Re: [RFC] [patch 4/6 -rt] powerpc 2.6.20-rt8: fix a runtime warnings for xmon

Ingo Molnar
2007-03-07T09:17:00Z

* Tsutomu OWA <tsutomu.owa@toshiba.co.jp> wrote:

> @@ -342,6 +342,7 @@ static int xmon_core(struct pt_regs *reg
>
> msr = mfmsr();
> mtmsr(msr & ~MSR_EE); /* disable interrupts */
> + preempt_disable();

i'm not an xmon expert, but maybe it might make more sense to first
disable preemption, then interrupts - otherwise you could be preempted
right after having disabled these interrupts (and be scheduled to
another CPU, etc.). What is the difference between local_irq_save() and
the above 'disable interrupts' sequence? If it's not the same and
xmon_core() relied on having hardirqs disabled then it might make sense
to do a local_irq_save() there, instead of a preempt_disable().

Ingo