taglinefilesource code
wspace193net/inet/datagram.cif (sk->prot && sk->prot->wspace(sk) >= MIN_WRITE_SPACE)
wspace189net/inet/sock.hunsigned long    (*wspace)(struct sock *sk);
wspace453net/inet/tcp.cif (sk->prot->wspace(sk) >= sk->mss) 
wspace521net/inet/tcp.camount = sk->prot->wspace(sk);
wspace413net/inet/udp.camount = sk->prot->wspace(sk)/*/2*/;