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Date:   Sat, 23 Jun 2018 14:47:16 -0500
From:   Segher Boessenkool <segher@kernel.crashing.org>
To:     christophe leroy <christophe.leroy@c-s.fr>
Cc:     Mathieu Malaterre <malat@debian.org>,
        Michael Ellerman <mpe@ellerman.id.au>,
        Yisheng Xie <xieyisheng1@huawei.com>,
        Vaibhav Jain <vaibhav@linux.vnet.ibm.com>,
        Nicholas Piggin <npiggin@gmail.com>,
        linux-kernel@vger.kernel.org, Paul Mackerras <paulus@samba.org>,
        Breno Leitao <leitao@debian.org>, linuxppc-dev@lists.ozlabs.org
Subject: Re: [PATCH] powerpc/xmon: =?utf-8?Q?avoid_?=
        =?utf-8?Q?warnings_about_variables_that_might_be_clobbered_by_=E2=80=98lo?=
        =?utf-8?B?bmdqbXDigJk=?=
Message-ID: <20180623194716.GY16221@gate.crashing.org>
References: <20180622192718.24242-1-malat@debian.org> <b41b244e-78b8-c85f-9122-427ad04cccf8@c-s.fr>
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On Sat, Jun 23, 2018 at 06:59:27PM +0200, christophe leroy wrote:
> 
> 
> Le 22/06/2018 à 21:27, Mathieu Malaterre a écrit :
> >Move initialization of variables after data definitions. This silence
> >warnings treated as error with W=1:
> >
> >   arch/powerpc/xmon/xmon.c:3389:14: error: variable ‘name’ might be 
> >   clobbered by ‘longjmp’ or ‘vfork’ [-Werror=clobbered]
> >   arch/powerpc/xmon/xmon.c:3100:22: error: variable ‘tsk’ might be 
> >   clobbered by ‘longjmp’ or ‘vfork’ [-Werror=clobbered]
> 
> Is that an invalid warning ?

No, both are correct warnings.  GCC can not see which functions it only
has a declaration of can call longjmp.

> Otherwise, I'd expect one to fix the warning, not just cheat on GCC.

Yes, the patch seems to change the code in such a way that some versions
of GCC will no longer warn.  Which does not make to code any more correct.

Either restructure the code, or make the var non-automatic, or make it
volatile.


Segher