morgan@UCI-750A.ARPA (10/03/84)
From: Tim Morgan <morgan@UCI-750A.ARPA>
Description:
The dmf driver does not contain code to wake up processes which
are select'ing on output.
Repeat-By:
Log onto a terminal on a dmf32 or clone. Telnet to any system,
including the local one. Run something on that system which will
produce lots of output (such as cat'ing /etc/termcap). After a
few hundred characters, the output will stop. It will not start
again until you type something. Telnet is waiting until the output
buffer empties to write more, but the dmf driver never does a
selwakeup() call, so the select() call never returns unless something
else occurs, such as a character in the input buffer.
Fix:
Here is a diff listing of the fix. The code inserted is from the
dz driver; it also occurs in the dh driver and possibly others. You
line numbers may differ.
*** old_dmf.c Sat Sep 22 21:44:11 1984
--- dmf.c Sat Sep 22 21:44:45 1984
***************
*** 609,617
* If there are sleepers, and output has drained below low
* water mark, wake up the sleepers.
*/
! if ((tp->t_state&TS_ASLEEP) && tp->t_outq.c_cc<=TTLOWAT(tp)) {
! tp->t_state &= ~TS_ASLEEP;
! wakeup((caddr_t)&tp->t_outq);
}
/*
* Now restart transmission unless the output queue is
--- 609,624 -----
* If there are sleepers, and output has drained below low
* water mark, wake up the sleepers.
*/
! if (tp->t_outq.c_cc<=TTLOWAT(tp)) {
! if (tp->t_state&TS_ASLEEP) {
! tp->t_state &= ~TS_ASLEEP;
! wakeup((caddr_t)&tp->t_outq);
! }
! if (tp->t_wsel) {
! selwakeup(tp->t_wsel, tp->t_state & TS_WCOLL);
! tp->t_wsel = 0;
! tp->t_state &= ~TS_WCOLL;
! }
}
/*
* Now restart transmission unless the output queue is