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The Advanced Linux Sound Architecture (ALSA) - library
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Takashi Iwai df483d3fe5 pcm: Fix the wrong PCM object passed for locking/unlocking 
Most of PCM API functions have snd_pcm_lock()/unlock() wraps for the
actual calls of ops, and some plugins try to unlock/relock internally
for the given PCM object.  This, unfortunately, causes a problem in
some configurations and leads to the unexpected behavior or deadlock.

The main problem is that we call snd_pcm_lock() with the given PCM
object, while calling the ops with pcm->op_arg or pcm->fast_op_arg as
the slave PCM object.  Meanwhile the plugin code assumes that the
passed PCM object is already locked, and calls snd_pcm_unlock().
This bug doesn't hit always because in most cases pcm->op_arg and
fast_op_arg are identical with pcm itself.  But in some configurations
they have different values, so the problem surfaces.

This patch is an attempt to resolve these inconsistencies.  It
replaces most of snd_pcm_lock()/unlock() calls with either pcm->op_arg
or pcm->fast_op_arg, depending on the call pattern, so that the plugin
code can safely run snd_pcm_unlock() to the given PCM object.

Fixes: 54931e5a54 ("pcm: Add thread-safety to PCM API")
Reported-by: Ben Russell <thematrixeatsyou@gmail.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
2019-09-24 13:55:16 +02:00
alsalisp Change FSF address (Franklin Street) 2017-11-14 14:29:26 +01:00
aserver Use __func__ instead of __FUNCTION__ 2019-06-12 08:52:07 +02:00
doc doxygen: Suppress timestamp 2016-06-23 16:29:07 +02:00
include Use __func__ instead of __FUNCTION__ 2019-06-12 08:52:07 +02:00
m4 Add the attributes.m4 macro file from xine/lscube. 2008-11-21 13:04:19 +01:00
modules modules: smixer_python - add support for python3 2018-03-27 14:51:39 +02:00
src pcm: Fix the wrong PCM object passed for locking/unlocking 2019-09-24 13:55:16 +02:00
test Printf unsigned longs with %lu instead of %ld (playmidi1.c) 2019-04-09 10:27:36 +02:00
utils Drop -I$includedir/alsa from alsa.pc 2019-03-28 08:01:34 +01:00
.gitignore initial version of .travis.yml file 2018-10-24 16:07:58 +02:00
.travis.yml initial version of .travis.yml file 2018-10-24 16:07:58 +02:00
acinclude.m4 fixed for the recent autoconf. 2004-01-26 15:52:17 +00:00
ChangeLog * update to libtool 1.3.3 1999-07-22 12:18:42 +00:00
configure.ac ucm: Add UCM profile for CX2072X codec on Baytrail/Cherrytrail profiles 2019-05-23 17:42:42 +02:00
COPYING Change FSF address (Franklin Street) 2017-11-14 14:29:26 +01:00
gitcompile add support for GCC's LTO 2019-04-09 12:44:14 +02:00
INSTALL pcm: Add thread-safety to PCM API 2016-07-11 15:25:30 +02:00
Makefile.am autotools: update style 2014-02-26 08:16:22 +01:00
MEMORY-LEAK Initial version 2003-02-04 14:56:07 +00:00
NOTES Change assert condition in error message handler 2007-10-24 12:53:08 +02:00
README.md README.md: add link to www.alsa-project.org 2018-10-24 17:33:10 +02:00
TODO Added snd_config_load_override(). 2002-01-09 21:28:15 +00:00

README.md

alsa-lib

Advanced Linux Sound Architecture (ALSA) project

The alsa-lib is a library to interface with ALSA in the Linux kernel and virtual devices using a plugin system.

The up-to-date reference generated from sources can be accessed here:

http://www.alsa-project.org/alsa-doc/alsa-lib/

You may give a look for more information about the ALSA project to URL http://www.alsa-project.org.