mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
synced 2024-10-30 08:02:30 +00:00
61c22c34c6
The issue of the endless reprogramming loop due to a too small min_delta_ns was fixed with the previous updates of the clock events code, but we had no information about the spread of this problem. I added a WARN_ON to get automated information via kerneloops.org and to get some direct reports, which allowed me to analyse the affected machines. The WARN_ON has served its purpose and would be annoying for a release kernel. Remove it and just keep the information about the increase of the min_delta_ns value. Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
141 lines
3.4 KiB
C
141 lines
3.4 KiB
C
/*
|
|
* linux/kernel/time/tick-oneshot.c
|
|
*
|
|
* This file contains functions which manage high resolution tick
|
|
* related events.
|
|
*
|
|
* 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/tick.h>
|
|
|
|
#include "tick-internal.h"
|
|
|
|
/**
|
|
* tick_program_event internal worker function
|
|
*/
|
|
int tick_dev_program_event(struct clock_event_device *dev, ktime_t expires,
|
|
int force)
|
|
{
|
|
ktime_t now = ktime_get();
|
|
int i;
|
|
|
|
for (i = 0;;) {
|
|
int ret = clockevents_program_event(dev, expires, now);
|
|
|
|
if (!ret || !force)
|
|
return ret;
|
|
|
|
/*
|
|
* We tried 2 times to program the device with the given
|
|
* min_delta_ns. If that's not working then we double it
|
|
* and emit a warning.
|
|
*/
|
|
if (++i > 2) {
|
|
/* Increase the min. delta and try again */
|
|
if (!dev->min_delta_ns)
|
|
dev->min_delta_ns = 5000;
|
|
else
|
|
dev->min_delta_ns += dev->min_delta_ns >> 1;
|
|
|
|
printk(KERN_WARNING
|
|
"CE: %s increasing min_delta_ns to %lu nsec\n",
|
|
dev->name ? dev->name : "?",
|
|
dev->min_delta_ns << 1);
|
|
|
|
i = 0;
|
|
}
|
|
|
|
now = ktime_get();
|
|
expires = ktime_add_ns(now, dev->min_delta_ns);
|
|
}
|
|
}
|
|
|
|
/**
|
|
* tick_program_event
|
|
*/
|
|
int tick_program_event(ktime_t expires, int force)
|
|
{
|
|
struct clock_event_device *dev = __get_cpu_var(tick_cpu_device).evtdev;
|
|
|
|
return tick_dev_program_event(dev, expires, force);
|
|
}
|
|
|
|
/**
|
|
* tick_resume_onshot - resume oneshot mode
|
|
*/
|
|
void tick_resume_oneshot(void)
|
|
{
|
|
struct tick_device *td = &__get_cpu_var(tick_cpu_device);
|
|
struct clock_event_device *dev = td->evtdev;
|
|
|
|
clockevents_set_mode(dev, CLOCK_EVT_MODE_ONESHOT);
|
|
tick_program_event(ktime_get(), 1);
|
|
}
|
|
|
|
/**
|
|
* tick_setup_oneshot - setup the event device for oneshot mode (hres or nohz)
|
|
*/
|
|
void tick_setup_oneshot(struct clock_event_device *newdev,
|
|
void (*handler)(struct clock_event_device *),
|
|
ktime_t next_event)
|
|
{
|
|
newdev->event_handler = handler;
|
|
clockevents_set_mode(newdev, CLOCK_EVT_MODE_ONESHOT);
|
|
tick_dev_program_event(newdev, next_event, 1);
|
|
}
|
|
|
|
/**
|
|
* tick_switch_to_oneshot - switch to oneshot mode
|
|
*/
|
|
int tick_switch_to_oneshot(void (*handler)(struct clock_event_device *))
|
|
{
|
|
struct tick_device *td = &__get_cpu_var(tick_cpu_device);
|
|
struct clock_event_device *dev = td->evtdev;
|
|
|
|
if (!dev || !(dev->features & CLOCK_EVT_FEAT_ONESHOT) ||
|
|
!tick_device_is_functional(dev)) {
|
|
|
|
printk(KERN_INFO "Clockevents: "
|
|
"could not switch to one-shot mode:");
|
|
if (!dev) {
|
|
printk(" no tick device\n");
|
|
} else {
|
|
if (!tick_device_is_functional(dev))
|
|
printk(" %s is not functional.\n", dev->name);
|
|
else
|
|
printk(" %s does not support one-shot mode.\n",
|
|
dev->name);
|
|
}
|
|
return -EINVAL;
|
|
}
|
|
|
|
td->mode = TICKDEV_MODE_ONESHOT;
|
|
dev->event_handler = handler;
|
|
clockevents_set_mode(dev, CLOCK_EVT_MODE_ONESHOT);
|
|
tick_broadcast_switch_to_oneshot();
|
|
return 0;
|
|
}
|
|
|
|
#ifdef CONFIG_HIGH_RES_TIMERS
|
|
/**
|
|
* tick_init_highres - switch to high resolution mode
|
|
*
|
|
* Called with interrupts disabled.
|
|
*/
|
|
int tick_init_highres(void)
|
|
{
|
|
return tick_switch_to_oneshot(hrtimer_interrupt);
|
|
}
|
|
#endif
|