Subject: Re: [PATCH 2/2] powerpc: Update of_remove_property() call sites to remove null checking

From: Michael Ellerman <[email-masked]>
Date: Mon, 09 May 2016 19:41:55 +1000

On Fri, 2016-05-06 at 13:00 +1000, Suraj Jitindar Singh wrote:
> On 05/05/16 16:50, Michael Ellerman wrote:
> > On Tue, 2016-05-03 at 15:32 -0700, Tyrel Datwyler wrote:
> > > On 04/27/2016 10:34 PM, Suraj Jitindar Singh wrote:
> > > > diff --git a/arch/powerpc/platforms/pseries/mobility.c b/arch/powerpc/platforms/pseries/mobility.c
> > > > index ceb18d3..a560a98 100644
> > > > --- a/arch/powerpc/platforms/pseries/mobility.c
> > > > +++ b/arch/powerpc/platforms/pseries/mobility.c
> > > > @@ -191,8 +191,8 @@ static int update_dt_node(__be32 phandle, s32 scope)
> > > >  				break;
> > > >  
> > > >  			case 0x80000000:
> > > > -				prop = of_find_property(dn, prop_name, NULL);
> > > > -				of_remove_property(dn, prop);
> > > > +				of_remove_property(dn, of_find_property(dn,
> > > > +							prop_name, NULL));
> > > >  				prop = NULL;
> > > >  				break;
> > > > 
> > > You haven't removed a NULL check here, as suggested by the changelog,
> > > but instead made a cosmetic change to the code that still leaves behind
> > > a now unnecessary "prop = NULL;" to bit rot.

> > Yeah I think you're right. Though it's not very clear how prop is used in that
> > function.
>
> I didn't delete the prop = NULL; initially as I didn't fully understand
> how it was used in the rest of the function and the effect of deleting
> it.

Yeah, it's pretty convoluted. I don't think you can actually prove it's safe to
remove the prop = NULL for arbitrary inputs.

cheers