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db70089722
Most of users of flush_workqueue() can be changed to use cancel_work_sync(), but sometimes we really need to wait for the completion and cancelling is not an option. schedule_on_each_cpu() is good example. Add the new helper, flush_work(work), which waits for the completion of the specific work_struct. More precisely, it "flushes" the result of of the last queue_work() which is visible to the caller. For example, this code queue_work(wq, work); /* WINDOW */ queue_work(wq, work); flush_work(work); doesn't necessary work "as expected". What can happen in the WINDOW above is - wq starts the execution of work->func() - the caller migrates to another CPU now, after the 2nd queue_work() this work is active on the previous CPU, and at the same time it is queued on another. In this case flush_work(work) may return before the first work->func() completes. It is trivial to add another helper int flush_work_sync(struct work_struct *work) { return flush_work(work) || wait_on_work(work); } which works "more correctly", but it has to iterate over all CPUs and thus it much slower than flush_work(). Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru> Acked-by: Max Krasnyansky <maxk@qualcomm.com> Acked-by: Jarek Poplawski <jarkao2@gmail.com> Cc: Peter Zijlstra <peterz@infradead.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
242 lines
6.6 KiB
C
242 lines
6.6 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 <linux/lockdep.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_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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#ifdef CONFIG_LOCKDEP
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struct lockdep_map lockdep_map;
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#endif
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};
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#define WORK_DATA_INIT() ATOMIC_LONG_INIT(0)
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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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#ifdef CONFIG_LOCKDEP
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/*
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* NB: because we have to copy the lockdep_map, setting _key
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* here is required, otherwise it could get initialised to the
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* copy of the lockdep_map!
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*/
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#define __WORK_INIT_LOCKDEP_MAP(n, k) \
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.lockdep_map = STATIC_LOCKDEP_MAP_INIT(n, k),
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#else
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#define __WORK_INIT_LOCKDEP_MAP(n, k)
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#endif
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#define __WORK_INITIALIZER(n, f) { \
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.data = WORK_DATA_INIT(), \
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.entry = { &(n).entry, &(n).entry }, \
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.func = (f), \
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__WORK_INIT_LOCKDEP_MAP(#n, &(n)) \
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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 DECLARE_WORK(n, f) \
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struct work_struct n = __WORK_INITIALIZER(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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/*
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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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#ifdef CONFIG_LOCKDEP
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#define INIT_WORK(_work, _func) \
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do { \
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static struct lock_class_key __key; \
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\
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(_work)->data = (atomic_long_t) WORK_DATA_INIT(); \
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lockdep_init_map(&(_work)->lockdep_map, #_work, &__key, 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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#else
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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(); \
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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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#endif
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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_DEFERRABLE(_work, _func) \
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do { \
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INIT_WORK(&(_work)->work, (_func)); \
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init_timer_deferrable(&(_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_clear_pending - for internal use only, mark a work item as not pending
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* @work: The work item in question
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*/
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#define work_clear_pending(work) \
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clear_bit(WORK_STRUCT_PENDING, work_data_bits(work))
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extern struct workqueue_struct *
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__create_workqueue_key(const char *name, int singlethread,
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int freezeable, struct lock_class_key *key,
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const char *lock_name);
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#ifdef CONFIG_LOCKDEP
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#define __create_workqueue(name, singlethread, freezeable) \
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({ \
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static struct lock_class_key __key; \
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const char *__lock_name; \
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\
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if (__builtin_constant_p(name)) \
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__lock_name = (name); \
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else \
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__lock_name = #name; \
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\
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__create_workqueue_key((name), (singlethread), \
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(freezeable), &__key, \
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__lock_name); \
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})
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#else
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#define __create_workqueue(name, singlethread, freezeable) \
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__create_workqueue_key((name), (singlethread), (freezeable), NULL, NULL)
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#endif
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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), 1, 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 queue_work(struct workqueue_struct *wq, struct work_struct *work);
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extern int queue_work_on(int cpu, struct workqueue_struct *wq,
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struct work_struct *work);
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extern int queue_delayed_work(struct workqueue_struct *wq,
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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 flush_workqueue(struct workqueue_struct *wq);
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extern void flush_scheduled_work(void);
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extern int schedule_work(struct work_struct *work);
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extern int schedule_work_on(int cpu, struct work_struct *work);
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extern int 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,
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unsigned long delay);
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extern int schedule_on_each_cpu(work_func_t func);
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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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int execute_in_process_context(work_func_t fn, struct execute_work *);
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extern int flush_work(struct work_struct *work);
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extern int cancel_work_sync(struct work_struct *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_sync(&work->timer);
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if (ret)
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work_clear_pending(&work->work);
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return ret;
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}
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extern int cancel_delayed_work_sync(struct delayed_work *work);
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/* Obsolete. use cancel_delayed_work_sync() */
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static inline
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void cancel_rearming_delayed_workqueue(struct workqueue_struct *wq,
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struct delayed_work *work)
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{
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cancel_delayed_work_sync(work);
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}
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/* Obsolete. use cancel_delayed_work_sync() */
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static inline
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void cancel_rearming_delayed_work(struct delayed_work *work)
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{
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cancel_delayed_work_sync(work);
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}
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#endif
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