Release 4.15 kernel/time/tick-broadcast.c

/*
 * linux/kernel/time/tick-broadcast.c
 *
 * This file contains functions which emulate a local clock-event
 * device via a broadcast event source.
 *
 * Copyright(C) 2005-2006, Thomas Gleixner <tglx@linutronix.de>
 * Copyright(C) 2005-2007, Red Hat, Inc., Ingo Molnar
 * Copyright(C) 2006-2007, Timesys Corp., Thomas Gleixner
 *
 * This code is licenced under the GPL version 2. For details see
 * kernel-base/COPYING.
 */
#include <linux/cpu.h>
#include <linux/err.h>
#include <linux/hrtimer.h>
#include <linux/interrupt.h>
#include <linux/percpu.h>
#include <linux/profile.h>
#include <linux/sched.h>
#include <linux/smp.h>
#include <linux/module.h>

#include "tick-internal.h"

/*
 * Broadcast support for broken x86 hardware, where the local apic
 * timer stops in C3 state.
 */


static struct tick_device tick_broadcast_device;

static cpumask_var_t tick_broadcast_mask __cpumask_var_read_mostly;

static cpumask_var_t tick_broadcast_on __cpumask_var_read_mostly;

static cpumask_var_t tmpmask __cpumask_var_read_mostly;

static int tick_broadcast_forced;

static __cacheline_aligned_in_smp DEFINE_RAW_SPINLOCK(tick_broadcast_lock);

#ifdef CONFIG_TICK_ONESHOT
static void tick_broadcast_setup_oneshot(struct clock_event_device *bc);
static void tick_broadcast_clear_oneshot(int cpu);
static void tick_resume_broadcast_oneshot(struct clock_event_device *bc);
#else


static inline void tick_broadcast_setup_oneshot(struct clock_event_device *bc) { BUG(); }
Contributors
Person
Tokens
Prop
Commits
CommitProp
Stephen Boyd
15
100.00%
1
100.00%
Total
15
100.00%
1
100.00%



static inline void tick_broadcast_clear_oneshot(int cpu) { }
Contributors
Person
Tokens
Prop
Commits
CommitProp
Thomas Gleixner
9
100.00%
1
100.00%
Total
9
100.00%
1
100.00%



static inline void tick_resume_broadcast_oneshot(struct clock_event_device *bc) { }
Contributors
Person
Tokens
Prop
Commits
CommitProp
Thomas Gleixner
11
100.00%
1
100.00%
Total
11
100.00%
1
100.00%

#endif

/*
 * Debugging: see timer_list.c
 */


struct tick_device *tick_get_broadcast_device(void)
{
	return &tick_broadcast_device;
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
Ingo Molnar
13
100.00%
1
100.00%
Total
13
100.00%
1
100.00%



struct cpumask *tick_get_broadcast_mask(void)
{
	return tick_broadcast_mask;
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
Ingo Molnar
10
83.33%
1
50.00%
Rusty Russell
2
16.67%
1
50.00%
Total
12
100.00%
2
100.00%

/*
 * Start the device in periodic mode
 */


static void tick_broadcast_start_periodic(struct clock_event_device *bc)
{
	if (bc)
		tick_setup_periodic(bc, 1);
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
Thomas Gleixner
22
100.00%
1
100.00%
Total
22
100.00%
1
100.00%

/*
 * Check, if the device can be utilized as broadcast device:
 */


static bool tick_check_broadcast_device(struct clock_event_device *curdev,
					struct clock_event_device *newdev)
{
	if ((newdev->features & CLOCK_EVT_FEAT_DUMMY) ||
	    (newdev->features & CLOCK_EVT_FEAT_PERCPU) ||
	    (newdev->features & CLOCK_EVT_FEAT_C3STOP))
		return false;

	if (tick_broadcast_device.mode == TICKDEV_MODE_ONESHOT &&
	    !(newdev->features & CLOCK_EVT_FEAT_ONESHOT))
		return false;

	return !curdev || newdev->rating > curdev->rating;
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
Thomas Gleixner
58
75.32%
3
50.00%
Sören Brinkmann
8
10.39%
1
16.67%
Mark Rutland
7
9.09%
1
16.67%
Venkatesh Pallipadi
4
5.19%
1
16.67%
Total
77
100.00%
6
100.00%

/*
 * Conditionally install/replace broadcast device
 */


void tick_install_broadcast_device(struct clock_event_device *dev)
{
	struct clock_event_device *cur = tick_broadcast_device.evtdev;

	if (!tick_check_broadcast_device(cur, dev))
		return;

	if (!try_module_get(dev->owner))
		return;

	clockevents_exchange_device(cur, dev);
	if (cur)
		cur->event_handler = clockevents_handle_noop;
	tick_broadcast_device.evtdev = dev;
	if (!cpumask_empty(tick_broadcast_mask))
		tick_broadcast_start_periodic(dev);
	/*
         * Inform all cpus about this. We might be in a situation
         * where we did not switch to oneshot mode because the per cpu
         * devices are affected by CLOCK_EVT_FEAT_C3STOP and the lack
         * of a oneshot capable broadcast device. Without that
         * notification the systems stays stuck in periodic mode
         * forever.
         */
	if (dev->features & CLOCK_EVT_FEAT_ONESHOT)
		tick_clock_notify();
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
Thomas Gleixner
76
85.39%
6
75.00%
Stephen Boyd
12
13.48%
1
12.50%
Rusty Russell
1
1.12%
1
12.50%
Total
89
100.00%
8
100.00%

/*
 * Check, if the device is the broadcast device
 */


int tick_is_broadcast_device(struct clock_event_device *dev)
{
	return (dev && tick_broadcast_device.evtdev == dev);
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
Thomas Gleixner
21
100.00%
1
100.00%
Total
21
100.00%
1
100.00%



int tick_broadcast_update_freq(struct clock_event_device *dev, u32 freq)
{
	int ret = -ENODEV;

	if (tick_is_broadcast_device(dev)) {
		raw_spin_lock(&tick_broadcast_lock);
		ret = __clockevents_update_freq(dev, freq);
		raw_spin_unlock(&tick_broadcast_lock);
	}
	return ret;
}


Contributors
Person
Tokens
Prop
Commits
CommitProp
Thomas Gleixner
52
100.00%
1
100.00%
Total
52
100.00%
1
100.00%



static void err_broadcast(const struct cpumask *mask)
{
	pr_crit_once("Failed to broadcast timer tick. Some CPUs may be unresponsive.\n");
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
Mark Rutland
17
100.00%
1
100.00%
Total
17
100.00%
1
100.00%



static void tick_device_setup_broadcast_func(struct clock_event_device *dev)
{
	if (!dev->broadcast)
		dev->broadcast = tick_broadcast;
	if (!dev->broadcast) {
		pr_warn_once("%s depends on broadcast, but no broadcast function available\n",
			     dev->name);
		dev->broadcast = err_broadcast;
	}
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
Mark Rutland
48
100.00%
1
100.00%
Total
48
100.00%
1
100.00%

/*
 * Check, if the device is disfunctional and a place holder, which
 * needs to be handled by the broadcast device.
 */


int tick_device_uses_broadcast(struct clock_event_device *dev, int cpu)
{
	struct clock_event_device *bc = tick_broadcast_device.evtdev;
	unsigned long flags;
	int ret = 0;

	raw_spin_lock_irqsave(&tick_broadcast_lock, flags);

	/*
         * Devices might be registered with both periodic and oneshot
         * mode disabled. This signals, that the device needs to be
         * operated from the broadcast device and is a placeholder for
         * the cpu local device.
         */
	if (!tick_device_is_functional(dev)) {
		dev->event_handler = tick_handle_periodic;
		tick_device_setup_broadcast_func(dev);
		cpumask_set_cpu(cpu, tick_broadcast_mask);
		if (tick_broadcast_device.mode == TICKDEV_MODE_PERIODIC)
			tick_broadcast_start_periodic(bc);
		else
			tick_broadcast_setup_oneshot(bc);
		ret = 1;
	} else {
		/*
                 * Clear the broadcast bit for this cpu if the
                 * device is not power state affected.
                 */
		if (!(dev->features & CLOCK_EVT_FEAT_C3STOP))
			cpumask_clear_cpu(cpu, tick_broadcast_mask);
		else
			tick_device_setup_broadcast_func(dev);

		/*
                 * Clear the broadcast bit if the CPU is not in
                 * periodic broadcast on state.
                 */
		if (!cpumask_test_cpu(cpu, tick_broadcast_on))
			cpumask_clear_cpu(cpu, tick_broadcast_mask);

		switch (tick_broadcast_device.mode) {
		case TICKDEV_MODE_ONESHOT:
			/*
                         * If the system is in oneshot mode we can
                         * unconditionally clear the oneshot mask bit,
                         * because the CPU is running and therefore
                         * not in an idle state which causes the power
                         * state affected device to stop. Let the
                         * caller initialize the device.
                         */
			tick_broadcast_clear_oneshot(cpu);
			ret = 0;
			break;

		case TICKDEV_MODE_PERIODIC:
			/*
                         * If the system is in periodic mode, check
                         * whether the broadcast device can be
                         * switched off now.
                         */
			if (cpumask_empty(tick_broadcast_mask) && bc)
				clockevents_shutdown(bc);
			/*
                         * If we kept the cpu in the broadcast mask,
                         * tell the caller to leave the per cpu device
                         * in shutdown state. The periodic interrupt
                         * is delivered by the broadcast device, if
                         * the broadcast device exists and is not
                         * hrtimer based.
                         */
			if (bc && !(bc->features & CLOCK_EVT_FEAT_HRTIMER))
				ret = cpumask_test_cpu(cpu, tick_broadcast_mask);
			break;
		default:
			break;
		}
	}
	raw_spin_unlock_irqrestore(&tick_broadcast_lock, flags);
	return ret;
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
Thomas Gleixner
189
88.32%
6
60.00%
Stephen Boyd
14
6.54%
1
10.00%
Mark Rutland
9
4.21%
2
20.00%
Rusty Russell
2
0.93%
1
10.00%
Total
214
100.00%
10
100.00%

#ifdef CONFIG_GENERIC_CLOCKEVENTS_BROADCAST


int tick_receive_broadcast(void)
{
	struct tick_device *td = this_cpu_ptr(&tick_cpu_device);
	struct clock_event_device *evt = td->evtdev;

	if (!evt)
		return -ENODEV;

	if (!evt->event_handler)
		return -EINVAL;

	evt->event_handler(evt);
	return 0;
}
Contributors
Person
Tokens
Prop
Commits
CommitProp
Mark Rutland
57
100.00%
1
100.00%
Total
57
100.00%
1
100.00%

#endif

/*
 * Broadcast the event to the cpus, which are set in the mask (mangled).
 */


static bool tick_do_broadcast(struct cpumask *mask)
{
	int cpu = smp_processor_id();
	struct tick_device *td;
	bool local = false;

	/*
         * Check, if the current cpu is in the mask
         */
	if (cpumask_test_cpu(cpu, mask)) {
		struct clock_event_device *bc = tick_broadcast_device.evtdev;

		cpumask_clear_cpu(cpu, mask);
		/*
                 * We only run the local handler, if the broadcast
                 * device is not hrtimer based. Otherwise we run into
                 * a hrtimer recursion.
                 *
                 * local timer_interrupt()
                 *   local_handler()
                 *     expire_hrtimers()
                 *       bc_handler()
                 *         local_handler()
                 *           expire_hrtimers()
                 */
		local = !(bc->features & CLOCK_EVT_FEAT_HRTIMER);
	}

	if (!cpumask_empty(mask)) {
		/*
                 * It might be necessary to actually check whether the devices
                 * have different broadcast functions. For now, just use the
                 * one of the first device. This works as long as we have this
                 * misfeature only on x86 (lapic)
                 */
		td = &per_cpu(tick_cpu_device, cpumask_first(mask));
		td->evtdev->broadcast(mask);
	}
	return local;
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
Thomas Gleixner
93
90.29%
4
80.00%
Rusty Russell
10
9.71%
1
20.00%
Total
103
100.00%
5
100.00%

/*
 * Periodic broadcast:
 * - invoke the broadcast handlers
 */


static bool tick_do_periodic_broadcast(void)
{
	cpumask_and(tmpmask, cpu_online_mask, tick_broadcast_mask);
	return tick_do_broadcast(tmpmask);
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
Thomas Gleixner
18
78.26%
3
75.00%
Rusty Russell
5
21.74%
1
25.00%
Total
23
100.00%
4
100.00%

/*
 * Event handler for periodic broadcast ticks
 */


static void tick_handle_periodic_broadcast(struct clock_event_device *dev)
{
	struct tick_device *td = this_cpu_ptr(&tick_cpu_device);
	bool bc_local;

	raw_spin_lock(&tick_broadcast_lock);

	/* Handle spurious interrupts gracefully */
	if (clockevent_state_shutdown(tick_broadcast_device.evtdev)) {
		raw_spin_unlock(&tick_broadcast_lock);
		return;
	}

	bc_local = tick_do_periodic_broadcast();

	if (clockevent_state_oneshot(dev)) {
		ktime_t next = ktime_add(dev->next_event, tick_period);

		clockevents_program_event(dev, next, true);
	}
	raw_spin_unlock(&tick_broadcast_lock);

	/*
         * We run the handler of the local cpu after dropping
         * tick_broadcast_lock because the handler might deadlock when
         * trying to switch to oneshot mode.
         */
	if (bc_local)
		td->evtdev->event_handler(td->evtdev);
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
Thomas Gleixner
104
97.20%
5
83.33%
Viresh Kumar
3
2.80%
1
16.67%
Total
107
100.00%
6
100.00%

/**
 * tick_broadcast_control - Enable/disable or force broadcast mode
 * @mode:       The selected broadcast mode
 *
 * Called when the system enters a state where affected tick devices
 * might stop. Note: TICK_BROADCAST_FORCE cannot be undone.
 */


void tick_broadcast_control(enum tick_broadcast_mode mode)
{
	struct clock_event_device *bc, *dev;
	struct tick_device *td;
	int cpu, bc_stopped;
	unsigned long flags;

	/* Protects also the local clockevent device. */
	raw_spin_lock_irqsave(&tick_broadcast_lock, flags);
	td = this_cpu_ptr(&tick_cpu_device);
	dev = td->evtdev;

	/*
         * Is the device not affected by the powerstate ?
         */
	if (!dev || !(dev->features & CLOCK_EVT_FEAT_C3STOP))
		goto out;

	if (!tick_device_is_functional(dev))
		goto out;

	cpu = smp_processor_id();
	bc = tick_broadcast_device.evtdev;
	bc_stopped = cpumask_empty(tick_broadcast_mask);

	switch (mode) {
	case TICK_BROADCAST_FORCE:
		tick_broadcast_forced = 1;
	case TICK_BROADCAST_ON:
		cpumask_set_cpu(cpu, tick_broadcast_on);
		if (!cpumask_test_and_set_cpu(cpu, tick_broadcast_mask)) {
			/*
                         * Only shutdown the cpu local device, if:
                         *
                         * - the broadcast device exists
                         * - the broadcast device is not a hrtimer based one
                         * - the broadcast device is in periodic mode to
                         *   avoid a hickup during switch to oneshot mode
                         */
			if (bc && !(bc->features & CLOCK_EVT_FEAT_HRTIMER) &&
			    tick_broadcast_device.mode == TICKDEV_MODE_PERIODIC)
				clockevents_shutdown(dev);
		}
		break;

	case TICK_BROADCAST_OFF:
		if (tick_broadcast_forced)
			break;
		cpumask_clear_cpu(cpu, tick_broadcast_on);
		if (!tick_device_is_functional(dev))
			break;
		if (cpumask_test_and_clear_cpu(cpu, tick_broadcast_mask)) {
			if (tick_broadcast_device.mode ==
			    TICKDEV_MODE_PERIODIC)
				tick_setup_periodic(dev, 0);
		}
		break;
	}

	if (bc) {
		if (cpumask_empty(tick_broadcast_mask)) {
			if (!bc_stopped)
				clockevents_shutdown(bc);
		} else if (bc_stopped) {
			if (tick_broadcast_device.mode == TICKDEV_MODE_PERIODIC)
				tick_broadcast_start_periodic(bc);
			else
				tick_broadcast_setup_oneshot(bc);
		}
	}
out:
	raw_spin_unlock_irqrestore(&tick_broadcast_lock, flags);
}
Contributors
Person
Tokens
Prop
Commits
CommitProp
Thomas Gleixner
248
90.51%
11
84.62%
Mike Galbraith
24
8.76%
1
7.69%
Rusty Russell
2
0.73%
1
7.69%
Total
274
100.00%
13
100.00%


EXPORT_SYMBOL_GPL(tick_broadcast_control);

/*
 * Set the periodic handler depending on broadcast on/off
 */


void tick_set_periodic_handler(struct clock_event_device *dev, int broadcast)
{
	if (!broadcast)
		dev->event_handler = tick_handle_periodic;
	else
		dev->event_handler = tick_handle_periodic_broadcast;
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
Thomas Gleixner
31
100.00%
1
100.00%
Total
31
100.00%
1
100.00%

#ifdef CONFIG_HOTPLUG_CPU
/*
 * Remove a CPU from broadcasting
 */


void tick_shutdown_broadcast(unsigned int cpu)
{
	struct clock_event_device *bc;
	unsigned long flags;

	raw_spin_lock_irqsave(&tick_broadcast_lock, flags);

	bc = tick_broadcast_device.evtdev;
	cpumask_clear_cpu(cpu, tick_broadcast_mask);
	cpumask_clear_cpu(cpu, tick_broadcast_on);

	if (tick_broadcast_device.mode == TICKDEV_MODE_PERIODIC) {
		if (bc && cpumask_empty(tick_broadcast_mask))
			clockevents_shutdown(bc);
	}

	raw_spin_unlock_irqrestore(&tick_broadcast_lock, flags);
}
Contributors
Person
Tokens
Prop
Commits
CommitProp
Thomas Gleixner
76
97.44%
6
85.71%
Rusty Russell
2
2.56%
1
14.29%
Total
78
100.00%
7
100.00%

#endif



void tick_suspend_broadcast(void)
{
	struct clock_event_device *bc;
	unsigned long flags;

	raw_spin_lock_irqsave(&tick_broadcast_lock, flags);

	bc = tick_broadcast_device.evtdev;
	if (bc)
		clockevents_shutdown(bc);

	raw_spin_unlock_irqrestore(&tick_broadcast_lock, flags);
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
Thomas Gleixner
47
100.00%
3
100.00%
Total
47
100.00%
3
100.00%

/*
 * This is called from tick_resume_local() on a resuming CPU. That's
 * called from the core resume function, tick_unfreeze() and the magic XEN
 * resume hackery.
 *
 * In none of these cases the broadcast device mode can change and the
 * bit of the resuming CPU in the broadcast mask is safe as well.
 */


bool tick_resume_check_broadcast(void)
{
	if (tick_broadcast_device.mode == TICKDEV_MODE_ONESHOT)
		return false;
	else
		return cpumask_test_cpu(smp_processor_id(), tick_broadcast_mask);
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
Thomas Gleixner
28
100.00%
1
100.00%
Total
28
100.00%
1
100.00%



void tick_resume_broadcast(void)
{
	struct clock_event_device *bc;
	unsigned long flags;

	raw_spin_lock_irqsave(&tick_broadcast_lock, flags);

	bc = tick_broadcast_device.evtdev;

	if (bc) {
		clockevents_tick_resume(bc);

		switch (tick_broadcast_device.mode) {
		case TICKDEV_MODE_PERIODIC:
			if (!cpumask_empty(tick_broadcast_mask))
				tick_broadcast_start_periodic(bc);
			break;
		case TICKDEV_MODE_ONESHOT:
			if (!cpumask_empty(tick_broadcast_mask))
				tick_resume_broadcast_oneshot(bc);
			break;
		}
	}
	raw_spin_unlock_irqrestore(&tick_broadcast_lock, flags);
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
Thomas Gleixner
82
90.11%
6
66.67%
Suresh B. Siddha
7
7.69%
1
11.11%
Rusty Russell
1
1.10%
1
11.11%
Viresh Kumar
1
1.10%
1
11.11%
Total
91
100.00%
9
100.00%

#ifdef CONFIG_TICK_ONESHOT


static cpumask_var_t tick_broadcast_oneshot_mask __cpumask_var_read_mostly;

static cpumask_var_t tick_broadcast_pending_mask __cpumask_var_read_mostly;

static cpumask_var_t tick_broadcast_force_mask __cpumask_var_read_mostly;

/*
 * Exposed for debugging: see timer_list.c
 */


struct cpumask *tick_get_broadcast_oneshot_mask(void)
{
	return tick_broadcast_oneshot_mask;
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
Ingo Molnar
10
83.33%
1
50.00%
Rusty Russell
2
16.67%
1
50.00%
Total
12
100.00%
2
100.00%

/*
 * Called before going idle with interrupts disabled. Checks whether a
 * broadcast event from the other core is about to happen. We detected
 * that in tick_broadcast_oneshot_control(). The callsite can use this
 * to avoid a deep idle transition as we are about to get the
 * broadcast IPI right away.
 */


int tick_check_broadcast_expired(void)
{
	return cpumask_test_cpu(smp_processor_id(), tick_broadcast_force_mask);
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
Thomas Gleixner
16
100.00%
1
100.00%
Total
16
100.00%
1
100.00%

/*
 * Set broadcast interrupt affinity
 */


static void tick_broadcast_set_affinity(struct clock_event_device *bc,
					const struct cpumask *cpumask)
{
	if (!(bc->features & CLOCK_EVT_FEAT_DYNIRQ))
		return;

	if (cpumask_equal(bc->cpumask, cpumask))
		return;

	bc->cpumask = cpumask;
	irq_set_affinity(bc->irq, bc->cpumask);
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
Daniel Lezcano
58
100.00%
1
100.00%
Total
58
100.00%
1
100.00%



static void tick_broadcast_set_event(struct clock_event_device *bc, int cpu,
				     ktime_t expires)
{
	if (!clockevent_state_oneshot(bc))
		clockevents_switch_state(bc, CLOCK_EVT_STATE_ONESHOT);

	clockevents_program_event(bc, expires, 1);
	tick_broadcast_set_affinity(bc, cpumask_of(cpu));
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
Thomas Gleixner
26
50.98%
4
44.44%
Daniel Lezcano
19
37.25%
2
22.22%
Viresh Kumar
5
9.80%
2
22.22%
Martin Schwidefsky
1
1.96%
1
11.11%
Total
51
100.00%
9
100.00%



static void tick_resume_broadcast_oneshot(struct clock_event_device *bc)
{
	clockevents_switch_state(bc, CLOCK_EVT_STATE_ONESHOT);
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
Thomas Gleixner
17
94.44%
3
75.00%
Viresh Kumar
1
5.56%
1
25.00%
Total
18
100.00%
4
100.00%

/*
 * Called from irq_enter() when idle was interrupted to reenable the
 * per cpu device.
 */


void tick_check_oneshot_broadcast_this_cpu(void)
{
	if (cpumask_test_cpu(smp_processor_id(), tick_broadcast_oneshot_mask)) {
		struct tick_device *td = this_cpu_ptr(&tick_cpu_device);

		/*
                 * We might be in the middle of switching over from
                 * periodic to oneshot. If the CPU has not yet
                 * switched over, leave the device alone.
                 */
		if (td->mode == TICKDEV_MODE_ONESHOT) {
			clockevents_switch_state(td->evtdev,
					      CLOCK_EVT_STATE_ONESHOT);
		}
	}
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
Thomas Gleixner
42
84.00%
3
42.86%
Frédéric Weisbecker
4
8.00%
1
14.29%
Christoph Lameter
2
4.00%
1
14.29%
Rusty Russell
1
2.00%
1
14.29%
Viresh Kumar
1
2.00%
1
14.29%
Total
50
100.00%
7
100.00%

/*
 * Handle oneshot mode broadcasting
 */


static void tick_handle_oneshot_broadcast(struct clock_event_device *dev)
{
	struct tick_device *td;
	ktime_t now, next_event;
	int cpu, next_cpu = 0;
	bool bc_local;

	raw_spin_lock(&tick_broadcast_lock);
	dev->next_event = KTIME_MAX;
	next_event = KTIME_MAX;
	cpumask_clear(tmpmask);
	now = ktime_get();
	/* Find all expired events */
	for_each_cpu(cpu, tick_broadcast_oneshot_mask) {
		td = &per_cpu(tick_cpu_device, cpu);
		if (td->evtdev->next_event <= now) {
			cpumask_set_cpu(cpu, tmpmask);
			/*
                         * Mark the remote cpu in the pending mask, so
                         * it can avoid reprogramming the cpu local
                         * timer in tick_broadcast_oneshot_control().
                         */
			cpumask_set_cpu(cpu, tick_broadcast_pending_mask);
		} else if (td->evtdev->next_event < next_event) {
			next_event = td->evtdev->next_event;
			next_cpu = cpu;
		}
	}

	/*
         * Remove the current cpu from the pending mask. The event is
         * delivered immediately in tick_do_broadcast() !
         */
	cpumask_clear_cpu(smp_processor_id(), tick_broadcast_pending_mask);

	/* Take care of enforced broadcast requests */
	cpumask_or(tmpmask, tmpmask, tick_broadcast_force_mask);
	cpumask_clear(tick_broadcast_force_mask);

	/*
         * Sanity check. Catch the case where we try to broadcast to
         * offline cpus.
         */
	if (WARN_ON_ONCE(!cpumask_subset(tmpmask, cpu_online_mask)))
		cpumask_and(tmpmask, tmpmask, cpu_online_mask);

	/*
         * Wakeup the cpus which have an expired event.
         */
	bc_local = tick_do_broadcast(tmpmask);

	/*
         * Two reasons for reprogram:
         *
         * - The global event did not expire any CPU local
         * events. This happens in dyntick mode, as the maximum PIT
         * delta is quite small.
         *
         * - There are pending events on sleeping CPUs which were not
         * in the event mask
         */
	if (next_event != KTIME_MAX)
		tick_broadcast_set_event(dev, next_cpu, next_event);

	raw_spin_unlock(&tick_broadcast_lock);

	if (bc_local) {
		td = this_cpu_ptr(&tick_cpu_device);
		td->evtdev->event_handler(td->evtdev);
	}
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
Thomas Gleixner
203
88.26%
10
71.43%
Daniel Lezcano
16
6.96%
2
14.29%
Rusty Russell
10
4.35%
1
7.14%
Mike Travis
1
0.43%
1
7.14%
Total
230
100.00%
14
100.00%



static int broadcast_needs_cpu(struct clock_event_device *bc, int cpu)
{
	if (!(bc->features & CLOCK_EVT_FEAT_HRTIMER))
		return 0;
	if (bc->next_event == KTIME_MAX)
		return 0;
	return bc->bound_on == cpu ? -EBUSY : 0;
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
Preeti U. Murthy
51
100.00%
1
100.00%
Total
51
100.00%
1
100.00%



static void broadcast_shutdown_local(struct clock_event_device *bc,
				     struct clock_event_device *dev)
{
	/*
         * For hrtimer based broadcasting we cannot shutdown the cpu
         * local device if our own event is the first one to expire or
         * if we own the broadcast timer.
         */
	if (bc->features & CLOCK_EVT_FEAT_HRTIMER) {
		if (broadcast_needs_cpu(bc, smp_processor_id()))
			return;
		if (dev->next_event < bc->next_event)
			return;
	}
	clockevents_switch_state(dev, CLOCK_EVT_STATE_SHUTDOWN);
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
Preeti U. Murthy
54
96.43%
1
33.33%
Thomas Gleixner
1
1.79%
1
33.33%
Viresh Kumar
1
1.79%
1
33.33%
Total
56
100.00%
3
100.00%



int __tick_broadcast_oneshot_control(enum tick_broadcast_state state)
{
	struct clock_event_device *bc, *dev;
	int cpu, ret = 0;
	ktime_t now;

	/*
         * If there is no broadcast device, tell the caller not to go
         * into deep idle.
         */
	if (!tick_broadcast_device.evtdev)
		return -EBUSY;

	dev = this_cpu_ptr(&tick_cpu_device)->evtdev;

	raw_spin_lock(&tick_broadcast_lock);
	bc = tick_broadcast_device.evtdev;
	cpu = smp_processor_id();

	if (state == TICK_BROADCAST_ENTER) {
		/*
                 * If the current CPU owns the hrtimer broadcast
                 * mechanism, it cannot go deep idle and we do not add
                 * the CPU to the broadcast mask. We don't have to go
                 * through the EXIT path as the local timer is not
                 * shutdown.
                 */
		ret = broadcast_needs_cpu(bc, cpu);
		if (ret)
			goto out;

		/*
                 * If the broadcast device is in periodic mode, we
                 * return.
                 */
		if (tick_broadcast_device.mode == TICKDEV_MODE_PERIODIC) {
			/* If it is a hrtimer based broadcast, return busy */
			if (bc->features & CLOCK_EVT_FEAT_HRTIMER)
				ret = -EBUSY;
			goto out;
		}

		if (!cpumask_test_and_set_cpu(cpu, tick_broadcast_oneshot_mask)) {
			WARN_ON_ONCE(cpumask_test_cpu(cpu, tick_broadcast_pending_mask));

			/* Conditionally shut down the local timer. */
			broadcast_shutdown_local(bc, dev);

			/*
                         * We only reprogram the broadcast timer if we
                         * did not mark ourself in the force mask and
                         * if the cpu local event is earlier than the
                         * broadcast event. If the current CPU is in
                         * the force mask, then we are going to be
                         * woken by the IPI right away; we return
                         * busy, so the CPU does not try to go deep
                         * idle.
                         */
			if (cpumask_test_cpu(cpu, tick_broadcast_force_mask)) {
				ret = -EBUSY;
			} else if (dev->next_event < bc->next_event) {
				tick_broadcast_set_event(bc, cpu, dev->next_event);
				/*
                                 * In case of hrtimer broadcasts the
                                 * programming might have moved the
                                 * timer to this cpu. If yes, remove
                                 * us from the broadcast mask and
                                 * return busy.
                                 */
				ret = broadcast_needs_cpu(bc, cpu);
				if (ret) {
					cpumask_clear_cpu(cpu,
						tick_broadcast_oneshot_mask);
				}
			}
		}
	} else {
		if (cpumask_test_and_clear_cpu(cpu, tick_broadcast_oneshot_mask)) {
			clockevents_switch_state(dev, CLOCK_EVT_STATE_ONESHOT);
			/*
                         * The cpu which was handling the broadcast
                         * timer marked this cpu in the broadcast
                         * pending mask and fired the broadcast
                         * IPI. So we are going to handle the expired
                         * event anyway via the broadcast IPI
                         * handler. No need to reprogram the timer
                         * with an already expired event.
                         */
			if (cpumask_test_and_clear_cpu(cpu,
				       tick_broadcast_pending_mask))
				goto out;

			/*
                         * Bail out if there is no next event.
                         */
			if (dev->next_event == KTIME_MAX)
				goto out;
			/*
                         * If the pending bit is not set, then we are
                         * either the CPU handling the broadcast
                         * interrupt or we got woken by something else.
                         *
                         * We are not longer in the broadcast mask, so
                         * if the cpu local expiry time is already
                         * reached, we would reprogram the cpu local
                         * timer with an already expired event.
                         *
                         * This can lead to a ping-pong when we return
                         * to idle and therefor rearm the broadcast
                         * timer before the cpu local timer was able
                         * to fire. This happens because the forced
                         * reprogramming makes sure that the event
                         * will happen in the future and depending on
                         * the min_delta setting this might be far
                         * enough out that the ping-pong starts.
                         *
                         * If the cpu local next_event has expired
                         * then we know that the broadcast timer
                         * next_event has expired as well and
                         * broadcast is about to be handled. So we
                         * avoid reprogramming and enforce that the
                         * broadcast handler, which did not run yet,
                         * will invoke the cpu local handler.
                         *
                         * We cannot call the handler directly from
                         * here, because we might be in a NOHZ phase
                         * and we did not go through the irq_enter()
                         * nohz fixups.
                         */
			now = ktime_get();
			if (dev->next_event <= now) {
				cpumask_set_cpu(cpu, tick_broadcast_force_mask);
				goto out;
			}
			/*
                         * We got woken by something else. Reprogram
                         * the cpu local timer device.
                         */
			tick_program_event(dev->next_event, 1);
		}
	}
out:
	raw_spin_unlock(&tick_broadcast_lock);
	return ret;
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
Thomas Gleixner
251
82.03%
13
65.00%
Preeti U. Murthy
31
10.13%
2
10.00%
Daniel Lezcano
16
5.23%
3
15.00%
Andi Kleen
7
2.29%
1
5.00%
Viresh Kumar
1
0.33%
1
5.00%
Total
306
100.00%
20
100.00%

/*
 * Reset the one shot broadcast for a cpu
 *
 * Called with tick_broadcast_lock held
 */


static void tick_broadcast_clear_oneshot(int cpu)
{
	cpumask_clear_cpu(cpu, tick_broadcast_oneshot_mask);
	cpumask_clear_cpu(cpu, tick_broadcast_pending_mask);
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
Thomas Gleixner
22
95.65%
3
75.00%
Rusty Russell
1
4.35%
1
25.00%
Total
23
100.00%
4
100.00%



static void tick_broadcast_init_next_event(struct cpumask *mask,
					   ktime_t expires)
{
	struct tick_device *td;
	int cpu;

	for_each_cpu(cpu, mask) {
		td = &per_cpu(tick_cpu_device, cpu);
		if (td->evtdev)
			td->evtdev->next_event = expires;
	}
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
Thomas Gleixner
50
92.59%
1
33.33%
Rusty Russell
4
7.41%
2
66.67%
Total
54
100.00%
3
100.00%

/**
 * tick_broadcast_setup_oneshot - setup the broadcast device
 */


static void tick_broadcast_setup_oneshot(struct clock_event_device *bc)
{
	int cpu = smp_processor_id();

	if (!bc)
		return;

	/* Set it up only once ! */
	if (bc->event_handler != tick_handle_oneshot_broadcast) {
		int was_periodic = clockevent_state_periodic(bc);

		bc->event_handler = tick_handle_oneshot_broadcast;

		/*
                 * We must be careful here. There might be other CPUs
                 * waiting for periodic broadcast. We need to set the
                 * oneshot_mask bits for those and program the
                 * broadcast device to fire.
                 */
		cpumask_copy(tmpmask, tick_broadcast_mask);
		cpumask_clear_cpu(cpu, tmpmask);
		cpumask_or(tick_broadcast_oneshot_mask,
			   tick_broadcast_oneshot_mask, tmpmask);

		if (was_periodic && !cpumask_empty(tmpmask)) {
			clockevents_switch_state(bc, CLOCK_EVT_STATE_ONESHOT);
			tick_broadcast_init_next_event(tmpmask,
						       tick_next_period);
			tick_broadcast_set_event(bc, cpu, tick_next_period);
		} else
			bc->next_event = KTIME_MAX;
	} else {
		/*
                 * The first cpu which switches to oneshot mode sets
                 * the bit for all other cpus which are in the general
                 * (periodic) broadcast mask. So the bit is set and
                 * would prevent the first broadcast enter after this
                 * to program the bc device.
                 */
		tick_broadcast_clear_oneshot(cpu);
	}
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
Thomas Gleixner
99
80.49%
8
57.14%
Rusty Russell
15
12.20%
1
7.14%
Viresh Kumar
4
3.25%
2
14.29%
Daniel Lezcano
4
3.25%
2
14.29%
Stephen Boyd
1
0.81%
1
7.14%
Total
123
100.00%
14
100.00%

/*
 * Select oneshot operating mode for the broadcast device
 */


void tick_broadcast_switch_to_oneshot(void)
{
	struct clock_event_device *bc;
	unsigned long flags;

	raw_spin_lock_irqsave(&tick_broadcast_lock, flags);

	tick_broadcast_device.mode = TICKDEV_MODE_ONESHOT;
	bc = tick_broadcast_device.evtdev;
	if (bc)
		tick_broadcast_setup_oneshot(bc);

	raw_spin_unlock_irqrestore(&tick_broadcast_lock, flags);
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
Thomas Gleixner
47
88.68%
2
66.67%
Suresh B. Siddha
6
11.32%
1
33.33%
Total
53
100.00%
3
100.00%

#ifdef CONFIG_HOTPLUG_CPU


void hotplug_cpu__broadcast_tick_pull(int deadcpu)
{
	struct clock_event_device *bc;
	unsigned long flags;

	raw_spin_lock_irqsave(&tick_broadcast_lock, flags);
	bc = tick_broadcast_device.evtdev;

	if (bc && broadcast_needs_cpu(bc, deadcpu)) {
		/* This moves the broadcast assignment to this CPU: */
		clockevents_program_event(bc, bc->next_event, 1);
	}
	raw_spin_unlock_irqrestore(&tick_broadcast_lock, flags);
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
Thomas Gleixner
64
100.00%
1
100.00%
Total
64
100.00%
1
100.00%

/*
 * Remove a dead CPU from broadcasting
 */


void tick_shutdown_broadcast_oneshot(unsigned int cpu)
{
	unsigned long flags;

	raw_spin_lock_irqsave(&tick_broadcast_lock, flags);

	/*
         * Clear the broadcast masks for the dead cpu, but do not stop
         * the broadcast device!
         */
	cpumask_clear_cpu(cpu, tick_broadcast_oneshot_mask);
	cpumask_clear_cpu(cpu, tick_broadcast_pending_mask);
	cpumask_clear_cpu(cpu, tick_broadcast_force_mask);

	raw_spin_unlock_irqrestore(&tick_broadcast_lock, flags);
}
Contributors
Person
Tokens
Prop
Commits
CommitProp
Thomas Gleixner
50
98.04%
5
83.33%
Rusty Russell
1
1.96%
1
16.67%
Total
51
100.00%
6
100.00%

#endif

/*
 * Check, whether the broadcast device is in one shot mode
 */


int tick_broadcast_oneshot_active(void)
{
	return tick_broadcast_device.mode == TICKDEV_MODE_ONESHOT;
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
Thomas Gleixner
14
100.00%
1
100.00%
Total
14
100.00%
1
100.00%

/*
 * Check whether the broadcast device supports oneshot.
 */


bool tick_broadcast_oneshot_available(void)
{
	struct clock_event_device *bc = tick_broadcast_device.evtdev;

	return bc ? bc->features & CLOCK_EVT_FEAT_ONESHOT : false;
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
Thomas Gleixner
27
100.00%
1
100.00%
Total
27
100.00%
1
100.00%

#else


int __tick_broadcast_oneshot_control(enum tick_broadcast_state state)
{
	struct clock_event_device *bc = tick_broadcast_device.evtdev;

	if (!bc || (bc->features & CLOCK_EVT_FEAT_HRTIMER))
		return -EBUSY;

	return 0;
}
Contributors
Person
Tokens
Prop
Commits
CommitProp
Thomas Gleixner
38
100.00%
1
100.00%
Total
38
100.00%
1
100.00%

#endif



void __init tick_broadcast_init(void)
{
	zalloc_cpumask_var(&tick_broadcast_mask, GFP_NOWAIT);
	zalloc_cpumask_var(&tick_broadcast_on, GFP_NOWAIT);
	zalloc_cpumask_var(&tmpmask, GFP_NOWAIT);
#ifdef CONFIG_TICK_ONESHOT
	zalloc_cpumask_var(&tick_broadcast_oneshot_mask, GFP_NOWAIT);
	zalloc_cpumask_var(&tick_broadcast_pending_mask, GFP_NOWAIT);
	zalloc_cpumask_var(&tick_broadcast_force_mask, GFP_NOWAIT);
#endif
}
Contributors
Person
Tokens
Prop
Commits
CommitProp
Thomas Gleixner
61
100.00%
5
100.00%
Total
61
100.00%
5
100.00%

Overall Contributors
Person
Tokens
Prop
Commits
CommitProp
Thomas Gleixner
2315
78.24%
56
62.92%
Mark Rutland
146
4.93%
4
4.49%
Preeti U. Murthy
136
4.60%
2
2.25%
Daniel Lezcano
114
3.85%
3
3.37%
Rusty Russell
63
2.13%
2
2.25%
Stephen Boyd
52
1.76%
3
3.37%
Ingo Molnar
34
1.15%
1
1.12%
Mike Galbraith
25
0.84%
1
1.12%
Viresh Kumar
17
0.57%
3
3.37%
Suresh B. Siddha
14
0.47%
3
3.37%
Waiman Long
13
0.44%
1
1.12%
Sören Brinkmann
8
0.27%
1
1.12%
Andi Kleen
7
0.24%
1
1.12%
Venkatesh Pallipadi
4
0.14%
1
1.12%
Frédéric Weisbecker
4
0.14%
1
1.12%
Christoph Lameter
2
0.07%
1
1.12%
Dmitri Vorobiev
1
0.03%
1
1.12%
Mike Travis
1
0.03%
1
1.12%
Martin Schwidefsky
1
0.03%
1
1.12%
Russell King
1
0.03%
1
1.12%
Li Zefan
1
0.03%
1
1.12%
Total
2959
100.00%
89
100.00%
Directory: kernel/time

Information contained on this website is for historical information purposes only and does not indicate or represent copyright ownership.