Re: [PATCH v2 10/17] drm/vram-helper: make drm_vram_mm_debugfs_init() return 0
From: Wambui Karuga
Date: Thu Mar 19 2020 - 08:28:03 EST
On Thu, 19 Mar 2020, Daniel Vetter wrote:
On Thu, Mar 19, 2020 at 08:55:24AM +0100, Greg KH wrote:
On Wed, Mar 18, 2020 at 08:10:43PM +0100, Daniel Vetter wrote:
On Wed, Mar 18, 2020 at 5:58 PM Greg KH <gregkh@xxxxxxxxxxxxxxxxxxx> wrote:
On Wed, Mar 18, 2020 at 05:31:47PM +0100, Daniel Vetter wrote:
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 ...
No, no one has suggested that, having the functions be static inline
should make it all "just work" properly if debugfs is not enabled. The
variables will not be used, so the compiler should just optimize them
away properly.
No checks for CONFIG_DEBUG_FS should be needed anywhere in .c code.
So the trouble with this one is that the static inline functions for
the debugfs file are wrapped in a #if too, and hence if we drop the
#if around the function call stuff won't compile. Should we drop all
the #if in the .c file and assume the compiler will remove all the
dead code and dead functions?
Yes you should :)
there should not be any need for #if in a .c file for debugfs stuff.
Wambui, can you pls try that out? I.e. removing all the #if for
CONFIG_DEBUG_FS from that file.
Removing them works with CONFIG_DEBUG_FS enabled or disabled.
I can send a patch for that.
wambui karuga
-Daniel
--
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch