Summary:	ASTERISK-03926: chan_alsa can't unload
Reporter:	cxseven (cxseven)	Labels:
Date Opened:	2005-04-13 01:20:11	Date Closed:	2008-01-15 15:31:47.000-0600
Priority:	Minor	Regression?	No
Status:	Closed/Complete	Components:	Core/General
Versions:		Frequency of Occurrence
Related Issues:
Environment:		Attachments:	( 0) alsa_unload_patch.diff ( 1) chan_alsa.diff
Description:	My card's ALSA only lets one process open it for writing. Preferably chan_alsa would only open the device when it needed to read/write to it, but as a workaround I thought I might be able to load/unload the module when needed even though ring detection and call queueing could get kludgy this way. At any rate this kludge doesn't work either because unloading the chan_alsa module and then reloading it results in a HANG. ****** ADDITIONAL INFORMATION ****** I wish I knew what all those ast_ functions were. Also, what category does this belong in?
Comments:	By: Matthew Fredrickson (mattf) 2005-04-13 10:01:26 Are you talking about at load time, Asterisk hangs if you start it and it's already opened by another process? By: cxseven (cxseven) 2005-04-13 10:56:14 Asterisk hangs when I load chan_alsa.so, unload, & reload chan_alsa.so because Asterisk itself is apparently still holding open /dev/snd/* files. Looking at chan_alsa.c and with my two day's experience it looks like unload_module should be closing the pcm fds. Maybe they linger on in another thread? Demo of the problem: /usr/sbin/asterisk -vvvvvc [...] Asterisk Ready. *CLI> load chan_alsa.so Loaded /usr/lib/asterisk/modules/chan_alsa.so => (ALSA Console Channel Driver)  == Parsing '/etc/asterisk/alsa.conf': Found  == Registered channel type 'Console' (ALSA Console Channel Driver) *CLI> unload chan_alsa.so  == Unregistered channel type 'Console' *CLI> load chan_alsa.so Loaded /usr/lib/asterisk/modules/chan_alsa.so => (ALSA Console Channel Driver)  == Parsing '/etc/asterisk/alsa.conf': Found help stop now [Asterisk hanging with no response until Ctrl+c] Asterisk will also hang if I'm currently holding open /dev/snd/pcm* files with madplay. Maybe my card is a bit limited in the number of writers it supports, but it's probably exhibiting a real asterisk bug that wants to be fixed :/ By: Matthew Fredrickson (mattf) 2005-04-13 11:09:07 Try the patch I attached and tell me if it fixes it. By: cxseven (cxseven) 2005-04-13 11:20:45 Thinking that it was odd that the alsa fds were disposed using regular close() instead of a pcm_ close, I tried changing unload_module slightly. This minor but aggravating bug is now fixed! Now if only chan_alsa/oss could refrain from opening the device until they need it. I'm attaching my diff - OOPS it looks like you made the same exact change in the meanwhile! Thanks! PS I believe this bug was further highlighted by my card's refusal to honor the ALSA O_NON_BLOCK flag. It honors it for OSS, though. edited on: 04-13-05 11:23 By: Matthew Fredrickson (mattf) 2005-04-13 11:32:15 Ok, I'm going to apply that fix and close this out. By: Matthew Fredrickson (mattf) 2005-04-13 11:34:22 Oh, you might want to read over the coding guidelines.  C++ style comments are a no no. :-) By: Matthew Fredrickson (mattf) 2005-04-13 11:34:33 fixed By: Russell Bryant (russell) 2005-04-15 03:08:42 fixed in 1.0 as well By: Digium Subversion (svnbot) 2008-01-15 15:31:35.000-0600 Repository: asterisk Revision: 5464 U   trunk/channels/chan_alsa.c ------------------------------------------------------------------------ r5464 | mattf | 2008-01-15 15:31:35 -0600 (Tue, 15 Jan 2008) | 2 lines Fixed chan_alsa.c unload bug (bug ASTERISK-3926) ------------------------------------------------------------------------ http://svn.digium.com/view/asterisk?view=rev&revision=5464 By: Digium Subversion (svnbot) 2008-01-15 15:31:47.000-0600 Repository: asterisk Revision: 5477 U   branches/v1-0/CHANGES U   branches/v1-0/channels/chan_alsa.c ------------------------------------------------------------------------ r5477 | russell | 2008-01-15 15:31:47 -0600 (Tue, 15 Jan 2008) | 2 lines fix unloading problems (bug ASTERISK-3926) ------------------------------------------------------------------------ http://svn.digium.com/view/asterisk?view=rev&revision=5477