071b638689
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>
209 lines
6.3 KiB
C
209 lines
6.3 KiB
C
/*
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* workqueue.h --- work queue handling for Linux.
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*/
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#ifndef _LINUX_WORKQUEUE_H
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#define _LINUX_WORKQUEUE_H
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#include <linux/timer.h>
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#include <linux/linkage.h>
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#include <linux/bitops.h>
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#include <asm/atomic.h>
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struct workqueue_struct;
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struct work_struct;
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typedef void (*work_func_t)(struct work_struct *work);
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/*
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* The first word is the work queue pointer and the flags rolled into
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* one
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*/
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#define work_data_bits(work) ((unsigned long *)(&(work)->data))
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struct work_struct {
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atomic_long_t data;
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#define WORK_STRUCT_PENDING 0 /* T if work item pending execution */
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#define WORK_STRUCT_NOAUTOREL 1 /* F if work item automatically released on exec */
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#define WORK_STRUCT_FLAG_MASK (3UL)
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#define WORK_STRUCT_WQ_DATA_MASK (~WORK_STRUCT_FLAG_MASK)
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struct list_head entry;
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work_func_t func;
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};
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#define WORK_DATA_INIT(autorelease) \
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ATOMIC_LONG_INIT((autorelease) << WORK_STRUCT_NOAUTOREL)
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struct delayed_work {
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struct work_struct work;
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struct timer_list timer;
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};
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struct execute_work {
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struct work_struct work;
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};
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#define __WORK_INITIALIZER(n, f) { \
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.data = WORK_DATA_INIT(0), \
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.entry = { &(n).entry, &(n).entry }, \
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.func = (f), \
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}
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#define __WORK_INITIALIZER_NAR(n, f) { \
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.data = WORK_DATA_INIT(1), \
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.entry = { &(n).entry, &(n).entry }, \
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.func = (f), \
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}
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#define __DELAYED_WORK_INITIALIZER(n, f) { \
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.work = __WORK_INITIALIZER((n).work, (f)), \
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.timer = TIMER_INITIALIZER(NULL, 0, 0), \
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}
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#define __DELAYED_WORK_INITIALIZER_NAR(n, f) { \
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.work = __WORK_INITIALIZER_NAR((n).work, (f)), \
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.timer = TIMER_INITIALIZER(NULL, 0, 0), \
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}
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#define DECLARE_WORK(n, f) \
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struct work_struct n = __WORK_INITIALIZER(n, f)
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#define DECLARE_WORK_NAR(n, f) \
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struct work_struct n = __WORK_INITIALIZER_NAR(n, f)
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#define DECLARE_DELAYED_WORK(n, f) \
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struct delayed_work n = __DELAYED_WORK_INITIALIZER(n, f)
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#define DECLARE_DELAYED_WORK_NAR(n, f) \
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struct dwork_struct n = __DELAYED_WORK_INITIALIZER_NAR(n, f)
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/*
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* initialize a work item's function pointer
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*/
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#define PREPARE_WORK(_work, _func) \
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do { \
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(_work)->func = (_func); \
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} while (0)
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#define PREPARE_DELAYED_WORK(_work, _func) \
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PREPARE_WORK(&(_work)->work, (_func))
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/*
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* initialize all of a work item in one go
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*
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* NOTE! No point in using "atomic_long_set()": useing a direct
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* assignment of the work data initializer allows the compiler
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* to generate better code.
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*/
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#define INIT_WORK(_work, _func) \
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do { \
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(_work)->data = (atomic_long_t) WORK_DATA_INIT(0); \
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INIT_LIST_HEAD(&(_work)->entry); \
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PREPARE_WORK((_work), (_func)); \
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} while (0)
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#define INIT_WORK_NAR(_work, _func) \
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do { \
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(_work)->data = (atomic_long_t) WORK_DATA_INIT(1); \
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INIT_LIST_HEAD(&(_work)->entry); \
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PREPARE_WORK((_work), (_func)); \
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} while (0)
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#define INIT_DELAYED_WORK(_work, _func) \
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do { \
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INIT_WORK(&(_work)->work, (_func)); \
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init_timer(&(_work)->timer); \
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} while (0)
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#define INIT_DELAYED_WORK_NAR(_work, _func) \
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do { \
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INIT_WORK_NAR(&(_work)->work, (_func)); \
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init_timer(&(_work)->timer); \
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} while (0)
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/**
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* work_pending - Find out whether a work item is currently pending
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* @work: The work item in question
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*/
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#define work_pending(work) \
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test_bit(WORK_STRUCT_PENDING, work_data_bits(work))
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/**
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* delayed_work_pending - Find out whether a delayable work item is currently
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* pending
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* @work: The work item in question
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*/
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#define delayed_work_pending(w) \
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work_pending(&(w)->work)
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/**
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* work_release - Release a work item under execution
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* @work: The work item to release
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*
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* This is used to release a work item that has been initialised with automatic
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* release mode disabled (WORK_STRUCT_NOAUTOREL is set). This gives the work
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* function the opportunity to grab auxiliary data from the container of the
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* work_struct before clearing the pending bit as the work_struct may be
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* subject to deallocation the moment the pending bit is cleared.
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*
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* In such a case, this should be called in the work function after it has
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* fetched any data it may require from the containter of the work_struct.
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* After this function has been called, the work_struct may be scheduled for
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* further execution or it may be deallocated unless other precautions are
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* taken.
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*
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* This should also be used to release a delayed work item.
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*/
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#define work_release(work) \
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clear_bit(WORK_STRUCT_PENDING, work_data_bits(work))
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extern struct workqueue_struct *__create_workqueue(const char *name,
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int singlethread,
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int freezeable);
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#define create_workqueue(name) __create_workqueue((name), 0, 0)
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#define create_freezeable_workqueue(name) __create_workqueue((name), 0, 1)
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#define create_singlethread_workqueue(name) __create_workqueue((name), 1, 0)
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extern void destroy_workqueue(struct workqueue_struct *wq);
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extern int FASTCALL(queue_work(struct workqueue_struct *wq, struct work_struct *work));
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extern int FASTCALL(queue_delayed_work(struct workqueue_struct *wq, struct delayed_work *work, unsigned long delay));
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extern int queue_delayed_work_on(int cpu, struct workqueue_struct *wq,
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struct delayed_work *work, unsigned long delay);
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extern void FASTCALL(flush_workqueue(struct workqueue_struct *wq));
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extern int FASTCALL(schedule_work(struct work_struct *work));
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extern int FASTCALL(run_scheduled_work(struct work_struct *work));
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extern int FASTCALL(schedule_delayed_work(struct delayed_work *work, unsigned long delay));
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extern int schedule_delayed_work_on(int cpu, struct delayed_work *work, unsigned long delay);
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extern int schedule_on_each_cpu(work_func_t func);
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extern void flush_scheduled_work(void);
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extern int current_is_keventd(void);
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extern int keventd_up(void);
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extern void init_workqueues(void);
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void cancel_rearming_delayed_work(struct delayed_work *work);
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void cancel_rearming_delayed_workqueue(struct workqueue_struct *,
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struct delayed_work *);
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int execute_in_process_context(work_func_t fn, struct execute_work *);
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/*
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* Kill off a pending schedule_delayed_work(). Note that the work callback
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* function may still be running on return from cancel_delayed_work(), unless
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* it returns 1 and the work doesn't re-arm itself. Run flush_workqueue() or
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* cancel_work_sync() to wait on it.
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*/
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static inline int cancel_delayed_work(struct delayed_work *work)
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{
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int ret;
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ret = del_timer(&work->timer);
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if (ret)
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work_release(&work->work);
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return ret;
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}
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#endif
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