linux-kernel - Re: [PATCH 3/6] x86, NMI: Add priorities to handlers

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Date:	Fri, 07 Jan 2011 14:09:51 +0100
From:	Peter Zijlstra <peterz@...radead.org>
To:	Don Zickus <dzickus@...hat.com>
Cc:	x86@...nel.org, Robert Richter <robert.richter@....com>,
	ying.huang@...el.com, gorcunov@...il.com,
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 3/6] x86, NMI: Add priorities to handlers

On Thu, 2011-01-06 at 16:18 -0500, Don Zickus wrote:
> In order to consolidate the NMI die_chain events, we need to setup the priorities
> for the die notifiers.
> 
> I started by defining a bunch of common priorities that can be used by the
> notifier blocks.  Then I modified the notifier blocks to use the newly created
> priorities.
> 
> Now that the priorities are straightened out, it should be easier to remove the
> event DIE_NMI_IPI.
> 
> Signed-off-by: Don Zickus <dzickus@...hat.com>
> ---
>  arch/x86/include/asm/nmi.h              |   20 ++++++++++++++++++++
>  arch/x86/kernel/apic/hw_nmi.c           |    2 +-
>  arch/x86/kernel/cpu/mcheck/mce-inject.c |    2 +-
>  arch/x86/kernel/cpu/perf_event.c        |    2 +-
>  arch/x86/kernel/kgdb.c                  |    2 +-
>  arch/x86/kernel/reboot.c                |    2 ++
>  arch/x86/oprofile/nmi_int.c             |    2 +-
>  arch/x86/oprofile/nmi_timer_int.c       |    2 +-
>  8 files changed, 28 insertions(+), 6 deletions(-)
> 
> diff --git a/arch/x86/include/asm/nmi.h b/arch/x86/include/asm/nmi.h
> index c4021b9..fb82fb6 100644
> --- a/arch/x86/include/asm/nmi.h
> +++ b/arch/x86/include/asm/nmi.h
> @@ -23,6 +23,26 @@ void arch_trigger_all_cpu_backtrace(void);
>  #define arch_trigger_all_cpu_backtrace arch_trigger_all_cpu_backtrace
>  #endif
>  
> +/*
> + * Define some priorities for the nmi notifier call chain.
> + *
> + * Create a local nmi bit that has a higher priority than
> + * external nmis, because the local ones are more frequent.
> + * 
> + * Also setup some default high/normal/low settings for
> + * subsystems to registers with.  Using 4 bits to seperate
> + * the priorities.  This can go alot higher if needed be.
> + */
> +
> +#define NMI_LOCAL_SHIFT		16	/* randomly picked */
> +#define NMI_LOCAL_BIT		(1ULL << NMI_LOCAL_SHIFT)
> +#define NMI_HIGH_PRIOR		(1ULL << 8)
> +#define NMI_NORMAL_PRIOR	(1ULL << 4)
> +#define NMI_LOW_PRIOR		(1ULL << 0)
> +#define NMI_LOCAL_HIGH_PRIOR	(NMI_LOCAL_BIT | NMI_HIGH_PRIOR)
> +#define NMI_LOCAL_NORMAL_PRIOR	(NMI_LOCAL_BIT | NMI_NORMAL_PRIOR)
> +#define NMI_LOCAL_LOW_PRIOR	(NMI_LOCAL_BIT | NMI_LOW_PRIOR)
> +
>  void stop_nmi(void);
>  void restart_nmi(void);
>  
 
>  static struct event_constraint unconstrained;
> diff --git a/arch/x86/kernel/kgdb.c b/arch/x86/kernel/kgdb.c
> index cd21b65..983fb54 100644
> --- a/arch/x86/kernel/kgdb.c
> +++ b/arch/x86/kernel/kgdb.c
> @@ -606,7 +606,7 @@ static struct notifier_block kgdb_notifier = {
>  	/*
>  	 * Lowest-prio notifier priority, we want to be notified last:
>  	 */
> -	.priority	= -INT_MAX,
> +	.priority	= NMI_LOCAL_LOW_PRIOR,
>  };
>  
>  /**


I had to add the below to make things build here.

---
Index: linux-2.6/arch/x86/kernel/kgdb.c
===================================================================
--- linux-2.6.orig/arch/x86/kernel/kgdb.c
+++ linux-2.6/arch/x86/kernel/kgdb.c
@@ -48,6 +48,7 @@
 #include <asm/apicdef.h>
 #include <asm/system.h>
 #include <asm/apic.h>
+#include <asm/nmi.h>
 
 struct dbg_reg_def_t dbg_reg_def[DBG_MAX_REG_NUM] =
 {


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