linux-kernel - Re: [PATCH 01/16] CONFIG_DISABLE_OBSOLETE_CPUMASK_FUNCTIONS: set if CPUMASK

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Date:	Tue, 03 Mar 2015 10:10:48 +1030
From:	Rusty Russell <rusty@...tcorp.com.au>
To:	Paul Bolle <pebolle@...cali.nl>
Cc:	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 01/16] CONFIG_DISABLE_OBSOLETE_CPUMASK_FUNCTIONS: set if CPUMASK_OFFSTACK.

Paul Bolle <pebolle@...cali.nl> writes:
> On Mon, 2015-03-02 at 22:05 +1030, Rusty Russell wrote:
>> Using these functions with offstack cpus is unsafe.  They use all NR_CPUS
>> bits, unstead of nr_cpumask_bits.
>> 
>> In particular, lustre (in staging) used cpus_ and that caused a bug.
>> 
>> Reported-by: Oleg Drokin <green@...uxhacker.ru>
>> Signed-off-by: Rusty Russell <rusty@...tcorp.com.au>
>> ---
>>  lib/Kconfig | 4 ++--
>>  1 file changed, 2 insertions(+), 2 deletions(-)
>> 
>> diff --git a/lib/Kconfig b/lib/Kconfig
>> index 87da53bb1fef..722427805220 100644
>> --- a/lib/Kconfig
>> +++ b/lib/Kconfig
>> @@ -398,8 +398,8 @@ config CPUMASK_OFFSTACK
>>  	  stack overflow.
>>  
>>  config DISABLE_OBSOLETE_CPUMASK_FUNCTIONS
>> -       bool "Disable obsolete cpumask functions" if DEBUG_PER_CPU_MAPS
>> -       depends on BROKEN
>> +       bool
>> +       depends on CPUMASK_OFFSTACK
>
> This removes the "prompt" from this symbol's entry. And nothing selects
> it either (not in next-20150302 nor in this series). So I think this
> just disables this Kconfig symbol entirely. Ie, it can't be set even if
> CPUMAK_OFFSTACK is set.
>
> Should this entry perhaps be using
>     def_bool y
>
> instead?

You're right.  In practice, I used a different patch to actually force
enable it.

The final patch deletes it altogether, so I will just squash the two
and this will never appear in the final series.

Thanks!
Rusty.
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