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

Don Zickus
2010-09-10T16:13:37Z

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?

Cheers,
Don