taglinefilesource code
wspace162net/inet/sock.hunsigned long    (*wspace)(struct sock *sk);
wspace51net/inet/sockinet.hunsigned long    (*wspace)(struct sock *sk);
wspace395net/inet/tcp.cif (sk->prot->wspace(sk) >= sk->mtu) 
wspace490net/inet/tcp.camount = sk->prot->wspace(sk);
wspace397net/inet/udp.camount = sk->prot->wspace(sk);
wspace197net/socket/datagram.cif(sk->prot && sk->prot->wspace(sk) >= MIN_WRITE_SPACE)