[kbuild-all] Re: [PATCH v2 2/2] drm: automatic legacy gamma support

[Dan Carpenter]

On Wed, Dec 16, 2020 at 09:06:50AM +0800, Philip Li wrote:
> On Mon, Dec 14, 2020 at 09:49:17PM +0300, Dan Carpenter wrote:
> > On Sat, Dec 12, 2020 at 04:54:45PM +0800, Philip Li wrote:
> > > On Fri, Dec 11, 2020 at 04:42:00PM +0200, Ville Syrjälä wrote:
> > > > On Fri, Dec 11, 2020 at 01:24:49PM +0200, Tomi Valkeinen wrote:
> > > > > On 10/12/2020 20:06, kernel test robot wrote:
> > > > > > Hi Tomi,
> > > > > > 
> > > > > > I love your patch! Perhaps something to improve:
> > > > > > 
> > > > > > [auto build test WARNING on drm-intel/for-linux-next]
> > > > > > [also build test WARNING on linus/master v5.10-rc7]
> > > > > > [cannot apply to drm-tip/drm-tip anholt/for-next next-20201210]
> > > > > > [If your patch is applied to the wrong git tree, kindly drop us a note.
> > > > > > And when submitting patch, we suggest to use '--base' as documented in
> > > > > > https://git-scm.com/docs/git-format-patch  ]
> > > > > > 
> > > > > > url:    https://github.com/0day-ci/linux/commits/Tomi-Valkeinen/drm-fix-and-cleanup-legacy-gamma-support/20201208-215917  
> > > > > > base:   git://anongit.freedesktop.org/drm-intel for-linux-next
> > > > > > config: i386-randconfig-m021-20201209 (attached as .config)
> > > > > > compiler: gcc-9 (Debian 9.3.0-15) 9.3.0
> > > > > > 
> > > > > > If you fix the issue, kindly add following tag as appropriate
> > > > > > Reported-by: kernel test robot <lkp at intel.com>
> > > > > > 
> > > > > > New smatch warnings:
> > > > > > drivers/gpu/drm/drm_color_mgmt.c:307 drm_crtc_legacy_gamma_set() error: potential null dereference 'blob'.  (drm_property_create_blob returns null)
> > > > > 
> > > > > I don't see how this could happen. There's no code path I see where drm_property_create_blob could
> > > > > return null...
> > > > 
> > > > IIRC we've received multiple similar nonsense reports from lkp, but
> > > > no explanation why it thinks it could ever be null. Hmm, maybe there
> > > > is a codepath somewhere that has a null check on the return value?
> > > hi Dan, can you help on this to share some idea?
> > > 
> > > The original report is at
> > > https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org/thread/F3MVBRGF2R4URBNLNY3GMTSDZUCBX6RF/  
> > 
> > Thanks, Philip.  I've pushed a fix for this.
> Thanks Dan for this, we will pack the new code to run in the robot.
> 
> > 
> > It didn't show up if you had the cross function DB built, so it's not
> > something I would see in my testing.
> Got it, do you recommend this "cross function DB" is necessary for us to
> setup or not a must?

It's not a must.  Smatch is supposed to work fine without it.

regards,
dan carpenter