		unicast = false;
 	} else if (is_multicast_ether_addr(dest)) {
 		mdst = br_mdb_get(br, skb, vid);
 		if ((mdst || BR_INPUT_SKB_CB_MROUTERS_ONLY(skb)) &&
 		    br_multicast_querier_exists(br, eth_hdr(skb))) {
 			if ((mdst && mdst->mglist) ||
-			    br_multicast_is_router(br))
-				skb2 = skb;
-			br_multicast_forward(mdst, skb, skb2);
-			skb = NULL;
-			if (!skb2)
-				goto out;
-		} else
-			skb2 = skb;
-
+			    br_multicast_is_router(br)) {
+				local_rcv = true;
+				br->dev->stats.multicast++;
+			}
+			mcast_hit = true;
+		} else {
+			local_rcv = true;
+			br->dev->stats.multicast++;
+		}
 		unicast = false;
-		br->dev->stats.multicast++;
-	} else if ((dst = __br_fdb_get(br, dest, vid)) &&
-			dst->is_local) {
-		skb2 = skb;
+	} else if ((dst = __br_fdb_get(br, dest, vid)) && dst->is_local) {
 		/* Do not forward the packet since it's local. */
-		skb = NULL;
+		return br_pass_frame_up(skb);
 	}
 
-	if (skb) {
-		if (dst) {
-			dst->used = jiffies;
-			br_forward(dst->dst, skb, skb2);
-		} else
-			br_flood_forward(br, skb, skb2, unicast);
+	if (dst) {
+		dst->used = jiffies;
+		br_forward(dst->dst, skb, local_rcv, false);
+	} else {
+		if (!mcast_hit)
+			br_flood(br, skb, unicast, local_rcv, false);
+		else
+			br_multicast_flood(mdst, skb, local_rcv, false);
 	}
 
-	if (skb2)
-		return br_pass_frame_up(skb2);
+	if (local_rcv)
+		return br_pass_frame_up(skb);
 
 out:
 	return 0;

net/bridge/br_private.h

@@ -505,14 +505,12 @@ int br_fdb_external_learn_del(struct net_bridge *br, struct net_bridge_port *p,
 			      const unsigned char *addr, u16 vid);
 
 /* br_forward.c */
-void br_deliver(const struct net_bridge_port *to, struct sk_buff *skb);
 int br_dev_queue_push_xmit(struct net *net, struct sock *sk, struct sk_buff *skb);
-void br_forward(const struct net_bridge_port *to,
-		struct sk_buff *skb, struct sk_buff *skb0);
+void br_forward(const struct net_bridge_port *to, struct sk_buff *skb,
+		bool local_rcv, bool local_orig);
 int br_forward_finish(struct net *net, struct sock *sk, struct sk_buff *skb);
-void br_flood_deliver(struct net_bridge *br, struct sk_buff *skb, bool unicast);
-void br_flood_forward(struct net_bridge *br, struct sk_buff *skb,
-		      struct sk_buff *skb2, bool unicast);
+void br_flood(struct net_bridge *br, struct sk_buff *skb,
+	      bool unicast, bool local_rcv, bool local_orig);
 
 /* br_if.c */
 void br_port_carrier_check(struct net_bridge_port *p);
@@ -560,10 +558,8 @@ void br_multicast_init(struct net_bridge *br);
 void br_multicast_open(struct net_bridge *br);
 void br_multicast_stop(struct net_bridge *br);
 void br_multicast_dev_del(struct net_bridge *br);
-void br_multicast_deliver(struct net_bridge_mdb_entry *mdst,
-			  struct sk_buff *skb);
-void br_multicast_forward(struct net_bridge_mdb_entry *mdst,
-			  struct sk_buff *skb, struct sk_buff *skb2);
+void br_multicast_flood(struct net_bridge_mdb_entry *mdst,
+			struct sk_buff *skb, bool local_rcv, bool local_orig);
 int br_multicast_set_router(struct net_bridge *br, unsigned long val);
 int br_multicast_set_port_router(struct net_bridge_port *p, unsigned long val);
 int br_multicast_toggle(struct net_bridge *br, unsigned long val);
@@ -691,28 +687,27 @@ static inline void br_multicast_dev_del(struct net_bridge *br)
 {
 }
 
-static inline void br_multicast_deliver(struct net_bridge_mdb_entry *mdst,
-					struct sk_buff *skb)
+static inline void br_multicast_flood(struct net_bridge_mdb_entry *mdst,
+				      struct sk_buff *skb,
+				      bool local_rcv, bool local_orig)
 {
 }
 
-static inline void br_multicast_forward(struct net_bridge_mdb_entry *mdst,
-					struct sk_buff *skb,
-					struct sk_buff *skb2)
-{
-}
 static inline bool br_multicast_is_router(struct net_bridge *br)
 {
 	return 0;
 }
+
 static inline bool br_multicast_querier_exists(struct net_bridge *br,
 					       struct ethhdr *eth)
 {
 	return false;
 }
+
 static inline void br_mdb_init(void)
 {
 }
+
 static inline void br_mdb_uninit(void)
 {
 }

net/bridge/netfilter/nft_reject_bridge.c

@@ -72,7 +72,7 @@ static void nft_reject_br_send_v4_tcp_reset(struct net *net,
 
 	nft_reject_br_push_etherhdr(oldskb, nskb);
 
-	br_deliver(br_port_get_rcu(dev), nskb);
+	br_forward(br_port_get_rcu(dev), nskb, false, true);
 }
 
 static void nft_reject_br_send_v4_unreach(struct net *net,
@@ -140,7 +140,7 @@ static void nft_reject_br_send_v4_unreach(struct net *net,
 
 	nft_reject_br_push_etherhdr(oldskb, nskb);
 
-	br_deliver(br_port_get_rcu(dev), nskb);
+	br_forward(br_port_get_rcu(dev), nskb, false, true);
 }
 
 static void nft_reject_br_send_v6_tcp_reset(struct net *net,
@@ -174,7 +174,7 @@ static void nft_reject_br_send_v6_tcp_reset(struct net *net,
 
 	nft_reject_br_push_etherhdr(oldskb, nskb);
 
-	br_deliver(br_port_get_rcu(dev), nskb);
+	br_forward(br_port_get_rcu(dev), nskb, false, true);
 }
 
 static bool reject6_br_csum_ok(struct sk_buff *skb, int hook)
@@ -255,7 +255,7 @@ static void nft_reject_br_send_v6_unreach(struct net *net,
 
 	nft_reject_br_push_etherhdr(oldskb, nskb);
 
-	br_deliver(br_port_get_rcu(dev), nskb);
+	br_forward(br_port_get_rcu(dev), nskb, false, true);
 }
 
 static void nft_reject_bridge_eval(const struct nft_expr *expr,