Re: [PATCH -tip] x86: atomic64: inline atomic64_read()

[Andi Kleen]

Arjan van de Ven <arjan@xxxxxxxxxxxxx> writes:

> On Fri, 3 Jul 2009 20:04:50 +0200
> Ingo Molnar <mingo@xxxxxxx> wrote:
>
>> > +static inline u64 atomic64_read(atomic64_t *ptr)
>> > +{
>> > +	u64 res;
>> > +
>> > +	asm volatile(
>> > +		"mov %%ebx, %%eax\n\t"
>> > +		"mov %%ecx, %%edx\n\t"
>> > +		LOCK_PREFIX "cmpxchg8b %1\n"
>
> also afaik cmpxchg implies the lock prefix, so no need to make an
> explicit one... it just adds code size and alternatives-work

No it doesn't; LOCK is implied for "xchg", but not for cmpxchg

-Andi

-- 
ak@xxxxxxxxxxxxxxx -- Speaking for myself only.
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