[PATCH v4 4/5] msm: hotplug: support cpu hotplug on msm

[Russell King - ARM Linux]

On Mon, Dec 13, 2010 at 08:50:32PM -0800, Jeff Ohlstein wrote:
> +static inline void platform_do_lowpower(unsigned int cpu)
> +{
> +	/* Just enter wfe for now. */
> +	for (;;) {
> +		asm("wfe" : : : "memory");
> +		if (pen_release == cpu) {
> +			/*
> +			 * OK, proper wakeup, we're done
> +			 */
> +			break;
> +		}
> +		smp_rmb();

I can't work out what this read memory barrier is doing here.  Could you
suggest what purpose it's serving please?