mirror of https://gitee.com/openkylin/linux.git
1009 lines
26 KiB
C
1009 lines
26 KiB
C
/*
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* linux/kernel/time/tick-broadcast.c
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*
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* This file contains functions which emulate a local clock-event
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* device via a broadcast event source.
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*
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* Copyright(C) 2005-2006, Thomas Gleixner <tglx@linutronix.de>
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* Copyright(C) 2005-2007, Red Hat, Inc., Ingo Molnar
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* Copyright(C) 2006-2007, Timesys Corp., Thomas Gleixner
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*
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* This code is licenced under the GPL version 2. For details see
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* kernel-base/COPYING.
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*/
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#include <linux/cpu.h>
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#include <linux/err.h>
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#include <linux/hrtimer.h>
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#include <linux/interrupt.h>
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#include <linux/percpu.h>
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#include <linux/profile.h>
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#include <linux/sched.h>
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#include <linux/smp.h>
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#include <linux/module.h>
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#include "tick-internal.h"
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/*
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* Broadcast support for broken x86 hardware, where the local apic
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* timer stops in C3 state.
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*/
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static struct tick_device tick_broadcast_device;
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static cpumask_var_t tick_broadcast_mask;
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static cpumask_var_t tick_broadcast_on;
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static cpumask_var_t tmpmask;
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static DEFINE_RAW_SPINLOCK(tick_broadcast_lock);
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static int tick_broadcast_forced;
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#ifdef CONFIG_TICK_ONESHOT
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static void tick_broadcast_clear_oneshot(int cpu);
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static void tick_resume_broadcast_oneshot(struct clock_event_device *bc);
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#else
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static inline void tick_broadcast_clear_oneshot(int cpu) { }
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static inline void tick_resume_broadcast_oneshot(struct clock_event_device *bc) { }
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#endif
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/*
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* Debugging: see timer_list.c
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*/
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struct tick_device *tick_get_broadcast_device(void)
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{
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return &tick_broadcast_device;
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}
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struct cpumask *tick_get_broadcast_mask(void)
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{
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return tick_broadcast_mask;
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}
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/*
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* Start the device in periodic mode
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*/
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static void tick_broadcast_start_periodic(struct clock_event_device *bc)
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{
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if (bc)
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tick_setup_periodic(bc, 1);
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}
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/*
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* Check, if the device can be utilized as broadcast device:
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*/
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static bool tick_check_broadcast_device(struct clock_event_device *curdev,
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struct clock_event_device *newdev)
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{
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if ((newdev->features & CLOCK_EVT_FEAT_DUMMY) ||
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(newdev->features & CLOCK_EVT_FEAT_PERCPU) ||
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(newdev->features & CLOCK_EVT_FEAT_C3STOP))
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return false;
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if (tick_broadcast_device.mode == TICKDEV_MODE_ONESHOT &&
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!(newdev->features & CLOCK_EVT_FEAT_ONESHOT))
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return false;
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return !curdev || newdev->rating > curdev->rating;
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}
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/*
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* Conditionally install/replace broadcast device
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*/
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void tick_install_broadcast_device(struct clock_event_device *dev)
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{
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struct clock_event_device *cur = tick_broadcast_device.evtdev;
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if (!tick_check_broadcast_device(cur, dev))
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return;
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if (!try_module_get(dev->owner))
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return;
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clockevents_exchange_device(cur, dev);
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if (cur)
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cur->event_handler = clockevents_handle_noop;
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tick_broadcast_device.evtdev = dev;
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if (!cpumask_empty(tick_broadcast_mask))
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tick_broadcast_start_periodic(dev);
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/*
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* Inform all cpus about this. We might be in a situation
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* where we did not switch to oneshot mode because the per cpu
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* devices are affected by CLOCK_EVT_FEAT_C3STOP and the lack
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* of a oneshot capable broadcast device. Without that
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* notification the systems stays stuck in periodic mode
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* forever.
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*/
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if (dev->features & CLOCK_EVT_FEAT_ONESHOT)
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tick_clock_notify();
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}
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/*
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* Check, if the device is the broadcast device
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*/
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int tick_is_broadcast_device(struct clock_event_device *dev)
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{
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return (dev && tick_broadcast_device.evtdev == dev);
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}
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int tick_broadcast_update_freq(struct clock_event_device *dev, u32 freq)
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{
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int ret = -ENODEV;
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if (tick_is_broadcast_device(dev)) {
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raw_spin_lock(&tick_broadcast_lock);
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ret = __clockevents_update_freq(dev, freq);
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raw_spin_unlock(&tick_broadcast_lock);
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}
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return ret;
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}
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static void err_broadcast(const struct cpumask *mask)
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{
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pr_crit_once("Failed to broadcast timer tick. Some CPUs may be unresponsive.\n");
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}
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static void tick_device_setup_broadcast_func(struct clock_event_device *dev)
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{
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if (!dev->broadcast)
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dev->broadcast = tick_broadcast;
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if (!dev->broadcast) {
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pr_warn_once("%s depends on broadcast, but no broadcast function available\n",
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dev->name);
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dev->broadcast = err_broadcast;
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}
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}
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/*
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* Check, if the device is disfunctional and a place holder, which
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* needs to be handled by the broadcast device.
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*/
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int tick_device_uses_broadcast(struct clock_event_device *dev, int cpu)
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{
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struct clock_event_device *bc = tick_broadcast_device.evtdev;
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unsigned long flags;
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int ret = 0;
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raw_spin_lock_irqsave(&tick_broadcast_lock, flags);
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/*
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* Devices might be registered with both periodic and oneshot
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* mode disabled. This signals, that the device needs to be
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* operated from the broadcast device and is a placeholder for
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* the cpu local device.
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*/
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if (!tick_device_is_functional(dev)) {
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dev->event_handler = tick_handle_periodic;
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tick_device_setup_broadcast_func(dev);
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cpumask_set_cpu(cpu, tick_broadcast_mask);
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if (tick_broadcast_device.mode == TICKDEV_MODE_PERIODIC)
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tick_broadcast_start_periodic(bc);
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else
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tick_broadcast_setup_oneshot(bc);
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ret = 1;
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} else {
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/*
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* Clear the broadcast bit for this cpu if the
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* device is not power state affected.
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*/
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if (!(dev->features & CLOCK_EVT_FEAT_C3STOP))
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cpumask_clear_cpu(cpu, tick_broadcast_mask);
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else
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tick_device_setup_broadcast_func(dev);
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/*
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* Clear the broadcast bit if the CPU is not in
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* periodic broadcast on state.
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*/
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if (!cpumask_test_cpu(cpu, tick_broadcast_on))
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cpumask_clear_cpu(cpu, tick_broadcast_mask);
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switch (tick_broadcast_device.mode) {
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case TICKDEV_MODE_ONESHOT:
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/*
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* If the system is in oneshot mode we can
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* unconditionally clear the oneshot mask bit,
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* because the CPU is running and therefore
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* not in an idle state which causes the power
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* state affected device to stop. Let the
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* caller initialize the device.
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*/
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tick_broadcast_clear_oneshot(cpu);
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ret = 0;
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break;
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case TICKDEV_MODE_PERIODIC:
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/*
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* If the system is in periodic mode, check
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* whether the broadcast device can be
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* switched off now.
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*/
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if (cpumask_empty(tick_broadcast_mask) && bc)
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clockevents_shutdown(bc);
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/*
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* If we kept the cpu in the broadcast mask,
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* tell the caller to leave the per cpu device
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* in shutdown state. The periodic interrupt
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* is delivered by the broadcast device, if
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* the broadcast device exists and is not
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* hrtimer based.
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*/
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if (bc && !(bc->features & CLOCK_EVT_FEAT_HRTIMER))
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ret = cpumask_test_cpu(cpu, tick_broadcast_mask);
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break;
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default:
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break;
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}
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}
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raw_spin_unlock_irqrestore(&tick_broadcast_lock, flags);
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return ret;
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}
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#ifdef CONFIG_GENERIC_CLOCKEVENTS_BROADCAST
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int tick_receive_broadcast(void)
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{
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struct tick_device *td = this_cpu_ptr(&tick_cpu_device);
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struct clock_event_device *evt = td->evtdev;
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if (!evt)
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return -ENODEV;
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if (!evt->event_handler)
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return -EINVAL;
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evt->event_handler(evt);
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return 0;
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}
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#endif
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/*
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* Broadcast the event to the cpus, which are set in the mask (mangled).
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*/
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static bool tick_do_broadcast(struct cpumask *mask)
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{
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int cpu = smp_processor_id();
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struct tick_device *td;
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bool local = false;
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/*
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* Check, if the current cpu is in the mask
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*/
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if (cpumask_test_cpu(cpu, mask)) {
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struct clock_event_device *bc = tick_broadcast_device.evtdev;
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cpumask_clear_cpu(cpu, mask);
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/*
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* We only run the local handler, if the broadcast
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* device is not hrtimer based. Otherwise we run into
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* a hrtimer recursion.
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*
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* local timer_interrupt()
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* local_handler()
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* expire_hrtimers()
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* bc_handler()
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* local_handler()
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* expire_hrtimers()
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*/
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local = !(bc->features & CLOCK_EVT_FEAT_HRTIMER);
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}
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if (!cpumask_empty(mask)) {
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/*
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* It might be necessary to actually check whether the devices
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* have different broadcast functions. For now, just use the
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* one of the first device. This works as long as we have this
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* misfeature only on x86 (lapic)
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*/
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td = &per_cpu(tick_cpu_device, cpumask_first(mask));
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td->evtdev->broadcast(mask);
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}
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return local;
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}
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/*
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* Periodic broadcast:
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* - invoke the broadcast handlers
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*/
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static bool tick_do_periodic_broadcast(void)
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{
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cpumask_and(tmpmask, cpu_online_mask, tick_broadcast_mask);
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return tick_do_broadcast(tmpmask);
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}
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/*
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* Event handler for periodic broadcast ticks
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*/
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static void tick_handle_periodic_broadcast(struct clock_event_device *dev)
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{
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struct tick_device *td = this_cpu_ptr(&tick_cpu_device);
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bool bc_local;
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raw_spin_lock(&tick_broadcast_lock);
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/* Handle spurious interrupts gracefully */
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if (clockevent_state_shutdown(tick_broadcast_device.evtdev)) {
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raw_spin_unlock(&tick_broadcast_lock);
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return;
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}
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bc_local = tick_do_periodic_broadcast();
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if (clockevent_state_oneshot(dev)) {
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ktime_t next = ktime_add(dev->next_event, tick_period);
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clockevents_program_event(dev, next, true);
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}
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raw_spin_unlock(&tick_broadcast_lock);
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/*
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* We run the handler of the local cpu after dropping
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* tick_broadcast_lock because the handler might deadlock when
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* trying to switch to oneshot mode.
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*/
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if (bc_local)
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td->evtdev->event_handler(td->evtdev);
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}
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/**
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* tick_broadcast_control - Enable/disable or force broadcast mode
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* @mode: The selected broadcast mode
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*
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* Called when the system enters a state where affected tick devices
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* might stop. Note: TICK_BROADCAST_FORCE cannot be undone.
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*
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* Called with interrupts disabled, so clockevents_lock is not
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* required here because the local clock event device cannot go away
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* under us.
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*/
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void tick_broadcast_control(enum tick_broadcast_mode mode)
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{
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struct clock_event_device *bc, *dev;
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struct tick_device *td;
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int cpu, bc_stopped;
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td = this_cpu_ptr(&tick_cpu_device);
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dev = td->evtdev;
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/*
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* Is the device not affected by the powerstate ?
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*/
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if (!dev || !(dev->features & CLOCK_EVT_FEAT_C3STOP))
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return;
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if (!tick_device_is_functional(dev))
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return;
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raw_spin_lock(&tick_broadcast_lock);
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cpu = smp_processor_id();
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bc = tick_broadcast_device.evtdev;
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bc_stopped = cpumask_empty(tick_broadcast_mask);
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switch (mode) {
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case TICK_BROADCAST_FORCE:
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tick_broadcast_forced = 1;
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case TICK_BROADCAST_ON:
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cpumask_set_cpu(cpu, tick_broadcast_on);
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if (!cpumask_test_and_set_cpu(cpu, tick_broadcast_mask)) {
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/*
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* Only shutdown the cpu local device, if:
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*
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* - the broadcast device exists
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* - the broadcast device is not a hrtimer based one
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* - the broadcast device is in periodic mode to
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* avoid a hickup during switch to oneshot mode
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*/
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if (bc && !(bc->features & CLOCK_EVT_FEAT_HRTIMER) &&
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tick_broadcast_device.mode == TICKDEV_MODE_PERIODIC)
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clockevents_shutdown(dev);
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}
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break;
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case TICK_BROADCAST_OFF:
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if (tick_broadcast_forced)
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break;
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cpumask_clear_cpu(cpu, tick_broadcast_on);
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if (!tick_device_is_functional(dev))
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break;
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if (cpumask_test_and_clear_cpu(cpu, tick_broadcast_mask)) {
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if (tick_broadcast_device.mode ==
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TICKDEV_MODE_PERIODIC)
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tick_setup_periodic(dev, 0);
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}
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break;
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}
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if (bc) {
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if (cpumask_empty(tick_broadcast_mask)) {
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if (!bc_stopped)
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clockevents_shutdown(bc);
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} else if (bc_stopped) {
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if (tick_broadcast_device.mode == TICKDEV_MODE_PERIODIC)
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tick_broadcast_start_periodic(bc);
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else
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tick_broadcast_setup_oneshot(bc);
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}
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}
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raw_spin_unlock(&tick_broadcast_lock);
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}
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EXPORT_SYMBOL_GPL(tick_broadcast_control);
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/*
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* Set the periodic handler depending on broadcast on/off
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*/
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void tick_set_periodic_handler(struct clock_event_device *dev, int broadcast)
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{
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if (!broadcast)
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dev->event_handler = tick_handle_periodic;
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else
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dev->event_handler = tick_handle_periodic_broadcast;
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}
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#ifdef CONFIG_HOTPLUG_CPU
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/*
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* Remove a CPU from broadcasting
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*/
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void tick_shutdown_broadcast(unsigned int cpu)
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{
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struct clock_event_device *bc;
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unsigned long flags;
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raw_spin_lock_irqsave(&tick_broadcast_lock, flags);
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bc = tick_broadcast_device.evtdev;
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cpumask_clear_cpu(cpu, tick_broadcast_mask);
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cpumask_clear_cpu(cpu, tick_broadcast_on);
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if (tick_broadcast_device.mode == TICKDEV_MODE_PERIODIC) {
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if (bc && cpumask_empty(tick_broadcast_mask))
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clockevents_shutdown(bc);
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}
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raw_spin_unlock_irqrestore(&tick_broadcast_lock, flags);
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}
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#endif
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void tick_suspend_broadcast(void)
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{
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struct clock_event_device *bc;
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unsigned long flags;
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raw_spin_lock_irqsave(&tick_broadcast_lock, flags);
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bc = tick_broadcast_device.evtdev;
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if (bc)
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clockevents_shutdown(bc);
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raw_spin_unlock_irqrestore(&tick_broadcast_lock, flags);
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}
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/*
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* This is called from tick_resume_local() on a resuming CPU. That's
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* called from the core resume function, tick_unfreeze() and the magic XEN
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* resume hackery.
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*
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* In none of these cases the broadcast device mode can change and the
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* bit of the resuming CPU in the broadcast mask is safe as well.
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*/
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bool tick_resume_check_broadcast(void)
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{
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if (tick_broadcast_device.mode == TICKDEV_MODE_ONESHOT)
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return false;
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else
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return cpumask_test_cpu(smp_processor_id(), tick_broadcast_mask);
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}
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|
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void tick_resume_broadcast(void)
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{
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struct clock_event_device *bc;
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unsigned long flags;
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raw_spin_lock_irqsave(&tick_broadcast_lock, flags);
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bc = tick_broadcast_device.evtdev;
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if (bc) {
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clockevents_tick_resume(bc);
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switch (tick_broadcast_device.mode) {
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case TICKDEV_MODE_PERIODIC:
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if (!cpumask_empty(tick_broadcast_mask))
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tick_broadcast_start_periodic(bc);
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break;
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case TICKDEV_MODE_ONESHOT:
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if (!cpumask_empty(tick_broadcast_mask))
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tick_resume_broadcast_oneshot(bc);
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break;
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}
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}
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raw_spin_unlock_irqrestore(&tick_broadcast_lock, flags);
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}
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|
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#ifdef CONFIG_TICK_ONESHOT
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|
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static cpumask_var_t tick_broadcast_oneshot_mask;
|
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static cpumask_var_t tick_broadcast_pending_mask;
|
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static cpumask_var_t tick_broadcast_force_mask;
|
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|
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/*
|
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* Exposed for debugging: see timer_list.c
|
|
*/
|
|
struct cpumask *tick_get_broadcast_oneshot_mask(void)
|
|
{
|
|
return tick_broadcast_oneshot_mask;
|
|
}
|
|
|
|
/*
|
|
* 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);
|
|
}
|
|
|
|
/*
|
|
* 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);
|
|
}
|
|
|
|
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));
|
|
}
|
|
|
|
static void tick_resume_broadcast_oneshot(struct clock_event_device *bc)
|
|
{
|
|
clockevents_switch_state(bc, CLOCK_EVT_STATE_ONESHOT);
|
|
}
|
|
|
|
/*
|
|
* 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);
|
|
}
|
|
}
|
|
}
|
|
|
|
/*
|
|
* 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.tv64 = KTIME_MAX;
|
|
next_event.tv64 = 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.tv64 <= now.tv64) {
|
|
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.tv64 < next_event.tv64) {
|
|
next_event.tv64 = td->evtdev->next_event.tv64;
|
|
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.tv64 != 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);
|
|
}
|
|
}
|
|
|
|
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.tv64 == KTIME_MAX)
|
|
return 0;
|
|
return bc->bound_on == cpu ? -EBUSY : 0;
|
|
}
|
|
|
|
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.tv64 < bc->next_event.tv64)
|
|
return;
|
|
}
|
|
clockevents_switch_state(dev, CLOCK_EVT_STATE_SHUTDOWN);
|
|
}
|
|
|
|
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.tv64 < bc->next_event.tv64) {
|
|
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.tv64 == 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.tv64 <= now.tv64) {
|
|
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;
|
|
}
|
|
|
|
/*
|
|
* 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);
|
|
}
|
|
|
|
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;
|
|
}
|
|
}
|
|
|
|
/**
|
|
* tick_broadcast_setup_oneshot - setup the broadcast device
|
|
*/
|
|
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.tv64 = 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);
|
|
}
|
|
}
|
|
|
|
/*
|
|
* 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);
|
|
}
|
|
|
|
#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);
|
|
}
|
|
|
|
/*
|
|
* 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);
|
|
}
|
|
#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;
|
|
}
|
|
|
|
/*
|
|
* 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;
|
|
}
|
|
|
|
#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;
|
|
}
|
|
#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
|
|
}
|