[Intel-gfx] [PATCH V3 5/6] drm/i915: Update the restrict check to filter out wrong Ring ID passed by user-space

[Imre Deak]

On Wed, 2014-04-16 at 10:41 +0800, Zhao Yakui wrote:
> One extra ring is added in the kernel driver but it is transparent to the
> user-space application/middleware. In such case the number of the rings
> in kernel driver is bigger than that exported to the user-space. So
> it needs to filter out the wrong Ring ID passed by user-space.
> 
> Signed-off-by: Zhao Yakui <yakui.zhao at intel.com>
> ---
>  drivers/gpu/drm/i915/i915_gem_execbuffer.c |    2 +-
>  drivers/gpu/drm/i915/intel_ringbuffer.h    |    1 +
>  2 files changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/i915/i915_gem_execbuffer.c b/drivers/gpu/drm/i915/i915_gem_execbuffer.c
> index 3491402..341ec68 100644
> --- a/drivers/gpu/drm/i915/i915_gem_execbuffer.c
> +++ b/drivers/gpu/drm/i915/i915_gem_execbuffer.c
> @@ -1035,7 +1035,7 @@ i915_gem_do_execbuffer(struct drm_device *dev, void *data,
>  	if (args->flags & I915_EXEC_IS_PINNED)
>  		flags |= I915_DISPATCH_PINNED;
>  
> -	if ((args->flags & I915_EXEC_RING_MASK) > I915_NUM_RINGS) {
> +	if ((args->flags & I915_EXEC_RING_MASK) > LAST_USER_RING) {
>  		DRM_DEBUG("execbuf with unknown ring: %d\n",
>  			  (int)(args->flags & I915_EXEC_RING_MASK));
>  		return -EINVAL;
> diff --git a/drivers/gpu/drm/i915/intel_ringbuffer.h b/drivers/gpu/drm/i915/intel_ringbuffer.h
> index 8ca4285..59f4cdd 100644
> --- a/drivers/gpu/drm/i915/intel_ringbuffer.h
> +++ b/drivers/gpu/drm/i915/intel_ringbuffer.h
> @@ -64,6 +64,7 @@ struct  intel_ring_buffer {
>  		VCS2,
>  	} id;
>  #define I915_NUM_RINGS 5
> +#define LAST_USER_RING (VECS + 1)

Defining this in the enum is cleaner IMO. Also this patch should ideally
be applied before 2/6 for bisectability. In any case:

Reviewed-by: Imre Deak <imre.deak at intel.com> 

>  	u32		mmio_base;
>  	void		__iomem *virtual_start;
>  	struct		drm_device *dev;

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