linux-kernel - Re: [RFC][PATCH] nmi watchdog: handle NMI_IO_APIC on nmi

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Message-ID: <20080326152417.GE25854@cathedrallabs.org>
Date:	Wed, 26 Mar 2008 11:24:17 -0400
From:	Aristeu Rozanski <aris@...vo.org>
To:	Ingo Molnar <mingo@...e.hu>
Cc:	Thomas Gleixner <tglx@...utronix.de>, linux-kernel@...r.kernel.org
Subject: Re: [RFC][PATCH] nmi watchdog: handle NMI_IO_APIC on nmi_watchdog

Hi Ingo,
> > This patch includes code to handle NMI_IO_APIC enabling/disabling by
> > nmi_watchdog proc file.
> 
> hm:
> 
> > +static void disable_ioapic_nmi_watchdog(void)
> > +{
> > +	on_each_cpu(stop_apic_nmi_watchdog, NULL, 0, 1);
> > +}
> 
> stop_apic_nmi_watchdog() doesnt currently properly disable the 
> generation of NMIs when they come from an IO-APIC, so this will need 
> more fixes i believe. One approach would be to save the IO-APIC id and 
> pin when the watchdog is set up, and use it later on to poke that 
> IO-APIC register to disable NMI generation there.
the patch I sent has this change:

@@ -270,6 +270,8 @@ void stop_apic_nmi_watchdog(void *unused
                return;
        if (nmi_watchdog == NMI_LOCAL_APIC)
                lapic_watchdog_stop();
+       else
+               __acpi_nmi_disable(NULL);
        __get_cpu_var(wd_enabled) = 0;
        atomic_dec(&nmi_active);
 }

and:
static void __acpi_nmi_disable(void *__unused)
{       
        apic_write(APIC_LVT0, APIC_DM_NMI | APIC_LVT_MASKED);
}

do you think this isn't enough?

-- 
Aristeu

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