taglinefilesource code
ssthresh812net/inet/sock.csk->ssthresh = 0;
ssthresh115net/inet/sock.hvolatile unsigned short  ssthresh;
ssthresh207net/inet/tcp.csk->ssthresh = sk->cong_window >> 1; /* remember window where we lost */
ssthresh1878net/inet/tcp.cnewsk->ssthresh = 0;
ssthresh2393net/inet/tcp.cif (sk->cong_window < sk->ssthresh)