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Message-ID: <20100226092252.GJ15885@elte.hu>
Date: Fri, 26 Feb 2010 10:22:52 +0100
From: Ingo Molnar <mingo@...e.hu>
To: Russ Anderson <rja@....com>
Cc: "H. Peter Anvin" <hpa@...or.com>, tglx@...utronix.de,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH] x86: Enable NMI on all cpus on UV
* Russ Anderson <rja@....com> wrote:
> On Mon, Feb 22, 2010 at 11:38:53AM +0100, Ingo Molnar wrote:
> >
> > * Russ Anderson <rja@....com> wrote:
> >
> > > Enable NMI on all cpus in UV system and add an NMI handler
> > > to dump_stack on each cpu.
> > >
> > > Signed-off-by: Russ Anderson <rja@....com>
> [...]
> > > struct mm_struct *mm,
> > > Index: linux/arch/x86/kernel/smpboot.c
> > > ===================================================================
> > > --- linux.orig/arch/x86/kernel/smpboot.c 2010-02-17 10:21:55.000000000 -0600
> > > +++ linux/arch/x86/kernel/smpboot.c 2010-02-17 10:32:20.000000000 -0600
> > > @@ -320,6 +320,8 @@ notrace static void __cpuinit start_seco
> > > unlock_vector_lock();
> > > ipi_call_unlock();
> > > per_cpu(cpu_state, smp_processor_id()) = CPU_ONLINE;
> > > + if (is_uv_system())
> > > + uv_nmi_init();
> >
> > Instead of cramming it into the init sequence open-coded, shouldnt this be
> > done via the x86_platform driver mechanism?
>
> Attached is the updated patch with the x86_platform driver mechanism
> used for uv_nmi_init.
ok, this looks far cleaner. A few nits:
> + * When NMI is received, print a stack trace.
> + */
> +int uv_handle_nmi(struct notifier_block *self,
> + unsigned long reason, void *data)
Please put prototypes on a single line if it's still below 100 cols or so.
> +{
> + unsigned long flags;
> + static DEFINE_SPINLOCK(uv_nmi_lock);
Please dont hide locks amongst local variables. (even if they are only used by
that function)
> +
> + if (reason != DIE_NMI_IPI)
> + return NOTIFY_OK;
> + /*
> + * Use a lock so only one cpu prints at a time
> + * to prevent intermixed output.
> + */
> + spin_lock_irqsave(&uv_nmi_lock, flags);
> + printk(KERN_INFO "NMI stack dump cpu %u:\n",
> + smp_processor_id());
Can be on a single line too.
Can use pr_info().
Should use a raw spinlock - this is NMI context.
> + dump_stack();
> + spin_unlock_irqrestore(&uv_nmi_lock, flags);
> +
> + return NOTIFY_STOP;
> +}
> +
> +static struct notifier_block uv_dump_stack_nmi_nb = {
> + .notifier_call = uv_handle_nmi,
> + .next = NULL,
> + .priority = 0
> +};
Please align structure initializations vertically.
Plus no need to open-code the setting of priority to 0 i guess.
> +
> +void uv_register_nmi_notifier(void)
> +{
> + if (register_die_notifier(&uv_dump_stack_nmi_nb))
> + printk(KERN_WARNING "UV NMI handler failed to register\n");
> +}
> +
> +void uv_nmi_init(void)
> +{
> + unsigned int value;
> +
> + /*
> + * Unmask NMI on all cpus
> + */
> + value = apic_read(APIC_LVT1) | APIC_DM_NMI;
> + value &= ~APIC_LVT_MASKED;
> + apic_write(APIC_LVT1, value);
> +}
>
> void __init uv_system_init(void)
> {
> @@ -690,5 +739,6 @@ void __init uv_system_init(void)
>
> uv_cpu_init();
> uv_scir_register_cpu_notifier();
> + uv_register_nmi_notifier();
> proc_mkdir("sgi_uv", NULL);
> }
> Index: linux/arch/x86/include/asm/uv/uv.h
> ===================================================================
> --- linux.orig/arch/x86/include/asm/uv/uv.h 2010-02-25 11:01:48.131694174 -0600
> +++ linux/arch/x86/include/asm/uv/uv.h 2010-02-25 11:02:17.622069711 -0600
> @@ -11,6 +11,7 @@ struct mm_struct;
> extern enum uv_system_type get_uv_system_type(void);
> extern int is_uv_system(void);
> extern void uv_cpu_init(void);
> +extern void uv_nmi_init(void);
> extern void uv_system_init(void);
> extern const struct cpumask *uv_flush_tlb_others(const struct cpumask *cpumask,
> struct mm_struct *mm,
> Index: linux/arch/x86/kernel/smpboot.c
> ===================================================================
> --- linux.orig/arch/x86/kernel/smpboot.c 2010-02-25 11:01:50.929770347 -0600
> +++ linux/arch/x86/kernel/smpboot.c 2010-02-25 11:02:17.664720876 -0600
> @@ -263,6 +263,11 @@ static void __cpuinit smp_callin(void)
> cpumask_set_cpu(cpuid, cpu_callin_mask);
> }
>
> +void default_nmi_init(void)
> +{
> + return;
> +}
That return is not needed.
> +
> /*
> * Activate a secondary processor.
> */
> @@ -320,6 +325,7 @@ notrace static void __cpuinit start_seco
> unlock_vector_lock();
> ipi_call_unlock();
> per_cpu(cpu_state, smp_processor_id()) = CPU_ONLINE;
> + x86_platform.nmi_init();
>
> /* enable local interrupts */
> local_irq_enable();
> Index: linux/arch/x86/include/asm/x86_init.h
> ===================================================================
> --- linux.orig/arch/x86/include/asm/x86_init.h 2010-02-25 11:01:48.131694174 -0600
> +++ linux/arch/x86/include/asm/x86_init.h 2010-02-25 11:02:17.696714616 -0600
> @@ -126,6 +126,7 @@ struct x86_cpuinit_ops {
> * @get_wallclock: get time from HW clock like RTC etc.
> * @set_wallclock: set time back to HW clock
> * @is_untracked_pat_range exclude from PAT logic
> + * @nmi_init enable NMI on cpus
> */
> struct x86_platform_ops {
> unsigned long (*calibrate_tsc)(void);
> @@ -133,6 +134,7 @@ struct x86_platform_ops {
> int (*set_wallclock)(unsigned long nowtime);
> void (*iommu_shutdown)(void);
> bool (*is_untracked_pat_range)(u64 start, u64 end);
> + void (*nmi_init)(void);
> };
>
> extern struct x86_init_ops x86_init;
> Index: linux/arch/x86/kernel/x86_init.c
> ===================================================================
> --- linux.orig/arch/x86/kernel/x86_init.c 2010-02-25 11:01:47.848760574 -0600
> +++ linux/arch/x86/kernel/x86_init.c 2010-02-25 11:02:17.732996103 -0600
> @@ -13,6 +13,7 @@
> #include <asm/e820.h>
> #include <asm/time.h>
> #include <asm/irq.h>
> +#include <asm/nmi.h>
> #include <asm/pat.h>
> #include <asm/tsc.h>
> #include <asm/iommu.h>
> @@ -82,4 +83,5 @@ struct x86_platform_ops x86_platform = {
> .set_wallclock = mach_set_rtc_mmss,
> .iommu_shutdown = iommu_shutdown_noop,
> .is_untracked_pat_range = is_ISA_range,
> + .nmi_init = default_nmi_init
> };
the default can be in this file too - then you can also make it 'static' and
save some space and not touch smpboot.c.
> Index: linux/arch/x86/include/asm/nmi.h
> ===================================================================
> --- linux.orig/arch/x86/include/asm/nmi.h 2010-02-25 11:01:48.131694174 -0600
> +++ linux/arch/x86/include/asm/nmi.h 2010-02-25 11:02:17.756721420 -0600
> @@ -24,6 +24,7 @@ extern int reserve_perfctr_nmi(unsigned
> extern void release_perfctr_nmi(unsigned int);
> extern int reserve_evntsel_nmi(unsigned int);
> extern void release_evntsel_nmi(unsigned int);
> +extern void default_nmi_init(void);
>
> extern void setup_apic_nmi_watchdog(void *);
> extern void stop_apic_nmi_watchdog(void *);
This will go away in that case as well.
Thanks,
Ingo
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