Re: [V3 PATCH] x86: avoid calling arch_trigger_all_cpu_backtrace()at the same time on SMP

[DDD]

Ingo Molnar wrote:
> Hm, another thing i noticed is that there's two of these:
>
> >  #ifdef ARCH_HAS_NMI_WATCHDOG
> > +/* "in progress" flag of arch_trigger_all_cpu_backtrace */
> > +static unsigned long backtrace_flag;
> > +
> >  void arch_trigger_all_cpu_backtrace(void)
> >  {
> >  	int i;
> > +	unsigned long flags;
> > +
> > +	/*
> > +	 * Have to disable irq here, as the
> > +	 * arch_trigger_all_cpu_backtrace() could be
> > +	 * triggered by "spin_lock()" with irqs on.
> > +	 */
> > +	local_irq_save(flags);
>
> > +/* "in progress" flag of arch_trigger_all_cpu_backtrace */
> > +static unsigned long backtrace_flag;
> > +
> >  void arch_trigger_all_cpu_backtrace(void)
> >  {
> >  	int i;
> > +	unsigned long flags;
> > +
> > +	/*
> > +	 * Have to disable irq here, as the
> > +	 * arch_trigger_all_cpu_backtrace() could be
> > +	 * triggered by "spin_lock()" with irqs on.
> > +	 */
> > +	local_irq_save(flags);
> > +
> > +	if (test_and_set_bit(0, &backtrace_flag))
>
> A fair amount of code is being duplicated in two places - which is not nice. Lets 
> try to create a shared facility instead?

Yep, It is a good idea, I will try to do that. :-)

Dongdong

> Thanks,
>
> 	Ingo

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