Re: [PATCH] drm/i915: Register debugfs interface last

["Ville Syrjälä" <ville.syrjala@linux.intel.com>]

On Thu, May 26, 2016 at 02:17:27PM +0100, Chris Wilson wrote:
> Currently debugfs files are created before the driver is even loads.
> This gives the opportunity for userspace to open that interface and poke
> around before the backing data structures are initialised - with the
> possibility of oopsing or worse.
> 
> Move the creation of the debugfs files to our registration phase, where
> we announce our presence to the world when we are ready.
> 
> Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
> Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>

Makes sense to me. I never understood why these kinds of hooks existed
in the first place.

So the sequence changes from

drm_dev_register()
 -> drm_minor_register()
   -> drm_debugfs_init()
     -> i915_debugfs_init()
 -> i915_driver_load()

to something like

drm_dev_register()
 -> drm_minor_register()
   -> drm_debugfs_init()
 -> i915_driver_load()
   -> i915_debugfs_register()

Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>

> ---
>  drivers/gpu/drm/i915/i915_debugfs.c | 6 ++++--
>  drivers/gpu/drm/i915/i915_dma.c     | 2 ++
>  drivers/gpu/drm/i915/i915_drv.c     | 4 ----
>  drivers/gpu/drm/i915/i915_drv.h     | 6 ++++--
>  4 files changed, 10 insertions(+), 8 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/i915_debugfs.c b/drivers/gpu/drm/i915/i915_debugfs.c
> index 615cef736356..4a3546f114c6 100644
> --- a/drivers/gpu/drm/i915/i915_debugfs.c
> +++ b/drivers/gpu/drm/i915/i915_debugfs.c
> @@ -5498,8 +5498,9 @@ void intel_display_crc_init(struct drm_device *dev)
>  	}
>  }
>  
> -int i915_debugfs_init(struct drm_minor *minor)
> +int i915_debugfs_register(struct drm_i915_private *dev_priv)
>  {
> +	struct drm_minor *minor = dev_priv->dev->primary;
>  	int ret, i;
>  
>  	ret = i915_forcewake_create(minor->debugfs_root, minor);
> @@ -5525,8 +5526,9 @@ int i915_debugfs_init(struct drm_minor *minor)
>  					minor->debugfs_root, minor);
>  }
>  
> -void i915_debugfs_cleanup(struct drm_minor *minor)
> +void i915_debugfs_unregister(struct drm_i915_private *dev_priv)
>  {
> +	struct drm_minor *minor = dev_priv->dev->primary;
>  	int i;
>  
>  	drm_debugfs_remove_files(i915_debugfs_list,
> diff --git a/drivers/gpu/drm/i915/i915_dma.c b/drivers/gpu/drm/i915/i915_dma.c
> index 07edaed9d5a2..af0a6ce6f0b9 100644
> --- a/drivers/gpu/drm/i915/i915_dma.c
> +++ b/drivers/gpu/drm/i915/i915_dma.c
> @@ -1372,6 +1372,7 @@ static void i915_driver_register(struct drm_i915_private *dev_priv)
>  	if (intel_vgpu_active(dev_priv))
>  		I915_WRITE(vgtif_reg(display_ready), VGT_DRV_DISPLAY_READY);
>  
> +	i915_debugfs_register(dev_priv);
>  	i915_setup_sysfs(dev);
>  
>  	if (INTEL_INFO(dev_priv)->num_pipes) {
> @@ -1397,6 +1398,7 @@ static void i915_driver_unregister(struct drm_i915_private *dev_priv)
>  	acpi_video_unregister();
>  	intel_opregion_unregister(dev_priv);
>  	i915_teardown_sysfs(dev_priv->dev);
> +	i915_debugfs_unregister(dev_priv);
>  	i915_gem_shrinker_cleanup(dev_priv);
>  }
>  
> diff --git a/drivers/gpu/drm/i915/i915_drv.c b/drivers/gpu/drm/i915/i915_drv.c
> index 943d7b222fd4..fa9e16b2247c 100644
> --- a/drivers/gpu/drm/i915/i915_drv.c
> +++ b/drivers/gpu/drm/i915/i915_drv.c
> @@ -1761,10 +1761,6 @@ static struct drm_driver driver = {
>  	.postclose = i915_driver_postclose,
>  	.set_busid = drm_pci_set_busid,
>  
> -#if defined(CONFIG_DEBUG_FS)
> -	.debugfs_init = i915_debugfs_init,
> -	.debugfs_cleanup = i915_debugfs_cleanup,
> -#endif
>  	.gem_free_object = i915_gem_free_object,
>  	.gem_vm_ops = &i915_gem_vm_ops,
>  
> diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
> index b9d9a4205992..8f2994ef4386 100644
> --- a/drivers/gpu/drm/i915/i915_drv.h
> +++ b/drivers/gpu/drm/i915/i915_drv.h
> @@ -3543,12 +3543,14 @@ int i915_verify_lists(struct drm_device *dev);
>  #endif
>  
>  /* i915_debugfs.c */
> -int i915_debugfs_init(struct drm_minor *minor);
> -void i915_debugfs_cleanup(struct drm_minor *minor);
>  #ifdef CONFIG_DEBUG_FS
> +int i915_debugfs_register(struct drm_i915_private *dev_priv);
> +void i915_debugfs_unregister(struct drm_i915_private *dev_priv);
>  int i915_debugfs_connector_add(struct drm_connector *connector);
>  void intel_display_crc_init(struct drm_device *dev);
>  #else
> +static inline int i915_debugfs_register(struct drm_i915_private *) {return 0;}
> +static inline void i915_debugfs_unregister(struct drm_i915_private *) {}
>  static inline int i915_debugfs_connector_add(struct drm_connector *connector)
>  { return 0; }
>  static inline void intel_display_crc_init(struct drm_device *dev) {}
> -- 
> 2.8.1

-- 
Ville Syrjälä
Intel OTC
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