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

Srivatsa Vaddagiri
2005-09-19T07:08:54Z

On Mon, Sep 19, 2005 at 02:37:09PM +0800, Shaohua Li wrote:
> > - if (need_resched())
> > + if (need_resched() || cpu_is_offline(cpu))
> > break;
> if the breakpoint is here, you will still have trouble.

[snip]

> Why default_idle should be fine? it can be preempted before the
> 'local_irq_disable' check.
> Even with Nigel's patch, there is a very
> small window at safe_halt (after 'sti' but before 'hlt').

Good point. Sounds like the patch that Nick has for disabling premption
while it is idle may be a cure for these problems.

--

Thanks and Regards,
Srivatsa Vaddagiri,
Linux Technology Center,
IBM Software Labs,
Bangalore, INDIA - 560017