taglinefilesource code
sock_wspace307include/net/sock.hextern unsigned long    sock_wspace(struct sock *sk);
sock_wspace387net/ipv4/packet.csock_wspace,
sock_wspace286net/ipv4/raw.csock_wspace,
sock_wspace5231net/ipv4/tcp.csock_wspace,
sock_wspace669net/ipv4/udp.csock_wspace,