[PATCH 4/4] ALSA: hda: hda_component: Protect shared data with a mutex

[Simon Trimmer <simont@opensource.cirrus.com>]

The hda_component contains information shared from the amp drivers to
the codec that can be altered (for example as the driver unloads). Guard
the update and use of these to prevent use of stale data.

Signed-off-by: Simon Trimmer <simont@opensource.cirrus.com>
---
 sound/pci/hda/hda_component.c | 13 ++++++++++++-
 sound/pci/hda/hda_component.h |  4 ++++
 2 files changed, 16 insertions(+), 1 deletion(-)

diff --git a/sound/pci/hda/hda_component.c b/sound/pci/hda/hda_component.c
index 1a9950b76866..7b19cb38b4e0 100644
--- a/sound/pci/hda/hda_component.c
+++ b/sound/pci/hda/hda_component.c
@@ -21,11 +21,13 @@ void hda_component_acpi_device_notify(struct hda_component_parent *parent,
 	struct hda_component *comp;
 	int i;
 
+	mutex_lock(&parent->mutex);
 	for (i = 0; i < ARRAY_SIZE(parent->comps); i++) {
 		comp = hda_component_from_index(parent, i);
 		if (comp->dev && comp->acpi_notify)
 			comp->acpi_notify(acpi_device_handle(comp->adev), event, comp->dev);
 	}
+	mutex_unlock(&parent->mutex);
 }
 EXPORT_SYMBOL_NS_GPL(hda_component_acpi_device_notify, SND_HDA_SCODEC_COMPONENT);
 
@@ -87,6 +89,7 @@ void hda_component_manager_playback_hook(struct hda_component_parent *parent, in
 	struct hda_component *comp;
 	int i;
 
+	mutex_lock(&parent->mutex);
 	for (i = 0; i < ARRAY_SIZE(parent->comps); i++) {
 		comp = hda_component_from_index(parent, i);
 		if (comp->dev && comp->pre_playback_hook)
@@ -102,6 +105,7 @@ void hda_component_manager_playback_hook(struct hda_component_parent *parent, in
 		if (comp->dev && comp->post_playback_hook)
 			comp->post_playback_hook(comp->dev, action);
 	}
+	mutex_unlock(&parent->mutex);
 }
 EXPORT_SYMBOL_NS_GPL(hda_component_manager_playback_hook, SND_HDA_SCODEC_COMPONENT);
 
@@ -134,11 +138,18 @@ static int hda_comp_match_dev_name(struct device *dev, void *data)
 int hda_component_manager_bind(struct hda_codec *cdc,
 			       struct hda_component_parent *parent)
 {
+	int ret;
+
 	/* Init shared and component specific data */
 	memset(parent, 0, sizeof(*parent));
+	mutex_init(&parent->mutex);
 	parent->codec = cdc;
 
-	return component_bind_all(hda_codec_dev(cdc), parent);
+	mutex_lock(&parent->mutex);
+	ret = component_bind_all(hda_codec_dev(cdc), parent);
+	mutex_unlock(&parent->mutex);
+
+	return ret;
 }
 EXPORT_SYMBOL_NS_GPL(hda_component_manager_bind, SND_HDA_SCODEC_COMPONENT);
 
diff --git a/sound/pci/hda/hda_component.h b/sound/pci/hda/hda_component.h
index dd4dabeae9ee..9f786608144c 100644
--- a/sound/pci/hda/hda_component.h
+++ b/sound/pci/hda/hda_component.h
@@ -11,6 +11,7 @@
 
 #include <linux/acpi.h>
 #include <linux/component.h>
+#include <linux/mutex.h>
 #include <sound/hda_codec.h>
 
 #define HDA_MAX_COMPONENTS	4
@@ -28,6 +29,7 @@ struct hda_component {
 };
 
 struct hda_component_parent {
+	struct mutex mutex;
 	struct hda_codec *codec;
 	struct hda_component comps[HDA_MAX_COMPONENTS];
 };
@@ -93,7 +95,9 @@ static inline struct hda_component *hda_component_from_index(struct hda_componen
 static inline void hda_component_manager_unbind(struct hda_codec *cdc,
 						struct hda_component_parent *parent)
 {
+	mutex_lock(&parent->mutex);
 	component_unbind_all(hda_codec_dev(cdc), parent);
+	mutex_unlock(&parent->mutex);
 }
 
 #endif /* ifndef __HDA_COMPONENT_H__ */
-- 
2.34.1