mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
synced 2024-08-28 20:02:17 +00:00
![Thomas Gleixner](/assets/img/avatar_default.png)
Tearing down timers which have circular dependencies to other functionality, e.g. workqueues, where the timer can schedule work and work can arm timers, is not trivial. In those cases it is desired to shutdown the timer in a way which prevents rearming of the timer. The mechanism to do so is to set timer->function to NULL and use this as an indicator for the timer arming functions to ignore the (re)arm request. Expose new interfaces for this: timer_shutdown_sync() and timer_shutdown(). timer_shutdown_sync() has the same functionality as timer_delete_sync() plus the NULL-ification of the timer function. timer_shutdown() has the same functionality as timer_delete() plus the NULL-ification of the timer function. In both cases the rearming of the timer is prevented by silently discarding rearm attempts due to timer->function being NULL. Co-developed-by: Steven Rostedt <rostedt@goodmis.org> Signed-off-by: Steven Rostedt <rostedt@goodmis.org> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Tested-by: Guenter Roeck <linux@roeck-us.net> Reviewed-by: Jacob Keller <jacob.e.keller@intel.com> Reviewed-by: Anna-Maria Behnsen <anna-maria@linutronix.de> Link: https://lore.kernel.org/all/20220407161745.7d6754b3@gandalf.local.home Link: https://lore.kernel.org/all/20221110064101.429013735@goodmis.org Link: https://lore.kernel.org/r/20221123201625.314230270@linutronix.de
238 lines
7.7 KiB
C
238 lines
7.7 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
|
|
#ifndef _LINUX_TIMER_H
|
|
#define _LINUX_TIMER_H
|
|
|
|
#include <linux/list.h>
|
|
#include <linux/ktime.h>
|
|
#include <linux/stddef.h>
|
|
#include <linux/debugobjects.h>
|
|
#include <linux/stringify.h>
|
|
|
|
struct timer_list {
|
|
/*
|
|
* All fields that change during normal runtime grouped to the
|
|
* same cacheline
|
|
*/
|
|
struct hlist_node entry;
|
|
unsigned long expires;
|
|
void (*function)(struct timer_list *);
|
|
u32 flags;
|
|
|
|
#ifdef CONFIG_LOCKDEP
|
|
struct lockdep_map lockdep_map;
|
|
#endif
|
|
};
|
|
|
|
#ifdef CONFIG_LOCKDEP
|
|
/*
|
|
* NB: because we have to copy the lockdep_map, setting the lockdep_map key
|
|
* (second argument) here is required, otherwise it could be initialised to
|
|
* the copy of the lockdep_map later! We use the pointer to and the string
|
|
* "<file>:<line>" as the key resp. the name of the lockdep_map.
|
|
*/
|
|
#define __TIMER_LOCKDEP_MAP_INITIALIZER(_kn) \
|
|
.lockdep_map = STATIC_LOCKDEP_MAP_INIT(_kn, &_kn),
|
|
#else
|
|
#define __TIMER_LOCKDEP_MAP_INITIALIZER(_kn)
|
|
#endif
|
|
|
|
/**
|
|
* @TIMER_DEFERRABLE: A deferrable timer will work normally when the
|
|
* system is busy, but will not cause a CPU to come out of idle just
|
|
* to service it; instead, the timer will be serviced when the CPU
|
|
* eventually wakes up with a subsequent non-deferrable timer.
|
|
*
|
|
* @TIMER_IRQSAFE: An irqsafe timer is executed with IRQ disabled and
|
|
* it's safe to wait for the completion of the running instance from
|
|
* IRQ handlers, for example, by calling del_timer_sync().
|
|
*
|
|
* Note: The irq disabled callback execution is a special case for
|
|
* workqueue locking issues. It's not meant for executing random crap
|
|
* with interrupts disabled. Abuse is monitored!
|
|
*
|
|
* @TIMER_PINNED: A pinned timer will not be affected by any timer
|
|
* placement heuristics (like, NOHZ) and will always expire on the CPU
|
|
* on which the timer was enqueued.
|
|
*
|
|
* Note: Because enqueuing of timers can migrate the timer from one
|
|
* CPU to another, pinned timers are not guaranteed to stay on the
|
|
* initialy selected CPU. They move to the CPU on which the enqueue
|
|
* function is invoked via mod_timer() or add_timer(). If the timer
|
|
* should be placed on a particular CPU, then add_timer_on() has to be
|
|
* used.
|
|
*/
|
|
#define TIMER_CPUMASK 0x0003FFFF
|
|
#define TIMER_MIGRATING 0x00040000
|
|
#define TIMER_BASEMASK (TIMER_CPUMASK | TIMER_MIGRATING)
|
|
#define TIMER_DEFERRABLE 0x00080000
|
|
#define TIMER_PINNED 0x00100000
|
|
#define TIMER_IRQSAFE 0x00200000
|
|
#define TIMER_INIT_FLAGS (TIMER_DEFERRABLE | TIMER_PINNED | TIMER_IRQSAFE)
|
|
#define TIMER_ARRAYSHIFT 22
|
|
#define TIMER_ARRAYMASK 0xFFC00000
|
|
|
|
#define TIMER_TRACE_FLAGMASK (TIMER_MIGRATING | TIMER_DEFERRABLE | TIMER_PINNED | TIMER_IRQSAFE)
|
|
|
|
#define __TIMER_INITIALIZER(_function, _flags) { \
|
|
.entry = { .next = TIMER_ENTRY_STATIC }, \
|
|
.function = (_function), \
|
|
.flags = (_flags), \
|
|
__TIMER_LOCKDEP_MAP_INITIALIZER( \
|
|
__FILE__ ":" __stringify(__LINE__)) \
|
|
}
|
|
|
|
#define DEFINE_TIMER(_name, _function) \
|
|
struct timer_list _name = \
|
|
__TIMER_INITIALIZER(_function, 0)
|
|
|
|
/*
|
|
* LOCKDEP and DEBUG timer interfaces.
|
|
*/
|
|
void init_timer_key(struct timer_list *timer,
|
|
void (*func)(struct timer_list *), unsigned int flags,
|
|
const char *name, struct lock_class_key *key);
|
|
|
|
#ifdef CONFIG_DEBUG_OBJECTS_TIMERS
|
|
extern void init_timer_on_stack_key(struct timer_list *timer,
|
|
void (*func)(struct timer_list *),
|
|
unsigned int flags, const char *name,
|
|
struct lock_class_key *key);
|
|
#else
|
|
static inline void init_timer_on_stack_key(struct timer_list *timer,
|
|
void (*func)(struct timer_list *),
|
|
unsigned int flags,
|
|
const char *name,
|
|
struct lock_class_key *key)
|
|
{
|
|
init_timer_key(timer, func, flags, name, key);
|
|
}
|
|
#endif
|
|
|
|
#ifdef CONFIG_LOCKDEP
|
|
#define __init_timer(_timer, _fn, _flags) \
|
|
do { \
|
|
static struct lock_class_key __key; \
|
|
init_timer_key((_timer), (_fn), (_flags), #_timer, &__key);\
|
|
} while (0)
|
|
|
|
#define __init_timer_on_stack(_timer, _fn, _flags) \
|
|
do { \
|
|
static struct lock_class_key __key; \
|
|
init_timer_on_stack_key((_timer), (_fn), (_flags), \
|
|
#_timer, &__key); \
|
|
} while (0)
|
|
#else
|
|
#define __init_timer(_timer, _fn, _flags) \
|
|
init_timer_key((_timer), (_fn), (_flags), NULL, NULL)
|
|
#define __init_timer_on_stack(_timer, _fn, _flags) \
|
|
init_timer_on_stack_key((_timer), (_fn), (_flags), NULL, NULL)
|
|
#endif
|
|
|
|
/**
|
|
* timer_setup - prepare a timer for first use
|
|
* @timer: the timer in question
|
|
* @callback: the function to call when timer expires
|
|
* @flags: any TIMER_* flags
|
|
*
|
|
* Regular timer initialization should use either DEFINE_TIMER() above,
|
|
* or timer_setup(). For timers on the stack, timer_setup_on_stack() must
|
|
* be used and must be balanced with a call to destroy_timer_on_stack().
|
|
*/
|
|
#define timer_setup(timer, callback, flags) \
|
|
__init_timer((timer), (callback), (flags))
|
|
|
|
#define timer_setup_on_stack(timer, callback, flags) \
|
|
__init_timer_on_stack((timer), (callback), (flags))
|
|
|
|
#ifdef CONFIG_DEBUG_OBJECTS_TIMERS
|
|
extern void destroy_timer_on_stack(struct timer_list *timer);
|
|
#else
|
|
static inline void destroy_timer_on_stack(struct timer_list *timer) { }
|
|
#endif
|
|
|
|
#define from_timer(var, callback_timer, timer_fieldname) \
|
|
container_of(callback_timer, typeof(*var), timer_fieldname)
|
|
|
|
/**
|
|
* timer_pending - is a timer pending?
|
|
* @timer: the timer in question
|
|
*
|
|
* timer_pending will tell whether a given timer is currently pending,
|
|
* or not. Callers must ensure serialization wrt. other operations done
|
|
* to this timer, eg. interrupt contexts, or other CPUs on SMP.
|
|
*
|
|
* return value: 1 if the timer is pending, 0 if not.
|
|
*/
|
|
static inline int timer_pending(const struct timer_list * timer)
|
|
{
|
|
return !hlist_unhashed_lockless(&timer->entry);
|
|
}
|
|
|
|
extern void add_timer_on(struct timer_list *timer, int cpu);
|
|
extern int mod_timer(struct timer_list *timer, unsigned long expires);
|
|
extern int mod_timer_pending(struct timer_list *timer, unsigned long expires);
|
|
extern int timer_reduce(struct timer_list *timer, unsigned long expires);
|
|
|
|
/*
|
|
* The jiffies value which is added to now, when there is no timer
|
|
* in the timer wheel:
|
|
*/
|
|
#define NEXT_TIMER_MAX_DELTA ((1UL << 30) - 1)
|
|
|
|
extern void add_timer(struct timer_list *timer);
|
|
|
|
extern int try_to_del_timer_sync(struct timer_list *timer);
|
|
extern int timer_delete_sync(struct timer_list *timer);
|
|
extern int timer_delete(struct timer_list *timer);
|
|
extern int timer_shutdown_sync(struct timer_list *timer);
|
|
extern int timer_shutdown(struct timer_list *timer);
|
|
|
|
/**
|
|
* del_timer_sync - Delete a pending timer and wait for a running callback
|
|
* @timer: The timer to be deleted
|
|
*
|
|
* See timer_delete_sync() for detailed explanation.
|
|
*
|
|
* Do not use in new code. Use timer_delete_sync() instead.
|
|
*/
|
|
static inline int del_timer_sync(struct timer_list *timer)
|
|
{
|
|
return timer_delete_sync(timer);
|
|
}
|
|
|
|
/**
|
|
* del_timer - Delete a pending timer
|
|
* @timer: The timer to be deleted
|
|
*
|
|
* See timer_delete() for detailed explanation.
|
|
*
|
|
* Do not use in new code. Use timer_delete() instead.
|
|
*/
|
|
static inline int del_timer(struct timer_list *timer)
|
|
{
|
|
return timer_delete(timer);
|
|
}
|
|
|
|
extern void init_timers(void);
|
|
struct hrtimer;
|
|
extern enum hrtimer_restart it_real_fn(struct hrtimer *);
|
|
|
|
unsigned long __round_jiffies(unsigned long j, int cpu);
|
|
unsigned long __round_jiffies_relative(unsigned long j, int cpu);
|
|
unsigned long round_jiffies(unsigned long j);
|
|
unsigned long round_jiffies_relative(unsigned long j);
|
|
|
|
unsigned long __round_jiffies_up(unsigned long j, int cpu);
|
|
unsigned long __round_jiffies_up_relative(unsigned long j, int cpu);
|
|
unsigned long round_jiffies_up(unsigned long j);
|
|
unsigned long round_jiffies_up_relative(unsigned long j);
|
|
|
|
#ifdef CONFIG_HOTPLUG_CPU
|
|
int timers_prepare_cpu(unsigned int cpu);
|
|
int timers_dead_cpu(unsigned int cpu);
|
|
#else
|
|
#define timers_prepare_cpu NULL
|
|
#define timers_dead_cpu NULL
|
|
#endif
|
|
|
|
#endif
|