Merge branch 'timers-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull timer updates from Thomas Gleixner:
 - watchdog fixes for full dynticks
 - improved debug output for full dynticks
 - remove an obsolete full dynticks check
 - two ARM SoC clocksource drivers for sharing across SoCs
 - tick broadcast fix for CPU hotplug

* 'timers-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  tick: broadcast: Check broadcast mode on CPU hotplug
  clocksource: arm_global_timer: Add ARM global timer support
  clocksource: Add Marvell Orion SoC timer
  nohz: Remove obsolete check for full dynticks CPUs to be RCU nocbs
  watchdog: Boot-disable by default on full dynticks
  watchdog: Rename confusing state variable
  watchdog: Register / unregister watchdog kthreads on sysctl control
  nohz: Warn if the machine can not perform nohz_full

11 files changed, 608 insertions, 63 deletions

diff --git a/Documentation/devicetree/bindings/arm/global_timer.txt b/Documentation/devicetree/bindings/arm/global_timer.txt
new file mode 100644
index 000000000000..1e548981eda4
--- /dev/null
+++ b/Documentation/devicetree/bindings/arm/global_timer.txt
@@ -0,0 +1,24 @@
+
+* ARM Global Timer
+        Cortex-A9 are often associated with a per-core Global timer.
+
+** Timer node required properties:
+
+- compatible : Should be "arm,cortex-a9-global-timer"
+                Driver supports versions r2p0 and above.
+
+- interrupts : One interrupt to each core
+
+- reg : Specify the base address and the size of the GT timer
+        register window.
+
+- clocks : Should be phandle to a clock.
+
+Example:
+
+        timer@2c000600 {
+                compatible = "arm,cortex-a9-global-timer";
+                reg = <0x2c000600 0x20>;
+                interrupts = <1 13 0xf01>;
+                clocks = <&arm_periph_clk>;
+        };
diff --git a/Documentation/devicetree/bindings/timer/marvell,orion-timer.txt b/Documentation/devicetree/bindings/timer/marvell,orion-timer.txt
new file mode 100644
index 000000000000..62bb8260cf6a
--- /dev/null
+++ b/Documentation/devicetree/bindings/timer/marvell,orion-timer.txt
@@ -0,0 +1,17 @@
+Marvell Orion SoC timer
+
+Required properties:
+- compatible: shall be "marvell,orion-timer"
+- reg: base address of the timer register starting with TIMERS CONTROL register
+- interrupt-parent: phandle of the bridge interrupt controller
+- interrupts: should contain the interrupts for Timer0 and Timer1
+- clocks: phandle of timer reference clock (tclk)
+
+Example:
+        timer: timer {
+                compatible = "marvell,orion-timer";
+                reg = <0x20300 0x20>;
+                interrupt-parent = <&bridge_intc>;
+                interrupts = <1>, <2>;
+                clocks = <&core_clk 0>;
+        };
diff --git a/drivers/clocksource/Kconfig b/drivers/clocksource/Kconfig
index 81465c21f873..b7b9b040a89b 100644
--- a/drivers/clocksource/Kconfig
+++ b/drivers/clocksource/Kconfig
@@ -27,6 +27,11 @@ config DW_APB_TIMER_OF
 config ARMADA_370_XP_TIMER
         bool
 
+config ORION_TIMER
+        select CLKSRC_OF
+        select CLKSRC_MMIO
+        bool
+
 config SUN4I_TIMER
         bool
 
@@ -69,6 +74,19 @@ config ARM_ARCH_TIMER
         bool
         select CLKSRC_OF if OF
 
+config ARM_GLOBAL_TIMER
+        bool
+        select CLKSRC_OF if OF
+        help
+          This options enables support for the ARM global timer unit
+
+config CLKSRC_ARM_GLOBAL_TIMER_SCHED_CLOCK
+        bool
+        depends on ARM_GLOBAL_TIMER
+        default y
+        help
+         Use ARM global timer clock source as sched_clock
+
 config CLKSRC_METAG_GENERIC
         def_bool y if METAG
         help
diff --git a/drivers/clocksource/Makefile b/drivers/clocksource/Makefile
index 9ba8b4d867e3..8b00c5cebfa4 100644
--- a/drivers/clocksource/Makefile
+++ b/drivers/clocksource/Makefile
@@ -15,6 +15,7 @@ obj-$(CONFIG_DW_APB_TIMER_OF)	+= dw_apb_timer_of.o
 obj-$(CONFIG_CLKSRC_NOMADIK_MTU)        += nomadik-mtu.o
 obj-$(CONFIG_CLKSRC_DBX500_PRCMU)       += clksrc-dbx500-prcmu.o
 obj-$(CONFIG_ARMADA_370_XP_TIMER)       += time-armada-370-xp.o
+obj-$(CONFIG_ORION_TIMER)       += time-orion.o
 obj-$(CONFIG_ARCH_BCM2835)      += bcm2835_timer.o
 obj-$(CONFIG_ARCH_MARCO)        += timer-marco.o
 obj-$(CONFIG_ARCH_MXS)          += mxs_timer.o
@@ -30,5 +31,6 @@ obj-$(CONFIG_CLKSRC_SAMSUNG_PWM)	+= samsung_pwm_timer.o
 obj-$(CONFIG_VF_PIT_TIMER)      += vf_pit_timer.o
 
 obj-$(CONFIG_ARM_ARCH_TIMER)            += arm_arch_timer.o
+obj-$(CONFIG_ARM_GLOBAL_TIMER)          += arm_global_timer.o
 obj-$(CONFIG_CLKSRC_METAG_GENERIC)      += metag_generic.o
 obj-$(CONFIG_ARCH_HAS_TICK_BROADCAST)   += dummy_timer.o
diff --git a/drivers/clocksource/arm_global_timer.c b/drivers/clocksource/arm_global_timer.c
new file mode 100644
index 000000000000..db8afc7427a6
--- /dev/null
+++ b/drivers/clocksource/arm_global_timer.c
@@ -0,0 +1,321 @@
+/*
+ * drivers/clocksource/arm_global_timer.c
+ *
+ * Copyright (C) 2013 STMicroelectronics (R&D) Limited.
+ * Author: Stuart Menefy <stuart.menefy@st.com>
+ * Author: Srinivas Kandagatla <srinivas.kandagatla@st.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#include <linux/init.h>
+#include <linux/interrupt.h>
+#include <linux/clocksource.h>
+#include <linux/clockchips.h>
+#include <linux/cpu.h>
+#include <linux/clk.h>
+#include <linux/err.h>
+#include <linux/io.h>
+#include <linux/of.h>
+#include <linux/of_irq.h>
+#include <linux/of_address.h>
+#include <linux/sched_clock.h>
+
+#include <asm/cputype.h>
+
+#define GT_COUNTER0     0x00
+#define GT_COUNTER1     0x04
+
+#define GT_CONTROL      0x08
+#define GT_CONTROL_TIMER_ENABLE         BIT(0)  /* this bit is NOT banked */
+#define GT_CONTROL_COMP_ENABLE          BIT(1)  /* banked */
+#define GT_CONTROL_IRQ_ENABLE           BIT(2)  /* banked */
+#define GT_CONTROL_AUTO_INC             BIT(3)  /* banked */
+
+#define GT_INT_STATUS   0x0c
+#define GT_INT_STATUS_EVENT_FLAG        BIT(0)
+
+#define GT_COMP0        0x10
+#define GT_COMP1        0x14
+#define GT_AUTO_INC     0x18
+
+/*
+ * We are expecting to be clocked by the ARM peripheral clock.
+ *
+ * Note: it is assumed we are using a prescaler value of zero, so this is
+ * the units for all operations.
+ */
+static void __iomem *gt_base;
+static unsigned long gt_clk_rate;
+static int gt_ppi;
+static struct clock_event_device __percpu *gt_evt;
+
+/*
+ * To get the value from the Global Timer Counter register proceed as follows:
+ * 1. Read the upper 32-bit timer counter register
+ * 2. Read the lower 32-bit timer counter register
+ * 3. Read the upper 32-bit timer counter register again. If the value is
+ *  different to the 32-bit upper value read previously, go back to step 2.
+ *  Otherwise the 64-bit timer counter value is correct.
+ */
+static u64 gt_counter_read(void)
+{
+        u64 counter;
+        u32 lower;
+        u32 upper, old_upper;
+
+        upper = readl_relaxed(gt_base + GT_COUNTER1);
+        do {
+                old_upper = upper;
+                lower = readl_relaxed(gt_base + GT_COUNTER0);
+                upper = readl_relaxed(gt_base + GT_COUNTER1);
+        } while (upper != old_upper);
+
+        counter = upper;
+        counter <<= 32;
+        counter |= lower;
+        return counter;
+}
+
+/**
+ * To ensure that updates to comparator value register do not set the
+ * Interrupt Status Register proceed as follows:
+ * 1. Clear the Comp Enable bit in the Timer Control Register.
+ * 2. Write the lower 32-bit Comparator Value Register.
+ * 3. Write the upper 32-bit Comparator Value Register.
+ * 4. Set the Comp Enable bit and, if necessary, the IRQ enable bit.
+ */
+static void gt_compare_set(unsigned long delta, int periodic)
+{
+        u64 counter = gt_counter_read();
+        unsigned long ctrl;
+
+        counter += delta;
+        ctrl = GT_CONTROL_TIMER_ENABLE;
+        writel(ctrl, gt_base + GT_CONTROL);
+        writel(lower_32_bits(counter), gt_base + GT_COMP0);
+        writel(upper_32_bits(counter), gt_base + GT_COMP1);
+
+        if (periodic) {
+                writel(delta, gt_base + GT_AUTO_INC);
+                ctrl |= GT_CONTROL_AUTO_INC;
+        }
+
+        ctrl |= GT_CONTROL_COMP_ENABLE | GT_CONTROL_IRQ_ENABLE;
+        writel(ctrl, gt_base + GT_CONTROL);
+}
+
+static void gt_clockevent_set_mode(enum clock_event_mode mode,
+                                   struct clock_event_device *clk)
+{
+        unsigned long ctrl;
+
+        switch (mode) {
+        case CLOCK_EVT_MODE_PERIODIC:
+                gt_compare_set(DIV_ROUND_CLOSEST(gt_clk_rate, HZ), 1);
+                break;
+        case CLOCK_EVT_MODE_ONESHOT:
+        case CLOCK_EVT_MODE_UNUSED:
+        case CLOCK_EVT_MODE_SHUTDOWN:
+                ctrl = readl(gt_base + GT_CONTROL);
+                ctrl &= ~(GT_CONTROL_COMP_ENABLE |
+                                GT_CONTROL_IRQ_ENABLE | GT_CONTROL_AUTO_INC);
+                writel(ctrl, gt_base + GT_CONTROL);
+                break;
+        default:
+                break;
+        }
+}
+
+static int gt_clockevent_set_next_event(unsigned long evt,
+                                        struct clock_event_device *unused)
+{
+        gt_compare_set(evt, 0);
+        return 0;
+}
+
+static irqreturn_t gt_clockevent_interrupt(int irq, void *dev_id)
+{
+        struct clock_event_device *evt = dev_id;
+
+        if (!(readl_relaxed(gt_base + GT_INT_STATUS) &
+                                GT_INT_STATUS_EVENT_FLAG))
+                return IRQ_NONE;
+
+        /**
+         * ERRATA 740657( Global Timer can send 2 interrupts for
+         * the same event in single-shot mode)
+         * Workaround:
+         *      Either disable single-shot mode.
+         *      Or
+         *      Modify the Interrupt Handler to avoid the
+         *      offending sequence. This is achieved by clearing
+         *      the Global Timer flag _after_ having incremented
+         *      the Comparator register value to a higher value.
+         */
+        if (evt->mode == CLOCK_EVT_MODE_ONESHOT)
+                gt_compare_set(ULONG_MAX, 0);
+
+        writel_relaxed(GT_INT_STATUS_EVENT_FLAG, gt_base + GT_INT_STATUS);
+        evt->event_handler(evt);
+
+        return IRQ_HANDLED;
+}
+
+static int __cpuinit gt_clockevents_init(struct clock_event_device *clk)
+{
+        int cpu = smp_processor_id();
+
+        clk->name = "arm_global_timer";
+        clk->features = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT;
+        clk->set_mode = gt_clockevent_set_mode;
+        clk->set_next_event = gt_clockevent_set_next_event;
+        clk->cpumask = cpumask_of(cpu);
+        clk->rating = 300;
+        clk->irq = gt_ppi;
+        clockevents_config_and_register(clk, gt_clk_rate,
+                                        1, 0xffffffff);
+        enable_percpu_irq(clk->irq, IRQ_TYPE_NONE);
+        return 0;
+}
+
+static void gt_clockevents_stop(struct clock_event_device *clk)
+{
+        gt_clockevent_set_mode(CLOCK_EVT_MODE_UNUSED, clk);
+        disable_percpu_irq(clk->irq);
+}
+
+static cycle_t gt_clocksource_read(struct clocksource *cs)
+{
+        return gt_counter_read();
+}
+
+static struct clocksource gt_clocksource = {
+        .name   = "arm_global_timer",
+        .rating = 300,
+        .read   = gt_clocksource_read,
+        .mask   = CLOCKSOURCE_MASK(64),
+        .flags  = CLOCK_SOURCE_IS_CONTINUOUS,
+};
+
+#ifdef CONFIG_CLKSRC_ARM_GLOBAL_TIMER_SCHED_CLOCK
+static u32 notrace gt_sched_clock_read(void)
+{
+        return gt_counter_read();
+}
+#endif
+
+static void __init gt_clocksource_init(void)
+{
+        writel(0, gt_base + GT_CONTROL);
+        writel(0, gt_base + GT_COUNTER0);
+        writel(0, gt_base + GT_COUNTER1);
+        /* enables timer on all the cores */
+        writel(GT_CONTROL_TIMER_ENABLE, gt_base + GT_CONTROL);
+
+#ifdef CONFIG_CLKSRC_ARM_GLOBAL_TIMER_SCHED_CLOCK
+        setup_sched_clock(gt_sched_clock_read, 32, gt_clk_rate);
+#endif
+        clocksource_register_hz(&gt_clocksource, gt_clk_rate);
+}
+
+static int __cpuinit gt_cpu_notify(struct notifier_block *self,
+                                           unsigned long action, void *hcpu)
+{
+        switch (action & ~CPU_TASKS_FROZEN) {
+        case CPU_STARTING:
+                gt_clockevents_init(this_cpu_ptr(gt_evt));
+                break;
+        case CPU_DYING:
+                gt_clockevents_stop(this_cpu_ptr(gt_evt));
+                break;
+        }
+
+        return NOTIFY_OK;
+}
+static struct notifier_block gt_cpu_nb __cpuinitdata = {
+        .notifier_call = gt_cpu_notify,
+};
+
+static void __init global_timer_of_register(struct device_node *np)
+{
+        struct clk *gt_clk;
+        int err = 0;
+
+        /*
+         * In r2p0 the comparators for each processor with the global timer
+         * fire when the timer value is greater than or equal to. In previous
+         * revisions the comparators fired when the timer value was equal to.
+         */
+        if ((read_cpuid_id() & 0xf0000f) < 0x200000) {
+                pr_warn("global-timer: non support for this cpu version.\n");
+                return;
+        }
+
+        gt_ppi = irq_of_parse_and_map(np, 0);
+        if (!gt_ppi) {
+                pr_warn("global-timer: unable to parse irq\n");
+                return;
+        }
+
+        gt_base = of_iomap(np, 0);
+        if (!gt_base) {
+                pr_warn("global-timer: invalid base address\n");
+                return;
+        }
+
+        gt_clk = of_clk_get(np, 0);
+        if (!IS_ERR(gt_clk)) {
+                err = clk_prepare_enable(gt_clk);
+                if (err)
+                        goto out_unmap;
+        } else {
+                pr_warn("global-timer: clk not found\n");
+                err = -EINVAL;
+                goto out_unmap;
+        }
+
+        gt_clk_rate = clk_get_rate(gt_clk);
+        gt_evt = alloc_percpu(struct clock_event_device);
+        if (!gt_evt) {
+                pr_warn("global-timer: can't allocate memory\n");
+                err = -ENOMEM;
+                goto out_clk;
+        }
+
+        err = request_percpu_irq(gt_ppi, gt_clockevent_interrupt,
+                                 "gt", gt_evt);
+        if (err) {
+                pr_warn("global-timer: can't register interrupt %d (%d)\n",
+                        gt_ppi, err);
+                goto out_free;
+        }
+
+        err = register_cpu_notifier(&gt_cpu_nb);
+        if (err) {
+                pr_warn("global-timer: unable to register cpu notifier.\n");
+                goto out_irq;
+        }
+
+        /* Immediately configure the timer on the boot CPU */
+        gt_clocksource_init();
+        gt_clockevents_init(this_cpu_ptr(gt_evt));
+
+        return;
+
+out_irq:
+        free_percpu_irq(gt_ppi, gt_evt);
+out_free:
+        free_percpu(gt_evt);
+out_clk:
+        clk_disable_unprepare(gt_clk);
+out_unmap:
+        iounmap(gt_base);
+        WARN(err, "ARM Global timer register failed (%d)\n", err);
+}
+
+/* Only tested on r2p2 and r3p0  */
+CLOCKSOURCE_OF_DECLARE(arm_gt, "arm,cortex-a9-global-timer",
+                        global_timer_of_register);
diff --git a/drivers/clocksource/time-orion.c b/drivers/clocksource/time-orion.c
new file mode 100644
index 000000000000..ecbeb6810215
--- /dev/null
+++ b/drivers/clocksource/time-orion.c
@@ -0,0 +1,150 @@
+/*
+ * Marvell Orion SoC timer handling.
+ *
+ * Sebastian Hesselbarth <sebastian.hesselbarth@gmail.com>
+ *
+ * This file is licensed under the terms of the GNU General Public
+ * License version 2.  This program is licensed "as is" without any
+ * warranty of any kind, whether express or implied.
+ *
+ * Timer 0 is used as free-running clocksource, while timer 1 is
+ * used as clock_event_device.
+ */
+
+#include <linux/kernel.h>
+#include <linux/bitops.h>
+#include <linux/clk.h>
+#include <linux/clockchips.h>
+#include <linux/interrupt.h>
+#include <linux/of_address.h>
+#include <linux/of_irq.h>
+#include <linux/spinlock.h>
+#include <asm/sched_clock.h>
+
+#define TIMER_CTRL              0x00
+#define  TIMER0_EN              BIT(0)
+#define  TIMER0_RELOAD_EN       BIT(1)
+#define  TIMER1_EN              BIT(2)
+#define  TIMER1_RELOAD_EN       BIT(3)
+#define TIMER0_RELOAD           0x10
+#define TIMER0_VAL              0x14
+#define TIMER1_RELOAD           0x18
+#define TIMER1_VAL              0x1c
+
+#define ORION_ONESHOT_MIN       1
+#define ORION_ONESHOT_MAX       0xfffffffe
+
+static void __iomem *timer_base;
+static DEFINE_SPINLOCK(timer_ctrl_lock);
+
+/*
+ * Thread-safe access to TIMER_CTRL register
+ * (shared with watchdog timer)
+ */
+void orion_timer_ctrl_clrset(u32 clr, u32 set)
+{
+        spin_lock(&timer_ctrl_lock);
+        writel((readl(timer_base + TIMER_CTRL) & ~clr) | set,
+                timer_base + TIMER_CTRL);
+        spin_unlock(&timer_ctrl_lock);
+}
+EXPORT_SYMBOL(orion_timer_ctrl_clrset);
+
+/*
+ * Free-running clocksource handling.
+ */
+static u32 notrace orion_read_sched_clock(void)
+{
+        return ~readl(timer_base + TIMER0_VAL);
+}
+
+/*
+ * Clockevent handling.
+ */
+static u32 ticks_per_jiffy;
+
+static int orion_clkevt_next_event(unsigned long delta,
+                                   struct clock_event_device *dev)
+{
+        /* setup and enable one-shot timer */
+        writel(delta, timer_base + TIMER1_VAL);
+        orion_timer_ctrl_clrset(TIMER1_RELOAD_EN, TIMER1_EN);
+
+        return 0;
+}
+
+static void orion_clkevt_mode(enum clock_event_mode mode,
+                              struct clock_event_device *dev)
+{
+        if (mode == CLOCK_EVT_MODE_PERIODIC) {
+                /* setup and enable periodic timer at 1/HZ intervals */
+                writel(ticks_per_jiffy - 1, timer_base + TIMER1_RELOAD);
+                writel(ticks_per_jiffy - 1, timer_base + TIMER1_VAL);
+                orion_timer_ctrl_clrset(0, TIMER1_RELOAD_EN | TIMER1_EN);
+        } else {
+                /* disable timer */
+                orion_timer_ctrl_clrset(TIMER1_RELOAD_EN | TIMER1_EN, 0);
+        }
+}
+
+static struct clock_event_device orion_clkevt = {
+        .name           = "orion_event",
+        .features       = CLOCK_EVT_FEAT_ONESHOT | CLOCK_EVT_FEAT_PERIODIC,
+        .shift          = 32,
+        .rating         = 300,
+        .set_next_event = orion_clkevt_next_event,
+        .set_mode       = orion_clkevt_mode,
+};
+
+static irqreturn_t orion_clkevt_irq_handler(int irq, void *dev_id)
+{
+        orion_clkevt.event_handler(&orion_clkevt);
+        return IRQ_HANDLED;
+}
+
+static struct irqaction orion_clkevt_irq = {
+        .name           = "orion_event",
+        .flags          = IRQF_TIMER,
+        .handler        = orion_clkevt_irq_handler,
+};
+
+static void __init orion_timer_init(struct device_node *np)
+{
+        struct clk *clk;
+        int irq;
+
+        /* timer registers are shared with watchdog timer */
+        timer_base = of_iomap(np, 0);
+        if (!timer_base)
+                panic("%s: unable to map resource\n", np->name);
+
+        clk = of_clk_get(np, 0);
+        if (IS_ERR(clk))
+                panic("%s: unable to get clk\n", np->name);
+        clk_prepare_enable(clk);
+
+        /* we are only interested in timer1 irq */
+        irq = irq_of_parse_and_map(np, 1);
+        if (irq <= 0)
+                panic("%s: unable to parse timer1 irq\n", np->name);
+
+        /* setup timer0 as free-running clocksource */
+        writel(~0, timer_base + TIMER0_VAL);
+        writel(~0, timer_base + TIMER0_RELOAD);
+        orion_timer_ctrl_clrset(0, TIMER0_RELOAD_EN | TIMER0_EN);
+        clocksource_mmio_init(timer_base + TIMER0_VAL, "orion_clocksource",
+                              clk_get_rate(clk), 300, 32,
+                              clocksource_mmio_readl_down);
+        setup_sched_clock(orion_read_sched_clock, 32, clk_get_rate(clk));
+
+        /* setup timer1 as clockevent timer */
+        if (setup_irq(irq, &orion_clkevt_irq))
+                panic("%s: unable to setup irq\n", np->name);
+
+        ticks_per_jiffy = (clk_get_rate(clk) + HZ/2) / HZ;
+        orion_clkevt.cpumask = cpumask_of(0);
+        orion_clkevt.irq = irq;
+        clockevents_config_and_register(&orion_clkevt, clk_get_rate(clk),
+                                        ORION_ONESHOT_MIN, ORION_ONESHOT_MAX);
+}
+CLOCKSOURCE_OF_DECLARE(orion_timer, "marvell,orion-timer", orion_timer_init);
diff --git a/include/linux/nmi.h b/include/linux/nmi.h
index db50840e6355..6a45fb583ff1 100644
--- a/include/linux/nmi.h
+++ b/include/linux/nmi.h
@@ -46,7 +46,7 @@ static inline bool trigger_all_cpu_backtrace(void)
 #ifdef CONFIG_LOCKUP_DETECTOR
 int hw_nmi_is_cpu_stuck(struct pt_regs *);
 u64 hw_nmi_get_sample_period(int watchdog_thresh);
-extern int watchdog_enabled;
+extern int watchdog_user_enabled;
 extern int watchdog_thresh;
 struct ctl_table;
 extern int proc_dowatchdog(struct ctl_table *, int ,
diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index e5b31aff67aa..ac09d98490aa 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -807,7 +807,7 @@ static struct ctl_table kern_table[] = {
 #if defined(CONFIG_LOCKUP_DETECTOR)
         {
                 .procname       = "watchdog",
-                .data           = &watchdog_enabled,
+                .data           = &watchdog_user_enabled,
                 .maxlen         = sizeof (int),
                 .mode           = 0644,
                 .proc_handler   = proc_dowatchdog,
@@ -834,7 +834,7 @@ static struct ctl_table kern_table[] = {
         },
         {
                 .procname       = "nmi_watchdog",
-                .data           = &watchdog_enabled,
+                .data           = &watchdog_user_enabled,
                 .maxlen         = sizeof (int),
                 .mode           = 0644,
                 .proc_handler   = proc_dowatchdog,
diff --git a/kernel/time/tick-broadcast.c b/kernel/time/tick-broadcast.c
index 6d3f91631de6..218bcb565fed 100644
--- a/kernel/time/tick-broadcast.c
+++ b/kernel/time/tick-broadcast.c
@@ -157,7 +157,10 @@ int tick_device_uses_broadcast(struct clock_event_device *dev, int cpu)
                 dev->event_handler = tick_handle_periodic;
                 tick_device_setup_broadcast_func(dev);
                 cpumask_set_cpu(cpu, tick_broadcast_mask);
-                tick_broadcast_start_periodic(bc);
+                if (tick_broadcast_device.mode == TICKDEV_MODE_PERIODIC)
+                        tick_broadcast_start_periodic(bc);
+                else
+                        tick_broadcast_setup_oneshot(bc);
                 ret = 1;
         } else {
                 /*
diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c
index 0cf1c1453181..69601726a745 100644
--- a/kernel/time/tick-sched.c
+++ b/kernel/time/tick-sched.c
@@ -178,6 +178,11 @@ static bool can_stop_full_tick(void)
          */
         if (!sched_clock_stable) {
                 trace_tick_stop(0, "unstable sched clock\n");
+                /*
+                 * Don't allow the user to think they can get
+                 * full NO_HZ with this machine.
+                 */
+                WARN_ONCE(1, "NO_HZ FULL will not work with unstable sched clock");
                 return false;
         }
 #endif
@@ -346,16 +351,6 @@ void __init tick_nohz_init(void)
         }
 
         cpu_notifier(tick_nohz_cpu_down_callback, 0);
-
-        /* Make sure full dynticks CPU are also RCU nocbs */
-        for_each_cpu(cpu, nohz_full_mask) {
-                if (!rcu_is_nocb_cpu(cpu)) {
-                        pr_warning("NO_HZ: CPU %d is not RCU nocb: "
-                                   "cleared from nohz_full range", cpu);
-                        cpumask_clear_cpu(cpu, nohz_full_mask);
-                }
-        }
-
         cpulist_scnprintf(nohz_full_buf, sizeof(nohz_full_buf), nohz_full_mask);
         pr_info("NO_HZ: Full dynticks CPUs: %s.\n", nohz_full_buf);
 }
diff --git a/kernel/watchdog.c b/kernel/watchdog.c
index 05039e348f07..1241d8c91d5e 100644
--- a/kernel/watchdog.c
+++ b/kernel/watchdog.c
@@ -29,9 +29,9 @@
 #include <linux/kvm_para.h>
 #include <linux/perf_event.h>
 
-int watchdog_enabled = 1;
+int watchdog_user_enabled = 1;
 int __read_mostly watchdog_thresh = 10;
-static int __read_mostly watchdog_disabled;
+static int __read_mostly watchdog_running;
 static u64 __read_mostly sample_period;
 
 static DEFINE_PER_CPU(unsigned long, watchdog_touch_ts);
@@ -63,7 +63,7 @@ static int __init hardlockup_panic_setup(char *str)
         else if (!strncmp(str, "nopanic", 7))
                 hardlockup_panic = 0;
         else if (!strncmp(str, "0", 1))
-                watchdog_enabled = 0;
+                watchdog_user_enabled = 0;
         return 1;
 }
 __setup("nmi_watchdog=", hardlockup_panic_setup);
@@ -82,7 +82,7 @@ __setup("softlockup_panic=", softlockup_panic_setup);
 
 static int __init nowatchdog_setup(char *str)
 {
-        watchdog_enabled = 0;
+        watchdog_user_enabled = 0;
         return 1;
 }
 __setup("nowatchdog", nowatchdog_setup);
@@ -90,7 +90,7 @@ __setup("nowatchdog", nowatchdog_setup);
 /* deprecated */
 static int __init nosoftlockup_setup(char *str)
 {
-        watchdog_enabled = 0;
+        watchdog_user_enabled = 0;
         return 1;
 }
 __setup("nosoftlockup", nosoftlockup_setup);
@@ -158,7 +158,7 @@ void touch_all_softlockup_watchdogs(void)
 #ifdef CONFIG_HARDLOCKUP_DETECTOR
 void touch_nmi_watchdog(void)
 {
-        if (watchdog_enabled) {
+        if (watchdog_user_enabled) {
                 unsigned cpu;
 
                 for_each_present_cpu(cpu) {
@@ -347,11 +347,6 @@ static void watchdog_enable(unsigned int cpu)
         hrtimer_init(hrtimer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
         hrtimer->function = watchdog_timer_fn;
 
-        if (!watchdog_enabled) {
-                kthread_park(current);
-                return;
-        }
-
         /* Enable the perf event */
         watchdog_nmi_enable(cpu);
 
@@ -374,6 +369,11 @@ static void watchdog_disable(unsigned int cpu)
         watchdog_nmi_disable(cpu);
 }
 
+static void watchdog_cleanup(unsigned int cpu, bool online)
+{
+        watchdog_disable(cpu);
+}
+
 static int watchdog_should_run(unsigned int cpu)
 {
         return __this_cpu_read(hrtimer_interrupts) !=
@@ -475,28 +475,40 @@ static int watchdog_nmi_enable(unsigned int cpu) { return 0; }
 static void watchdog_nmi_disable(unsigned int cpu) { return; }
 #endif /* CONFIG_HARDLOCKUP_DETECTOR */
 
-/* prepare/enable/disable routines */
-/* sysctl functions */
-#ifdef CONFIG_SYSCTL
-static void watchdog_enable_all_cpus(void)
+static struct smp_hotplug_thread watchdog_threads = {
+        .store                  = &softlockup_watchdog,
+        .thread_should_run      = watchdog_should_run,
+        .thread_fn              = watchdog,
+        .thread_comm            = "watchdog/%u",
+        .setup                  = watchdog_enable,
+        .cleanup                = watchdog_cleanup,
+        .park                   = watchdog_disable,
+        .unpark                 = watchdog_enable,
+};
+
+static int watchdog_enable_all_cpus(void)
 {
-        unsigned int cpu;
+        int err = 0;
 
-        if (watchdog_disabled) {
-                watchdog_disabled = 0;
-                for_each_online_cpu(cpu)
-                        kthread_unpark(per_cpu(softlockup_watchdog, cpu));
+        if (!watchdog_running) {
+                err = smpboot_register_percpu_thread(&watchdog_threads);
+                if (err)
+                        pr_err("Failed to create watchdog threads, disabled\n");
+                else
+                        watchdog_running = 1;
         }
+
+        return err;
 }
 
+/* prepare/enable/disable routines */
+/* sysctl functions */
+#ifdef CONFIG_SYSCTL
 static void watchdog_disable_all_cpus(void)
 {
-        unsigned int cpu;
-
-        if (!watchdog_disabled) {
-                watchdog_disabled = 1;
-                for_each_online_cpu(cpu)
-                        kthread_park(per_cpu(softlockup_watchdog, cpu));
+        if (watchdog_running) {
+                watchdog_running = 0;
+                smpboot_unregister_percpu_thread(&watchdog_threads);
         }
 }
 
@@ -507,45 +519,48 @@ static void watchdog_disable_all_cpus(void)
 int proc_dowatchdog(struct ctl_table *table, int write,
                     void __user *buffer, size_t *lenp, loff_t *ppos)
 {
-        int ret;
+        int err, old_thresh, old_enabled;
 
-        if (watchdog_disabled < 0)
-                return -ENODEV;
+        old_thresh = ACCESS_ONCE(watchdog_thresh);
+        old_enabled = ACCESS_ONCE(watchdog_user_enabled);
 
-        ret = proc_dointvec_minmax(table, write, buffer, lenp, ppos);
-        if (ret || !write)
-                return ret;
+        err = proc_dointvec_minmax(table, write, buffer, lenp, ppos);
+        if (err || !write)
+                return err;
 
         set_sample_period();
         /*
          * Watchdog threads shouldn't be enabled if they are
-         * disabled. The 'watchdog_disabled' variable check in
+         * disabled. The 'watchdog_running' variable check in
          * watchdog_*_all_cpus() function takes care of this.
          */
-        if (watchdog_enabled && watchdog_thresh)
-                watchdog_enable_all_cpus();
+        if (watchdog_user_enabled && watchdog_thresh)
+                err = watchdog_enable_all_cpus();
         else
                 watchdog_disable_all_cpus();
 
-        return ret;
+        /* Restore old values on failure */
+        if (err) {
+                watchdog_thresh = old_thresh;
+                watchdog_user_enabled = old_enabled;
+        }
+
+        return err;
 }
 #endif /* CONFIG_SYSCTL */
 
-static struct smp_hotplug_thread watchdog_threads = {
-        .store                  = &softlockup_watchdog,
-        .thread_should_run      = watchdog_should_run,
-        .thread_fn              = watchdog,
-        .thread_comm            = "watchdog/%u",
-        .setup                  = watchdog_enable,
-        .park                   = watchdog_disable,
-        .unpark                 = watchdog_enable,
-};
-
 void __init lockup_detector_init(void)
 {
         set_sample_period();
-        if (smpboot_register_percpu_thread(&watchdog_threads)) {
-                pr_err("Failed to create watchdog threads, disabled\n");
-                watchdog_disabled = -ENODEV;
+
+#ifdef CONFIG_NO_HZ_FULL
+        if (watchdog_user_enabled) {
+                watchdog_user_enabled = 0;
+                pr_warning("Disabled lockup detectors by default for full dynticks\n");
+                pr_warning("You can reactivate it with 'sysctl -w kernel.watchdog=1'\n");
         }
+#endif
+
+        if (watchdog_user_enabled)
+                watchdog_enable_all_cpus();
 }