* 3.4.10 N_GSM tty_io WARNING and lockup
@ 2012-09-05 10:56 Krzysztof Hałasa
2012-09-06 13:01 ` Alan Cox
0 siblings, 1 reply; 6+ messages in thread
From: Krzysztof Hałasa @ 2012-09-05 10:56 UTC (permalink / raw)
To: linux-kernel
Hi,
I'm trying to use GSM tty line discipline. Basically
echo AT+CMUX=0 > /dev/ttyS0
set termios (speed etc.)
int ldisc = N_GSM0710;
ioctl(fd, TIOCSETD, &ldisc);
...
The ioctl first fails with EIO (probably due to inactive DCD line) in
tty_set_ldisc():
if (test_bit(TTY_HUPPED, &tty->flags)) {
/* We were raced by the hangup method. It will have stomped
the ldisc data and closed the ldisc down */
clear_bit(TTY_LDISC_CHANGING, &tty->flags);
mutex_unlock(&tty->ldisc_mutex);
tty_ldisc_put(new_ldisc);
tty_unlock();
return -EIO; <<<<<< HERE
}
Now trying to run the program again:
------------[ cut here ]------------
WARNING: at /home/khalasa/src/linux-3.4/drivers/tty/tty_io.c:1368 tty_open+0x2e8/0x55c()
Modules linked in: m25p80 ag71xx
Call Trace:
[<8030a02c>] dump_stack+0x8/0x34
[<8007a35c>] warn_slowpath_common+0x78/0xa4
[<8007a3a0>] warn_slowpath_null+0x18/0x24
[<80193cac>] tty_open+0x2e8/0x55c
[<800f1500>] chrdev_open+0x120/0x164
[<800eb320>] __dentry_open.isra.12+0x1bc/0x318
[<800fae54>] do_last.isra.32+0x774/0x78c
[<800fb094>] path_openat+0xcc/0x3b4
[<800fb498>] do_filp_open+0x3c/0xa4
[<800ec3dc>] do_sys_open+0x13c/0x1ec
[<80068dc4>] stack_done+0x20/0x40
---[ end trace 5958cc366bfb54c4 ]---
then it locks up (task "D" state, though interruptible).
A known problem probably?
Any ideas? (I know about CLOCAL).
--
Krzysztof Halasa
Research Institute for Automation and Measurements PIAP
Al. Jerozolimskie 202, 02-486 Warsaw, Poland
^ permalink raw reply [flat|nested] 6+ messages in thread* Re: 3.4.10 N_GSM tty_io WARNING and lockup 2012-09-05 10:56 3.4.10 N_GSM tty_io WARNING and lockup Krzysztof Hałasa @ 2012-09-06 13:01 ` Alan Cox 2012-09-07 11:07 ` Krzysztof Hałasa 0 siblings, 1 reply; 6+ messages in thread From: Alan Cox @ 2012-09-06 13:01 UTC (permalink / raw) To: Krzysztof Hałasa; +Cc: linux-kernel On Wed, 05 Sep 2012 12:56:03 +0200 khalasa@piap.pl (Krzysztof Hałasa) wrote: > Hi, > > I'm trying to use GSM tty line discipline. Basically > > echo AT+CMUX=0 > /dev/ttyS0 > > set termios (speed etc.) > int ldisc = N_GSM0710; > ioctl(fd, TIOCSETD, &ldisc); Baffled at this point. If you set some other ldisc instead (eg PPP) can you reproduce it the same way ? ^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: 3.4.10 N_GSM tty_io WARNING and lockup 2012-09-06 13:01 ` Alan Cox @ 2012-09-07 11:07 ` Krzysztof Hałasa 2012-09-07 12:59 ` Krzysztof Halasa 0 siblings, 1 reply; 6+ messages in thread From: Krzysztof Hałasa @ 2012-09-07 11:07 UTC (permalink / raw) To: Alan Cox; +Cc: linux-kernel Alan Cox <alan@lxorguk.ukuu.org.uk> writes: >> I'm trying to use GSM tty line discipline. Basically >> >> echo AT+CMUX=0 > /dev/ttyS0 >> >> set termios (speed etc.) >> int ldisc = N_GSM0710; >> ioctl(fd, TIOCSETD, &ldisc); > > Baffled at this point. If you set some other ldisc instead (eg PPP) can > you reproduce it the same way ? In the meantime I've rebased to v3.5.3 and it started to work. Do you think it is worth it investigating v3.4.10 at this point? This is Atheros AR71xx based RouterStation Pro board (MIPS). I'm using several patches supporting this board, though I can't see anything relevant to serial/tty, except maybe the following (which is IMHO not the problem source either): @@ -1941,17 +1941,20 @@ static int serial8250_startup(struct uart_port *port) if (port->type == PORT_16C950) { /* Wake up and initialize UART */ - up->acr = 0; + up->acr = UART_ACR_RTS_485; + serial_icr_write(up, UART_ACR, up->acr); serial_port_out(port, UART_LCR, UART_LCR_CONF_MODE_B); serial_port_out(port, UART_EFR, UART_EFR_ECB); serial_port_out(port, UART_IER, 0); serial_port_out(port, UART_LCR, 0); +#if 0 serial_icr_write(up, UART_CSR, 0); /* Reset the UART */ serial_port_out(port, UART_LCR, UART_LCR_CONF_MODE_B); serial_port_out(port, UART_EFR, UART_EFR_ECB); serial_port_out(port, UART_LCR, 0); +#endif Anyway the patchsets are almost identical with both kernel versions. -- Krzysztof Halasa Research Institute for Automation and Measurements PIAP Al. Jerozolimskie 202, 02-486 Warsaw, Poland ^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: 3.4.10 N_GSM tty_io WARNING and lockup 2012-09-07 11:07 ` Krzysztof Hałasa @ 2012-09-07 12:59 ` Krzysztof Halasa 2012-09-07 13:29 ` Alan Cox 0 siblings, 1 reply; 6+ messages in thread From: Krzysztof Halasa @ 2012-09-07 12:59 UTC (permalink / raw) To: Krzysztof Hałasa; +Cc: Alan Cox, linux-kernel > In the meantime I've rebased to v3.5.3 and it started to work. Do you > think it is worth it investigating v3.4.10 at this point? BTW I'm not sure if it's a known bug: I closed the /dev/ttyS0 with /dev/gsmmuxX still open, and then tried to set N_TTY ldisc on the master device. It didn't work so well :-( # killall -9 microcom # they use /dev/gsmmux[0-3] # killall -9 iru # the program messing with ldiscs # ps axf 344 ? Ss 0:00 \_ sshd: root@pts/1 346 pts/1 Ss 0:00 | \_ -sh 405 pts/1 D+ 0:00 | \_ [microcom] 347 ? Ss 0:00 \_ sshd: root@pts/2 349 pts/2 Ss 0:00 | \_ -sh 403 pts/2 D+ 0:00 | \_ [microcom] 406 ? Ss 0:00 \_ sshd: root@pts/3 408 pts/3 Ss 0:00 | \_ -sh 412 pts/3 D+ 0:00 | \_ [microcom] 409 ? Ss 0:00 \_ sshd: root@pts/4 411 pts/4 Ss 0:00 \_ -sh 413 pts/4 D+ 0:00 \_ [microcom] 415 pts/0 D 0:00 iru -- Krzysztof Halasa ^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: 3.4.10 N_GSM tty_io WARNING and lockup 2012-09-07 12:59 ` Krzysztof Halasa @ 2012-09-07 13:29 ` Alan Cox 2012-09-07 16:14 ` Krzysztof Halasa 0 siblings, 1 reply; 6+ messages in thread From: Alan Cox @ 2012-09-07 13:29 UTC (permalink / raw) To: Krzysztof Halasa; +Cc: Krzysztof Hałasa, linux-kernel On Fri, 07 Sep 2012 14:59:26 +0200 Krzysztof Halasa <khc@pm.waw.pl> wrote: > > In the meantime I've rebased to v3.5.3 and it started to work. Do you > > think it is worth it investigating v3.4.10 at this point? > > BTW I'm not sure if it's a known bug: I closed the /dev/ttyS0 with > /dev/gsmmuxX still open, and then tried to set N_TTY ldisc on the > master device. It didn't work so well :-( That should be fixed in 3.7. It's unfixable until the lock splitting work is merged. ^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: 3.4.10 N_GSM tty_io WARNING and lockup 2012-09-07 13:29 ` Alan Cox @ 2012-09-07 16:14 ` Krzysztof Halasa 0 siblings, 0 replies; 6+ messages in thread From: Krzysztof Halasa @ 2012-09-07 16:14 UTC (permalink / raw) To: Alan Cox; +Cc: linux-kernel Alan Cox <alan@lxorguk.ukuu.org.uk> writes: >> BTW I'm not sure if it's a known bug: I closed the /dev/ttyS0 with >> /dev/gsmmuxX still open, and then tried to set N_TTY ldisc on the >> master device. It didn't work so well :-( > > That should be fixed in 3.7. It's unfixable until the lock splitting work > is merged. I see. Thanks. -- Krzysztof Halasa ^ permalink raw reply [flat|nested] 6+ messages in thread
end of thread, other threads:[~2012-09-07 16:14 UTC | newest] Thread overview: 6+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- 2012-09-05 10:56 3.4.10 N_GSM tty_io WARNING and lockup Krzysztof Hałasa 2012-09-06 13:01 ` Alan Cox 2012-09-07 11:07 ` Krzysztof Hałasa 2012-09-07 12:59 ` Krzysztof Halasa 2012-09-07 13:29 ` Alan Cox 2012-09-07 16:14 ` Krzysztof Halasa
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