Linux内核如何接收不同类型以太帧 （3）

/* net/8021q/vlan.c */
static struct packet_type vlan_packet_type = {
.type = __constant_htons(ETH_P_8021Q),
.func = vlan_skb_recv, /* VLAN receive method */
};
......
static int __init vlan_proto_init(void)
{
......
dev_add_pack(&vlan_packet_type);
......

static void __exit vlan_cleanup_module(void)
{
......
dev_remove_pack(&vlan_packet_type);
......

/* net/core/dev.c */
int netif_receive_skb(struct sk_buff *skb)
{
......
// 先查处理所有以太类型的链表各节点
list_for_each_entry_rcu(ptype, &ptype_all, list) {
if (!ptype->dev || ptype->dev == skb->dev) {
if (pt_prev) 
ret = deliver_skb(skb, pt_prev, orig_dev);
pt_prev = ptype;
}
}
......
// 再查指定协议的HASH链表
list_for_each_entry_rcu(ptype, &ptype_base[ntohs(type)&15], list) {
if (ptype->type == type &&
(!ptype->dev || ptype->dev == skb->dev)) {
if (pt_prev) 
ret = deliver_skb(skb, pt_prev, orig_dev);
pt_prev = ptype;
}
}
......

// 该函数就是调用个协议的接收函数处理该skb包，进入第三层网络层处理
static __inline__ int deliver_skb(struct sk_buff *skb,
struct packet_type *pt_prev,
struct net_device *orig_dev)
{
atomic_inc(&skb->users);
return pt_prev->func(skb, skb->dev, pt_prev, orig_dev);
}