Add support to track media device unregister in progress
state to prevent more than one driver entering unregister.
This enables fixing the general protection faults while
snd-usb-audio was cleaning up media resources for pcm
streams and mixers. In this patch a new interface is added
to return the unregister in progress state. Subsequent
patches to snd-usb-audio and au0828-core use this interface
to avoid entering unregister and attempting to unregister
entities and remove devnodes while unregister is in progress.
Media device unregister removes entities and interface nodes.
Signed-off-by: Shuah Khan <shuahkh@xxxxxxxxxxxxxxx>
---
drivers/media/media-device.c | 5 ++++-
include/media/media-device.h | 17 +++++++++++++++++
2 files changed, 21 insertions(+), 1 deletion(-)
diff --git a/drivers/media/media-device.c b/drivers/media/media-device.c
index 20c85a9..1bb9a5f 100644
--- a/drivers/media/media-device.c
+++ b/drivers/media/media-device.c
@@ -749,10 +749,13 @@ void media_device_unregister(struct media_device *mdev)
spin_lock(&mdev->lock);
/* Check if mdev was ever registered at all */
- if (!media_devnode_is_registered(&mdev->devnode)) {
+ /* check if unregister is in progress */
+ if (!media_devnode_is_registered(&mdev->devnode) ||
+ mdev->unregister_in_progress) {
spin_unlock(&mdev->lock);
return;
}
+ mdev->unregister_in_progress = true;
/* Remove all entities from the media device */
list_for_each_entry_safe(entity, next, &mdev->entities, graph_obj.list)
diff --git a/include/media/media-device.h b/include/media/media-device.h
index 04b6c2e..0807292 100644
--- a/include/media/media-device.h
+++ b/include/media/media-device.h
@@ -332,6 +332,10 @@ struct media_device {
spinlock_t lock;
/* Serializes graph operations. */
struct mutex graph_mutex;
+ /* Tracks unregister in progress state to prevent
+ * more than one driver entering unregister
+ */
+ bool unregister_in_progress;
/* Handlers to find source entity for the sink entity and
* check if it is available, and activate the link using
@@ -365,6 +369,7 @@ struct media_device {
/* media_devnode to media_device */
#define to_media_device(node) container_of(node, struct media_device, devnode)
+
/**
* media_entity_enum_init - Initialise an entity enumeration
*
@@ -553,6 +558,12 @@ struct media_device *media_device_get_devres(struct device *dev);
* @dev: pointer to struct &device.
*/
struct media_device *media_device_find_devres(struct device *dev);
+/* return unregister in progress state */
+static inline bool media_device_is_unregister_in_progress(
+ struct media_device *mdev)
+{
+ return mdev->unregister_in_progress;
+}
/* Iterate over all entities. */
#define media_device_for_each_entity(entity, mdev) \
@@ -569,6 +580,7 @@ struct media_device *media_device_find_devres(struct device *dev);
/* Iterate over all links. */
#define media_device_for_each_link(link, mdev) \
list_for_each_entry(link, &(mdev)->links, graph_obj.list)
+
#else
static inline int media_device_register(struct media_device *mdev)
{
@@ -604,5 +616,10 @@ static inline struct media_device *media_device_find_devres(struct device *dev)
{
return NULL;
}
+static inline bool media_device_is_unregister_in_progress(
+ struct media_device *mdev)
+{
+ return false;
+}
#endif /* CONFIG_MEDIA_CONTROLLER */
#endif
--
2.5.0
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