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

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Date:	Wed, 10 Jun 2009 11:30:51 -0700
From:	"H. Peter Anvin" <hpa@...or.com>
To:	David Miller <davem@...emloft.net>
CC:	tj@...nel.org, JBeulich@...ell.com, andi@...stfloor.org,
	mingo@...e.hu, tglx@...utronix.de, linux-kernel@...r.kernel.org,
	x86@...nel.org, ink@...assic.park.msu.ru, rth@...ddle.net,
	linux@....linux.org.uk, hskinnemoen@...el.com, cooloney@...nel.org,
	starvik@...s.com, jesper.nilsson@...s.com, dhowells@...hat.com,
	ysato@...rs.sourceforge.jp, tony.luck@...el.com,
	takata@...ux-m32r.org, monstr@...str.eu, ralf@...ux-mips.org,
	kyle@...artin.ca, benh@...nel.crashing.org, paulus@...ba.org,
	schwidefsky@...ibm.com, heiko.carstens@...ibm.com,
	lethal@...ux-sh.org, jdike@...toit.com, chris@...kel.net,
	rusty@...tcorp.com.au, jens.axboe@...cle.com, davej@...hat.com,
	jeremy@...source.com, linux-mm@...ck.org
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 :-/

Shouldn't the "volatile" go inside the DECLARE_PER_CPU() with the rest
of the type?  [Disclaimer: I haven't actually looked.]

	-hpa

-- 
H. Peter Anvin, Intel Open Source Technology Center
I work for Intel.  I don't speak on their behalf.

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/