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

[Christian König]

Am 19.10.21 um 10:02 schrieb Yang, Stanley:
[AMD Official Use Only]

-----邮件原件-----
发件人: amd-gfx <amd-gfx-boun...@lists.freedesktop.org> 代表 Das,
Nirmoy
发送时间: Thursday, October 14, 2021 2:11 AM
收件人: Christian König <ckoenig.leichtzumer...@gmail.com>; amd-
g...@lists.freedesktop.org
主题: Re: [PATCH Review 1/1] drm/ttm: fix debugfs node create failed


On 10/13/2021 2:29 PM, Christian König wrote:
Am 12.10.21 um 15:12 schrieb Das, Nirmoy:
On 10/12/2021 1:58 PM, Stanley.Yang wrote:
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!

We should instead add a check if those debugfs files already
exist/created in ttm debugfs dir using debugfs_lookup() before creating.
No, IIRC the Intel guys had fixed that already by adding/removing the
debugfs file on module load/unload.

Adding/removing on ttm module load/unload is nicer.
The point is that page_pool, page_pool_shrink and buffer_objects are created by 
amdgpu driver,

Yeah, but the debugfs files are not created by the driver. Those are 
global to TTM and can trivially be created during module load/unload.

Christian.

  I think it's better to remove them by amdgpu module due to amdgpu module 
create them,
otherwise, there will be a scene create them failed only reload amdgpu module.

Stanley

Nirmoy


Christian.


Regards,

Nirmoy



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.y...@amd.com>
---
   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