Re: [PATCH v2 10/17] drm/vram-helper: make drm_vram_mm_debugfs_init() return 0

[Daniel Vetter]

On Wed, Mar 18, 2020 at 5:03 PM Wambui Karuga <wambui.karugax@xxxxxxxxx> wrote:
>
>
>
> On Wed, 18 Mar 2020, Daniel Vetter wrote:
>
> > On Tue, Mar 10, 2020 at 04:31:14PM +0300, Wambui Karuga wrote:
> >> Since 987d65d01356 (drm: debugfs: make
> >> drm_debugfs_create_files() never fail), drm_debugfs_create_files() never
> >> fails and should return void. Therefore, remove its use as the
> >> return value of drm_vram_mm_debugfs_init(), and have the function
> >> return 0 directly.
> >>
> >> v2: have drm_vram_mm_debugfs_init() return 0 instead of void to avoid
> >> introducing build issues and build breakage.
> >>
> >> References: https://lists.freedesktop.org/archives/dri-devel/2020-February/257183.html
> >> Signed-off-by: Wambui Karuga <wambui.karugax@xxxxxxxxx>
> >> Acked-by: Thomas Zimmermann <tzimmermann@xxxxxxx>
> >> ---
> >>  drivers/gpu/drm/drm_gem_vram_helper.c | 10 ++++------
> >>  1 file changed, 4 insertions(+), 6 deletions(-)
> >>
> >> diff --git a/drivers/gpu/drm/drm_gem_vram_helper.c b/drivers/gpu/drm/drm_gem_vram_helper.c
> >> index 92a11bb42365..c8bcc8609650 100644
> >> --- a/drivers/gpu/drm/drm_gem_vram_helper.c
> >> +++ b/drivers/gpu/drm/drm_gem_vram_helper.c
> >> @@ -1048,14 +1048,12 @@ static const struct drm_info_list drm_vram_mm_debugfs_list[] = {
> >>   */
> >>  int drm_vram_mm_debugfs_init(struct drm_minor *minor)
> >>  {
> >> -    int ret = 0;
> >> -
> >>  #if defined(CONFIG_DEBUG_FS)
> >
> > Just noticed that this #if here is not needed, we already have a dummy
> > function for that case. Care to write a quick patch to remove it? On top
> > of this patch series here ofc, I'm in the processing of merging the entire
> > pile.
> >
> > Thanks, Daniel
> Hi Daniel,
> Without this check here, and compiling without CONFIG_DEBUG_FS, this
> function is run and the drm_debugfs_create_files() does not have access to
> the parameters also protected by an #if above this function. So the change
> throws an error for me. Is that correct?

Hm right. Other drivers don't #ifdef out their debugfs file functions
... kinda a bit disappointing that we can't do this in the neatest way
possible.

Greg, has anyone ever suggested to convert the debugfs_create_file
function (and similar things) to macros that don't use any of the
arguments, and then also annotating all the static functions/tables as
__maybe_unused and let the compiler garbage collect everything?
Instead of explicit #ifdef in all the drivers ...
-Daniel

>
> Thanks,
> wambui karuga
>
> >> -    ret = drm_debugfs_create_files(drm_vram_mm_debugfs_list,
> >> -                                   ARRAY_SIZE(drm_vram_mm_debugfs_list),
> >> -                                   minor->debugfs_root, minor);
> >> +    drm_debugfs_create_files(drm_vram_mm_debugfs_list,
> >> +                             ARRAY_SIZE(drm_vram_mm_debugfs_list),
> >> +                             minor->debugfs_root, minor);
> >>  #endif
> >> -    return ret;
> >> +    return 0;
> >>  }
> >>  EXPORT_SYMBOL(drm_vram_mm_debugfs_init);
> >>
> >> --
> >> 2.25.1
> >>
> >
> > --
> > Daniel Vetter
> > Software Engineer, Intel Corporation
> > http://blog.ffwll.ch
> >



-- 
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch