kernel-ark/kernel/time/tick-broadcast.c
Thomas Gleixner b7e113dc9d clockevents: remove the suspend/resume workaround^Wthinko
In a desparate attempt to fix the suspend/resume problem on Andrews
VAIO I added a workaround which enforced the broadcast of the oneshot
timer on resume. This was actually resolving the problem on the VAIO
but was just a stupid workaround, which was not tackling the root
cause: the assignement of lower idle C-States in the ACPI processor_idle
code. The cpuidle patches, which utilize the dynamic tick feature and
go faster into deeper C-states exposed the problem again. The correct
solution is the previous patch, which prevents lower C-states across
the suspend/resume.

Remove the enforcement code, including the conditional broadcast timer
arming, which helped to pamper over the real problem for quite a time.
The oneshot broadcast flag for the cpu, which runs the resume code can
never be set at the time when this code is executed. It only gets set,
when the CPU is entering a lower idle C-State.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Len Brown <lenb@kernel.org>
Cc: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Cc: Rafael J. Wysocki <rjw@sisk.pl>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-09-22 17:15:34 -07:00

563 lines
13 KiB
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/irq.h>
#include <linux/percpu.h>
#include <linux/profile.h>
#include <linux/sched.h>
#include <linux/tick.h>
#include "tick-internal.h"
/*
* Broadcast support for broken x86 hardware, where the local apic
* timer stops in C3 state.
*/
struct tick_device tick_broadcast_device;
static cpumask_t tick_broadcast_mask;
static DEFINE_SPINLOCK(tick_broadcast_lock);
#ifdef CONFIG_TICK_ONESHOT
static void tick_broadcast_clear_oneshot(int cpu);
#else
static inline void tick_broadcast_clear_oneshot(int cpu) { }
#endif
/*
* Debugging: see timer_list.c
*/
struct tick_device *tick_get_broadcast_device(void)
{
return &tick_broadcast_device;
}
cpumask_t *tick_get_broadcast_mask(void)
{
return &tick_broadcast_mask;
}
/*
* Start the device in periodic mode
*/
static void tick_broadcast_start_periodic(struct clock_event_device *bc)
{
if (bc)
tick_setup_periodic(bc, 1);
}
/*
* Check, if the device can be utilized as broadcast device:
*/
int tick_check_broadcast_device(struct clock_event_device *dev)
{
if (tick_broadcast_device.evtdev ||
(dev->features & CLOCK_EVT_FEAT_C3STOP))
return 0;
clockevents_exchange_device(NULL, dev);
tick_broadcast_device.evtdev = dev;
if (!cpus_empty(tick_broadcast_mask))
tick_broadcast_start_periodic(dev);
return 1;
}
/*
* 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);
}
/*
* 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)
{
unsigned long flags;
int ret = 0;
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;
cpu_set(cpu, tick_broadcast_mask);
tick_broadcast_start_periodic(tick_broadcast_device.evtdev);
ret = 1;
} else {
/*
* When the new device is not affected by the stop
* feature and the cpu is marked in the broadcast mask
* then clear the broadcast bit.
*/
if (!(dev->features & CLOCK_EVT_FEAT_C3STOP)) {
int cpu = smp_processor_id();
cpu_clear(cpu, tick_broadcast_mask);
tick_broadcast_clear_oneshot(cpu);
}
}
spin_unlock_irqrestore(&tick_broadcast_lock, flags);
return ret;
}
/*
* Broadcast the event to the cpus, which are set in the mask
*/
int tick_do_broadcast(cpumask_t mask)
{
int ret = 0, cpu = smp_processor_id();
struct tick_device *td;
/*
* Check, if the current cpu is in the mask
*/
if (cpu_isset(cpu, mask)) {
cpu_clear(cpu, mask);
td = &per_cpu(tick_cpu_device, cpu);
td->evtdev->event_handler(td->evtdev);
ret = 1;
}
if (!cpus_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)
*/
cpu = first_cpu(mask);
td = &per_cpu(tick_cpu_device, cpu);
td->evtdev->broadcast(mask);
ret = 1;
}
return ret;
}
/*
* Periodic broadcast:
* - invoke the broadcast handlers
*/
static void tick_do_periodic_broadcast(void)
{
cpumask_t mask;
spin_lock(&tick_broadcast_lock);
cpus_and(mask, cpu_online_map, tick_broadcast_mask);
tick_do_broadcast(mask);
spin_unlock(&tick_broadcast_lock);
}
/*
* Event handler for periodic broadcast ticks
*/
static void tick_handle_periodic_broadcast(struct clock_event_device *dev)
{
dev->next_event.tv64 = KTIME_MAX;
tick_do_periodic_broadcast();
/*
* The device is in periodic mode. No reprogramming necessary:
*/
if (dev->mode == CLOCK_EVT_MODE_PERIODIC)
return;
/*
* Setup the next period for devices, which do not have
* periodic mode:
*/
for (;;) {
ktime_t next = ktime_add(dev->next_event, tick_period);
if (!clockevents_program_event(dev, next, ktime_get()))
return;
tick_do_periodic_broadcast();
}
}
/*
* Powerstate information: The system enters/leaves a state, where
* affected devices might stop
*/
static void tick_do_broadcast_on_off(void *why)
{
struct clock_event_device *bc, *dev;
struct tick_device *td;
unsigned long flags, *reason = why;
int cpu;
spin_lock_irqsave(&tick_broadcast_lock, flags);
cpu = smp_processor_id();
td = &per_cpu(tick_cpu_device, cpu);
dev = td->evtdev;
bc = tick_broadcast_device.evtdev;
/*
* Is the device in broadcast mode forever or is it not
* affected by the powerstate ?
*/
if (!dev || !tick_device_is_functional(dev) ||
!(dev->features & CLOCK_EVT_FEAT_C3STOP))
goto out;
if (*reason == CLOCK_EVT_NOTIFY_BROADCAST_ON) {
if (!cpu_isset(cpu, tick_broadcast_mask)) {
cpu_set(cpu, tick_broadcast_mask);
if (td->mode == TICKDEV_MODE_PERIODIC)
clockevents_set_mode(dev,
CLOCK_EVT_MODE_SHUTDOWN);
}
} else {
if (cpu_isset(cpu, tick_broadcast_mask)) {
cpu_clear(cpu, tick_broadcast_mask);
if (td->mode == TICKDEV_MODE_PERIODIC)
tick_setup_periodic(dev, 0);
}
}
if (cpus_empty(tick_broadcast_mask))
clockevents_set_mode(bc, CLOCK_EVT_MODE_SHUTDOWN);
else {
if (tick_broadcast_device.mode == TICKDEV_MODE_PERIODIC)
tick_broadcast_start_periodic(bc);
else
tick_broadcast_setup_oneshot(bc);
}
out:
spin_unlock_irqrestore(&tick_broadcast_lock, flags);
}
/*
* Powerstate information: The system enters/leaves a state, where
* affected devices might stop.
*/
void tick_broadcast_on_off(unsigned long reason, int *oncpu)
{
int cpu = get_cpu();
if (!cpu_isset(*oncpu, cpu_online_map)) {
printk(KERN_ERR "tick-braodcast: ignoring broadcast for "
"offline CPU #%d\n", *oncpu);
} else {
if (cpu == *oncpu)
tick_do_broadcast_on_off(&reason);
else
smp_call_function_single(*oncpu,
tick_do_broadcast_on_off,
&reason, 1, 1);
}
put_cpu();
}
/*
* 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;
}
/*
* Remove a CPU from broadcasting
*/
void tick_shutdown_broadcast(unsigned int *cpup)
{
struct clock_event_device *bc;
unsigned long flags;
unsigned int cpu = *cpup;
spin_lock_irqsave(&tick_broadcast_lock, flags);
bc = tick_broadcast_device.evtdev;
cpu_clear(cpu, tick_broadcast_mask);
if (tick_broadcast_device.mode == TICKDEV_MODE_PERIODIC) {
if (bc && cpus_empty(tick_broadcast_mask))
clockevents_set_mode(bc, CLOCK_EVT_MODE_SHUTDOWN);
}
spin_unlock_irqrestore(&tick_broadcast_lock, flags);
}
void tick_suspend_broadcast(void)
{
struct clock_event_device *bc;
unsigned long flags;
spin_lock_irqsave(&tick_broadcast_lock, flags);
bc = tick_broadcast_device.evtdev;
if (bc)
clockevents_set_mode(bc, CLOCK_EVT_MODE_SHUTDOWN);
spin_unlock_irqrestore(&tick_broadcast_lock, flags);
}
int tick_resume_broadcast(void)
{
struct clock_event_device *bc;
unsigned long flags;
int broadcast = 0;
spin_lock_irqsave(&tick_broadcast_lock, flags);
bc = tick_broadcast_device.evtdev;
if (bc) {
clockevents_set_mode(bc, CLOCK_EVT_MODE_RESUME);
switch (tick_broadcast_device.mode) {
case TICKDEV_MODE_PERIODIC:
if(!cpus_empty(tick_broadcast_mask))
tick_broadcast_start_periodic(bc);
broadcast = cpu_isset(smp_processor_id(),
tick_broadcast_mask);
break;
case TICKDEV_MODE_ONESHOT:
broadcast = tick_resume_broadcast_oneshot(bc);
break;
}
}
spin_unlock_irqrestore(&tick_broadcast_lock, flags);
return broadcast;
}
#ifdef CONFIG_TICK_ONESHOT
static cpumask_t tick_broadcast_oneshot_mask;
/*
* Debugging: see timer_list.c
*/
cpumask_t *tick_get_broadcast_oneshot_mask(void)
{
return &tick_broadcast_oneshot_mask;
}
static int tick_broadcast_set_event(ktime_t expires, int force)
{
struct clock_event_device *bc = tick_broadcast_device.evtdev;
ktime_t now = ktime_get();
int res;
for(;;) {
res = clockevents_program_event(bc, expires, now);
if (!res || !force)
return res;
now = ktime_get();
expires = ktime_add(now, ktime_set(0, bc->min_delta_ns));
}
}
int tick_resume_broadcast_oneshot(struct clock_event_device *bc)
{
clockevents_set_mode(bc, CLOCK_EVT_MODE_ONESHOT);
return 0;
}
/*
* Reprogram the broadcast device:
*
* Called with tick_broadcast_lock held and interrupts disabled.
*/
static int tick_broadcast_reprogram(void)
{
ktime_t expires = { .tv64 = KTIME_MAX };
struct tick_device *td;
int cpu;
/*
* Find the event which expires next:
*/
for (cpu = first_cpu(tick_broadcast_oneshot_mask); cpu != NR_CPUS;
cpu = next_cpu(cpu, tick_broadcast_oneshot_mask)) {
td = &per_cpu(tick_cpu_device, cpu);
if (td->evtdev->next_event.tv64 < expires.tv64)
expires = td->evtdev->next_event;
}
if (expires.tv64 == KTIME_MAX)
return 0;
return tick_broadcast_set_event(expires, 0);
}
/*
* Handle oneshot mode broadcasting
*/
static void tick_handle_oneshot_broadcast(struct clock_event_device *dev)
{
struct tick_device *td;
cpumask_t mask;
ktime_t now;
int cpu;
spin_lock(&tick_broadcast_lock);
again:
dev->next_event.tv64 = KTIME_MAX;
mask = CPU_MASK_NONE;
now = ktime_get();
/* Find all expired events */
for (cpu = first_cpu(tick_broadcast_oneshot_mask); cpu != NR_CPUS;
cpu = next_cpu(cpu, tick_broadcast_oneshot_mask)) {
td = &per_cpu(tick_cpu_device, cpu);
if (td->evtdev->next_event.tv64 <= now.tv64)
cpu_set(cpu, mask);
}
/*
* Wakeup the cpus which have an expired event. The broadcast
* device is reprogrammed in the return from idle code.
*/
if (!tick_do_broadcast(mask)) {
/*
* The global event did not expire any CPU local
* events. This happens in dyntick mode, as the
* maximum PIT delta is quite small.
*/
if (tick_broadcast_reprogram())
goto again;
}
spin_unlock(&tick_broadcast_lock);
}
/*
* Powerstate information: The system enters/leaves a state, where
* affected devices might stop
*/
void tick_broadcast_oneshot_control(unsigned long reason)
{
struct clock_event_device *bc, *dev;
struct tick_device *td;
unsigned long flags;
int cpu;
spin_lock_irqsave(&tick_broadcast_lock, flags);
/*
* Periodic mode does not care about the enter/exit of power
* states
*/
if (tick_broadcast_device.mode == TICKDEV_MODE_PERIODIC)
goto out;
bc = tick_broadcast_device.evtdev;
cpu = smp_processor_id();
td = &per_cpu(tick_cpu_device, cpu);
dev = td->evtdev;
if (!(dev->features & CLOCK_EVT_FEAT_C3STOP))
goto out;
if (reason == CLOCK_EVT_NOTIFY_BROADCAST_ENTER) {
if (!cpu_isset(cpu, tick_broadcast_oneshot_mask)) {
cpu_set(cpu, tick_broadcast_oneshot_mask);
clockevents_set_mode(dev, CLOCK_EVT_MODE_SHUTDOWN);
if (dev->next_event.tv64 < bc->next_event.tv64)
tick_broadcast_set_event(dev->next_event, 1);
}
} else {
if (cpu_isset(cpu, tick_broadcast_oneshot_mask)) {
cpu_clear(cpu, tick_broadcast_oneshot_mask);
clockevents_set_mode(dev, CLOCK_EVT_MODE_ONESHOT);
if (dev->next_event.tv64 != KTIME_MAX)
tick_program_event(dev->next_event, 1);
}
}
out:
spin_unlock_irqrestore(&tick_broadcast_lock, flags);
}
/*
* Reset the one shot broadcast for a cpu
*
* Called with tick_broadcast_lock held
*/
static void tick_broadcast_clear_oneshot(int cpu)
{
cpu_clear(cpu, tick_broadcast_oneshot_mask);
}
/**
* tick_broadcast_setup_highres - setup the broadcast device for highres
*/
void tick_broadcast_setup_oneshot(struct clock_event_device *bc)
{
if (bc->mode != CLOCK_EVT_MODE_ONESHOT) {
bc->event_handler = tick_handle_oneshot_broadcast;
clockevents_set_mode(bc, CLOCK_EVT_MODE_ONESHOT);
bc->next_event.tv64 = KTIME_MAX;
}
}
/*
* Select oneshot operating mode for the broadcast device
*/
void tick_broadcast_switch_to_oneshot(void)
{
struct clock_event_device *bc;
unsigned long flags;
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);
spin_unlock_irqrestore(&tick_broadcast_lock, flags);
}
/*
* Remove a dead CPU from broadcasting
*/
void tick_shutdown_broadcast_oneshot(unsigned int *cpup)
{
unsigned long flags;
unsigned int cpu = *cpup;
spin_lock_irqsave(&tick_broadcast_lock, flags);
/*
* Clear the broadcast mask flag for the dead cpu, but do not
* stop the broadcast device!
*/
cpu_clear(cpu, tick_broadcast_oneshot_mask);
spin_unlock_irqrestore(&tick_broadcast_lock, flags);
}
#endif