drm/gem: switch dev->object_name_lock to a mutex

I want to wrap the creation of a dma-buf from a gem object in it,
so that the obj->export_dma_buf cache can be atomically filled in.

Instead of creating a new mutex just for that variable I've figured
I can reuse the existing dev->object_name_lock, especially since
the new semantics will exactly mirror the flink obj->name already
protected by that lock.

v2: idr_preload/idr_preload_end is now an atomic section, so need to
move the mutex locking outside.

[airlied: fix up conflict with patch to make debugfs use lock]
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Dave Airlie <airlied@redhat.com>

drivers/gpu/drm/drm_gem.c

@@ -93,7 +93,7 @@ drm_gem_init(struct drm_device *dev)
 {
 	struct drm_gem_mm *mm;
 
-	spin_lock_init(&dev->object_name_lock);
+	mutex_init(&dev->object_name_lock);
 	idr_init(&dev->object_name_idr);
 
 	mm = kzalloc(sizeof(struct drm_gem_mm), GFP_KERNEL);
@@ -243,10 +243,10 @@ drm_gem_object_handle_unreference_unlocked(struct drm_gem_object *obj)
 	* checked for a name
 	*/
 
-	spin_lock(&obj->dev->object_name_lock);
+	mutex_lock(&obj->dev->object_name_lock);
 	if (--obj->handle_count == 0)
 		drm_gem_object_handle_free(obj);
-	spin_unlock(&obj->dev->object_name_lock);
+	mutex_unlock(&obj->dev->object_name_lock);
 
 	drm_gem_object_unreference_unlocked(obj);
 }
@@ -324,16 +324,16 @@ drm_gem_handle_create(struct drm_file *file_priv,
 	 * Get the user-visible handle using idr.  Preload and perform
 	 * allocation under our spinlock.
 	 */
+	mutex_lock(&dev->object_name_lock);
 	idr_preload(GFP_KERNEL);
-	spin_lock(&dev->object_name_lock);
 	spin_lock(&file_priv->table_lock);
 
 	ret = idr_alloc(&file_priv->object_idr, obj, 1, 0, GFP_NOWAIT);
 	drm_gem_object_reference(obj);
 	obj->handle_count++;
 	spin_unlock(&file_priv->table_lock);
-	spin_unlock(&dev->object_name_lock);
 	idr_preload_end();
+	mutex_unlock(&dev->object_name_lock);
 	if (ret < 0) {
 		drm_gem_object_handle_unreference_unlocked(obj);
 		return ret;
@@ -578,8 +578,8 @@ drm_gem_flink_ioctl(struct drm_device *dev, void *data,
 	if (obj == NULL)
 		return -ENOENT;
 
+	mutex_lock(&dev->object_name_lock);
 	idr_preload(GFP_KERNEL);
-	spin_lock(&dev->object_name_lock);
 	/* prevent races with concurrent gem_close. */
 	if (obj->handle_count == 0) {
 		ret = -ENOENT;
@@ -601,8 +601,8 @@ drm_gem_flink_ioctl(struct drm_device *dev, void *data,
 	ret = 0;
 
 err:
-	spin_unlock(&dev->object_name_lock);
 	idr_preload_end();
+	mutex_unlock(&dev->object_name_lock);
 	drm_gem_object_unreference_unlocked(obj);
 	return ret;
 }
@@ -625,11 +625,11 @@ drm_gem_open_ioctl(struct drm_device *dev, void *data,
 	if (!(dev->driver->driver_features & DRIVER_GEM))
 		return -ENODEV;
 
-	spin_lock(&dev->object_name_lock);
+	mutex_lock(&dev->object_name_lock);
 	obj = idr_find(&dev->object_name_idr, (int) args->name);
 	if (obj)
 		drm_gem_object_reference(obj);
-	spin_unlock(&dev->object_name_lock);
+	mutex_unlock(&dev->object_name_lock);
 	if (!obj)
 		return -ENOENT;
 

drivers/gpu/drm/drm_info.c

@@ -219,9 +219,9 @@ int drm_gem_name_info(struct seq_file *m, void *data)
 
 	seq_printf(m, "  name     size handles refcount\n");
 
-	spin_lock(&dev->object_name_lock);
+	mutex_lock(&dev->object_name_lock);
 	idr_for_each(&dev->object_name_idr, drm_gem_one_name_info, m);
-	spin_unlock(&dev->object_name_lock);
+	mutex_unlock(&dev->object_name_lock);
 
 	return 0;
 }

include/drm/drmP.h

@@ -1196,7 +1196,7 @@ struct drm_device {
 
 	/** \name GEM information */
 	/*@{ */
-	spinlock_t object_name_lock;
+	struct mutex object_name_lock;
 	struct idr object_name_idr;
 	/*@} */
 	int switch_power_state;