[Intel-gfx] [PATCH] [v2] drm/i915: Check for get_pages instead of shmem (filp)

[Chris Wilson]

On Wed, Feb 10, 2016 at 07:42:23AM -0800, Ben Widawsky wrote:
> Do you guys get the CI mails? This version has regressions. v1 did not. I don't
> know what to trust.

I didn't even see v2 itself!
 
> On Tue, Feb 09, 2016 at 11:44:12AM -0800, Ben Widawsky wrote:
> > This behavior of checking for a shmem backed GEM object was introduced here:
> > commit 4c914c0c7c787b8f730128a8cdcca9c50b0784ab
> > Author: Brad Volkin <bradley.d.volkin at intel.com>
> > Date:   Tue Feb 18 10:15:45 2014 -0800
> > 
> >     drm/i915: Refactor shmem pread setup
> > 
> > It is possible for an object to not be a shmem backed GEM object (for example
> > userptr objects). An example of how we hit this failure can be found through
> > copy_batch() in the command parser because we allocate a userptr object for the
> > batch which contains privileged instructions. Userptr calls
> > drm_gem_private_object_init() which explicitly sets the filp to none.
> > 
> > NOTE: I manually retyped this from a test machine. So I haven't even compiled
> > this exact patch.
> > 
> > v2: Use same logic as from a2a4f916c2f (Kristian, Dave Gordon)
> > 
> > Cc: Chris Wilson <chris at chris-wilson.co.uk>
> > Cc: Kristian Høgsberg <krh at bitplanet.net>
> > Cc: Dave Gordon <david.s.gordon at intel.com>
> > Signed-off-by: Ben Widawsky <benjamin.widawsky at intel.com>
> > Tested-by: Jordan Justen <jordan.l.justen at intel.com> (v1)
> > Reviewed-by: Jordan Justen <jordan.l.justen at intel.com> (v1)

> > ---
> >  drivers/gpu/drm/i915/i915_gem.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> > 
> > diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
> > index e9b19bc..7fd79b0 100644
> > --- a/drivers/gpu/drm/i915/i915_gem.c
> > +++ b/drivers/gpu/drm/i915/i915_gem.c
> > @@ -489,7 +489,7 @@ int i915_gem_obj_prepare_shmem_read(struct drm_i915_gem_object *obj,
> >  
> >  	*needs_clflush = 0;
> >  
> > -	if (!obj->base.filp)
> > +	if (WARN_ON((obj->ops->flags & I915_GEM_OBJECT_HAS_STRUCT_PAGE) == 0))

Don't use WARN_ON, there is code (or will be) where we use
prepare_shmem_read/write to determine if we can use the shmem paths.

Also i915_gem_obj_prepare_shmem_write() requires the same treatment.

My apologies I had this patch but appear to have accidentally squashed
it whilst rebasing. Thanks!
-Chris

-- 
Chris Wilson, Intel Open Source Technology Centre