[PATCH Review 1/1] drm/ttm: fix debugfs node create failed

["Stanley.Yang" <Stanley.Yang@xxxxxxx>]

Test scenario:
    modprobe amdgpu -> rmmod amdgpu -> modprobe amdgpu
Error log:
    [   54.396807] debugfs: File 'page_pool' in directory 'amdttm' already present!
    [   54.396833] debugfs: File 'page_pool_shrink' in directory 'amdttm' already present!
    [   54.396848] debugfs: File 'buffer_objects' in directory 'amdttm' already present!
Reason:
    page_pool, page_pool_shrink and buffer_objects can be removed when
    rmmod amdttm, in the above test scenario only rmmod amdgpu, so those
    debugfs node will not be removed, this caused file create failed.
Soultion:
    create ttm_page directory under ttm_root directory when insmod amdgpu,
    page_pool, page_pool_shrink and buffer_objects are stored in ttm_page directiry,
    remove ttm_page directory when do rmmod amdgpu, this can fix above issue.

Signed-off-by: Stanley.Yang <Stanley.Yang@xxxxxxx>
---
 drivers/gpu/drm/ttm/ttm_device.c | 12 +++++++++++-
 drivers/gpu/drm/ttm/ttm_module.c |  1 +
 drivers/gpu/drm/ttm/ttm_module.h |  1 +
 drivers/gpu/drm/ttm/ttm_pool.c   |  4 ++--
 4 files changed, 15 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/ttm/ttm_device.c b/drivers/gpu/drm/ttm/ttm_device.c
index 1de23edbc182..ad170328f0c8 100644
--- a/drivers/gpu/drm/ttm/ttm_device.c
+++ b/drivers/gpu/drm/ttm/ttm_device.c
@@ -55,6 +55,10 @@ static void ttm_global_release(void)
 
 	ttm_pool_mgr_fini();
 
+#ifdef CONFIG_DEBUG_FS
+	debugfs_remove(ttm_debugfs_page);
+#endif
+
 	__free_page(glob->dummy_read_page);
 	memset(glob, 0, sizeof(*glob));
 out:
@@ -85,6 +89,10 @@ static int ttm_global_init(void)
 		>> PAGE_SHIFT;
 	num_dma32 = min(num_dma32, 2UL << (30 - PAGE_SHIFT));
 
+#ifdef CONFIG_DEBUG_FS
+	ttm_debugfs_page = debugfs_create_dir("ttm_page", ttm_debugfs_root);
+#endif
+
 	ttm_pool_mgr_init(num_pages);
 	ttm_tt_mgr_init(num_pages, num_dma32);
 
@@ -98,8 +106,10 @@ static int ttm_global_init(void)
 	INIT_LIST_HEAD(&glob->device_list);
 	atomic_set(&glob->bo_count, 0);
 
-	debugfs_create_atomic_t("buffer_objects", 0444, ttm_debugfs_root,
+#ifdef CONFIG_DEBUG_FS
+	debugfs_create_atomic_t("buffer_objects", 0444, ttm_debugfs_page,
 				&glob->bo_count);
+#endif
 out:
 	mutex_unlock(&ttm_global_mutex);
 	return ret;
diff --git a/drivers/gpu/drm/ttm/ttm_module.c b/drivers/gpu/drm/ttm/ttm_module.c
index 88970a6b8e32..66595e6e7087 100644
--- a/drivers/gpu/drm/ttm/ttm_module.c
+++ b/drivers/gpu/drm/ttm/ttm_module.c
@@ -38,6 +38,7 @@
 #include "ttm_module.h"
 
 struct dentry *ttm_debugfs_root;
+struct dentry *ttm_debugfs_page;
 
 static int __init ttm_init(void)
 {
diff --git a/drivers/gpu/drm/ttm/ttm_module.h b/drivers/gpu/drm/ttm/ttm_module.h
index d7cac5d4b835..6007dc66f44e 100644
--- a/drivers/gpu/drm/ttm/ttm_module.h
+++ b/drivers/gpu/drm/ttm/ttm_module.h
@@ -36,5 +36,6 @@
 struct dentry;
 
 extern struct dentry *ttm_debugfs_root;
+extern struct dentry *ttm_debugfs_page;
 
 #endif /* _TTM_MODULE_H_ */
diff --git a/drivers/gpu/drm/ttm/ttm_pool.c b/drivers/gpu/drm/ttm/ttm_pool.c
index 8be7fd7161fd..ecb33daad7b5 100644
--- a/drivers/gpu/drm/ttm/ttm_pool.c
+++ b/drivers/gpu/drm/ttm/ttm_pool.c
@@ -709,9 +709,9 @@ int ttm_pool_mgr_init(unsigned long num_pages)
 	}
 
 #ifdef CONFIG_DEBUG_FS
-	debugfs_create_file("page_pool", 0444, ttm_debugfs_root, NULL,
+	debugfs_create_file("page_pool", 0444, ttm_debugfs_page, NULL,
 			    &ttm_pool_debugfs_globals_fops);
-	debugfs_create_file("page_pool_shrink", 0400, ttm_debugfs_root, NULL,
+	debugfs_create_file("page_pool_shrink", 0400, ttm_debugfs_page, NULL,
 			    &ttm_pool_debugfs_shrink_fops);
 #endif
 
-- 
2.17.1