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

[Chris Wilson]

Quoting Daniel Vetter (2017-08-15 11:49:51)
> On Tue, Aug 15, 2017 at 10:42 AM, Tina Zhang <tina.zhang at intel.com> wrote:
> > Prime objects have no backing filp to GEM mmap pages from. So, for Prime
> > objects, such operation is not permitted.
> 
> EPERM is when you don't have enough permissions, but it's possible
> (e.g. a feature requiring root, or drm master). -EINVAL is if
> something is invalid, and not even root can change that. So from a
> consistency pov, EINVAL is the right error code here I think.

Consistency is that we wanted the same error code for all objects where
you did not have the ability to change the underlying storage.

The question is that an access issue or a permission issue. But at the
very least, mmap_ioctl is the odd one out. Which the changelog did not
explain and being sent out of context does not help.
-Chris