Re: PATCH: Fix race in cpu_down (hotplug cpu)

Nigel Cunningham
2005-09-19T05:35:27Z

On Mon, 2005-09-19 at 15:28, Srivatsa Vaddagiri wrote:
> On Mon, Sep 19, 2005 at 03:23:01PM +1000, Nigel Cunningham wrote:
> > Maybe I'm just an ignoramus, but I was thinking (without being a
> > scheduler expert at all) that if the idle thread was already running,
> > trying to set it up to run next might possibly have zero effect. I've
>
> sched_idle_next actually adds the idle task to its runqueue (normally
> it is not present in a runqueue while running) and as well changes its
> priority/policy. So it does have *some* effect!

Ok.

> > added a bit of debugging code to try and see in better detail what's
> > happening.
>
> Could you elaborate (with some stack traces maybe) on the deadlock you are
> seeing during resume? Maybe that can throw some light.

I'll try. I'm having trouble reproducing it now (yes, having reversed my
patch!).

Regards,

Nigel
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