[patch] powerpc: implement optimised mutex fastpaths

[Nick Piggin]

On Sun, Oct 12, 2008 at 07:47:32AM +0200, Nick Piggin wrote:
> 
> Implement a more optimal mutex fastpath for powerpc, making use of acquire
> and release barrier semantics. This takes the mutex lock+unlock benchmark
> from 203 to 173 cycles on a G5.
> 
> +static inline int
> +__mutex_fastpath_trylock(atomic_t *count, int (*fail_fn)(atomic_t *))
> +{
> +	if (likely(__mutex_cmpxchg_lock(count, 1, 0) == 1))
> +		return 1;

Oops, I must have sent the wrong version. This needs a return 0 here.

> +}