Netlink与Genetlink接口执行流程简要分析

Netlink与Genetlink接口执行流程简要分析：

netlink_proto_init　　///< 内核层
    proto_register(&netlink_proto, 0);
    nl_table = kcalloc(MAX_LINKS, sizeof(*nl_table), GFP_KERNEL);
    netlink_add_usersock_entry();
    sock_register(&netlink_family_ops);

sys_socket　　///< 应用层
    retval = sock_create(family, type, protocol, &sock);
        pf = rcu_dereference(net_families[family]);
        err = pf->create(net, sock, protocol, kern);
            netlink_create
                __netlink_create(net, sock, cb_mutex, protocol, kern);
                    sk->sk_data_ready = sock_def_readable;        ///< 应用层注册为-

sys_bind ///< bind之后可以使用 recv、recvmsg 接收消息
    sock = sockfd_lookup_light(fd, &err, &fput_needed);
    err = move_addr_to_kernel(umyaddr, addrlen, &address);
    err = security_socket_bind(sock, (struct sockaddr *)&address, addrlen);
    err = sock->ops->bind(sock, (struct sockaddr *)&address, addrlen);

sys_send　　///< 内核层
    sys_sendto
        import_single_range(WRITE, buff, len, &iov, &msg.msg_iter);
        sockfd_lookup_light(fd, &err, &fput_needed);
        move_addr_to_kernel(addr, addr_len, &address);
        sock_sendmsg(sock, &msg);
            netlink_sendmsg
                memcpy_from_msg(skb_put(skb, len), msg, len)
                security_netlink_send(sk, skb);
　　　　　　　　　　/* 单播 */
                netlink_unicast(sk, skb, dst_portid, msg->msg_flags&MSG_DONTWAIT);
                    netlink_unicast_kernel(sk, skb, ssk);
                        nlk->netlink_rcv(skb);    ///< 之前 nlk_sk(sk)->netlink_rcv = cfg->input;
                /* 多播 */
                netlink_broadcast(sk, skb, dst_portid, dst_group, GFP_KERNEL);
                    netlink_broadcast_filtered
                        sk_for_each_bound(sk, &nl_table[ssk->sk_protocol].mc_list)
                        do_one_broadcast(sk, &info);
                            netlink_broadcast_deliver(sk, p->skb2);
                                __netlink_sendskb(sk, skb);
                                    sk->sk_data_ready(sk);
                                        BUG();

sys_recv　　///< 内核层
    sys_recvfrom
        sock = sockfd_lookup_light(fd, &err, &fput_needed);
        err = sock_recvmsg(sock, &msg, flags);
            security_socket_recvmsg(sock, msg, msg_data_left(msg), flags);
            sock_recvmsg_nosec(sock, msg, flags);
                sock->ops->recvmsg(sock, msg, msg_data_left(msg), flags);
                    netlink_recvmsg
                        skb = skb_recv_datagram(sk, flags, noblock, &err);
                            __skb_try_recv_datagram
                            __skb_wait_for_more_packets
                                prepare_to_wait_exclusive(sk_sleep(sk), &wait, TASK_INTERRUPTIBLE); ///< 阻塞等待消息

nlmsg_unicast　　///< 内核层
    netlink_unicast(sk, skb, portid, MSG_DONTWAIT);
        netlink_sendskb(sk, skb);
            __netlink_sendskb(sk, skb);
                sk->sk_data_ready(sk);    ///< sock_def_readable
                    sock_def_readable
                        wake_up_interruptible_sync_poll(&wq->wait, POLLIN | POLLPRI | POLLRDNORM | POLLRDBAND);    ///< 唤醒

-------------------------------------------------------------------------------------------------------------
genetlink

genl_register_family(&genl_ctrl)　　///< 内核层
    genl_validate_ops(family);
    family->id = idr_alloc(&genl_fam_idr, family, start, end + 1, GFP_KERNEL);    ///< 加入genl_fam_idr, 分配ID

register_pernet_subsys(&genl_pernet_ops);    ///< 注册netlink

.input = genl_rcv　　///< 接收函数
    netlink_rcv_skb(skb, &genl_rcv_msg);
        family = genl_family_find_byid(nlh->nlmsg_type);    ///< 通过ID找到family
        genl_family_rcv_msg(family, skb, nlh, extack);
            ops = genl_get_cmd(hdr->cmd, family);
            nlmsg_parse(nlh, hdrlen, attrbuf, family->maxattr, ops->policy, extack);
                tb[type] = (struct nlattr *)nla;    ///< tb <==> attrbuf
            info.attrs = attrbuf;
            ops->doit(skb, &info);
                if (info->attrs[CTRL_ATTR_FAMILY_NAME])
                    res = genl_family_find_byname(name);
                msg = ctrl_build_family_msg(res, info->snd_portid, info->snd_seq, CTRL_CMD_NEWFAMILY);
                genlmsg_reply(msg, info);

详细的分析过程可以查看这位博主的文章，很全面：blog.csdn.net/luckyapple1028/article/details/50839395