Re: [patch 2/5] atomic: cmpxchg

[Russell King]

On Sat, Nov 05, 2005 at 06:57:28PM +1100, Nick Piggin wrote:
> Index: linux-2.6/include/asm-arm/atomic.h
> ===================================================================
> --- linux-2.6.orig/include/asm-arm/atomic.h
> +++ linux-2.6/include/asm-arm/atomic.h
> @@ -80,6 +80,23 @@ static inline int atomic_sub_return(int 
>  	return result;
>  }
>  
> +static inline int atomic_cmpxchg(atomic_t *ptr, int old, int new)
> +{
> +	u32 oldval, res;
> +
> +	do {
> +		__asm__ __volatile__("@ atomic_cmpxchg\n"
> +		"ldrex	%1, [%2]\n"
> +		"teq	%1, %3\n"
> +		"strexeq %0, %4, [%2]\n"
> +		    : "=&r" (res), "=&r" (oldval)
> +		    : "r" (&ptr->counter), "r" (old), "r" (new)
> +		    : "cc");
> +	} while (res);
> +
> +	return oldval;
> +}
> +
>  static inline void atomic_clear_mask(unsigned long mask, unsigned long *addr)
>  {
>  	unsigned long tmp, tmp2;
> @@ -131,6 +148,21 @@ static inline int atomic_sub_return(int 
>  	return val;
>  }
>  
> +static inline int atomic_cmpxchg(atomic_t *v, int old, int new)
> +{
> +	int ret;
> +	unsigned long flags;
> +
> +	local_irq_save(flags);
> +	ret = v->counter;
> +	if (likely(ret == old))
> +		v->counter = new;
> +	local_irq_restore(flags);
> +
> +	return ret;
> +}
> +
> +static inline void atomic_clear_mask(unsigned long mask, unsigned long *addr)
>  static inline void atomic_clear_mask(unsigned long mask, unsigned long *addr)

This is obviously going to break ARM...

-- 
Russell King
 Linux kernel    2.6 ARM Linux   - http://www.arm.linux.org.uk/
 maintainer of:  2.6 Serial core
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