Re: [PATCH v2 3/7] drm/i915: use gtt_get_size() instead of open coding it

[Imre Deak <imre.deak@intel.com>]

On Mon, 2013-01-14 at 17:14 +0100, Daniel Vetter wrote:
> On Mon, Jan 07, 2013 at 09:47:35PM +0200, Imre Deak wrote:
> > Signed-off-by: Imre Deak <imre.deak@intel.com>
> 
> I've applied patches 1-3 from this series, since they look like nice
> cleanups. Like discussed on irc, I'm not sold on the later ones since I
> don't see a clear upside ...

I understood there are other ways to corrupt buffers than what this
patch would fix, so I agree that it's not a security fix. I would still
argue that eliminating this particular way makes things more robust
against obscure application bugs.

--Imre

> -Daniel
> > ---
> >  drivers/gpu/drm/i915/i915_drv.h        |    2 ++
> >  drivers/gpu/drm/i915/i915_gem.c        |    2 +-
> >  drivers/gpu/drm/i915/i915_gem_tiling.c |   13 +------------
> >  3 files changed, 4 insertions(+), 13 deletions(-)
> > 
> > diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
> > index 154323a..3b73615 100644
> > --- a/drivers/gpu/drm/i915/i915_drv.h
> > +++ b/drivers/gpu/drm/i915/i915_drv.h
> > @@ -1566,6 +1566,8 @@ void i915_gem_free_all_phys_object(struct drm_device *dev);
> >  void i915_gem_release(struct drm_device *dev, struct drm_file *file);
> >  
> >  uint32_t
> > +i915_gem_get_gtt_size(struct drm_device *dev, uint32_t size, int tiling_mode);
> > +uint32_t
> >  i915_gem_get_gtt_alignment(struct drm_device *dev, uint32_t size,
> >  			    int tiling_mode, bool fenced);
> >  
> > diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
> > index 5e00dc1..aa6653d 100644
> > --- a/drivers/gpu/drm/i915/i915_gem.c
> > +++ b/drivers/gpu/drm/i915/i915_gem.c
> > @@ -1435,7 +1435,7 @@ i915_gem_release_mmap(struct drm_i915_gem_object *obj)
> >  	obj->fault_mappable = false;
> >  }
> >  
> > -static uint32_t
> > +uint32_t
> >  i915_gem_get_gtt_size(struct drm_device *dev, uint32_t size, int tiling_mode)
> >  {
> >  	uint32_t gtt_size;
> > diff --git a/drivers/gpu/drm/i915/i915_gem_tiling.c b/drivers/gpu/drm/i915/i915_gem_tiling.c
> > index cb71ded..e76f0d8 100644
> > --- a/drivers/gpu/drm/i915/i915_gem_tiling.c
> > +++ b/drivers/gpu/drm/i915/i915_gem_tiling.c
> > @@ -272,18 +272,7 @@ i915_gem_object_fence_ok(struct drm_i915_gem_object *obj, int tiling_mode)
> >  			return false;
> >  	}
> >  
> > -	/*
> > -	 * Previous chips need to be aligned to the size of the smallest
> > -	 * fence register that can contain the object.
> > -	 */
> > -	if (INTEL_INFO(obj->base.dev)->gen == 3)
> > -		size = 1024*1024;
> > -	else
> > -		size = 512*1024;
> > -
> > -	while (size < obj->base.size)
> > -		size <<= 1;
> > -
> > +	size = i915_gem_get_gtt_size(obj->base.dev, obj->base.size, tiling_mode);
> >  	if (obj->gtt_space->size != size)
> >  		return false;
> >  
> > -- 
> > 1.7.10.4
> > 
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>