linux-kernel - Re: [PATCH v2 3/3] sched/wait: avoid double initialization in ___wait

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Date:   Mon, 2 Mar 2020 19:39:54 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     Alexander Potapenko <glider@...gle.com>
Cc:     Todd Kjos <tkjos@...gle.com>,
        "open list:ANDROID DRIVERS" <devel@...verdev.osuosl.org>,
        Kees Cook <keescook@...omium.org>,
        Jann Horn <jannh@...gle.com>,
        Peter Zijlstra <peterz@...radead.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Arve Hjønnevåg <arve@...roid.com>,
        Ingo Molnar <mingo@...hat.com>,
        Dmitry Vyukov <dvyukov@...gle.com>
Subject: Re: [PATCH v2 3/3] sched/wait: avoid double initialization in
 ___wait_event()

On Mon, Mar 02, 2020 at 07:03:19PM +0100, Alexander Potapenko wrote:
> > >         case BINDER_SET_MAX_THREADS: {
> > > -               int max_threads;
> > > +               int max_threads __no_initialize;
> >
> > Is this really needed? A single integer in a rarely called ioctl()
> > being initialized twice doesn't warrant this optimization.
> 
> It really does not, and I didn't have this bit in v1.
> But if we don't want this diff to bit rot, we'd better have a
> Coccinelle script generating it.
> The script I added to the description of patch 2/3 introduced this
> annotation, and I thought keeping it is better than trying to teach
> the script about the size of the arguments.

Please fix the script, don't add stuff to the kernel that is not needed.

thanks,

greg k-h