Re: [PATCH 5/6] xen/hvm kexec: unregister timer interrupt during reboot

[Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>]

On Tue, Jul 26, 2011 at 01:52:14PM +0200, Olaf Hering wrote:
> The kexec kernel will crash because the timer interrupt is already
> registerd with EVTCHNOP_bind_virq.  Unbind the event channel during
> shutdown so that the kexec kernel can reregister the interrupt.
> 
> Signed-off-by: Olaf Hering <olaf@aepfle.de>
> 
> ---
>  arch/x86/xen/time.c |   27 ++++++++++++++++++++++++---
>  1 file changed, 24 insertions(+), 3 deletions(-)
> 
> Index: linux-3.0/arch/x86/xen/time.c
> ===================================================================
> --- linux-3.0.orig/arch/x86/xen/time.c
> +++ linux-3.0/arch/x86/xen/time.c
> @@ -14,6 +14,7 @@
>  #include <linux/kernel_stat.h>
>  #include <linux/math64.h>
>  #include <linux/gfp.h>
> +#include <linux/syscore_ops.h>
>  
>  #include <asm/pvclock.h>
>  #include <asm/xen/hypervisor.h>
> @@ -405,12 +406,20 @@ void xen_setup_timer(int cpu)
>  	evt->irq = irq;
>  }
>  
> -void xen_teardown_timer(int cpu)
> +static void xen_unbind_timer(int cpu)
>  {
>  	struct clock_event_device *evt;
> -	BUG_ON(cpu == 0);
>  	evt = &per_cpu(xen_clock_events, cpu);
> -	unbind_from_irqhandler(evt->irq, NULL);
> +	if (evt->irq >= 0) {
> +		unbind_from_irqhandler(evt->irq, NULL);
> +		evt->irq = -1;
> +	}
> +}
> +
> +void xen_teardown_timer(int cpu)
> +{
> +	BUG_ON(cpu == 0);

Why the BUG? Ah you just copied it from xen_unbind_timer.
Hm, I wonder if we actually need that BUG_ON.

> +	xen_unbind_timer(cpu);
>  }
>  
>  void xen_setup_cpu_clockevents(void)
> @@ -478,6 +487,17 @@ void __init xen_init_time_ops(void)
>  }
>  
>  #ifdef CONFIG_XEN_PVHVM
> +static void xen_hvmtimer_shutdown(void)
> +{
> +	int cpu;
> +	for_each_online_cpu(cpu)
> +		xen_unbind_timer(cpu);
> +}
> +
> +static struct syscore_ops xen_hvmtimer_syscore_ops = {
> +	.shutdown = xen_hvmtimer_shutdown,
> +};
> +
>  static void xen_hvm_setup_cpu_clockevents(void)
>  {
>  	int cpu = smp_processor_id();
> @@ -506,5 +526,6 @@ void __init xen_hvm_init_time_ops(void)
>  	x86_platform.calibrate_tsc = xen_tsc_khz;
>  	x86_platform.get_wallclock = xen_get_wallclock;
>  	x86_platform.set_wallclock = xen_set_wallclock;
> +	register_syscore_ops(&xen_hvmtimer_syscore_ops);
>  }
>  #endif
> 
> 
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