[net.unix-wizards] Flushing and HUPCLS

ptw@vaxine.UUCP (06/10/83)

My reading of my (4.1) dz/dh drivers says that a remote terminal with HUPCLS
set and default line discipline could drop its last few characters, since the
modem is turned off before it is flushed.  The relevant lines are as follows:

	/*** dh.c circa line 295 ***/

	(*linesw[tp->t_line].l_close)(tp);
	((struct dhdevice *)(tp->t_addr))->dhbreak &= ~(1<<(unit&017));
	if (tp->t_state&HUPCLS || (tp->t_state&ISOPEN)==0)
		dmctl(unit, DML_OFF, DMSET);
	ttyclose(tp);

This is probably no big deal for a terminal session, but I suspect it might
give something like UUCP gas.

My real problem is that I'm trying to do the dialin/dialout dance and once in
a yellow/white moon my uucico hangs in ttyclose, I think because a race
condition is letting init turn DTR back on before CD drops.

Switching the flushing and HUPCLS isn't the right solution to my problem, but
the present arrangement does concern me.

Any commments?

pn@amd70.UUCP (06/13/83)

I have noticed some machines hangup on my uucico before
the end of session handshake is concluded, possibly due to what
you mention.