Re: [PATCH] drm/i915: Return -EPERM when i915_gem_mmap_ioctl handling prime objects

From: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
To: Tina Zhang <tina.zhang@intel.com>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>,
	intel-gfx@lists.freedesktop.org,
	intel-gvt-dev@lists.freedesktop.org
Subject: Re: [PATCH] drm/i915: Return -EPERM when i915_gem_mmap_ioctl handling prime objects
Date: Tue, 15 Aug 2017 16:37:02 +0300	[thread overview]
Message-ID: <1502804222.4217.4.camel@linux.intel.com> (raw)
In-Reply-To: <1502786527-8958-1-git-send-email-tina.zhang@intel.com>

On Tue, 2017-08-15 at 16:42 +0800, Tina Zhang wrote:
> Prime objects have no backing filp to GEM mmap pages from. So, for Prime
> objects, such operation is not permitted.
> 
> v1:
> - Separate this patch from dma-buf patch set. (Joonas)
> 
> Signed-off-by: Tina Zhang <tina.zhang@intel.com>
> Cc: Chris Wilson <chris@chris-wilson.co.uk>
> Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
> 
> diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
> index 0628fb1..bb9d5ed 100644
> --- a/drivers/gpu/drm/i915/i915_gem.c
> +++ b/drivers/gpu/drm/i915/i915_gem.c
> @@ -1704,7 +1704,7 @@ i915_gem_mmap_ioctl(struct drm_device *dev, void *data,
>  	 */
>  	if (!obj->base.filp) {
>  		i915_gem_object_put(obj);
> -		return -EINVAL;
> +		return -EPERM;

+ Daniel (in case he wants to explain in more detail)

The existing usecases in the driver for -EPERM are all conditional to
not being privileged user or DRM master, so we should rather stick to
"-EINVAL" and augment with DRM_DEBUG_DRIVER in case the developer may
want to know read more about the -EINVAL.

Lets stick to that convention here and in the GVT dma-buf patches.

Regards, Joonas
-- 
Joonas Lahtinen
Open Source Technology Center
Intel Corporation
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