drm/ttm: add debugfs directory v2

As far as I can tell the buffer_count was never used by an
userspace application.

The number of BOs in the system is far better suited in
debugfs than sysfs and we now should be able to add other
information here as well.

v2: add that additionally to sysfs
Signed-off-by: Christian König <christian.koenig@amd.com>
Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/414954/

drivers/gpu/drm/ttm/ttm_bo.c

@@ -44,8 +44,6 @@
 
 #include "ttm_module.h"
 
-static void ttm_bo_global_kobj_release(struct kobject *kobj);
-
 /*
  * ttm_global_mutex - protecting the global BO state
  */
@@ -54,11 +52,6 @@ unsigned ttm_bo_glob_use_count;
 struct ttm_bo_global ttm_bo_glob;
 EXPORT_SYMBOL(ttm_bo_glob);
 
-static struct attribute ttm_bo_count = {
-	.name = "bo_count",
-	.mode = S_IRUGO
-};
-
 /* default destructor */
 static void ttm_bo_default_destroy(struct ttm_buffer_object *bo)
 {
@@ -84,32 +77,6 @@ static void ttm_bo_mem_space_debug(struct ttm_buffer_object *bo,
 	}
 }
 
-static ssize_t ttm_bo_global_show(struct kobject *kobj,
-				  struct attribute *attr,
-				  char *buffer)
-{
-	struct ttm_bo_global *glob =
-		container_of(kobj, struct ttm_bo_global, kobj);
-
-	return snprintf(buffer, PAGE_SIZE, "%d\n",
-				atomic_read(&glob->bo_count));
-}
-
-static struct attribute *ttm_bo_global_attrs[] = {
-	&ttm_bo_count,
-	NULL
-};
-
-static const struct sysfs_ops ttm_bo_global_ops = {
-	.show = &ttm_bo_global_show
-};
-
-static struct kobj_type ttm_bo_glob_kobj_type  = {
-	.release = &ttm_bo_global_kobj_release,
-	.sysfs_ops = &ttm_bo_global_ops,
-	.default_attrs = ttm_bo_global_attrs
-};
-
 static void ttm_bo_del_from_lru(struct ttm_buffer_object *bo)
 {
 	struct ttm_bo_device *bdev = bo->bdev;
@@ -1228,14 +1195,6 @@ size_t ttm_bo_dma_acc_size(struct ttm_bo_device *bdev,
 }
 EXPORT_SYMBOL(ttm_bo_dma_acc_size);
 
-static void ttm_bo_global_kobj_release(struct kobject *kobj)
-{
-	struct ttm_bo_global *glob =
-		container_of(kobj, struct ttm_bo_global, kobj);
-
-	__free_page(glob->dummy_read_page);
-}
-
 static void ttm_bo_global_release(void)
 {
 	struct ttm_bo_global *glob = &ttm_bo_glob;
@@ -1247,6 +1206,7 @@ static void ttm_bo_global_release(void)
 	kobject_del(&glob->kobj);
 	kobject_put(&glob->kobj);
 	ttm_mem_global_release(&ttm_mem_glob);
+	__free_page(glob->dummy_read_page);
 	memset(glob, 0, sizeof(*glob));
 out:
 	mutex_unlock(&ttm_global_mutex);
@@ -1279,10 +1239,8 @@ static int ttm_bo_global_init(void)
 	INIT_LIST_HEAD(&glob->device_list);
 	atomic_set(&glob->bo_count, 0);
 
-	ret = kobject_init_and_add(
-		&glob->kobj, &ttm_bo_glob_kobj_type, ttm_get_kobj(), "buffer_objects");
-	if (unlikely(ret != 0))
-		kobject_put(&glob->kobj);
+	debugfs_create_atomic_t("buffer_objects", 0444, ttm_debugfs_root,
+				&glob->bo_count);
 out:
 	mutex_unlock(&ttm_global_mutex);
 	return ret;

drivers/gpu/drm/ttm/ttm_module.c

@@ -32,12 +32,14 @@
 #include <linux/module.h>
 #include <linux/device.h>
 #include <linux/sched.h>
+#include <linux/debugfs.h>
 #include <drm/drm_sysfs.h>
 
 #include "ttm_module.h"
 
 static DECLARE_WAIT_QUEUE_HEAD(exit_q);
 static atomic_t device_released;
+struct dentry *ttm_debugfs_root;
 
 static struct device_type ttm_drm_class_type = {
 	.name = "ttm",
@@ -77,6 +79,7 @@ static int __init ttm_init(void)
 	if (unlikely(ret != 0))
 		goto out_no_dev_reg;
 
+	ttm_debugfs_root = debugfs_create_dir("ttm", NULL);
 	return 0;
 out_no_dev_reg:
 	atomic_set(&device_released, 1);
@@ -94,6 +97,7 @@ static void __exit ttm_exit(void)
 	 */
 
 	wait_event(exit_q, atomic_read(&device_released) == 1);
+	debugfs_remove(ttm_debugfs_root);
 }
 
 module_init(ttm_init);

drivers/gpu/drm/ttm/ttm_module.h

@@ -31,10 +31,12 @@
 #ifndef _TTM_MODULE_H_
 #define _TTM_MODULE_H_
 
-#include <linux/kernel.h>
+#define TTM_PFX "[TTM] "
+
 struct kobject;
+struct dentry;
 
-#define TTM_PFX "[TTM] "
 extern struct kobject *ttm_get_kobj(void);
+extern struct dentry *ttm_debugfs_root;
 
 #endif /* _TTM_MODULE_H_ */