Re: [RFC 6/6] x86, NMI, Remove do_nmi_callback logic

Ingo Molnar
2010-09-13T06:24:51Z

* Huang Ying <ying.huang@intel.com> wrote:

> On Sat, 2010-09-11 at 00:13 +0800, Don Zickus wrote:
> > On Fri, Sep 10, 2010 at 10:51:05AM +0800, Huang Ying wrote:
> > >
> > > +#if defined(CONFIG_X86_LOCAL_APIC) && !defined(CONFIG_LOCKUP_DETECTOR)
> > > +extern int nmi_watchdog_tick(struct pt_regs *regs);
> > > +#else
> > > +static inline int nmi_watchdog_tick(struct pt_regs *regs)
> > > +{
> > > + return 0;
> > > +}
> > > +#endif
> > > +
> > > extern atomic_t nmi_active;
> > > extern unsigned int nmi_watchdog;
> > > #define NMI_NONE 0
> >
> > <snip>
> >
> > > @@ -421,12 +429,8 @@ static notrace __kprobes void default_do
> > > }
> > > raw_spin_unlock(&nmi_reason_lock);
> > >
> > > -#if defined(CONFIG_X86_LOCAL_APIC) && !defined(CONFIG_LOCKUP_DETECTOR)
> > > - if (nmi_watchdog_tick(regs, reason))
> > > - return;
> > > - if (do_nmi_callback(regs, smp_processor_id()))
> > > + if (nmi_watchdog_tick(regs))
> > > return;
> > > -#endif
> > >
> > > if (notify_die(DIE_NMIUNKNOWN, "nmi_unknown", regs, reason, 2, SIGINT)
> > > == NOTIFY_STOP)
> >
> > I wonder if these two chunks are going to confuse people when they read
> > the code. The old nmi watchdog exists in the arch/x86 area but the new
> > nmi watchdog code is now in kernel/watchdog.c.
> >
> > If someone sees nmi_watchdog_tick() here will they assume the nmi watchdog
> > code is still inside arch/x86?
> >
> > I would suggest keep it wrapped with CONFIG_LOCKUP_DETECTOR to make it
> > obvious. Thoughts?
>
> Is it planned to remove old NMI watchdog implementation in near
> future?

Yes. With the new Pentium4 PMU driver we've covered the last
old-NMI-watchdog hardware support corner too, so we can and should
remove the old code. (keeping the boot option to stay compatible)

Thanks,

Ingo