Re: [PATCH 2/4] nmi_backtrace: generate one-line reports for idle cpus

[Chris Metcalf]

On 03/07/2016 03:26 AM, Daniel Thompson wrote:
> > Chris Metcalf wrote:
> > +static DEFINE_PER_CPU(bool, cpu_idling);
> > +
> > +/* Was the cpu was in the low-level idle code when interrupted? */
> > +bool in_cpu_idle(void)
> > +{
> > +    return this_cpu_read(cpu_idling);
>
> I think we continue to need the code to identify a core that is 
> running an interrupt handler. Interrupts are not masked at the point 
> we set cpu_idling to false meaning we can easily be preempted before 
> we clear the flag.

Yes, good catch.  However, mooted by PeterZ wanting to keep any extra 
state-switching code out of the idle path.  See my reply to him for more 
on that.

--
Chris Metcalf, Mellanox Technologies
http://www.mellanox.com