Re: [PATCH] include/linux/kernel.h: Make might_fault to be a nop for!MMU

[Michael S. Tsirkin]

On Fri, Nov 29, 2013 at 03:42:14PM +0800, Axel Lin wrote:
> No fault if !MUU, thus make might_fault to be a nop for !MMU.
> 
> This fixes below build error if
> !CONFIG_MMU && (CONFIG_PROVE_LOCKING=y || CONFIG_DEBUG_ATOMIC_SLEEP=y):
> 
> arch/arm/kernel/built-in.o: In function `arch_ptrace':
> arch/arm/kernel/ptrace.c:852: undefined reference to `might_fault'
> arch/arm/kernel/built-in.o: In function `restore_sigframe':
> arch/arm/kernel/signal.c:173: undefined reference to `might_fault'
> arch/arm/kernel/signal.c:174: undefined reference to `might_fault'
> arch/arm/kernel/signal.c:175: undefined reference to `might_fault'
> arch/arm/kernel/signal.c:176: undefined reference to `might_fault'
> arch/arm/kernel/built-in.o:arch/arm/kernel/signal.c:177: more undefined references to `might_fault' follow
> make: *** [vmlinux] Error 1
> 
> Signed-off-by: Axel Lin <axel.lin@xxxxxxxxxx>
> Cc: Michael S. Tsirkin <mst@xxxxxxxxxx>
> Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>

Makes sense. FWIW

Acked-by: Michael S. Tsirkin <mst@xxxxxxxxxx>

> ---
>  include/linux/kernel.h | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/include/linux/kernel.h b/include/linux/kernel.h
> index 2ac0277..8b0ad48 100644
> --- a/include/linux/kernel.h
> +++ b/include/linux/kernel.h
> @@ -193,7 +193,8 @@ extern int _cond_resched(void);
>  		(__x < 0) ? -__x : __x;		\
>  	})
>  
> -#if defined(CONFIG_PROVE_LOCKING) || defined(CONFIG_DEBUG_ATOMIC_SLEEP)
> +#if defined(CONFIG_MMU) && \
> +	(defined(CONFIG_PROVE_LOCKING) || defined(CONFIG_DEBUG_ATOMIC_SLEEP))
>  void might_fault(void);
>  #else
>  static inline void might_fault(void) { }
> -- 
> 1.8.1.2
> 
> 
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