RE: Linux-2.4.20 modem control

["Richard B. Johnson" <root@chaos.analogic.com>]

On Wed, 19 Mar 2003, Ed Vance wrote:
[SNIPPED...]

> Hi Richard,
>
> The following patch to serial.c in 2.4.20 is a brute-force addition
> of a hang-up delay of 0.5 sec just before close returns to the user,
> if the hupcl flag is set. Please try this to determine if there are
> any other issues with the remote login. If it works, I'll write a
> better patch that does not duplicate other delays, etc.
>
> Cheers,
> Ed
>

Well, it's the "right church, but wrong pew". As soon as anything
closes STDIO_FILENO, **bang** the modem hangs up. NotGood(tm)!
So as long as I just execute the shell which was exec'ed ...
getty...rlogin...bash never called close. However, `ls` on my
machine is `color-ls` when it calls exit(0)... well you get
the idea! I can log in, but can't actually execute anything that
terminates, closing STDIO_FILENO...


> diff -urN -X dontdiff.txt linux-2.4.20/drivers/char/serial.c
> patched-2.4.20/drivers/char/serial.c
> --- linux-2.4.20/drivers/char/serial.c	Thu Nov 28 15:53:12 2002
> +++ patched-2.4.20/drivers/char/serial.c	Tue Mar 18 16:03:43 2003
> @@ -2848,6 +2848,10 @@
>  		tty->driver.flush_buffer(tty);
>  	if (tty->ldisc.flush_buffer)
>  		tty->ldisc.flush_buffer(tty);
> +	if (tty->termios->c_cflag & HUPCL) {
> +		set_current_state(TASK_INTERRUPTIBLE);
> +		schedule_timeout(HZ/2);	/* 0.5 sec to disconnect modem */
> +	}
>  	tty->closing = 0;
>  	info->event = 0;
>  	info->tty = 0;
>

Cheers,
Dick Johnson
Penguin : Linux version 2.4.20 on an i686 machine (797.90 BogoMips).
Why is the government concerned about the lunatic fringe? Think about it.