[PATCH] drm/gem: modernize locks to use scoped_guard()

[Biren Pandya <birenpandya@gmail.com>]

Several GEM core functions manually managed mutex_lock() and
mutex_unlock() over single scopes or error paths. This adds boilerplate
and carries the risk of lock leaks if error paths are refactored.

Modernize these locks by deploying the <linux/cleanup.h> scoped_guard()
macro. This ensures that the locks are reliably dropped when the block
exits, cleanly removing goto out_unlock paths and tightening the
lifecycle.

Signed-off-by: Biren Pandya <birenpandya@gmail.com>

Compiled locally, but requires IGT validation by the DRM CI.
---
 drivers/gpu/drm/drm_gem.c | 66 ++++++++++++++++++---------------------
 1 file changed, 30 insertions(+), 36 deletions(-)

diff --git a/drivers/gpu/drm/drm_gem.c b/drivers/gpu/drm/drm_gem.c
index 891c3bff5ae0..d3a061d42ba7 100644
--- a/drivers/gpu/drm/drm_gem.c
+++ b/drivers/gpu/drm/drm_gem.c
@@ -346,13 +346,13 @@ void drm_gem_object_handle_put_unlocked(struct drm_gem_object *obj)
 	 * we checked for a name.
 	 */
 
-	mutex_lock(&dev->object_name_lock);
-	if (--obj->handle_count == 0) {
-		drm_gem_object_handle_free(obj);
-		drm_gem_object_exported_dma_buf_free(obj);
-		final = true;
+	scoped_guard(mutex, &dev->object_name_lock) {
+		if (--obj->handle_count == 0) {
+			drm_gem_object_handle_free(obj);
+			drm_gem_object_exported_dma_buf_free(obj);
+			final = true;
+		}
 	}
-	mutex_unlock(&dev->object_name_lock);
 
 	if (final)
 		drm_gem_object_put(obj);
@@ -374,11 +374,8 @@ drm_gem_object_release_handle(int id, void *ptr, void *data)
 	if (obj->funcs->close)
 		obj->funcs->close(obj, file_priv);
 
-	mutex_lock(&file_priv->prime.lock);
-
-	drm_prime_remove_buf_handle(&file_priv->prime, id);
-
-	mutex_unlock(&file_priv->prime.lock);
+	scoped_guard(mutex, &file_priv->prime.lock)
+		drm_prime_remove_buf_handle(&file_priv->prime, id);
 
 	drm_vma_node_revoke(&obj->vma_node, file_priv);
 
@@ -1021,37 +1018,34 @@ int drm_gem_change_handle_ioctl(struct drm_device *dev, void *data,
 		goto out;
 	}
 
-	mutex_lock(&file_priv->prime.lock);
+	scoped_guard(mutex, &file_priv->prime.lock) {
+		spin_lock(&file_priv->table_lock);
+		ret = idr_alloc(&file_priv->object_idr, obj, handle, handle + 1,
+				GFP_NOWAIT);
+		spin_unlock(&file_priv->table_lock);
 
-	spin_lock(&file_priv->table_lock);
-	ret = idr_alloc(&file_priv->object_idr, obj, handle, handle + 1,
-			GFP_NOWAIT);
-	spin_unlock(&file_priv->table_lock);
+		if (ret < 0)
+			break;
 
-	if (ret < 0)
-		goto out_unlock;
+		if (obj->dma_buf) {
+			ret = drm_prime_add_buf_handle(&file_priv->prime, obj->dma_buf,
+						       handle);
+			if (ret < 0) {
+				spin_lock(&file_priv->table_lock);
+				idr_remove(&file_priv->object_idr, handle);
+				spin_unlock(&file_priv->table_lock);
+				break;
+			}
 
-	if (obj->dma_buf) {
-		ret = drm_prime_add_buf_handle(&file_priv->prime, obj->dma_buf,
-					       handle);
-		if (ret < 0) {
-			spin_lock(&file_priv->table_lock);
-			idr_remove(&file_priv->object_idr, handle);
-			spin_unlock(&file_priv->table_lock);
-			goto out_unlock;
+			drm_prime_remove_buf_handle(&file_priv->prime, args->handle);
 		}
 
-		drm_prime_remove_buf_handle(&file_priv->prime, args->handle);
-	}
-
-	ret = 0;
-
-	spin_lock(&file_priv->table_lock);
-	idr_remove(&file_priv->object_idr, args->handle);
-	spin_unlock(&file_priv->table_lock);
+		ret = 0;
 
-out_unlock:
-	mutex_unlock(&file_priv->prime.lock);
+		spin_lock(&file_priv->table_lock);
+		idr_remove(&file_priv->object_idr, args->handle);
+		spin_unlock(&file_priv->table_lock);
+	}
 out:
 	drm_gem_object_put(obj);
 

base-commit: 72c25183cac9bc584c9de21797a5883af44bcc7a
-- 
2.50.1 (Apple Git-155)