linux-kernel - Re: [PATCH] drm/panthor: fix building without CONFIG_DEBUG

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Message-ID: <20250424134105.087ec2f8@collabora.com>
Date: Thu, 24 Apr 2025 13:41:05 +0200
From: Boris Brezillon <boris.brezillon@...labora.com>
To: Arnd Bergmann <arnd@...nel.org>
Cc: Steven Price <steven.price@....com>, Liviu Dudau <liviu.dudau@....com>,
 Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>, Maxime Ripard
 <mripard@...nel.org>, Thomas Zimmermann <tzimmermann@...e.de>, David Airlie
 <airlied@...il.com>, Simona Vetter <simona@...ll.ch>, Adrián Larumbe <adrian.larumbe@...labora.com>, Arnd Bergmann
 <arnd@...db.de>, Dmitry Osipenko <dmitry.osipenko@...labora.com>, Florent
 Tomasin <florent.tomasin@....com>, dri-devel@...ts.freedesktop.org,
 linux-kernel@...r.kernel.org
Subject: Re: [PATCH] drm/panthor: fix building without CONFIG_DEBUG_FS

On Thu, 24 Apr 2025 13:25:47 +0200
Arnd Bergmann <arnd@...nel.org> wrote:

> From: Arnd Bergmann <arnd@...db.de>
> 
> When debugfs is disabled, including panthor_gem.h causes warnings
> about a non-static global function defined in a header:
> 
> In file included from drivers/gpu/drm/panthor/panthor_drv.c:30:
> drivers/gpu/drm/panthor/panthor_gem.h:222:6: error: no previous prototype for 'panthor_gem_debugfs_set_usage_flags' [-Werror=missing-prototypes]
>   222 | void panthor_gem_debugfs_set_usage_flags(struct panthor_gem_object *bo, u32 usage_flags) {};
> 
> This could be changed to a static inline function, but as the normal
> one is also static inline, just move the #ifdef check in there.
> The #ifdef is still needed to avoid accessing a struct member that
> does not exist without debugfs.
> 
> Fixes: a3707f53eb3f ("drm/panthor: show device-wide list of DRM GEM objects over DebugFS")
> Signed-off-by: Arnd Bergmann <arnd@...db.de>
> ---
>  drivers/gpu/drm/panthor/panthor_gem.h | 7 ++-----
>  1 file changed, 2 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/gpu/drm/panthor/panthor_gem.h b/drivers/gpu/drm/panthor/panthor_gem.h
> index 4641994ddd7f..693842e10dee 100644
> --- a/drivers/gpu/drm/panthor/panthor_gem.h
> +++ b/drivers/gpu/drm/panthor/panthor_gem.h
> @@ -209,17 +209,14 @@ panthor_kernel_bo_create(struct panthor_device *ptdev, struct panthor_vm *vm,
>  
>  void panthor_kernel_bo_destroy(struct panthor_kernel_bo *bo);
>  
> -#ifdef CONFIG_DEBUG_FS
>  void panthor_gem_debugfs_print_bos(struct panthor_device *pfdev,
>  				   struct seq_file *m);
>  static inline void
>  panthor_gem_debugfs_set_usage_flags(struct panthor_gem_object *bo, u32 usage_flags)
>  {
> +#ifdef CONFIG_DEBUG_FS
>  	bo->debugfs.flags = usage_flags | PANTHOR_DEBUGFS_GEM_USAGE_FLAG_INITIALIZED;
> -}
> -
> -#else
> -void panthor_gem_debugfs_set_usage_flags(struct panthor_gem_object *bo, u32 usage_flags) {};
>  #endif
> +}
>  

Oops. I actually don't see a good reason to expose this function, so
could we go for something like that instead?

diff --git a/drivers/gpu/drm/panthor/panthor_gem.c b/drivers/gpu/drm/panthor/panthor_gem.c
index 2dcf308094b2..962c2dc075db 100644
--- a/drivers/gpu/drm/panthor/panthor_gem.c
+++ b/drivers/gpu/drm/panthor/panthor_gem.c
@@ -42,11 +42,20 @@ static void panthor_gem_debugfs_bo_rm(struct panthor_gem_object *bo)
        mutex_unlock(&ptdev->gems.lock);
 }
 
+static void panthor_gem_debugfs_set_usage_flags(struct panthor_gem_object *bo,
+                                               u32 usage_flags)
+{
+       bo->debugfs.flags = usage_flags | PANTHOR_DEBUGFS_GEM_USAGE_FLAG_INITIALIZED;
+}
 #else
 static void panthor_gem_debugfs_bo_add(struct panthor_device *ptdev,
                                       struct panthor_gem_object *bo)
 {}
 static void panthor_gem_debugfs_bo_rm(struct panthor_gem_object *bo) {}
+static void panthor_gem_debugfs_set_usage_flags(struct panthor_gem_object *bo,
+                                               u32 usage_flags)
+{
+}
 #endif
 
 static void panthor_gem_free_object(struct drm_gem_object *obj)
diff --git a/drivers/gpu/drm/panthor/panthor_gem.h b/drivers/gpu/drm/panthor/panthor_gem.h
index 4641994ddd7f..4dd732dcd59f 100644
--- a/drivers/gpu/drm/panthor/panthor_gem.h
+++ b/drivers/gpu/drm/panthor/panthor_gem.h
@@ -212,14 +212,6 @@ void panthor_kernel_bo_destroy(struct panthor_kernel_bo *bo);
 #ifdef CONFIG_DEBUG_FS
 void panthor_gem_debugfs_print_bos(struct panthor_device *pfdev,
                                   struct seq_file *m);
-static inline void
-panthor_gem_debugfs_set_usage_flags(struct panthor_gem_object *bo, u32 usage_flags)
-{
-       bo->debugfs.flags = usage_flags | PANTHOR_DEBUGFS_GEM_USAGE_FLAG_INITIALIZED;
-}
-
-#else
-void panthor_gem_debugfs_set_usage_flags(struct panthor_gem_object *bo, u32 usage_flags) {};
 #endif
 
 #endif /* __PANTHOR_GEM_H__ */