Re: [patch 2/5] atomic: cmpxchg

[Nick Piggin]

Russell King wrote:
> 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...

Ah dang sorry. Must be a cut-n-paste-o.

While you're here, does the assembly code for the SMP version look
OK? You basically provided me with it but I don't think you saw its
final form.

--
SUSE Labs, Novell Inc.

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