[alsa-devel] [PATCH] ASoC: core: Fix component_list corruption when unloading modules

[Jarkko Nikula]

This fixes module unload regressions introduced by commits 98e639fb8a3e
("ASoC: Track which components have been registered with
snd_soc_register_component()") and b37f1d123c69 ("ASoC: Let snd_soc_platform
subclass snd_soc_component").

First commit causes component_list to be corrupted when removing codec and
second when removing platform. Reason for both is that components associated
with platform or codec are never removed from the list because for them
registered_as_component field in struct snd_soc_component is always false.

Now list becomes corrupted when snd_soc_unregister_platform() or
snd_soc_unregister_codec() frees the platform or codec structure and where
the associated struct snd_soc_component is embedded.

Fix these by moving component unregistration and cleanup to a new local
function __snd_soc_unregister_component() that takes component as its
argument.

Since component is known for platforms and codecs the
__snd_soc_unregister_component() can be called directly and
snd_soc_unregister_component() takes care to find and unregister only
components that were registered using snd_soc_register_component().

Signed-off-by: Jarkko Nikula <jarkko.nikula at linux.intel.com>
---
 sound/soc/soc-core.c | 25 +++++++++++++++----------
 1 file changed, 15 insertions(+), 10 deletions(-)

diff --git a/sound/soc/soc-core.c b/sound/soc/soc-core.c
index f18112a32541..62c3980fad5b 100644
--- a/sound/soc/soc-core.c
+++ b/sound/soc/soc-core.c
@@ -4061,6 +4061,18 @@ int snd_soc_register_component(struct device *dev,
 }
 EXPORT_SYMBOL_GPL(snd_soc_register_component);
 
+static void __snd_soc_unregister_component(struct snd_soc_component *cmpnt)
+{
+	snd_soc_unregister_dais(cmpnt);
+
+	mutex_lock(&client_mutex);
+	list_del(&cmpnt->list);
+	mutex_unlock(&client_mutex);
+
+	dev_dbg(cmpnt->dev, "ASoC: Unregistered component '%s'\n", cmpnt->name);
+	kfree(cmpnt->name);
+}
+
 /**
  * snd_soc_unregister_component - Unregister a component from the ASoC core
  *
@@ -4076,14 +4088,7 @@ void snd_soc_unregister_component(struct device *dev)
 	return;
 
 found:
-	snd_soc_unregister_dais(cmpnt);
-
-	mutex_lock(&client_mutex);
-	list_del(&cmpnt->list);
-	mutex_unlock(&client_mutex);
-
-	dev_dbg(dev, "ASoC: Unregistered component '%s'\n", cmpnt->name);
-	kfree(cmpnt->name);
+	__snd_soc_unregister_component(cmpnt);
 }
 EXPORT_SYMBOL_GPL(snd_soc_unregister_component);
 
@@ -4183,7 +4188,7 @@ EXPORT_SYMBOL_GPL(snd_soc_register_platform);
  */
 void snd_soc_remove_platform(struct snd_soc_platform *platform)
 {
-	snd_soc_unregister_component(platform->dev);
+	__snd_soc_unregister_component(&platform->component);
 
 	mutex_lock(&client_mutex);
 	list_del(&platform->list);
@@ -4388,7 +4393,7 @@ void snd_soc_unregister_codec(struct device *dev)
 	return;
 
 found:
-	snd_soc_unregister_component(dev);
+	__snd_soc_unregister_component(&codec->component);
 
 	mutex_lock(&client_mutex);
 	list_del(&codec->list);
-- 
1.9.2