Re: [patch 2/5] atomic: cmpxchg

[Nick Piggin <nickpiggin@yahoo.com.au>]

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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