[PATCH v2 2/3] drm: Use a const drm_driver for legacy PCI devices

[Daniel Vetter]

On Tue, Dec 15, 2020 at 10:31:25PM +0200, Laurent Pinchart wrote:
> Now that the legacy PCI support code doesn't need to write to the
> drm_driver structure, it can be treated as const through the whole DRM
> core, unconditionally. This allows declaring the structure as const in
> all drivers, removing one possible attack vector.
> 
> Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas at ideasonboard.com>

I didn't inquire the compiler whether you got all the combos right, but
looks complete.

Reviewed-by: Daniel Vetter <daniel.vetter at ffwll.ch>

> ---
>  drivers/gpu/drm/drm_drv.c |  4 ----
>  drivers/gpu/drm/drm_pci.c |  8 +++++---
>  include/drm/drm_device.h  |  4 ----
>  include/drm/drm_legacy.h  | 10 ++++++----
>  4 files changed, 11 insertions(+), 15 deletions(-)
> 
> diff --git a/drivers/gpu/drm/drm_drv.c b/drivers/gpu/drm/drm_drv.c
> index 734303802bc3..3f57e880685e 100644
> --- a/drivers/gpu/drm/drm_drv.c
> +++ b/drivers/gpu/drm/drm_drv.c
> @@ -589,11 +589,7 @@ static int drm_dev_init(struct drm_device *dev,
>  
>  	kref_init(&dev->ref);
>  	dev->dev = get_device(parent);
> -#ifdef CONFIG_DRM_LEGACY
> -	dev->driver = (struct drm_driver *)driver;
> -#else
>  	dev->driver = driver;
> -#endif
>  
>  	INIT_LIST_HEAD(&dev->managed.resources);
>  	spin_lock_init(&dev->managed.lock);
> diff --git a/drivers/gpu/drm/drm_pci.c b/drivers/gpu/drm/drm_pci.c
> index dfb138aaccba..5370e6b492fd 100644
> --- a/drivers/gpu/drm/drm_pci.c
> +++ b/drivers/gpu/drm/drm_pci.c
> @@ -201,7 +201,7 @@ static void drm_pci_agp_init(struct drm_device *dev)
>  
>  static int drm_get_pci_dev(struct pci_dev *pdev,
>  			   const struct pci_device_id *ent,
> -			   struct drm_driver *driver)
> +			   const struct drm_driver *driver)
>  {
>  	struct drm_device *dev;
>  	int ret;
> @@ -255,7 +255,8 @@ static int drm_get_pci_dev(struct pci_dev *pdev,
>   *
>   * Return: 0 on success or a negative error code on failure.
>   */
> -int drm_legacy_pci_init(struct drm_driver *driver, struct pci_driver *pdriver)
> +int drm_legacy_pci_init(const struct drm_driver *driver,
> +			struct pci_driver *pdriver)
>  {
>  	struct pci_dev *pdev = NULL;
>  	const struct pci_device_id *pid;
> @@ -300,7 +301,8 @@ EXPORT_SYMBOL(drm_legacy_pci_init);
>   * Unregister a DRM driver shadow-attached through drm_legacy_pci_init(). This
>   * is deprecated and only used by dri1 drivers.
>   */
> -void drm_legacy_pci_exit(struct drm_driver *driver, struct pci_driver *pdriver)
> +void drm_legacy_pci_exit(const struct drm_driver *driver,
> +			 struct pci_driver *pdriver)
>  {
>  	struct drm_device *dev, *tmp;
>  
> diff --git a/include/drm/drm_device.h b/include/drm/drm_device.h
> index bd5abe7cd48f..939904ae88fc 100644
> --- a/include/drm/drm_device.h
> +++ b/include/drm/drm_device.h
> @@ -76,11 +76,7 @@ struct drm_device {
>  	} managed;
>  
>  	/** @driver: DRM driver managing the device */
> -#ifdef CONFIG_DRM_LEGACY
> -	struct drm_driver *driver;
> -#else
>  	const struct drm_driver *driver;
> -#endif
>  
>  	/**
>  	 * @dev_private:
> diff --git a/include/drm/drm_legacy.h b/include/drm/drm_legacy.h
> index 852d7451eeb1..8ed04e9be997 100644
> --- a/include/drm/drm_legacy.h
> +++ b/include/drm/drm_legacy.h
> @@ -198,8 +198,10 @@ struct drm_dma_handle *drm_pci_alloc(struct drm_device *dev, size_t size,
>  				     size_t align);
>  void drm_pci_free(struct drm_device *dev, struct drm_dma_handle *dmah);
>  
> -int drm_legacy_pci_init(struct drm_driver *driver, struct pci_driver *pdriver);
> -void drm_legacy_pci_exit(struct drm_driver *driver, struct pci_driver *pdriver);
> +int drm_legacy_pci_init(const struct drm_driver *driver,
> +			struct pci_driver *pdriver);
> +void drm_legacy_pci_exit(const struct drm_driver *driver,
> +			 struct pci_driver *pdriver);
>  
>  #else
>  
> @@ -214,13 +216,13 @@ static inline void drm_pci_free(struct drm_device *dev,
>  {
>  }
>  
> -static inline int drm_legacy_pci_init(struct drm_driver *driver,
> +static inline int drm_legacy_pci_init(const struct drm_driver *driver,
>  				      struct pci_driver *pdriver)
>  {
>  	return -EINVAL;
>  }
>  
> -static inline void drm_legacy_pci_exit(struct drm_driver *driver,
> +static inline void drm_legacy_pci_exit(const struct drm_driver *driver,
>  				       struct pci_driver *pdriver)
>  {
>  }
> -- 
> Regards,
> 
> Laurent Pinchart
> 
> _______________________________________________
> dri-devel mailing list
> dri-devel at lists.freedesktop.org
> https://lists.freedesktop.org/mailman/listinfo/dri-devel

-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch