linux-kernel - Re: checkpatch.pl bug? (was Re: [PATCH] random: Make CPU trust a boot parameter)

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Message-ID: <c07f1fd50d25077f62efbe586bfc40428959d175.camel@perches.com>
Date:   Mon, 27 Aug 2018 22:12:18 -0700
From:   Joe Perches <joe@...ches.com>
To:     Kees Cook <keescook@...omium.org>
Cc:     LKML <linux-kernel@...r.kernel.org>
Subject: Re: checkpatch.pl bug? (was Re: [PATCH] random: Make CPU trust a
 boot parameter)

On Mon, 2018-08-27 at 14:55 -0700, Kees Cook wrote:
> On Mon, Aug 27, 2018 at 2:51 PM, Kees Cook <keescook@...omium.org> wrote:
> > Instead of forcing a distro or other system builder to choose
> > at build time whether the CPU is trusted for CRNG seeding via
> > CONFIG_RANDOM_TRUST_CPU, provide a boot-time parameter for end users to
> > control the choice. The CONFIG will set the default state instead.
[]
> > diff --git a/drivers/char/random.c b/drivers/char/random.c
[]
> > @@ -779,6 +779,13 @@ static struct crng_state **crng_node_pool __read_mostly;
> > 
> >  static void invalidate_batched_entropy(void);
> > 
> > +static bool trust_cpu __ro_after_init = IS_ENABLED(CONFIG_RANDOM_TRUST_CPU);
> > +static int __init parse_trust_cpu(char *arg)
> > +{
> > +       return kstrtobool(arg, &trust_cpu);
> > +}
> > +early_param("random.trust_cpu", parse_trust_cpu);
> > +
> >  static void crng_initialize(struct crng_state *crng)
> >  {
> >         int             i;
> > @@ -799,12 +806,10 @@ static void crng_initialize(struct crng_state *crng)
> >                 }
> >                 crng->state[i] ^= rv;
> >         }
> > -#ifdef CONFIG_RANDOM_TRUST_CPU
> > -       if (arch_init) {
> > +       if (trust_cpu && arch_init) {
> 
> checkpatch.pl complains:
> 
> ERROR: space prohibited after that '&&' (ctx:WxW)
> #79: FILE: drivers/char/random.c:809:
> +       if (trust_cpu && arch_init) {
>                       ^
> 
> I can't figure out what is going on here. Using "||" doesn't trigger
> the issue; it seems related to the earlier "&trust_cpu" use in the
> patch, but I can't figure out what checkpatch was trying to do with
> this...

It's the __ro_after_init after the declaration of
static bool trust_cpu that confuses checkpatch.

I'll see what can be done for that.