Linux核心資料包bridge上轉發流程

轉載：

https://blog.csdn.net/Sophisticated_/article/details/87923362

http://blog.chinaunix.net/uid-28541347-id-5750406.html

https://blog.csdn.net/linyt/article/details/5191512

https://blog.csdn.net/NW_NW_NW/article/details/76674232

https://www.cnblogs.com/super-king/p/bridge_implement.html

https://www.cnblogs.com/ck1020/p/5894235.html

https://blog.csdn.net/one_clouder/article/details/52877737

linux核心源代碼變動怎麼這麼大，handle_bridge函數居然沒有了，本來接着準備以3.9.1分析的，但發現和後面的又變了，還是以4.15.1現在電腦上用的版本分析吧。

linux kernel：4.15.1

先看兩張圖檔

轉載：https://blog.csdn.net/NW_NW_NW/article/details/76153027

linux核心版本不一樣，函數發生了些許小改變，對圖檔進行細微更改。

轉載：https://blog.csdn.net/u012247418/article/details/90137663

1. br_handle_frame()

作用：

1. 對于需要轉發的封包，調用NF_BR_PRE_ROUTING處鈎子函數，結束後，進入br_handle_frame_finish()函數；

2. 對于STP封包，調用NF_BR_LOCAL_IN處鈎子函數，結束後，進入br_handle_local_finish()函數，在br_handle_local_finish()函數中會調用br_pass_frame_up()函數。

//linux/net/bridge/br_input.c
/*
 * Return NULL if skb is handled
 * note: already called with rcu_read_lock
 */
rx_handler_result_t br_handle_frame(struct sk_buff **pskb)
{
	struct net_bridge_port *p;
	struct sk_buff *skb = *pskb;
	const unsigned char *dest = eth_hdr(skb)->h_dest;
	br_should_route_hook_t *rhook;

	/*如果是環回位址，直接傳回RX_HANDLER_PASS*/
	if (unlikely(skb->pkt_type == PACKET_LOOPBACK))
		return RX_HANDLER_PASS;
	
	/*判斷源MAC位址是否是有效的位址，不是直接丢棄，源MAC位址不能是多點傳播位址和全0位址*/
	if (!is_valid_ether_addr(eth_hdr(skb)->h_source))
		goto drop;
	/*判斷是否是共享資料包，若是則clone該資料包；若clone時配置設定記憶體出錯，傳回NULL*/
	skb = skb_share_check(skb, GFP_ATOMIC);
	if (!skb)
		return RX_HANDLER_CONSUMED;

	/*擷取dev對應的網橋端口*/
	p = br_port_get_rcu(skb->dev);
	if (p->flags & BR_VLAN_TUNNEL) {
		if (br_handle_ingress_vlan_tunnel(skb, p,
						  nbp_vlan_group_rcu(p)))
			goto drop;
	}
	
	/*特殊MAC位址處理*/
	//如果目的mac位址是本地鍊路位址link local reserved addr (01:80:c2:00:00:0X) STP封包
	if (unlikely(is_link_local_ether_addr(dest))) {
		u16 fwd_mask = p->br->group_fwd_mask_required;

		/*
		 * See IEEE 802.1D Table 7-10 Reserved addresses
		 *
		 * Assignment		 		Value
		 * Bridge Group Address		01-80-C2-00-00-00
		 * (MAC Control) 802.3		01-80-C2-00-00-01
		 * (Link Aggregation) 802.3	01-80-C2-00-00-02
		 * 802.1X PAE address		01-80-C2-00-00-03
		 *
		 * 802.1AB LLDP 		01-80-C2-00-00-0E
		 *
		 * Others reserved for future standardization
		 */
		fwd_mask |= p->group_fwd_mask;
		switch (dest[5]) {
		case 0x00:	/* Bridge Group Address */
			/* If STP is turned off,
			   then must forward to keep loop detection */
			if (p->br->stp_enabled == BR_NO_STP ||
			    fwd_mask & (1u << dest[5]))
				goto forward;
			*pskb = skb;
			__br_handle_local_finish(skb);
			return RX_HANDLER_PASS;

		case 0x01:	/* IEEE MAC (Pause) */
			goto drop;

		case 0x0E:	/* 802.1AB LLDP */
			fwd_mask |= p->br->group_fwd_mask;
			if (fwd_mask & (1u << dest[5]))
				goto forward;
			*pskb = skb;
			__br_handle_local_finish(skb);
			return RX_HANDLER_PASS;

		default:
			/* Allow selective forwarding for most other protocols */
			fwd_mask |= p->br->group_fwd_mask;
			if (fwd_mask & (1u << dest[5]))
				goto forward;
		}

		/* Deliver packet to local host only */
		/*調用NF_BR_LOCAL_IN處鈎子函數，結束後，進入br_handle_local_finish函數*/
		NF_HOOK(NFPROTO_BRIDGE, NF_BR_LOCAL_IN, dev_net(skb->dev),
			NULL, skb, skb->dev, NULL, br_handle_local_finish);
		return RX_HANDLER_CONSUMED;
	}

forward:
	switch (p->state) {
	//網橋端口處于轉發狀态
	case BR_STATE_FORWARDING:
		rhook = rcu_dereference(br_should_route_hook);
		if (rhook) {
			if ((*rhook)(skb)) {
				*pskb = skb;
				return RX_HANDLER_PASS;
			}
			dest = eth_hdr(skb)->h_dest;
		}
		/* fall through */
	/*網橋端口處于學習狀态，處于轉發狀态也會執行下面的代碼，因為上面的case沒有break。*/
	case BR_STATE_LEARNING:
	/*資料包目的MAC為網橋的Mac，發往本地的資料包*/
		if (ether_addr_equal(p->br->dev->dev_addr, dest))
			skb->pkt_type = PACKET_HOST;
		/*調用NF_BR_PRE_ROUTING處鈎子函數，結束後進入br_handle_frame_finish函數*/
		NF_HOOK(NFPROTO_BRIDGE, NF_BR_PRE_ROUTING,
			dev_net(skb->dev), NULL, skb, skb->dev, NULL,
			br_handle_frame_finish);
		break;
	default:
drop:
		kfree_skb(skb);
	}
	return RX_HANDLER_CONSUMED;
}
           

相關函數

1. rx_handler_result_t枚舉類型

enum rx_handler_result {
	RX_HANDLER_CONSUMED,
	RX_HANDLER_ANOTHER,
	RX_HANDLER_EXACT,
	RX_HANDLER_PASS,
};
typedef enum rx_handler_result rx_handler_result_t;
           

2. is_valid_ether_addr()

/**
 * is_valid_ether_addr - Determine if the given Ethernet address is valid
 * @addr: Pointer to a six-byte array containing the Ethernet address
 *
 * Check that the Ethernet address (MAC) is not 00:00:00:00:00:00, is not
 * a multicast address, and is not FF:FF:FF:FF:FF:FF.
 *
 * Return true if the address is valid.
 *
 * Please note: addr must be aligned to u16.
 */
static inline bool is_valid_ether_addr(const u8 *addr)
{
	/* FF:FF:FF:FF:FF:FF is a multicast address so we don't need to
	 * explicitly check for it here. */
	return !is_multicast_ether_addr(addr) && !is_zero_ether_addr(addr);
}
           

3.br_handle_local_finish()

br_handle_local_finish()函數中調用br_pass_fame_up()函數。

/* note: already called with rcu_read_lock */
static int br_handle_local_finish(struct net *net, struct sock *sk, struct sk_buff *skb)
{
	struct net_bridge_port *p = br_port_get_rcu(skb->dev);

	__br_handle_local_finish(skb);

	BR_INPUT_SKB_CB(skb)->brdev = p->br->dev;
	br_pass_frame_up(skb);
	return 0;
}
           

2. br_handle_frame_finish()

作用：

網橋裝置是否處于混雜模式，如果是，則會發一份到本地進行處理

如果是廣播包，則會進行廣播洪泛，并會發一份到本地處理

如果是多點傳播包，則根據多點傳播表進行多點傳播轉發，并發一份數數包到本地處理

如果是單點傳播包，發往本地的單點傳播包則送到本地處理，在fdb表中可以找到轉發表項的單點傳播包則進行轉發，未知單點傳播包在廣播域内進行洪泛

//linux/net/bridge/br_input.c
/* note: already called with rcu_read_lock */
int br_handle_frame_finish(struct net *net, struct sock *sk, struct sk_buff *skb)
{
	struct net_bridge_port *p = br_port_get_rcu(skb->dev);
	enum br_pkt_type pkt_type = BR_PKT_UNICAST;
	struct net_bridge_fdb_entry *dst = NULL;
	struct net_bridge_mdb_entry *mdst;
	bool local_rcv, mcast_hit = false;
	const unsigned char *dest;
	struct net_bridge *br;
	u16 vid = 0;
	
	/*如果網橋端口不存在或者網橋端口狀态為BR_STATE_DISABLED，則丢棄*/
	if (!p || p->state == BR_STATE_DISABLED)
		goto drop;
	/*判斷是否允許進入橋内，如果沒有開啟VLAN則所有資料包都可以進入，
	如果開啟了VLAN,則根據VLAN相應的規則，從橋上進行資料包轉發。*/
	if (!br_allowed_ingress(p->br, nbp_vlan_group_rcu(p), skb, &vid))
		goto out;

	nbp_switchdev_frame_mark(p, skb);

	/* insert into forwarding database after filtering to avoid spoofing */
	br = p->br;
	/*如果網橋端口标志有BR_LEARNING,則更新fdb表。
    一般建立網橋端口p->flags=BR_LEARNING| BR_FLOOD | BR_MCAST_FLOOD | BR_BCAST_FLOOD*/
	if (p->flags & BR_LEARNING)
		br_fdb_update(br, p, eth_hdr(skb)->h_source, vid, false);
	
	//發往本地資料包标記，!!的作用是轉換為bool值
	local_rcv = !!(br->dev->flags & IFF_PROMISC);
	dest = eth_hdr(skb)->h_dest;
	/*目的位址為多點傳播位址*/
	if (is_multicast_ether_addr(dest)) {
		/* by definition the broadcast is also a multicast address */
		/*如果目的位址是廣播位址，将資料包也發往本地一份*/
		if (is_broadcast_ether_addr(dest)) {
			pkt_type = BR_PKT_BROADCAST;
			local_rcv = true;
		} else {
			pkt_type = BR_PKT_MULTICAST;
			//igmp snooping留給網橋子系統的外部接口函數，
			//當網橋接收了igmp資料包後就會調用該函數進行後續處理
			if (br_multicast_rcv(br, p, skb, vid))
				goto drop;
		}
	}
	//如果網橋端口狀态此時還是BR_STATE_LEARNING,則丢棄。
	if (p->state == BR_STATE_LEARNING)
		goto drop;
	//将網橋所屬的net_device放入skb的私有資料中（struct br_input_skb_cb）
	BR_INPUT_SKB_CB(skb)->brdev = br->dev;

	if (IS_ENABLED(CONFIG_INET) &&
	    (skb->protocol == htons(ETH_P_ARP) ||
	     skb->protocol == htons(ETH_P_RARP))) {
		br_do_proxy_suppress_arp(skb, br, vid, p);
	} else if (IS_ENABLED(CONFIG_IPV6) &&
		   skb->protocol == htons(ETH_P_IPV6) &&
		   br->neigh_suppress_enabled &&
		   pskb_may_pull(skb, sizeof(struct ipv6hdr) +
				 sizeof(struct nd_msg)) &&
		   ipv6_hdr(skb)->nexthdr == IPPROTO_ICMPV6) {
			struct nd_msg *msg, _msg;

			msg = br_is_nd_neigh_msg(skb, &_msg);
			if (msg)
				br_do_suppress_nd(skb, br, vid, p, msg);
	}

	switch (pkt_type) {
	//多點傳播包
	case BR_PKT_MULTICAST:
		//擷取多點傳播轉發項，設定local_rcv為true，多點傳播包也要發往本地一份。
		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->host_joined) ||
			    br_multicast_is_router(br)) {
				local_rcv = true;
				br->dev->stats.multicast++;
			}
			mcast_hit = true;
		} else {
			local_rcv = true;
			br->dev->stats.multicast++;
		}
		break;
	//單點傳播包
	case BR_PKT_UNICAST:
		//根據目的MAC位址查找fdb表，看是否有對應的表項
		dst = br_fdb_find_rcu(br, dest, vid);
	default:
		break;
	}
	
	//如果找到目的MAC對應的表項
	if (dst) {
		unsigned long now = jiffies;
		//送入上層處理
		if (dst->is_local)
			return br_pass_frame_up(skb);

		if (now != dst->used)
			dst->used = now;
		//根據fdb轉發表項進行轉發，若這裡local_rcv 為1,（即端口處于混雜模式IFF_PROMISC），則會克隆一份再轉發
		//傳入的第一個參數dst->dst 即為要轉發的目的端口
		br_forward(dst->dst, skb, local_rcv, false);
	} else {
		//進行廣播或者多點傳播洪泛
		if (!mcast_hit)
			br_flood(br, skb, pkt_type, local_rcv, false);
		else
			br_multicast_flood(mdst, skb, local_rcv, false);
	}
	//local_rcv标記為1，送入上層處理。
	if (local_rcv)
		return br_pass_frame_up(skb);

out:
	return 0;
drop:
	kfree_skb(skb);
	goto out;
}
           

3.br_pass_frame_up

資料包的目的MAC是本地的單點傳播封包，廣播，多點傳播和網橋處于混雜模式時，封包都會通過br_pass_frame_up函數交由上層處理。

作用：

調用NF_BR_LOCAL_IN處鈎子函數，最後調用br_netif_receive_skb函數，繞一圈後，交友上層處理。

//linux/net/bridge/br_input.c
static int br_pass_frame_up(struct sk_buff *skb)
{
	struct net_device *indev, *brdev = BR_INPUT_SKB_CB(skb)->brdev;
	struct net_bridge *br = netdev_priv(brdev);
	struct net_bridge_vlan_group *vg;
	struct pcpu_sw_netstats *brstats = this_cpu_ptr(br->stats);
	
	//統計網橋裝置上的收包流量資料
	u64_stats_update_begin(&brstats->syncp);
	brstats->rx_packets++;
	brstats->rx_bytes += skb->len;
	u64_stats_update_end(&brstats->syncp);
	
	//擷取網橋裝置上的VLAN組
	vg = br_vlan_group_rcu(br);
	/* Bridge is just like any other port.  Make sure the
	 * packet is allowed except in promisc modue when someone
	 * may be running packet capture.
	 */
	if (!(brdev->flags & IFF_PROMISC) &&
	    !br_allowed_egress(vg, skb)) {
		kfree_skb(skb);
		return NET_RX_DROP;
	}
	
	//記錄資料包的收包網絡裝置
	indev = skb->dev;
	//将資料包的收包裝置改為網橋裝置
	//當再次進入__netif_receive_skb_core時就不會再次進入橋處理了，因為網橋上沒有注冊rx_handler 函數
	skb->dev = brdev;
	//配置資料包vlan相關資訊
	skb = br_handle_vlan(br, NULL, vg, skb);
	if (!skb)
		return NET_RX_DROP;
	/* update the multicast stats if the packet is IGMP/MLD */
	//如果資料包是多點傳播，更新多點傳播資料包的統計資訊
	br_multicast_count(br, NULL, skb, br_multicast_igmp_type(skb),
			   BR_MCAST_DIR_TX);
	
	//調用NF_BR_LOCAL_IN處鈎子函數，最後調用br_netif_receive_skb函數。
	return NF_HOOK(NFPROTO_BRIDGE, NF_BR_LOCAL_IN,
		       dev_net(indev), NULL, skb, indev, NULL,
		       br_netif_receive_skb);
}
           

再次進入netif_receive_skb，由于skb-dev被設定成了bridge，而bridge裝置的rx_handler函數是沒有被設定的，是以就不會再次進入bridge邏輯，而直接進入了主機上層協定棧。

相關函數

1. br_netif_receive_skb()

可以看到在br_netif_receive_skb()函數中調用了netif_receive_skb()函數。

static int
br_netif_receive_skb(struct net *net, struct sock *sk, struct sk_buff *skb)
{
	br_drop_fake_rtable(skb);
	return netif_receive_skb(skb);
}
           

4. br_forward()

不是發往本地的資料包，但在fdb表中能找到對應的表項，則進行轉發br_forward()，若在fdb表中找不到對應表項就進行洪泛br_blood().

作用：

主要是調用__br_forward()轉發封包

//linux/net/bridge/br_forward.c
/**
 * 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)
{
	//should_deliver測試是否應該将該包轉發出去
	if (to && should_deliver(to, skb)) {
		//如果local_rcv為1，表明端口為混雜模式，先clone一份資料包再進行轉發
		if (local_rcv)
			deliver_clone(to, skb, local_orig);
		else
			__br_forward(to, skb, local_orig);
		return;
	}

	if (!local_rcv)
		kfree_skb(skb);
}
           

5. __br_forward()

感覺這個函數很重要

作用

__br_forward()函數根據資料包的來源（local_orig）分别進入不同的鈎子點，如果資料包是從本地發出的，則進入NF_BR_LOCAL_OUT，如果不是本地發出的，則進入NF_BR_FORWARD鈎子，最後都進入br_forward_finish()函數。

//linux/net/bridge/br_forward.c
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;
	//擷取vlan組，這個組中有許多的vlanid，br_handle_vlan函數就是要在這個組中查找自己的vid
	vg = nbp_vlan_group_rcu(to);
	
	//添加vlan的相關配置
	skb = br_handle_vlan(to->br, to, vg, skb);
	if (!skb)
		return;
	//記錄資料包的原始收包網絡裝置
	indev = skb->dev;
	
	//将skb的dev修改為出口網絡裝置
	skb->dev = to->dev;
	/*如果local_orig标志位(判斷是否從本地發出的資料包)為false，就進入NF_BR_FORWARD鈎子
	若為true，就進入NF_BR_LOCAL_OUT鈎子點*/
	if (!local_orig) {
		if (skb_warn_if_lro(skb)) {
			kfree_skb(skb);
			return;
		}
		//不是本地發出的資料包，進入NF_BR_FORWARD
		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;
		}
		//若是本地發出的資料包，進入NF_BR_LOCAL_OUT處理
		br_hook = NF_BR_LOCAL_OUT;
		net = dev_net(skb->dev);
		indev = NULL;
	}
	
	//進入鈎子點，最後執行br_forward_finish函數。
	NF_HOOK(NFPROTO_BRIDGE, br_hook,
		net, NULL, skb, indev, skb->dev,
		br_forward_finish);
}
           

6. br_forward_finish()

br_forward_finish()函數比較簡單，調用NF_BR_POST_ROUTING處的鈎子函數，最後進入br_dev_queue_push_xmit函數。

//linux/net/bridge/br_forward.c
int br_forward_finish(struct net *net, struct sock *sk, struct sk_buff *skb)
{
	return NF_HOOK(NFPROTO_BRIDGE, NF_BR_POST_ROUTING,
		       net, sk, skb, NULL, skb->dev,
		       br_dev_queue_push_xmit);

}
           

7. br_dev_queue_push_xmit

在br_dev_queue_push_xmit()中，會先skb_push(skb,ETH,HLEN);将data指向二層頭部，然後調用dev_queue_xmit()發送封包。

//linux/net/bridge/br_forward.c
int br_dev_queue_push_xmit(struct net *net, struct sock *sk, struct sk_buff *skb)
{
	if (!is_skb_forwardable(skb->dev, skb))
		goto drop;

        //注意這句操作
	skb_push(skb, ETH_HLEN);
	br_drop_fake_rtable(skb);

	if (skb->ip_summed == CHECKSUM_PARTIAL &&
	    (skb->protocol == htons(ETH_P_8021Q) ||
	     skb->protocol == htons(ETH_P_8021AD))) {
		int depth;

		if (!__vlan_get_protocol(skb, skb->protocol, &depth))
			goto drop;

		skb_set_network_header(skb, depth);
	}

	dev_queue_xmit(skb);

	return 0;

drop:
	kfree_skb(skb);
	return 0;
}
           

8. br_flood

br_flood()也是調用__br_forward()函數轉發封包。

//linux/net/bridge/br_forward.c
/* called under rcu_read_lock */
void br_flood(struct net_bridge *br, struct sk_buff *skb,
	      enum br_pkt_type pkt_type, bool local_rcv, bool local_orig)
{
	u8 igmp_type = br_multicast_igmp_type(skb);
	struct net_bridge_port *prev = NULL;
	struct net_bridge_port *p;

	/*周遊網橋裝置的port_list，取出所有的網橋端口*/
	list_for_each_entry_rcu(p, &br->port_list, list) 
        {
		/* Do not flood unicast traffic to ports that turn it off, nor
		 * other traffic if flood off, except for traffic we originate
		 */
		switch (pkt_type) 
                {
		case BR_PKT_UNICAST:
			if (!(p->flags & BR_FLOOD))
				continue;
			break;
		case BR_PKT_MULTICAST:
			if (!(p->flags & BR_MCAST_FLOOD) && skb->dev != br->dev)
				continue;
			break;
		case BR_PKT_BROADCAST:
			if (!(p->flags & BR_BCAST_FLOOD) && skb->dev != br->dev)
				continue;
			break;
		}

		/* Do not flood to ports that enable proxy ARP */
                /*代理arp*/
		if (p->flags & BR_PROXYARP)
			continue;
		if ((p->flags & (BR_PROXYARP_WIFI | BR_NEIGH_SUPPRESS)) &&
		    BR_INPUT_SKB_CB(skb)->proxyarp_replied)
			continue;

		prev = maybe_deliver(prev, p, skb, local_orig);
		if (IS_ERR(prev))
			goto out;
		if (prev == p)
			br_multicast_count(p->br, p, skb, igmp_type,
					   BR_MCAST_DIR_TX);
	}

	if (!prev)
		goto out;

	if (local_rcv)
		deliver_clone(prev, skb, local_orig);
	else
		__br_forward(prev, skb, local_orig);
	return;

out:
	if (!local_rcv)
		kfree_skb(skb);
}
           

9. br_mulicast_flood()

以後再分析，肚子餓了。

//linux/net/bridge/br_forward.c
/* called with rcu_read_lock */
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);
	struct net_bridge *br = netdev_priv(dev);
	struct net_bridge_port *prev = NULL;
	struct net_bridge_port_group *p;
	struct hlist_node *rp;

	rp = rcu_dereference(hlist_first_rcu(&br->router_list));
	p = mdst ? rcu_dereference(mdst->ports) : NULL;
	while (p || rp) {
		struct net_bridge_port *port, *lport, *rport;

		lport = p ? p->port : NULL;
		rport = rp ? hlist_entry(rp, struct net_bridge_port, rlist) :
			     NULL;

		if ((unsigned long)lport > (unsigned long)rport) {
			port = lport;

			if (port->flags & BR_MULTICAST_TO_UNICAST) {
				maybe_deliver_addr(lport, skb, p->eth_addr,
						   local_orig);
				goto delivered;
			}
		} else {
			port = rport;
		}

		prev = maybe_deliver(prev, port, skb, local_orig);
delivered:
		if (IS_ERR(prev))
			goto out;
		if (prev == port)
			br_multicast_count(port->br, port, skb, igmp_type,
					   BR_MCAST_DIR_TX);

		if ((unsigned long)lport >= (unsigned long)port)
			p = rcu_dereference(p->next);
		if ((unsigned long)rport >= (unsigned long)port)
			rp = rcu_dereference(hlist_next_rcu(rp));
	}

	if (!prev)
		goto out;

	if (local_rcv)
		deliver_clone(prev, skb, local_orig);
	else
		__br_forward(prev, skb, local_orig);
	return;

out:
	if (!local_rcv)
		kfree_skb(skb);
}