linux-kernel - Re: [PATCH] ARM: NOMMU: work around maybe-uninitialized warning

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Date:   Thu, 2 Nov 2017 13:11:23 +0000
From:   Vladimir Murzin <vladimir.murzin@....com>
To:     Russell King - ARM Linux <linux@...linux.org.uk>
Cc:     Arnd Bergmann <arnd@...db.de>,
        Nicolas Pitre <nicolas.pitre@...aro.org>,
        afzal mohammed <afzal.mohd.ma@...il.com>,
        Laura Abbott <labbott@...hat.com>,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] ARM: NOMMU: work around maybe-uninitialized warning

On 02/11/17 13:07, Russell King - ARM Linux wrote:
> On Thu, Nov 02, 2017 at 12:25:47PM +0000, Vladimir Murzin wrote:
>> On 02/11/17 09:21, Arnd Bergmann wrote:
>>> The reworked MPU code produces a new warning in some configurations,
>>> presumably starting with the code move after the compiler now makes
>>> different inlining decisions:
>>>
>>> arch/arm/mm/pmsa-v7.c: In function 'adjust_lowmem_bounds_mpu':
>>> arch/arm/mm/pmsa-v7.c:310:5: error: 'specified_mem_size' may be used uninitialized in this function [-Werror=maybe-uninitialized]
>>>
>>> This appears to be harmless, as we know that there is always at
>>> least one memblock, and the only way this could get triggered is
>>> if the for_each_memblock() loop was never entered.
>>>
>>> I could not come up with a better workaround than initializing
>>> the specified_mem_size to zero, but at least that is the value
>>> that the variable would have in the hypothetical case of no
>>> memblocks.
>>>
>>> Fixes: 877ec119dbbf ("ARM: 8706/1: NOMMU: Move out MPU setup in separate module")
>>> Signed-off-by: Arnd Bergmann <arnd@...db.de>
>>> ---
>>> Vladimir, if this looks good to you, can you forward it to Russell's
>>> patch tracker, or otherwise suggest a different fix?
>>
>> Accepted as patch 8719/1. Not sure if Russell will pick it up or not... anyway,
>> thanks for the patch!
> 
> I'd prefer not to at this stage.  Same things that apply that I said
> in the "ARM: early_printk: use printascii() rather than printch()"
> thread - I need to ensure that what I have is stable before 4.14 is
> released, so I'm not accepting anything further unless it is _really_
> urgent.

Yes, I saw that thread, it is why that "not sure" thing.

> 
> This isn't urgent.
> 

Should I resubmit after -rc1 or you'll apply it directly from patch tracker?

Thanks
Vladimir