Re: [PATCH v2 4/5] powerpc: Fix duplicate const clang warning in user access code

Christophe LEROY [off-list ref] writes:

Le 19/09/2018 =C3=A0 09:45, Joel Stanley a =C3=A9crit=C2=A0:

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On Sat, 15 Sep 2018 at 03:27, Nick Desaulniers [off-list ref]=

 wrote:

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On Thu, Sep 13, 2018 at 9:07 PM Joel Stanley [off-list ref] wrote:

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From: Anton Blanchard <redacted>

This re-applies b91c1e3e7a6f which was reverted in f2ca80905929
d466f6c5cac1 f84ed59a612d (powerpc/sparse: Constify the address pointer
...").

We see a large number of duplicate const errors in the user access
code when building with llvm/clang:

   include/linux/pagemap.h:576:8: warning: duplicate 'const' declarati=

on specifier

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       [-Wduplicate-decl-specifier]
         ret =3D __get_user(c, uaddr);

The problem is we are doing const __typeof__(*(ptr)), which will hit t=

he

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warning if ptr is marked const.

Removing const does not seem to have any effect on GCC code generation.

I wouldn't expect it to for a local variable with such localized
usage.  I myself am quite liberal in applying `const` to everything,
so I will try to fix this in Clang as well, but this should silence
the warning for users of older versions of Clang and results in no
functional change.
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>

=20
Nick has written a clang patch that suppresses the warning in the same
way as GCC. Assuming it gets merged, as we depend on clang-8 we could
chose to not merge the kernel patch.
=20
https://reviews.llvm.org/D52248

Seems like Michael has merged this patch anyway.

I'll happily revert it though if someone tells me to.

cheers