netlink用戶層到內核——一步一步

android 層以上比較簡單，有空補上。從JNI開始

 

   static jstring android_net_ethernet_waitForEvent(JNIEnv *env,

                                                     jobject clazz)
    {
            if((len = recvmsg(nl_socket_poll, &msg, 0))>= 0)
  }

static jint android_net_ethernet_initEthernetNative(JNIEnv *env,
                                                        jobject clazz)
    {     
        /*
         *Create connection to netlink socket
         */
        nl_socket_msg = socket(AF_NETLINK,SOCK_RAW,NETLINK_ROUTE);

   }

 

內核部分：

SYSCALL_DEFINE3(socket, int, family, int, type, int, protocol)
{
      retval = sock_create(family, type, protocol, &sock);

}

static int __sock_create(struct net *net, int family, int type, int protocol,
             struct socket **res, int kern)
{

    pf = rcu_dereference(net_families[family]);
      /*
     * We will call the ->create function, that possibly is in a loadable
     * module, so we have to bump that loadable module refcnt first.
     */
    err = pf->create(net, sock, protocol, kern);

}

net_families哪裏來的？？look here

static int __init netlink_proto_init(void)
{
    sock_register(&netlink_family_ops);

}

int sock_register(const struct net_proto_family *ops)
{
       spin_lock(&net_family_lock);
    if (net_families[ops->family])
        err = -EEXIST;
    else {
        net_families[ops->family] = ops;
        err = 0;
    }
 
}