Re: [RFC 6/9] drm/i915: Add sync framework support to execbuff IOCTL

Chris Wilson
2016-01-14T12:07:58Z

On Thu, Jan 14, 2016 at 11:47:17AM +0000, John Harrison wrote:
> On 13/01/2016 18:43, Chris Wilson wrote:
> >Use the upper s32 for the output, so again you are not overwriting user
> >state without good reason.
> >
> Makes sense. Will do.

It would also be useful (for nefarious reasons) to only copy back the
rsvd2 field, i.e. keep it as DRM_IOW(EXECBUFFER2) and do the small
fixed-sized copy_to_user of rsvd2 as required. That means we can avoid
the copy mostly, and treat args as a private copy of the user
parameters, i.e. space we can scribble over with impunity.
-Chris

--
Chris Wilson, Intel Open Source Technology Centre