Problem with modem ports (bug in 4.2BSD dmf driver)

[Ken Lalonde]

The DMF driver stops listening for carrier transitions when the
other end hangs up.  Look at vaxuba/dmf.c, function dmfrint().
Change the code to read as shown below.
			
			} else {
				if (tp->t_state & TS_CARR_ON) {
					gsignal(tp->t_pgrp, SIGHUP);
					gsignal(tp->t_pgrp, SIGCONT);
					addr->dmfcsr = DMF_IE | DMFIR_LCR |
						((c>>8)&07);
				/* next line used to read addr->dmftms = 0; */
					addr->dmfun.dmfirw = DMFLCR_ENA;
					ttyflush(tp, FREAD|FWRITE);
				}
				tp->t_state &= ~TS_CARR_ON;
			}

In fact, all references to field dmftms are in error, since that register
is not byte addressable.
While you have your feet wet, there is a missing splx() in dmfparam():
	
	/*
	 * Block interrupts so parameters will be set
	 * before the line interrupts.
	 */
	s = spl5();
	addr->dmfcsr = (unit&07) | DMFIR_LCR | DMF_IE;
	if ((tp->t_ispeed)==0) {
		tp->t_state |= TS_HUPCLS;
		(void) dmfmctl(unit, DMF_OFF, DMSET);
		splx(s);	/* This was missing */
		return;
	}

Also, the first argument to dmfparam() is sometimes a device number,
sometimes a minor number.  It should always be the minor number,
since some callers don't have the device number handy.

	- Ken Lalonde		ihnp4!watmath!kwlalonde