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

[Laurent Pinchart]

On Wed, Dec 16, 2020 at 03:29:00PM +0100, Daniel Vetter wrote:
> 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.

I've compile-tested with CONFIG_DRM_LEGACY enabled and disabled, and
CONFIG_PCI enabled, so we should be good.

> 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