Re: [PATH -mm] Fix a race condtion of oops_in_progress

[Huang Ying]

On Mon, 2008-08-18 at 21:06 -0700, Andrew Morton wrote:
> On Mon, 18 Aug 2008 10:03:27 +0800 Huang Ying <ying.huang@xxxxxxxxx> wrote:
> 
> > This patch fix a race condition of oops_in_progress. Which may be
> > changed on multiple CPU simultaneously, but it is changed via
> > non-atomic operation ++/--. This patch changes the definition of
> > oops_in_process from int to atomic_t, and accessing method to atomic
> > operations.
> 
> 
> > extern atomic_t oops_in_progress;
> 
> In file included from include/asm/system.h:10,
>                  from include/asm/processor.h:17,
>                  from include/asm/atomic_32.h:5,
>                  from include/asm/atomic.h:2,
>                  from include/linux/crypto.h:20,
>                  from arch/x86/kernel/asm-offsets_32.c:7,
>                  from arch/x86/kernel/asm-offsets.c:2:
> include/linux/kernel.h:236: error: expected '=', ',', ';', 'asm' or '__attribute__' before 'oops_in_progress'
> make[1]: *** [arch/x86/kernel/asm-offsets.s] Error 1
> make: *** [prepare0] Error 2
> 
> we can't inlude asm/atomic.h from linux/kernel.h because asm/atomic.h
> includes linux/kernel.h via the above route.
> 
> And we cannot forward-declare atomic_t by hand because it's a typedef.
> 
> Not sure what to do, really.  Find a different header file in which to
> declare oops_in_progress?

It seems that asm/atomic.h is used for both atomic_t declaration and
implementation, how about separate them? That it, add a new file
asm/atomic_def.h, put typedef there, and include asm/atomic_def.h in
kernel.h?

Best Regards,
Huang Ying


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