From: Mauro Carvalho Chehab <mchehab@osg.samsung.com>
Date: Wed, 9 Dec 2015 21:47:35 +0000 (-0200)
Subject: [media] media-entity: protect object creation/removal using spin lock
X-Git-Tag: v4.5-rc1~115^2~113
X-Git-Url: https://asedeno.scripts.mit.edu/gitweb/?a=commitdiff_plain;h=a08fad1ec80c69c79b3ffb6d84968b0952d32da1;p=linux.git

[media] media-entity: protect object creation/removal using spin lock

Some parts of the media controller are using mutexes while
others are using spin locks in order to protect creation
and removal of elements in the graph. That's wrong!

Also, the V4L2 core can remove graph elements on non-interactive
context:
	BUG: sleeping function called from invalid context at include/linux/sched.h:2776

Fix it by always using spin locks for graph element addition/removal,
just like entity creation/removal is protected at media-device.c

Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>
---

diff --git a/drivers/media/media-entity.c b/drivers/media/media-entity.c
index ee0f81364960..b1390d843909 100644
--- a/drivers/media/media-entity.c
+++ b/drivers/media/media-entity.c
@@ -700,9 +700,9 @@ void media_entity_remove_links(struct media_entity *entity)
 	if (entity->graph_obj.mdev == NULL)
 		return;
 
-	mutex_lock(&entity->graph_obj.mdev->graph_mutex);
+	spin_lock(&entity->graph_obj.mdev->lock);
 	__media_entity_remove_links(entity);
-	mutex_unlock(&entity->graph_obj.mdev->graph_mutex);
+	spin_unlock(&entity->graph_obj.mdev->lock);
 }
 EXPORT_SYMBOL_GPL(media_entity_remove_links);
 
@@ -792,9 +792,9 @@ int media_entity_setup_link(struct media_link *link, u32 flags)
 {
 	int ret;
 
-	mutex_lock(&link->source->entity->graph_obj.mdev->graph_mutex);
+	spin_lock(&link->source->entity->graph_obj.mdev->lock);
 	ret = __media_entity_setup_link(link, flags);
-	mutex_unlock(&link->source->entity->graph_obj.mdev->graph_mutex);
+	spin_unlock(&link->source->entity->graph_obj.mdev->lock);
 
 	return ret;
 }
@@ -932,9 +932,9 @@ EXPORT_SYMBOL_GPL(__media_remove_intf_link);
 
 void media_remove_intf_link(struct media_link *link)
 {
-	mutex_lock(&link->graph_obj.mdev->graph_mutex);
+	spin_lock(&link->graph_obj.mdev->lock);
 	__media_remove_intf_link(link);
-	mutex_unlock(&link->graph_obj.mdev->graph_mutex);
+	spin_unlock(&link->graph_obj.mdev->lock);
 }
 EXPORT_SYMBOL_GPL(media_remove_intf_link);
 
@@ -954,8 +954,8 @@ void media_remove_intf_links(struct media_interface *intf)
 	if (intf->graph_obj.mdev == NULL)
 		return;
 
-	mutex_lock(&intf->graph_obj.mdev->graph_mutex);
+	spin_lock(&intf->graph_obj.mdev->lock);
 	__media_remove_intf_links(intf);
-	mutex_unlock(&intf->graph_obj.mdev->graph_mutex);
+	spin_unlock(&intf->graph_obj.mdev->lock);
 }
 EXPORT_SYMBOL_GPL(media_remove_intf_links);
diff --git a/include/media/media-device.h b/include/media/media-device.h
index 1b12774a9ab4..87ff299e1265 100644
--- a/include/media/media-device.h
+++ b/include/media/media-device.h
@@ -88,7 +88,7 @@ struct media_device {
 	struct list_head pads;
 	struct list_head links;
 
-	/* Protects the entities list */
+	/* Protects the graph objects creation/removal */
 	spinlock_t lock;
 	/* Serializes graph operations. */
 	struct mutex graph_mutex;