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

[Christian König <ckoenig.leichtzumerken@xxxxxxxxx>]

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-bounces@xxxxxxxxxxxxxxxxxxxxx> 代表 Das,
> > Nirmoy
> > 发送时间: Thursday, October 14, 2021 2:11 AM
> > 收件人: Christian König <ckoenig.leichtzumerken@xxxxxxxxx>; amd-
> > gfx@xxxxxxxxxxxxxxxxxxxxx
> > 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.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