x86, nmi_watchdog: Remove the old nmi_watchdog

Now that we have a new nmi_watchdog that is more generic and
sits on top of the perf subsystem, we really do not need the old
nmi_watchdog any more.

In addition, the old nmi_watchdog doesn't really work if you are
using the default clocksource, hpet.  The old nmi_watchdog code
relied on local apic interrupts to determine if the cpu is still
alive.  With hpet as the clocksource, these interrupts don't
increment any more and the old nmi_watchdog triggers false
postives.

This piece removes the old nmi_watchdog code and stubs out any
variables and functions calls.  The stubs are the same ones used
by the new nmi_watchdog code, so it should be well tested.

Signed-off-by: Don Zickus <dzickus@redhat.com>
Cc: fweisbec@gmail.com
Cc: gorcunov@openvz.org
LKML-Reference: <1289578944-28564-2-git-send-email-dzickus@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

3 files changed, 4 insertions, 574 deletions

diff --git a/arch/x86/kernel/apic/Makefile b/arch/x86/kernel/apic/Makefile
index 910f20b457c4..3966b564ea47 100644
--- a/arch/x86/kernel/apic/Makefile
+++ b/arch/x86/kernel/apic/Makefile
@@ -3,10 +3,7 @@
 #
 
 obj-$(CONFIG_X86_LOCAL_APIC)    += apic.o apic_noop.o probe_$(BITS).o ipi.o
-ifneq ($(CONFIG_HARDLOCKUP_DETECTOR),y)
-obj-$(CONFIG_X86_LOCAL_APIC)    += nmi.o
-endif
-obj-$(CONFIG_HARDLOCKUP_DETECTOR)       += hw_nmi.o
+obj-y                           += hw_nmi.o
 
 obj-$(CONFIG_X86_IO_APIC)       += io_apic.o
 obj-$(CONFIG_SMP)               += ipi.o
diff --git a/arch/x86/kernel/apic/hw_nmi.c b/arch/x86/kernel/apic/hw_nmi.c
index cefd6942f0e9..b68b17460016 100644
--- a/arch/x86/kernel/apic/hw_nmi.c
+++ b/arch/x86/kernel/apic/hw_nmi.c
@@ -20,12 +20,14 @@
 /* For reliability, we're prepared to waste bits here. */
 static DECLARE_BITMAP(backtrace_mask, NR_CPUS) __read_mostly;
 
+#ifdef CONFIG_HARDLOCKUP_DETECTOR
 u64 hw_nmi_get_sample_period(void)
 {
         return (u64)(cpu_khz) * 1000 * 60;
 }
+#endif
 
-#ifdef ARCH_HAS_NMI_WATCHDOG
+#ifdef arch_trigger_all_cpu_backtrace
 void arch_trigger_all_cpu_backtrace(void)
 {
         int i;
@@ -95,8 +97,6 @@ early_initcall(register_trigger_all_cpu_backtrace);
 #if defined(CONFIG_X86_LOCAL_APIC)
 unsigned int nmi_watchdog = NMI_NONE;
 EXPORT_SYMBOL(nmi_watchdog);
-void acpi_nmi_enable(void) { return; }
-void acpi_nmi_disable(void) { return; }
 #endif
 atomic_t nmi_active = ATOMIC_INIT(0);           /* oprofile uses this */
 EXPORT_SYMBOL(nmi_active);
diff --git a/arch/x86/kernel/apic/nmi.c b/arch/x86/kernel/apic/nmi.c
deleted file mode 100644
index c90041ccb742..000000000000
--- a/arch/x86/kernel/apic/nmi.c
+++ /dev/null
@@ -1,567 +0,0 @@
-/*
- *  NMI watchdog support on APIC systems
- *
- *  Started by Ingo Molnar <mingo@redhat.com>
- *
- *  Fixes:
- *  Mikael Pettersson   : AMD K7 support for local APIC NMI watchdog.
- *  Mikael Pettersson   : Power Management for local APIC NMI watchdog.
- *  Mikael Pettersson   : Pentium 4 support for local APIC NMI watchdog.
- *  Pavel Machek and
- *  Mikael Pettersson   : PM converted to driver model. Disable/enable API.
- */
-
-#include <asm/apic.h>
-
-#include <linux/nmi.h>
-#include <linux/mm.h>
-#include <linux/delay.h>
-#include <linux/interrupt.h>
-#include <linux/module.h>
-#include <linux/slab.h>
-#include <linux/sysdev.h>
-#include <linux/sysctl.h>
-#include <linux/percpu.h>
-#include <linux/kprobes.h>
-#include <linux/cpumask.h>
-#include <linux/kernel_stat.h>
-#include <linux/kdebug.h>
-#include <linux/smp.h>
-
-#include <asm/i8259.h>
-#include <asm/io_apic.h>
-#include <asm/proto.h>
-#include <asm/timer.h>
-
-#include <asm/mce.h>
-
-#include <asm/mach_traps.h>
-
-int unknown_nmi_panic;
-int nmi_watchdog_enabled;
-
-/* For reliability, we're prepared to waste bits here. */
-static DECLARE_BITMAP(backtrace_mask, NR_CPUS) __read_mostly;
-
-/* nmi_active:
- * >0: the lapic NMI watchdog is active, but can be disabled
- * <0: the lapic NMI watchdog has not been set up, and cannot
- *     be enabled
- *  0: the lapic NMI watchdog is disabled, but can be enabled
- */
-atomic_t nmi_active = ATOMIC_INIT(0);           /* oprofile uses this */
-EXPORT_SYMBOL(nmi_active);
-
-unsigned int nmi_watchdog = NMI_NONE;
-EXPORT_SYMBOL(nmi_watchdog);
-
-static int panic_on_timeout;
-
-static unsigned int nmi_hz = HZ;
-static DEFINE_PER_CPU(short, wd_enabled);
-static int endflag __initdata;
-
-static inline unsigned int get_nmi_count(int cpu)
-{
-        return per_cpu(irq_stat, cpu).__nmi_count;
-}
-
-static inline int mce_in_progress(void)
-{
-#if defined(CONFIG_X86_MCE)
-        return atomic_read(&mce_entry) > 0;
-#endif
-        return 0;
-}
-
-/*
- * Take the local apic timer and PIT/HPET into account. We don't
- * know which one is active, when we have highres/dyntick on
- */
-static inline unsigned int get_timer_irqs(int cpu)
-{
-        return per_cpu(irq_stat, cpu).apic_timer_irqs +
-                per_cpu(irq_stat, cpu).irq0_irqs;
-}
-
-#ifdef CONFIG_SMP
-/*
- * The performance counters used by NMI_LOCAL_APIC don't trigger when
- * the CPU is idle. To make sure the NMI watchdog really ticks on all
- * CPUs during the test make them busy.
- */
-static __init void nmi_cpu_busy(void *data)
-{
-        local_irq_enable_in_hardirq();
-        /*
-         * Intentionally don't use cpu_relax here. This is
-         * to make sure that the performance counter really ticks,
-         * even if there is a simulator or similar that catches the
-         * pause instruction. On a real HT machine this is fine because
-         * all other CPUs are busy with "useless" delay loops and don't
-         * care if they get somewhat less cycles.
-         */
-        while (endflag == 0)
-                mb();
-}
-#endif
-
-static void report_broken_nmi(int cpu, unsigned int *prev_nmi_count)
-{
-        printk(KERN_CONT "\n");
-
-        printk(KERN_WARNING
-                "WARNING: CPU#%d: NMI appears to be stuck (%d->%d)!\n",
-                        cpu, prev_nmi_count[cpu], get_nmi_count(cpu));
-
-        printk(KERN_WARNING
-                "Please report this to bugzilla.kernel.org,\n");
-        printk(KERN_WARNING
-                "and attach the output of the 'dmesg' command.\n");
-
-        per_cpu(wd_enabled, cpu) = 0;
-        atomic_dec(&nmi_active);
-}
-
-static void __acpi_nmi_disable(void *__unused)
-{
-        apic_write(APIC_LVT0, APIC_DM_NMI | APIC_LVT_MASKED);
-}
-
-int __init check_nmi_watchdog(void)
-{
-        unsigned int *prev_nmi_count;
-        int cpu;
-
-        if (!nmi_watchdog_active() || !atomic_read(&nmi_active))
-                return 0;
-
-        prev_nmi_count = kmalloc(nr_cpu_ids * sizeof(int), GFP_KERNEL);
-        if (!prev_nmi_count)
-                goto error;
-
-        printk(KERN_INFO "Testing NMI watchdog ... ");
-
-#ifdef CONFIG_SMP
-        if (nmi_watchdog == NMI_LOCAL_APIC)
-                smp_call_function(nmi_cpu_busy, (void *)&endflag, 0);
-#endif
-
-        for_each_possible_cpu(cpu)
-                prev_nmi_count[cpu] = get_nmi_count(cpu);
-        local_irq_enable();
-        mdelay((20 * 1000) / nmi_hz); /* wait 20 ticks */
-
-        for_each_online_cpu(cpu) {
-                if (!per_cpu(wd_enabled, cpu))
-                        continue;
-                if (get_nmi_count(cpu) - prev_nmi_count[cpu] <= 5)
-                        report_broken_nmi(cpu, prev_nmi_count);
-        }
-        endflag = 1;
-        if (!atomic_read(&nmi_active)) {
-                kfree(prev_nmi_count);
-                atomic_set(&nmi_active, -1);
-                goto error;
-        }
-        printk("OK.\n");
-
-        /*
-         * now that we know it works we can reduce NMI frequency to
-         * something more reasonable; makes a difference in some configs
-         */
-        if (nmi_watchdog == NMI_LOCAL_APIC)
-                nmi_hz = lapic_adjust_nmi_hz(1);
-
-        kfree(prev_nmi_count);
-        return 0;
-error:
-        if (nmi_watchdog == NMI_IO_APIC) {
-                if (!timer_through_8259)
-                        legacy_pic->mask(0);
-                on_each_cpu(__acpi_nmi_disable, NULL, 1);
-        }
-
-#ifdef CONFIG_X86_32
-        timer_ack = 0;
-#endif
-        return -1;
-}
-
-static int __init setup_nmi_watchdog(char *str)
-{
-        unsigned int nmi;
-
-        if (!strncmp(str, "panic", 5)) {
-                panic_on_timeout = 1;
-                str = strchr(str, ',');
-                if (!str)
-                        return 1;
-                ++str;
-        }
-
-        if (!strncmp(str, "lapic", 5))
-                nmi_watchdog = NMI_LOCAL_APIC;
-        else if (!strncmp(str, "ioapic", 6))
-                nmi_watchdog = NMI_IO_APIC;
-        else {
-                get_option(&str, &nmi);
-                if (nmi >= NMI_INVALID)
-                        return 0;
-                nmi_watchdog = nmi;
-        }
-
-        return 1;
-}
-__setup("nmi_watchdog=", setup_nmi_watchdog);
-
-/*
- * Suspend/resume support
- */
-#ifdef CONFIG_PM
-
-static int nmi_pm_active; /* nmi_active before suspend */
-
-static int lapic_nmi_suspend(struct sys_device *dev, pm_message_t state)
-{
-        /* only CPU0 goes here, other CPUs should be offline */
-        nmi_pm_active = atomic_read(&nmi_active);
-        stop_apic_nmi_watchdog(NULL);
-        BUG_ON(atomic_read(&nmi_active) != 0);
-        return 0;
-}
-
-static int lapic_nmi_resume(struct sys_device *dev)
-{
-        /* only CPU0 goes here, other CPUs should be offline */
-        if (nmi_pm_active > 0) {
-                setup_apic_nmi_watchdog(NULL);
-                touch_nmi_watchdog();
-        }
-        return 0;
-}
-
-static struct sysdev_class nmi_sysclass = {
-        .name           = "lapic_nmi",
-        .resume         = lapic_nmi_resume,
-        .suspend        = lapic_nmi_suspend,
-};
-
-static struct sys_device device_lapic_nmi = {
-        .id     = 0,
-        .cls    = &nmi_sysclass,
-};
-
-static int __init init_lapic_nmi_sysfs(void)
-{
-        int error;
-
-        /*
-         * should really be a BUG_ON but b/c this is an
-         * init call, it just doesn't work.  -dcz
-         */
-        if (nmi_watchdog != NMI_LOCAL_APIC)
-                return 0;
-
-        if (atomic_read(&nmi_active) < 0)
-                return 0;
-
-        error = sysdev_class_register(&nmi_sysclass);
-        if (!error)
-                error = sysdev_register(&device_lapic_nmi);
-        return error;
-}
-
-/* must come after the local APIC's device_initcall() */
-late_initcall(init_lapic_nmi_sysfs);
-
-#endif  /* CONFIG_PM */
-
-static void __acpi_nmi_enable(void *__unused)
-{
-        apic_write(APIC_LVT0, APIC_DM_NMI);
-}
-
-/*
- * Enable timer based NMIs on all CPUs:
- */
-void acpi_nmi_enable(void)
-{
-        if (atomic_read(&nmi_active) && nmi_watchdog == NMI_IO_APIC)
-                on_each_cpu(__acpi_nmi_enable, NULL, 1);
-}
-
-/*
- * Disable timer based NMIs on all CPUs:
- */
-void acpi_nmi_disable(void)
-{
-        if (atomic_read(&nmi_active) && nmi_watchdog == NMI_IO_APIC)
-                on_each_cpu(__acpi_nmi_disable, NULL, 1);
-}
-
-/*
- * This function is called as soon the LAPIC NMI watchdog driver has everything
- * in place and it's ready to check if the NMIs belong to the NMI watchdog
- */
-void cpu_nmi_set_wd_enabled(void)
-{
-        __get_cpu_var(wd_enabled) = 1;
-}
-
-void setup_apic_nmi_watchdog(void *unused)
-{
-        if (__get_cpu_var(wd_enabled))
-                return;
-
-        /* cheap hack to support suspend/resume */
-        /* if cpu0 is not active neither should the other cpus */
-        if (smp_processor_id() != 0 && atomic_read(&nmi_active) <= 0)
-                return;
-
-        switch (nmi_watchdog) {
-        case NMI_LOCAL_APIC:
-                if (lapic_watchdog_init(nmi_hz) < 0) {
-                        __get_cpu_var(wd_enabled) = 0;
-                        return;
-                }
-                /* FALL THROUGH */
-        case NMI_IO_APIC:
-                __get_cpu_var(wd_enabled) = 1;
-                atomic_inc(&nmi_active);
-        }
-}
-
-void stop_apic_nmi_watchdog(void *unused)
-{
-        /* only support LOCAL and IO APICs for now */
-        if (!nmi_watchdog_active())
-                return;
-        if (__get_cpu_var(wd_enabled) == 0)
-                return;
-        if (nmi_watchdog == NMI_LOCAL_APIC)
-                lapic_watchdog_stop();
-        else
-                __acpi_nmi_disable(NULL);
-        __get_cpu_var(wd_enabled) = 0;
-        atomic_dec(&nmi_active);
-}
-
-/*
- * the best way to detect whether a CPU has a 'hard lockup' problem
- * is to check it's local APIC timer IRQ counts. If they are not
- * changing then that CPU has some problem.
- *
- * as these watchdog NMI IRQs are generated on every CPU, we only
- * have to check the current processor.
- *
- * since NMIs don't listen to _any_ locks, we have to be extremely
- * careful not to rely on unsafe variables. The printk might lock
- * up though, so we have to break up any console locks first ...
- * [when there will be more tty-related locks, break them up here too!]
- */
-
-static DEFINE_PER_CPU(unsigned, last_irq_sum);
-static DEFINE_PER_CPU(long, alert_counter);
-static DEFINE_PER_CPU(int, nmi_touch);
-
-void touch_nmi_watchdog(void)
-{
-        if (nmi_watchdog_active()) {
-                unsigned cpu;
-
-                /*
-                 * Tell other CPUs to reset their alert counters. We cannot
-                 * do it ourselves because the alert count increase is not
-                 * atomic.
-                 */
-                for_each_present_cpu(cpu) {
-                        if (per_cpu(nmi_touch, cpu) != 1)
-                                per_cpu(nmi_touch, cpu) = 1;
-                }
-        }
-
-        /*
-         * Tickle the softlockup detector too:
-         */
-        touch_softlockup_watchdog();
-}
-EXPORT_SYMBOL(touch_nmi_watchdog);
-
-notrace __kprobes int
-nmi_watchdog_tick(struct pt_regs *regs, unsigned reason)
-{
-        /*
-         * Since current_thread_info()-> is always on the stack, and we
-         * always switch the stack NMI-atomically, it's safe to use
-         * smp_processor_id().
-         */
-        unsigned int sum;
-        int touched = 0;
-        int cpu = smp_processor_id();
-        int rc = 0;
-
-        sum = get_timer_irqs(cpu);
-
-        if (__get_cpu_var(nmi_touch)) {
-                __get_cpu_var(nmi_touch) = 0;
-                touched = 1;
-        }
-
-        /* We can be called before check_nmi_watchdog, hence NULL check. */
-        if (cpumask_test_cpu(cpu, to_cpumask(backtrace_mask))) {
-                static DEFINE_RAW_SPINLOCK(lock); /* Serialise the printks */
-
-                raw_spin_lock(&lock);
-                printk(KERN_WARNING "NMI backtrace for cpu %d\n", cpu);
-                show_regs(regs);
-                dump_stack();
-                raw_spin_unlock(&lock);
-                cpumask_clear_cpu(cpu, to_cpumask(backtrace_mask));
-
-                rc = 1;
-        }
-
-        /* Could check oops_in_progress here too, but it's safer not to */
-        if (mce_in_progress())
-                touched = 1;
-
-        /* if the none of the timers isn't firing, this cpu isn't doing much */
-        if (!touched && __get_cpu_var(last_irq_sum) == sum) {
-                /*
-                 * Ayiee, looks like this CPU is stuck ...
-                 * wait a few IRQs (5 seconds) before doing the oops ...
-                 */
-                __this_cpu_inc(alert_counter);
-                if (__this_cpu_read(alert_counter) == 5 * nmi_hz)
-                        /*
-                         * die_nmi will return ONLY if NOTIFY_STOP happens..
-                         */
-                        die_nmi("BUG: NMI Watchdog detected LOCKUP",
-                                regs, panic_on_timeout);
-        } else {
-                __get_cpu_var(last_irq_sum) = sum;
-                __this_cpu_write(alert_counter, 0);
-        }
-
-        /* see if the nmi watchdog went off */
-        if (!__get_cpu_var(wd_enabled))
-                return rc;
-        switch (nmi_watchdog) {
-        case NMI_LOCAL_APIC:
-                rc |= lapic_wd_event(nmi_hz);
-                break;
-        case NMI_IO_APIC:
-                /*
-                 * don't know how to accurately check for this.
-                 * just assume it was a watchdog timer interrupt
-                 * This matches the old behaviour.
-                 */
-                rc = 1;
-                break;
-        }
-        return rc;
-}
-
-#ifdef CONFIG_SYSCTL
-
-static void enable_ioapic_nmi_watchdog_single(void *unused)
-{
-        __get_cpu_var(wd_enabled) = 1;
-        atomic_inc(&nmi_active);
-        __acpi_nmi_enable(NULL);
-}
-
-static void enable_ioapic_nmi_watchdog(void)
-{
-        on_each_cpu(enable_ioapic_nmi_watchdog_single, NULL, 1);
-        touch_nmi_watchdog();
-}
-
-static void disable_ioapic_nmi_watchdog(void)
-{
-        on_each_cpu(stop_apic_nmi_watchdog, NULL, 1);
-}
-
-static int __init setup_unknown_nmi_panic(char *str)
-{
-        unknown_nmi_panic = 1;
-        return 1;
-}
-__setup("unknown_nmi_panic", setup_unknown_nmi_panic);
-
-static int unknown_nmi_panic_callback(struct pt_regs *regs, int cpu)
-{
-        unsigned char reason = get_nmi_reason();
-        char buf[64];
-
-        sprintf(buf, "NMI received for unknown reason %02x\n", reason);
-        die_nmi(buf, regs, 1); /* Always panic here */
-        return 0;
-}
-
-/*
- * proc handler for /proc/sys/kernel/nmi
- */
-int proc_nmi_enabled(struct ctl_table *table, int write,
-                        void __user *buffer, size_t *length, loff_t *ppos)
-{
-        int old_state;
-
-        nmi_watchdog_enabled = (atomic_read(&nmi_active) > 0) ? 1 : 0;
-        old_state = nmi_watchdog_enabled;
-        proc_dointvec(table, write, buffer, length, ppos);
-        if (!!old_state == !!nmi_watchdog_enabled)
-                return 0;
-
-        if (atomic_read(&nmi_active) < 0 || !nmi_watchdog_active()) {
-                printk(KERN_WARNING
-                        "NMI watchdog is permanently disabled\n");
-                return -EIO;
-        }
-
-        if (nmi_watchdog == NMI_LOCAL_APIC) {
-                if (nmi_watchdog_enabled)
-                        enable_lapic_nmi_watchdog();
-                else
-                        disable_lapic_nmi_watchdog();
-        } else if (nmi_watchdog == NMI_IO_APIC) {
-                if (nmi_watchdog_enabled)
-                        enable_ioapic_nmi_watchdog();
-                else
-                        disable_ioapic_nmi_watchdog();
-        } else {
-                printk(KERN_WARNING
-                        "NMI watchdog doesn't know what hardware to touch\n");
-                return -EIO;
-        }
-        return 0;
-}
-
-#endif /* CONFIG_SYSCTL */
-
-int do_nmi_callback(struct pt_regs *regs, int cpu)
-{
-#ifdef CONFIG_SYSCTL
-        if (unknown_nmi_panic)
-                return unknown_nmi_panic_callback(regs, cpu);
-#endif
-        return 0;
-}
-
-void arch_trigger_all_cpu_backtrace(void)
-{
-        int i;
-
-        cpumask_copy(to_cpumask(backtrace_mask), cpu_online_mask);
-
-        printk(KERN_INFO "sending NMI to all CPUs:\n");
-        apic->send_IPI_all(NMI_VECTOR);
-
-        /* Wait for up to 10 seconds for all CPUs to do the backtrace */
-        for (i = 0; i < 10 * 1000; i++) {
-                if (cpumask_empty(to_cpumask(backtrace_mask)))
-                        break;
-                mdelay(1);
-        }
-}