Re: [Xen-devel] [PATCH 2/2] x86/crash: Disable the watchdog NMIs on the crashing cpu.

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 15.11.13 at 21:32, Andrew Cooper <andrew.cooper3@xxxxxxxxxx> wrote:
> --- a/xen/arch/x86/crash.c
> +++ b/xen/arch/x86/crash.c
> @@ -118,6 +118,7 @@ static void nmi_shootdown_cpus(void)
>      unsigned long msecs;
>      int i, cpu = smp_processor_id();
>  
> +    disable_lapic_nmi_watchdog();
>      local_irq_disable();
>  
>      crashing_cpu = cpu;

_If_ you do this here, I wonder why it's being done before
disabling interrupts.

But then again I wonder whether it wouldn't be better to do
this even earlier (i.e. by passing a flag to watchdog_disable()),
as the NMI watchdog becomes useless with that call being done
from kexec_common_shutdown().

> --- a/xen/arch/x86/nmi.c
> +++ b/xen/arch/x86/nmi.c
> @@ -165,7 +165,7 @@ static void nmi_timer_fn(void *unused)
>      set_timer(&this_cpu(nmi_timer), NOW() + MILLISECS(1000));
>  }
>  
> -static void disable_lapic_nmi_watchdog(void)
> +void disable_lapic_nmi_watchdog(void)

The suggested alternative would also make it unnecessary to
make this function non-static...

Jan


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