[PATCH] drm: Return error codes from struct drm_driver.gem_create_object

[Dan Carpenter]

On Mon, Dec 06, 2021 at 12:16:24PM +0100, Thomas Zimmermann wrote:
> Hi
> 
> Am 06.12.21 um 11:42 schrieb Dan Carpenter:
> > On Tue, Nov 30, 2021 at 10:52:55AM +0100, Thomas Zimmermann wrote:
> > > GEM helper libraries use struct drm_driver.gem_create_object to let
> > > drivers override GEM object allocation. On failure, the call returns
> > > NULL.
> > > 
> > > Change the semantics to make the calls return a pointer-encoded error.
> > > This aligns the callback with its callers. Fixes the ingenic driver,
> > > which already returns an error pointer.
> > > 
> > > Also update the callers to handle the involved types more strictly.
> > > 
> > > Signed-off-by: Thomas Zimmermann <tzimmermann at suse.de>
> > > ---
> > > There is an alternative patch at [1] that updates the value returned
> > > by ingenics' gem_create_object to NULL. Fixing the interface to return
> > > an errno code is more consistent with the rest of the GEM functions.
> > > 
> > > [1] https://lore.kernel.org/dri-devel/20211118111522.GD1147@kili/
> > 
> > My fix was already applied and backported to -stable etc...  Your
> > patch is not developed against a current tree so you broke it.
> 
> Do you have a specific link? I just checked the stable tree at [1] and there
> no trace of your patch.

It's in 5.15.6 and probably all the other supported -stable trees.

https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/tree/drivers/gpu/drm/vc4/vc4_bo.c?h=v5.15.6#n387

> 
> Patches for DRM should go through through DRM trees; drm-misc-fixes in this
> case. Exceptions should at least be announce on dri-devel. Neither is the
> case here.

Yeah.  That's a good question.  I don't know, because I just work
against linux-next...

regards,
dan carpenter