linux-kernel - Re: [PATCH 1/2] powerpc: drop dependency on <asm/machdep.h> in archrandom.h

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Message-ID: <87edy8bbtp.fsf@mpe.ellerman.id.au>
Date:   Tue, 26 Jul 2022 16:57:38 +1000
From:   Michael Ellerman <mpe@...erman.id.au>
To:     Yury Norov <yury.norov@...il.com>,
        Andy Shevchenko <andy.shevchenko@...il.com>
Cc:     Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Rasmus Villemoes <linux@...musvillemoes.dk>,
        "open list:LINUX FOR POWERPC PA SEMI PWRFICIENT" 
        <linuxppc-dev@...ts.ozlabs.org>,
        Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Paul Mackerras <paulus@...ba.org>,
        Stephen Rothwell <sfr@...b.auug.org.au>,
        "Jason A. Donenfeld" <Jason@...c4.com>
Subject: Re: [PATCH 1/2] powerpc: drop dependency on <asm/machdep.h> in
 archrandom.h

Yury Norov <yury.norov@...il.com> writes:
> On Mon, Jul 25, 2022 at 09:28:12AM +0200, Andy Shevchenko wrote:
>> On Sun, Jul 24, 2022 at 12:19 AM Yury Norov <yury.norov@...il.com> wrote:
>> >
>> > archrandom.h includes <asm/machdep.h> to refer ppc_md. This causes
>> > circular header dependency, if generic nodemask.h  includes random.h:
>> >
>> > In file included from include/linux/cred.h:16,
>> >                  from include/linux/seq_file.h:13,
>> >                  from arch/powerpc/include/asm/machdep.h:6,
>> >                  from arch/powerpc/include/asm/archrandom.h:5,
>> >                  from include/linux/random.h:109,
>> >                  from include/linux/nodemask.h:97,
>> >                  from include/linux/list_lru.h:12,
>> >                  from include/linux/fs.h:13,
>> >                  from include/linux/compat.h:17,
>> >                  from arch/powerpc/kernel/asm-offsets.c:12:
>> > include/linux/sched.h:1203:9: error: unknown type name 'nodemask_t'
>> >  1203 |         nodemask_t                      mems_allowed;
>> >       |         ^~~~~~~~~~
>> >
>> > Fix it by removing <asm/machdep.h> dependency from archrandom.h
>> 
>> ...
>> 
>> >  EXPORT_SYMBOL_GPL(pm_power_off);
>> 
>> ^^^ (Note this and read below)
>> 
>> ...
>> 
>> > +EXPORT_SYMBOL(arch_get_random_seed_long);
>> 
>> It can't be like this. Brief browsing of the callees shows that.
>
> Is my understanding correct that you're suggesting to make it GPL?
>
> ppc_md is exported with EXPORT_SYMBOL(), and the function is in header,
> so it's available for non-GPL code now. I don't want to change it.

That's true, your change maintains the status quo.

But I think we actually don't need it exported to modules, I think it's
a private detail of the RNG <-> architecture interface, not something
that modules should be calling.

So I think it's OK to drop the EXPORT_SYMBOL, either in this patch or a
subsequent one if you don't want to rebase.

cheers