[PATCH 17/20] drm/gem: switch dev->object_name_lock to a mutex

[Daniel Vetter]

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.

Signed-off-by: Daniel Vetter <daniel.vetter at ffwll.ch>
---
 drivers/gpu/drm/drm_gem.c | 18 +++++++++---------
 include/drm/drmP.h        |  2 +-
 2 files changed, 10 insertions(+), 10 deletions(-)

diff --git a/drivers/gpu/drm/drm_gem.c b/drivers/gpu/drm/drm_gem.c
index 1609a3d..2bcffb9 100644
--- a/drivers/gpu/drm/drm_gem.c
+++ b/drivers/gpu/drm/drm_gem.c
@@ -92,7 +92,7 @@ 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);
@@ -252,10 +252,10 @@ 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);
 }
@@ -333,16 +333,16 @@ 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;
@@ -513,8 +513,8 @@ 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;
@@ -536,8 +536,8 @@ 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;
 }
@@ -560,11 +560,11 @@ 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;
 
diff --git a/include/drm/drmP.h b/include/drm/drmP.h
index 4d7ea3d..59a1cf1 100644
--- a/include/drm/drmP.h
+++ b/include/drm/drmP.h
@@ -1229,7 +1229,7 @@ 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;
-- 
1.8.3.2