From: Jaroslav Kysela <jkysela@redhat.com>
Date: Thu, 11 Nov 2010 08:39:10 -0500
Subject: [sound] ALSA: fix sysfs unload and OSS mixer mutex issues
Message-id: <201011110839.oAB8dAFg024670@int-mx02.intmail.prod.int.phx2.redhat.com>
Patchwork-id: 29139
O-Subject: [RHEL 5.6 PATCH] ALSA - fix sysfs unloading issue and OSS mixer mutex
	issue
Bugzilla: 652165
RH-Acked-by: John Feeney <jfeeney@redhat.com>

Bugzilla
========
BZ#652165
https://bugzilla.redhat.com/bugzilla/show_bug.cgi?id=652165

Description
===========
In current RHEL 5.6 kernel, the ALSA device nodes in sysfs are not destroyed
correctly when the sound modules are unloaded. It prevents sound module
reloading (sysfs reports EEXIST error when new ALSA device node is created).

Also the OSS mixer emulation contains mutex bugs so all audio applications
using mixer API can be blocked until system reboot.

Upstream Status of the patch
============================
Both changes are in upstream.

Test Status
===========
I and Dreamworks tested both patches intensively (for the audio delay
project).

diff --git a/sound/core/oss/mixer_oss.c b/sound/core/oss/mixer_oss.c
index 74a2923..83f5f59 100644
--- a/sound/core/oss/mixer_oss.c
+++ b/sound/core/oss/mixer_oss.c
@@ -611,8 +611,10 @@ static void snd_mixer_oss_put_volume1_vol(struct snd_mixer_oss_file *fmixer,
 	if (numid == ID_UNKNOWN)
 		return;
 	down_read(&card->controls_rwsem);
-	if ((kctl = snd_ctl_find_numid(card, numid)) == NULL)
+	if ((kctl = snd_ctl_find_numid(card, numid)) == NULL) {
+		up_read(&card->controls_rwsem);
 		return;
+	}
 	uinfo = kzalloc(sizeof(*uinfo), GFP_KERNEL);
 	uctl = kzalloc(sizeof(*uctl), GFP_KERNEL);
 	if (uinfo == NULL || uctl == NULL)
@@ -651,7 +653,7 @@ static void snd_mixer_oss_put_volume1_sw(struct snd_mixer_oss_file *fmixer,
 		return;
 	down_read(&card->controls_rwsem);
 	if ((kctl = snd_ctl_find_numid(card, numid)) == NULL) {
-		up_read(&fmixer->card->controls_rwsem);
+		up_read(&card->controls_rwsem);
 		return;
 	}
 	uinfo = kzalloc(sizeof(*uinfo), GFP_KERNEL);
@@ -779,7 +781,7 @@ static int snd_mixer_oss_get_recsrc2(struct snd_mixer_oss_file *fmixer, unsigned
 	uctl = kzalloc(sizeof(*uctl), GFP_KERNEL);
 	if (uinfo == NULL || uctl == NULL) {
 		err = -ENOMEM;
-		goto __unlock;
+		goto __free_only;
 	}
 	down_read(&card->controls_rwsem);
 	kctl = snd_mixer_oss_test_id(mixer, "Capture Source", 0);
@@ -808,6 +810,7 @@ static int snd_mixer_oss_get_recsrc2(struct snd_mixer_oss_file *fmixer, unsigned
 	err = 0;
       __unlock:
      	up_read(&card->controls_rwsem);
+      __free_only:
       	kfree(uctl);
       	kfree(uinfo);
       	return err;
@@ -829,7 +832,7 @@ static int snd_mixer_oss_put_recsrc2(struct snd_mixer_oss_file *fmixer, unsigned
 	uctl = kzalloc(sizeof(*uctl), GFP_KERNEL);
 	if (uinfo == NULL || uctl == NULL) {
 		err = -ENOMEM;
-		goto __unlock;
+		goto __free_only;
 	}
 	down_read(&card->controls_rwsem);
 	kctl = snd_mixer_oss_test_id(mixer, "Capture Source", 0);
@@ -862,6 +865,7 @@ static int snd_mixer_oss_put_recsrc2(struct snd_mixer_oss_file *fmixer, unsigned
 	err = 0;
       __unlock:
 	up_read(&card->controls_rwsem);
+      __free_only:
 	kfree(uctl);
 	kfree(uinfo);
 	return err;
diff --git a/sound/core/sound.c b/sound/core/sound.c
index f9b0180..bc9054f 100644
--- a/sound/core/sound.c
+++ b/sound/core/sound.c
@@ -311,7 +311,7 @@ int snd_unregister_device(int type, struct snd_card *card, int dev)
 		return -EINVAL;
 	}
 
-	class_device_destroy(sound_class, MKDEV(major, minor));
+	device_destroy(sound_class, MKDEV(major, minor));
 
 	snd_minors[minor] = NULL;
 	mutex_unlock(&sound_mutex);