linux-kernel - Re: [PATCH 3/7] percpu: clean up percpu variable definitions

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Message-ID: <4A23BD20.5030500@kernel.org>
Date:	Mon, 01 Jun 2009 20:36:00 +0900
From:	Tejun Heo <tj@...nel.org>
To:	David Miller <davem@...emloft.net>
CC:	JBeulich@...ell.com, andi@...stfloor.org, mingo@...e.hu,
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Subject: Re: [PATCH 3/7] percpu: clean up percpu variable definitions

David Miller wrote:
> From: Tejun Heo <tj@...nel.org>
> Date: Mon,  1 Jun 2009 17:58:24 +0900
> 
>> --- a/arch/cris/include/asm/mmu_context.h
>> +++ b/arch/cris/include/asm/mmu_context.h
>> @@ -17,7 +17,7 @@ extern void switch_mm(struct mm_struct *prev, struct mm_struct *next,
>>   * registers like cr3 on the i386
>>   */
>>  
>> -extern volatile DEFINE_PER_CPU(pgd_t *,current_pgd); /* defined in arch/cris/mm/fault.c */
>> +DECLARE_PER_CPU(pgd_t *,current_pgd); /* defined in arch/cris/mm/fault.c */
>>  
>>  static inline void enter_lazy_tlb(struct mm_struct *mm, struct task_struct *tsk)
>>  {
> 
> Yes volatile sucks, but might this break something?
> 
> Whether the volatile is actually needed or not, it's bad to have this
> kind of potential behavior changing nugget hidden in this seemingly
> inocuous change.  Especially if you're the poor soul who ends up
> having to debug it :-/

You're right.  Aieee... how do I feed volatile to the DEFINE macro.
I'll think of something.

Thanks.

-- 
tejun
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