linux_dsm_epyc7002/include/linux/workqueue.h
Oleg Nesterov 071b638689 [WORKQUEUE]: cancel_delayed_work: use del_timer() instead of del_timer_sync()
del_timer_sync() buys nothing for cancel_delayed_work(), but it is less
efficient since it locks the timer unconditionally, and may wait for the
completion of the delayed_work_timer_fn().

cancel_delayed_work() == 0 means:

	before this patch:
		work->func may still be running or queued

	after this patch:
		work->func may still be running or queued, or
		delayed_work_timer_fn->__queue_work() in progress.

		The latter doesn't differ from the caller's POV,
		delayed_work_timer_fn() is called with _PENDING
		bit set.

cancel_delayed_work() == 1 with this patch adds a new possibility:

	delayed_work->work was cancelled, but delayed_work_timer_fn
	is still running (this is only possible for the re-arming
	works on single-threaded workqueue).

	In this case the timer was re-started by work->func(), nobody
	else can do this. This in turn means that delayed_work_timer_fn
	has already passed __queue_work() (and wont't touch delayed_work)
	because nobody else can queue delayed_work->work.

Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Signed-Off-By: David Howells <dhowells@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2007-04-26 15:45:32 -07:00

209 lines
6.3 KiB
C

/*
* workqueue.h --- work queue handling for Linux.
*/
#ifndef _LINUX_WORKQUEUE_H
#define _LINUX_WORKQUEUE_H
#include <linux/timer.h>
#include <linux/linkage.h>
#include <linux/bitops.h>
#include <asm/atomic.h>
struct workqueue_struct;
struct work_struct;
typedef void (*work_func_t)(struct work_struct *work);
/*
* The first word is the work queue pointer and the flags rolled into
* one
*/
#define work_data_bits(work) ((unsigned long *)(&(work)->data))
struct work_struct {
atomic_long_t data;
#define WORK_STRUCT_PENDING 0 /* T if work item pending execution */
#define WORK_STRUCT_NOAUTOREL 1 /* F if work item automatically released on exec */
#define WORK_STRUCT_FLAG_MASK (3UL)
#define WORK_STRUCT_WQ_DATA_MASK (~WORK_STRUCT_FLAG_MASK)
struct list_head entry;
work_func_t func;
};
#define WORK_DATA_INIT(autorelease) \
ATOMIC_LONG_INIT((autorelease) << WORK_STRUCT_NOAUTOREL)
struct delayed_work {
struct work_struct work;
struct timer_list timer;
};
struct execute_work {
struct work_struct work;
};
#define __WORK_INITIALIZER(n, f) { \
.data = WORK_DATA_INIT(0), \
.entry = { &(n).entry, &(n).entry }, \
.func = (f), \
}
#define __WORK_INITIALIZER_NAR(n, f) { \
.data = WORK_DATA_INIT(1), \
.entry = { &(n).entry, &(n).entry }, \
.func = (f), \
}
#define __DELAYED_WORK_INITIALIZER(n, f) { \
.work = __WORK_INITIALIZER((n).work, (f)), \
.timer = TIMER_INITIALIZER(NULL, 0, 0), \
}
#define __DELAYED_WORK_INITIALIZER_NAR(n, f) { \
.work = __WORK_INITIALIZER_NAR((n).work, (f)), \
.timer = TIMER_INITIALIZER(NULL, 0, 0), \
}
#define DECLARE_WORK(n, f) \
struct work_struct n = __WORK_INITIALIZER(n, f)
#define DECLARE_WORK_NAR(n, f) \
struct work_struct n = __WORK_INITIALIZER_NAR(n, f)
#define DECLARE_DELAYED_WORK(n, f) \
struct delayed_work n = __DELAYED_WORK_INITIALIZER(n, f)
#define DECLARE_DELAYED_WORK_NAR(n, f) \
struct dwork_struct n = __DELAYED_WORK_INITIALIZER_NAR(n, f)
/*
* initialize a work item's function pointer
*/
#define PREPARE_WORK(_work, _func) \
do { \
(_work)->func = (_func); \
} while (0)
#define PREPARE_DELAYED_WORK(_work, _func) \
PREPARE_WORK(&(_work)->work, (_func))
/*
* initialize all of a work item in one go
*
* NOTE! No point in using "atomic_long_set()": useing a direct
* assignment of the work data initializer allows the compiler
* to generate better code.
*/
#define INIT_WORK(_work, _func) \
do { \
(_work)->data = (atomic_long_t) WORK_DATA_INIT(0); \
INIT_LIST_HEAD(&(_work)->entry); \
PREPARE_WORK((_work), (_func)); \
} while (0)
#define INIT_WORK_NAR(_work, _func) \
do { \
(_work)->data = (atomic_long_t) WORK_DATA_INIT(1); \
INIT_LIST_HEAD(&(_work)->entry); \
PREPARE_WORK((_work), (_func)); \
} while (0)
#define INIT_DELAYED_WORK(_work, _func) \
do { \
INIT_WORK(&(_work)->work, (_func)); \
init_timer(&(_work)->timer); \
} while (0)
#define INIT_DELAYED_WORK_NAR(_work, _func) \
do { \
INIT_WORK_NAR(&(_work)->work, (_func)); \
init_timer(&(_work)->timer); \
} while (0)
/**
* work_pending - Find out whether a work item is currently pending
* @work: The work item in question
*/
#define work_pending(work) \
test_bit(WORK_STRUCT_PENDING, work_data_bits(work))
/**
* delayed_work_pending - Find out whether a delayable work item is currently
* pending
* @work: The work item in question
*/
#define delayed_work_pending(w) \
work_pending(&(w)->work)
/**
* work_release - Release a work item under execution
* @work: The work item to release
*
* This is used to release a work item that has been initialised with automatic
* release mode disabled (WORK_STRUCT_NOAUTOREL is set). This gives the work
* function the opportunity to grab auxiliary data from the container of the
* work_struct before clearing the pending bit as the work_struct may be
* subject to deallocation the moment the pending bit is cleared.
*
* In such a case, this should be called in the work function after it has
* fetched any data it may require from the containter of the work_struct.
* After this function has been called, the work_struct may be scheduled for
* further execution or it may be deallocated unless other precautions are
* taken.
*
* This should also be used to release a delayed work item.
*/
#define work_release(work) \
clear_bit(WORK_STRUCT_PENDING, work_data_bits(work))
extern struct workqueue_struct *__create_workqueue(const char *name,
int singlethread,
int freezeable);
#define create_workqueue(name) __create_workqueue((name), 0, 0)
#define create_freezeable_workqueue(name) __create_workqueue((name), 0, 1)
#define create_singlethread_workqueue(name) __create_workqueue((name), 1, 0)
extern void destroy_workqueue(struct workqueue_struct *wq);
extern int FASTCALL(queue_work(struct workqueue_struct *wq, struct work_struct *work));
extern int FASTCALL(queue_delayed_work(struct workqueue_struct *wq, struct delayed_work *work, unsigned long delay));
extern int queue_delayed_work_on(int cpu, struct workqueue_struct *wq,
struct delayed_work *work, unsigned long delay);
extern void FASTCALL(flush_workqueue(struct workqueue_struct *wq));
extern int FASTCALL(schedule_work(struct work_struct *work));
extern int FASTCALL(run_scheduled_work(struct work_struct *work));
extern int FASTCALL(schedule_delayed_work(struct delayed_work *work, unsigned long delay));
extern int schedule_delayed_work_on(int cpu, struct delayed_work *work, unsigned long delay);
extern int schedule_on_each_cpu(work_func_t func);
extern void flush_scheduled_work(void);
extern int current_is_keventd(void);
extern int keventd_up(void);
extern void init_workqueues(void);
void cancel_rearming_delayed_work(struct delayed_work *work);
void cancel_rearming_delayed_workqueue(struct workqueue_struct *,
struct delayed_work *);
int execute_in_process_context(work_func_t fn, struct execute_work *);
/*
* Kill off a pending schedule_delayed_work(). Note that the work callback
* function may still be running on return from cancel_delayed_work(), unless
* it returns 1 and the work doesn't re-arm itself. Run flush_workqueue() or
* cancel_work_sync() to wait on it.
*/
static inline int cancel_delayed_work(struct delayed_work *work)
{
int ret;
ret = del_timer(&work->timer);
if (ret)
work_release(&work->work);
return ret;
}
#endif