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linux/kernel/time/tick-internal.h
Paul E. McKenney d25a025201 clocksource: Make clocksource watchdog test safe for slow-HZ systems 
The clocksource watchdog test sets a local JIFFIES_SHIFT macro and assumes
that HZ is >= 100. For smaller HZ values this shift value is too large and
causes undefined behaviour.

Move the HZ-based definitions of JIFFIES_SHIFT from kernel/time/jiffies.c
to kernel/time/tick-internal.h so the clocksource watchdog test can utilize
them, which makes it work correctly with all HZ values.

[ tglx: Resolved conflicts and massaged changelog ]

Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/lkml/20210812000133.GA402890@paulmck-ThinkPad-P17-Gen-1/
2021-08-28 17:01:32 +02:00

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/* SPDX-License-Identifier: GPL-2.0 */
/*
* tick internal variable and functions used by low/high res code
*/
#include <linux/hrtimer.h>
#include <linux/tick.h>
#include "timekeeping.h"
#include "tick-sched.h"
#ifdef CONFIG_GENERIC_CLOCKEVENTS
# define TICK_DO_TIMER_NONE -1
# define TICK_DO_TIMER_BOOT -2
DECLARE_PER_CPU(struct tick_device, tick_cpu_device);
extern ktime_t tick_next_period;
extern int tick_do_timer_cpu __read_mostly;
extern void tick_setup_periodic(struct clock_event_device *dev, int broadcast);
extern void tick_handle_periodic(struct clock_event_device *dev);
extern void tick_check_new_device(struct clock_event_device *dev);
extern void tick_shutdown(unsigned int cpu);
extern void tick_suspend(void);
extern void tick_resume(void);
extern bool tick_check_replacement(struct clock_event_device *curdev,
struct clock_event_device *newdev);
extern void tick_install_replacement(struct clock_event_device *dev);
extern int tick_is_oneshot_available(void);
extern struct tick_device *tick_get_device(int cpu);
extern int clockevents_tick_resume(struct clock_event_device *dev);
/* Check, if the device is functional or a dummy for broadcast */
static inline int tick_device_is_functional(struct clock_event_device *dev)
{
return !(dev->features & CLOCK_EVT_FEAT_DUMMY);
}
static inline enum clock_event_state clockevent_get_state(struct clock_event_device *dev)
{
return dev->state_use_accessors;
}
static inline void clockevent_set_state(struct clock_event_device *dev,
enum clock_event_state state)
{
dev->state_use_accessors = state;
}
extern void clockevents_shutdown(struct clock_event_device *dev);
extern void clockevents_exchange_device(struct clock_event_device *old,
struct clock_event_device *new);
extern void clockevents_switch_state(struct clock_event_device *dev,
enum clock_event_state state);
extern int clockevents_program_event(struct clock_event_device *dev,
ktime_t expires, bool force);
extern void clockevents_handle_noop(struct clock_event_device *dev);
extern int __clockevents_update_freq(struct clock_event_device *dev, u32 freq);
extern ssize_t sysfs_get_uname(const char *buf, char *dst, size_t cnt);
/* Broadcasting support */
# ifdef CONFIG_GENERIC_CLOCKEVENTS_BROADCAST
extern int tick_device_uses_broadcast(struct clock_event_device *dev, int cpu);
extern void tick_install_broadcast_device(struct clock_event_device *dev, int cpu);
extern int tick_is_broadcast_device(struct clock_event_device *dev);
extern void tick_suspend_broadcast(void);
extern void tick_resume_broadcast(void);
extern bool tick_resume_check_broadcast(void);
extern void tick_broadcast_init(void);
extern void tick_set_periodic_handler(struct clock_event_device *dev, int broadcast);
extern int tick_broadcast_update_freq(struct clock_event_device *dev, u32 freq);
extern struct tick_device *tick_get_broadcast_device(void);
extern struct cpumask *tick_get_broadcast_mask(void);
extern const struct clock_event_device *tick_get_wakeup_device(int cpu);
# else /* !CONFIG_GENERIC_CLOCKEVENTS_BROADCAST: */
static inline void tick_install_broadcast_device(struct clock_event_device *dev, int cpu) { }
static inline int tick_is_broadcast_device(struct clock_event_device *dev) { return 0; }
static inline int tick_device_uses_broadcast(struct clock_event_device *dev, int cpu) { return 0; }
static inline void tick_do_periodic_broadcast(struct clock_event_device *d) { }
static inline void tick_suspend_broadcast(void) { }
static inline void tick_resume_broadcast(void) { }
static inline bool tick_resume_check_broadcast(void) { return false; }
static inline void tick_broadcast_init(void) { }
static inline int tick_broadcast_update_freq(struct clock_event_device *dev, u32 freq) { return -ENODEV; }
/* Set the periodic handler in non broadcast mode */
static inline void tick_set_periodic_handler(struct clock_event_device *dev, int broadcast)
{
dev->event_handler = tick_handle_periodic;
}
# endif /* !CONFIG_GENERIC_CLOCKEVENTS_BROADCAST */
#else /* !GENERIC_CLOCKEVENTS: */
static inline void tick_suspend(void) { }
static inline void tick_resume(void) { }
#endif /* !GENERIC_CLOCKEVENTS */
/* Oneshot related functions */
#ifdef CONFIG_TICK_ONESHOT
extern void tick_setup_oneshot(struct clock_event_device *newdev,
void (*handler)(struct clock_event_device *),
ktime_t nextevt);
extern int tick_program_event(ktime_t expires, int force);
extern void tick_oneshot_notify(void);
extern int tick_switch_to_oneshot(void (*handler)(struct clock_event_device *));
extern void tick_resume_oneshot(void);
static inline bool tick_oneshot_possible(void) { return true; }
extern int tick_oneshot_mode_active(void);
extern void tick_clock_notify(void);
extern int tick_check_oneshot_change(int allow_nohz);
extern int tick_init_highres(void);
#else /* !CONFIG_TICK_ONESHOT: */
static inline
void tick_setup_oneshot(struct clock_event_device *newdev,
void (*handler)(struct clock_event_device *),
ktime_t nextevt) { BUG(); }
static inline void tick_resume_oneshot(void) { BUG(); }
static inline int tick_program_event(ktime_t expires, int force) { return 0; }
static inline void tick_oneshot_notify(void) { }
static inline bool tick_oneshot_possible(void) { return false; }
static inline int tick_oneshot_mode_active(void) { return 0; }
static inline void tick_clock_notify(void) { }
static inline int tick_check_oneshot_change(int allow_nohz) { return 0; }
#endif /* !CONFIG_TICK_ONESHOT */
/* Functions related to oneshot broadcasting */
#if defined(CONFIG_GENERIC_CLOCKEVENTS_BROADCAST) && defined(CONFIG_TICK_ONESHOT)
extern void tick_broadcast_switch_to_oneshot(void);
extern int tick_broadcast_oneshot_active(void);
extern void tick_check_oneshot_broadcast_this_cpu(void);
bool tick_broadcast_oneshot_available(void);
extern struct cpumask *tick_get_broadcast_oneshot_mask(void);
#else /* !(BROADCAST && ONESHOT): */
static inline void tick_broadcast_switch_to_oneshot(void) { }
static inline int tick_broadcast_oneshot_active(void) { return 0; }
static inline void tick_check_oneshot_broadcast_this_cpu(void) { }
static inline bool tick_broadcast_oneshot_available(void) { return tick_oneshot_possible(); }
#endif /* !(BROADCAST && ONESHOT) */
#if defined(CONFIG_GENERIC_CLOCKEVENTS_BROADCAST) && defined(CONFIG_HOTPLUG_CPU)
extern void tick_broadcast_offline(unsigned int cpu);
#else
static inline void tick_broadcast_offline(unsigned int cpu) { }
#endif
/* NO_HZ_FULL internal */
#ifdef CONFIG_NO_HZ_FULL
extern void tick_nohz_init(void);
# else
static inline void tick_nohz_init(void) { }
#endif
#ifdef CONFIG_NO_HZ_COMMON
extern unsigned long tick_nohz_active;
extern void timers_update_nohz(void);
# ifdef CONFIG_SMP
extern struct static_key_false timers_migration_enabled;
# endif
#else /* CONFIG_NO_HZ_COMMON */
static inline void timers_update_nohz(void) { }
#define tick_nohz_active (0)
#endif
DECLARE_PER_CPU(struct hrtimer_cpu_base, hrtimer_bases);
extern u64 get_next_timer_interrupt(unsigned long basej, u64 basem);
void timer_clear_idle(void);
#define CLOCK_SET_WALL \
(BIT(HRTIMER_BASE_REALTIME) | BIT(HRTIMER_BASE_REALTIME_SOFT) | \
BIT(HRTIMER_BASE_TAI) | BIT(HRTIMER_BASE_TAI_SOFT))
#define CLOCK_SET_BOOT \
(BIT(HRTIMER_BASE_BOOTTIME) | BIT(HRTIMER_BASE_BOOTTIME_SOFT))
void clock_was_set(unsigned int bases);
void clock_was_set_delayed(void);
void hrtimers_resume_local(void);
/* Since jiffies uses a simple TICK_NSEC multiplier
* conversion, the .shift value could be zero. However
* this would make NTP adjustments impossible as they are
* in units of 1/2^.shift. Thus we use JIFFIES_SHIFT to
* shift both the nominator and denominator the same
* amount, and give ntp adjustments in units of 1/2^8
*
* The value 8 is somewhat carefully chosen, as anything
* larger can result in overflows. TICK_NSEC grows as HZ
* shrinks, so values greater than 8 overflow 32bits when
* HZ=100.
*/
#if HZ < 34
#define JIFFIES_SHIFT 6
#elif HZ < 67
#define JIFFIES_SHIFT 7
#else
#define JIFFIES_SHIFT 8
#endif
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