[asterisk-bugs] [Asterisk 0013959]: Zaptel/DAHDi freezes E1 PRI channels when recieving fax.

[Asterisk Bug Tracker]

A NOTE has been added to this issue. 
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https://issues.asterisk.org/view.php?id=13959 
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Reported By:                vinsik
Assigned To:                
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Project:                    Asterisk
Issue ID:                   13959
Category:                   Channels/chan_dahdi
Reproducibility:            always
Severity:                   major
Priority:                   normal
Status:                     feedback
Asterisk Version:           1.4.23 
Regression:                 Yes 
SVN Branch (only for SVN checkouts, not tarball releases):  1.4  
SVN Revision (number only!):  
Request Review:              
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Date Submitted:             2008-11-24 07:23 CST
Last Modified:              2009-05-27 06:40 CDT
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Summary:                    Zaptel/DAHDi freezes E1 PRI channels when recieving
fax.
Description: 
Asterisk locks up when trying to send fax from E1 PRI to SIP ATA device.
(Outbound works)
CLI stops responding when you try to access DAHDi or channel related
info.
Also 2M link is dropped down when this lock occurs.

Only asterisk restart helps.

This is 'core show locks' output:

=== <file> <line num> <function> <lock name> <lock addr> (times locked)
===
=== Thread ID: 3079187344 (pri_dchannel         started at [ 9697]
chan_dahdi.c start_pri())
=== ---> Lock https://issues.asterisk.org/view.php?id=0 (chan_dahdi.c): MUTEX
8678 pri_dchannel &pri->lock
0xb7940e24 (1)
=== ---> Waiting for Lock https://issues.asterisk.org/view.php?id=1
(chan_dahdi.c): MUTEX 9424 pri_dchannel
&pri->pvts[chanpos]->lock 0x821b6f8 (1)
=== --- ---> Locked Here: chan_dahdi.c line 4753 (dahdi_read)
=== -------------------------------------------------------------------
===
=== Thread ID: 3069733776 (autoservice_run      started at [  228]
autoservice.c ast_autoservice_start())
=== ---> Waiting for Lock https://issues.asterisk.org/view.php?id=0 (channel.c):
MUTEX 1682 ast_waitfor_nandfds
&c[x]->lock 0x8281548 (1)
=== --- ---> Locked Here: channel.c line 1978 (__ast_read)
=== -------------------------------------------------------------------
===
=== Thread ID: 3069979536 (ss_thread            started at [ 9060]
chan_dahdi.c pri_dchannel())
=== ---> Lock https://issues.asterisk.org/view.php?id=0 (channel.c): MUTEX 1978
__ast_read &chan->lock 0x8281548
(1)
=== ---> Lock https://issues.asterisk.org/view.php?id=1 (chan_dahdi.c): MUTEX
4753 dahdi_read &p->lock 0x821b6f8
(1)
=== ---> Lock https://issues.asterisk.org/view.php?id=2 (pbx.c): RDLOCK 6127
ast_rdlock_contexts &conlock
0x81bde40 (1)
=== -------------------------------------------------------------------

Have tried asterisk-1.4.23-rc1 and DAHDi (linux/tools) 2.1.0-rc4.

I can provide more information if needed.
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---------------------------------------------------------------------- 
 (0105498) dimas (reporter) - 2009-05-27 06:40
 https://issues.asterisk.org/view.php?id=13959#c105498 
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Well... Honestly I do not know how exactly async_goto works but my
imaginetion creates following picture for me:

1. for some reason autoservice is started on the channel
2. while in autoservice channels is bening read by autoservice thread
3. On one of reads, chan_dahdi detects CNG fax tone
4. chan_dahdi requests ast_async_goto for the channel to jump into fax
extension
5. What happens next i not quite understand :) that I believe that channel
starts bing read by another pbx thread simultaneously with autoservice_run.
And that causes problem and does not allow autoservice_run to continue.
(and rebuild the list which in turn blocks autoservice_stop from the first
thread)

I think if you disable fax detection it should work ok. 

Issue History 
Date Modified    Username       Field                    Change               
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2009-05-27 06:40 dimas          Note Added: 0105498                          
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