linux-kernel - Re: [PATCH 1/2] powerpc: mark more local variables as volatile

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Message-Id: <eeeef65a-fbf9-403f-8541-5169b06976d7@app.fastmail.com>
Date:   Wed, 09 Aug 2023 15:35:46 +0200
From:   "Arnd Bergmann" <arnd@...db.de>
To:     "Christophe Leroy" <christophe.leroy@...roup.eu>,
        "Arnd Bergmann" <arnd@...nel.org>,
        "Michael Ellerman" <mpe@...erman.id.au>
Cc:     "Nicholas Piggin" <npiggin@...il.com>,
        "Andrew Morton" <akpm@...ux-foundation.org>,
        "Jiri Slaby" <jirislaby@...nel.org>,
        "Maninder Singh" <maninder1.s@...sung.com>,
        "Hugh Dickins" <hughd@...gle.com>,
        "Gustavo A. R. Silva" <gustavoars@...nel.org>,
        "Nathan Lynch" <nathanl@...ux.ibm.com>,
        "linuxppc-dev@...ts.ozlabs.org" <linuxppc-dev@...ts.ozlabs.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 1/2] powerpc: mark more local variables as volatile

On Wed, Aug 9, 2023, at 15:17, Christophe Leroy wrote:
> Le 09/08/2023 à 15:10, Arnd Bergmann a écrit :
>> From: Arnd Bergmann <arnd@...db.de>
>> 
>> A while ago I created a2305e3de8193 ("powerpc: mark local variables
>> around longjmp as volatile") in order to allow building powerpc with
>> -Wextra enabled on gcc-11.
>
> Should this be explained in 
> https://docs.kernel.org/process/volatile-considered-harmful.html ?
>

My feeling is that these two files are special enough that we
don't have to worry about it in general, there is only one other
caller of setjmp in the kernel, and the setjmp() man page
explicitly mentions this problem and the workaround.

     Arnd