linux-kernel - [PATCH v2 2/6] drm: Convert object_name

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Message-ID: <20250821145429.305526-3-sidhartha.kumar@oracle.com>
Date: Thu, 21 Aug 2025 14:54:25 +0000
From: Sidhartha Kumar <sidhartha.kumar@...cle.com>
To: linux-kernel@...r.kernel.org, dri-devel@...ts.freedesktop.org
Cc: maarten.lankhorst@...ux.intel.com, mripard@...nel.org, tzimmermann@...e.de,
        airlied@...il.com, simona@...ll.ch, willy@...radead.org,
        sidhartha.kumar@...cle.com
Subject: [PATCH v2 2/6] drm: Convert object_name_idr to XArray

From: Matthew Wilcox <willy@...radead.org>

It's not possible to replace object_name_lock as it protects more
code than should be reasonably be run under a spinlock, so the xa_lock
is nested under the object_name_lock.

Signed-off-by: Matthew Wilcox <willy@...radead.org>
Signed-off-by: Sidhartha Kumar <sidhartha.kumar@...cle.com>
---
 drivers/gpu/drm/drm_debugfs.c | 19 ++++++-------------
 drivers/gpu/drm/drm_gem.c     | 11 +++++------
 include/drm/drm_device.h      |  4 ++--
 3 files changed, 13 insertions(+), 21 deletions(-)

diff --git a/drivers/gpu/drm/drm_debugfs.c b/drivers/gpu/drm/drm_debugfs.c
index 365cf337529f..3e57e3da5115 100644
--- a/drivers/gpu/drm/drm_debugfs.c
+++ b/drivers/gpu/drm/drm_debugfs.c
@@ -122,27 +122,20 @@ static int drm_clients_info(struct seq_file *m, void *data)
 	return 0;
 }
 
-static int drm_gem_one_name_info(int id, void *ptr, void *data)
-{
-	struct drm_gem_object *obj = ptr;
-	struct seq_file *m = data;
-
-	seq_printf(m, "%6d %8zd %7d %8d\n",
-		   obj->name, obj->size,
-		   obj->handle_count,
-		   kref_read(&obj->refcount));
-	return 0;
-}
-
 static int drm_gem_name_info(struct seq_file *m, void *data)
 {
 	struct drm_debugfs_entry *entry = m->private;
 	struct drm_device *dev = entry->dev;
+	struct drm_gem_object *obj;
+	unsigned long index;
 
 	seq_printf(m, "  name     size handles refcount\n");
 
 	mutex_lock(&dev->object_name_lock);
-	idr_for_each(&dev->object_name_idr, drm_gem_one_name_info, m);
+	xa_for_each(&dev->object_names, index, obj) {
+		seq_printf(m, "%6d %8zd %7d %8d\n", obj->name, obj->size,
+				obj->handle_count, kref_read(&obj->refcount));
+	}
 	mutex_unlock(&dev->object_name_lock);
 
 	return 0;
diff --git a/drivers/gpu/drm/drm_gem.c b/drivers/gpu/drm/drm_gem.c
index 6a44351e58b7..cef0c5935798 100644
--- a/drivers/gpu/drm/drm_gem.c
+++ b/drivers/gpu/drm/drm_gem.c
@@ -97,7 +97,7 @@ drm_gem_init(struct drm_device *dev)
 	struct drm_vma_offset_manager *vma_offset_manager;
 
 	mutex_init(&dev->object_name_lock);
-	idr_init_base(&dev->object_name_idr, 1);
+	xa_init_flags(&dev->object_names, XA_FLAGS_ALLOC1);
 
 	vma_offset_manager = drmm_kzalloc(dev, sizeof(*vma_offset_manager),
 					  GFP_KERNEL);
@@ -269,7 +269,7 @@ static void drm_gem_object_handle_free(struct drm_gem_object *obj)
 
 	/* Remove any name for this object */
 	if (obj->name) {
-		idr_remove(&dev->object_name_idr, obj->name);
+		xa_erase(&dev->object_names, obj->name);
 		obj->name = 0;
 	}
 }
@@ -927,11 +927,10 @@ drm_gem_flink_ioctl(struct drm_device *dev, void *data,
 	}
 
 	if (!obj->name) {
-		ret = idr_alloc(&dev->object_name_idr, obj, 1, 0, GFP_KERNEL);
+		ret = xa_alloc(&dev->object_names, &obj->name, obj,
+				xa_limit_32b, GFP_KERNEL);
 		if (ret < 0)
 			goto err;
-
-		obj->name = ret;
 	}
 
 	args->name = (uint64_t) obj->name;
@@ -967,7 +966,7 @@ drm_gem_open_ioctl(struct drm_device *dev, void *data,
 		return -EOPNOTSUPP;
 
 	mutex_lock(&dev->object_name_lock);
-	obj = idr_find(&dev->object_name_idr, (int) args->name);
+	obj = xa_load(&dev->object_names, (int) args->name);
 	if (obj) {
 		drm_gem_object_get(obj);
 	} else {
diff --git a/include/drm/drm_device.h b/include/drm/drm_device.h
index a33aedd5e9ec..6a28a9b134dd 100644
--- a/include/drm/drm_device.h
+++ b/include/drm/drm_device.h
@@ -325,8 +325,8 @@ struct drm_device {
 	/** @object_name_lock: GEM information */
 	struct mutex object_name_lock;
 
-	/** @object_name_idr: GEM information */
-	struct idr object_name_idr;
+	/** @object_names: GEM information */
+	struct xarray object_names;
 
 	/** @vma_offset_manager: GEM information */
 	struct drm_vma_offset_manager *vma_offset_manager;
-- 
2.43.0