taglinefilesource code
sock_wspace251net/inet/packet.csock_wspace,
sock_wspace386net/inet/raw.csock_wspace,
sock_wspace265net/inet/sock.hextern unsigned long    sock_wspace(struct sock *sk);
sock_wspace3899net/inet/tcp.csock_wspace,
sock_wspace622net/inet/udp.csock_wspace,