Re: [PATCH] Remove RCU abuse in cpu_idle()

[Andrew Morton <akpm@osdl.org>]

Zwane Mwaikambo <zwane@arm.linux.org.uk> wrote:
>
> On Sat, 11 Dec 2004, Zwane Mwaikambo wrote:
> 
> > > Introduce cpu_idle_wait() on architectures requiring modification of 
> > > pm_idle from modules, this will ensure that all processors have updated 
> > > their cached values of pm_idle upon exit. This patch is to address the bug 
> > > report at http://bugme.osdl.org/show_bug.cgi?id=1716 and replaces the 
> > > current code fix which is in violation of normal RCU usage as pointed out 
> > > by Stephen, Dipankar and Paul.
> 
> ...
> 
>  void cpu_idle (void)
>  {
> +	int cpu = smp_processor_id();
> +
>  	/* endless idle loop with no priority at all */

This gives me scadzillions of "using smp_procesor_id() in preemptible"
warnings.

I'll shut that up with _smp_processor_id() but one does wonder what happens
if we get preempted and `cpu' refers to some other CPU?