linux-kernel - Re: [PATCH] kernel: sysctl: use 'unsigned long' type for 'zero' variable

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Date:	Sat, 13 Dec 2014 21:51:02 +0100
From:	Manfred Spraul <manfred@...orfullife.com>
To:	Andrey Ryabinin <a.ryabinin@...sung.com>,
	Dmitry Vyukov <dvyukov@...gle.com>
CC:	Andrew Morton <akpm@...ux-foundation.org>,
	David Rientjes <rientjes@...gle.com>,
	Naoya Horiguchi <n-horiguchi@...jp.nec.com>,
	Luiz Capitulino <lcapitulino@...hat.com>,
	"Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>,
	Nadia.Derbey@...l.net, aquini@...hat.com,
	Joe Perches <joe@...ches.com>, avagin@...nvz.org,
	LKML <linux-kernel@...r.kernel.org>,
	Kostya Serebryany <kcc@...gle.com>,
	Dmitry Chernenkov <dmitryc@...gle.com>,
	Andrey Konovalov <andreyknvl@...gle.com>,
	Konstantin Khlebnikov <koct9i@...il.com>,
	kasan-dev <kasan-dev@...glegroups.com>,
	Davidlohr Bueso <dave@...olabs.net>
Subject: Re: [PATCH] kernel: sysctl: use 'unsigned long' type for 'zero' variable

Hi,

On 12/04/2014 12:25 AM, Andrew Morton wrote:
> On Wed, 03 Dec 2014 15:41:21 +0300 Andrey Ryabinin <a.ryabinin@...sung.com> wrote:
>
>> Use the 'unsigned long' type for 'zero' variable to fix this.
>> Changing type to 'unsigned long' shouldn't affect any other users
>> of this variable.
>>
>> Reported-by: Dmitry Vyukov <dvyukov@...gle.com>
>> Fixes: ed4d4902ebdd ("mm, hugetlb: remove hugetlb_zero and hugetlb_infinity")
>> Signed-off-by: Andrey Ryabinin <a.ryabinin@...sung.com>
>> ---
>>   kernel/sysctl.c | 2 +-
>>   1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/kernel/sysctl.c b/kernel/sysctl.c
>> index 15f2511..45c45c9 100644
>> --- a/kernel/sysctl.c
>> +++ b/kernel/sysctl.c
>> @@ -120,7 +120,7 @@ static int sixty = 60;
>>   
>>   static int __maybe_unused neg_one = -1;
>>   
>> -static int zero;
>> +static unsigned long zero;

After some (useless) playing around (see the attached patch):

Using
 >    .extra1=zero,
for proc_doulongvec_minmax doesn't make any sense:

  __do_proc_doulongvec_minmax() internally contains
>                       if ((min && val < *min) || (max && val > *max))
>                                 continue;

What about just deleting the offending .extra1=zero line?
.extra1=NULL has the same effect as .extra1=&zero.

--
     Manfred




View attachment "0001-kernel-sysctl.c-Type-safe-macros.patch" of type "text/x-patch" (5278 bytes)