1、系统初始化过程中会调用sock_init函数进行套接字的初始化，主要是进行缓存的初始化 static int __init sock_init(void) { int err; /* * 初始化.sock缓存 */ sk_init(); /* * 初始化sk_buff缓存 */ skb_init(); /* * 初始化协议模块缓存 */ init_inodecache(); //注册文件系统类型 err = register_filesystem(&sock_fs_type); if (err) goto out_fs; sock_mnt = kern_mount(&sock_fs_type); if (IS_ERR(sock_mnt)) { err = PTR_ERR(sock_mnt); goto out_mount; } /* The real protocol initialization is performed in later initcalls. */ #ifdef CONFIG_NETFILTER netfilter_init(); #endif #ifdef CONFIG_NETWORK_PHY_TIMESTAMPING skb_timestamping_init(); #endif out: return err; out_mount: unregister_filesystem(&sock_fs_type); out_fs: goto out; } 2、INET协议族的初始化函数 static int __init inet_init(void) { struct sk_buff *dummy_skb; struct inet_protosw *q; struct list_head *r; int rc = -EINVAL; BUILD_BUG_ON(sizeof(struct inet_skb_parm) > sizeof(dummy_skb->cb)); sysctl_local_reserved_ports = kzalloc(65536 / 8, GFP_KERNEL); if (!sysctl_local_reserved_ports) goto out; //下面注册传输层协议操作集 rc = proto_register(&tcp_prot, 1); if (rc) goto out_free_reserved_ports; rc = proto_register(&udp_prot, 1); if (rc) goto out_unregister_tcp_proto; rc = proto_register(&raw_prot, 1); if (rc) goto out_unregister_udp_proto; rc = proto_register(&ping_prot, 1); if (rc) goto out_unregister_raw_proto; //注册INET协议族的handler (void)sock_register(&inet_family_ops); #ifdef CONFIG_SYSCTL ip_static_sysctl_init(); #endif /* * Add all the base protocols. */ //将INET协议族协议数据包接收函数添加到系统中 if (inet_add_protocol(&icmp_protocol, IPPROTO_ICMP) < 0) printk(KERN_CRIT "inet_init: Cannot add ICMP protocol\n"); if (inet_add_protocol(&udp_protocol, IPPROTO_UDP) < 0) printk(KERN_CRIT "inet_init: Cannot add UDP protocol\n"); if (inet_add_protocol(&tcp_protocol, IPPROTO_TCP) < 0) printk(KERN_CRIT "inet_init: Cannot add TCP protocol\n"); #ifdef CONFIG_IP_MULTICAST if (inet_add_protocol(&igmp_protocol, IPPROTO_IGMP) < 0) printk(KERN_CRIT "inet_init: Cannot add IGMP protocol\n"); #endif /* Register the socket-side information for inet_create. */ for (r = &inetsw[0]; r < &inetsw[SOCK_MAX]; ++r) INIT_LIST_HEAD(r); //将inetsw_array中的元素按套接字类型注册到inetsw链表数组中 for (q = inetsw_array; q < &inetsw_array[INETSW_ARRAY_LEN]; ++q) inet_register_protosw(q); /* * Set the ARP module up */ arp_init(); /* * Set the IP module up */ ip_init(); tcp_v4_init(); /* Setup TCP slab cache for open requests. */ tcp_init(); /* Setup UDP memory threshold */ udp_init(); /* Add UDP-Lite (RFC 3828) */ udplite4_register(); ping_init(); /* * Set the ICMP layer up */ if (icmp_init() < 0) panic("Failed to create the ICMP control socket.\n"); /* * Initialise the multicast router */ #if defined(CONFIG_IP_MROUTE) if (ip_mr_init()) printk(KERN_CRIT "inet_init: Cannot init ipv4 mroute\n"); #endif /* * Initialise per-cpu ipv4 mibs */ if (init_ipv4_mibs()) printk(KERN_CRIT "inet_init: Cannot init ipv4 mibs\n"); ipv4_proc_init(); ipfrag_init(); dev_add_pack(&ip_packet_type); rc = 0; out: return rc; out_unregister_raw_proto: proto_unregister(&raw_prot); out_unregister_udp_proto: proto_unregister(&udp_prot); out_unregister_tcp_proto: proto_unregister(&tcp_prot); out_free_reserved_ports: kfree(sysctl_local_reserved_ports); goto out; }
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