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Date: Fri, 26 Feb 2010 10:49:12 -0600
From: Russ Anderson <rja@....com>
To: Ingo Molnar <mingo@...e.hu>
Cc: "H. Peter Anvin" <hpa@...or.com>, tglx@...utronix.de,
linux-kernel@...r.kernel.org, rja@....com
Subject: Re: [PATCH] x86: Enable NMI on all cpus on UV
Attached is a patch that cleans up Ingo's nits.
On Fri, Feb 26, 2010 at 10:22:52AM +0100, Ingo Molnar wrote:
>
> * 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.
Done.
> > +{
> > + 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)
Done.
> > +
> > + 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.
Done.
> > + 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.
Done.
> > +
> > +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.
Done and moved to x86_init.c.
> > +
> > /*
> > * 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.
Done.
> > 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.
Removed.
> Thanks,
>
> Ingo
--
Russ Anderson, OS RAS/Partitioning Project Lead
SGI - Silicon Graphics Inc rja@....com
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