Re: [PATCH n_gsm] GSM Mux in non-transparent mode

[Eric Bénard]

> > There is a problem that happens if the process that is holding the
> > attached line discipline tries to detach it before a process using a
> > virtual com manages to close it. Both processes end up dealocked. I
> > think this has to do with the tty lock. I don't have the backtrace with
> > me

here is the log I get here :

[ 1051.950000] ------------[ cut here ]------------
[ 1051.950000] WARNING: at drivers/tty/tty_mutex.c:31 tty_lock+0x30/0x50()
[ 1051.960000] Modules linked in:
[ 1051.960000] [<c0029478>] (unwind_backtrace+0x0/0xe4) from [<c0034f30>] 
(warn_slowpath_common+0x4c/0x64)
[ 1051.970000] [<c0034f30>] (warn_slowpath_common+0x4c/0x64) from [<c0034f60>] 
(warn_slowpath_null+0x18/0x1c)
[ 1051.980000] [<c0034f60>] (warn_slowpath_null+0x18/0x1c) from [<c031550c>] 
(tty_lock+0x30/0x50)
[ 1051.990000] [<c031550c>] (tty_lock+0x30/0x50) from [<c01af5b0>] 
(__tty_hangup+0x78/0x47c)
[ 1052.000000] [<c01af5b0>] (__tty_hangup+0x78/0x47c) from [<c01ba69c>] 
(gsm_cleanup_mux+0x198/0x214)
[ 1052.010000] [<c01ba69c>] (gsm_cleanup_mux+0x198/0x214) from [<c01baaf4>] 
(gsmld_close+0x28/0x4c)
[ 1052.020000] [<c01baaf4>] (gsmld_close+0x28/0x4c) from [<c01b5974>] 
(tty_ldisc_close+0x58/0x64)
[ 1052.030000] [<c01b5974>] (tty_ldisc_close+0x58/0x64) from [<c01b5b48>] 
(tty_ldisc_release+0x38/0x70)
[ 1052.040000] [<c01b5b48>] (tty_ldisc_release+0x38/0x70) from [<c01b0e2c>] 
(tty_release+0x41c/0x480)
[ 1052.050000] [<c01b0e2c>] (tty_release+0x41c/0x480) from [<c009667c>] 
(fput+0x108/0x200)
[ 1052.060000] [<c009667c>] (fput+0x108/0x200) from [<c00939c8>] 
(filp_close+0x60/0x6c)
[ 1052.070000] [<c00939c8>] (filp_close+0x60/0x6c) from [<c0036eb8>] 
(put_files_struct+0x80/0xdc)
[ 1052.080000] [<c0036eb8>] (put_files_struct+0x80/0xdc) from [<c0038500>] 
(do_exit+0x1b8/0x6bc)
[ 1052.080000] [<c0038500>] (do_exit+0x1b8/0x6bc) from [<c0038ac4>] 
(do_group_exit+0xc0/0xf4)
[ 1052.090000] [<c0038ac4>] (do_group_exit+0xc0/0xf4) from [<c0044460>] 
(get_signal_to_deliver+0x3ac/0x40c)
[ 1052.100000] [<c0044460>] (get_signal_to_deliver+0x3ac/0x40c) from 
[<c0027190>] (do_signal+0x68/0x614)
[ 1052.110000] [<c0027190>] (do_signal+0x68/0x614) from [<c0027754>] 
(do_notify_resume+0x18/0x60)
[ 1052.120000] [<c0027754>] (do_notify_resume+0x18/0x60) from [<c0024f94>] 
(work_pending+0x24/0x28)
[ 1052.130000] ---[ end trace ac06c34c1914deef ]---

Eric
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