Re: [Xen-devel] [PATCH 2 of 7] KEXEC BUG: nmi_shootdown_cpus doesn't look after the interrupt flag

["Jan Beulich" <JBeulich@xxxxxxxxxx>]

>>> On 13.06.11 at 19:02, Andrew Cooper <andrew.cooper3@xxxxxxxxxx> wrote:
> nmi_shootdown_cpus is part of the kexec path, coming from a panic, and
> as such can be called both with interrupts enabled or disabled. We
> really dont want to accidentally set IF.

Can interrupts really be enabled when entering this function?

> Therefore, use save/restore in preference to disable/enable.

I.e. wouldn't just removing the stray local_irq_enable() suffice?

Jan

> Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
> 
> diff -r 076c3034c8c7 -r 1c3d2e4d06fe xen/arch/x86/crash.c
> --- a/xen/arch/x86/crash.c    Mon Jun 13 17:45:43 2011 +0100
> +++ b/xen/arch/x86/crash.c    Mon Jun 13 17:45:43 2011 +0100
> @@ -55,9 +55,9 @@ static int crash_nmi_callback(struct cpu
>  
>  static void nmi_shootdown_cpus(void)
>  {
> -    unsigned long msecs;
> +    unsigned long msecs, flags;
>  
> -    local_irq_disable();
> +    local_irq_save(flags);
>  
>      crashing_cpu = smp_processor_id();
>      local_irq_count(crashing_cpu) = 0;
> @@ -80,7 +80,7 @@ static void nmi_shootdown_cpus(void)
>      __stop_this_cpu();
>      disable_IO_APIC();
>  
> -    local_irq_enable();
> +    local_irq_restore(flags);
>  }
>  
>  void machine_crash_shutdown(void)
> 
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