include/linux/completion.h

   1 #ifndef __LINUX_COMPLETION_H
   2 #define __LINUX_COMPLETION_H
   3
   4 /*
   5  * (C) Copyright 2001 Linus Torvalds
   6  *
   7  * Atomic wait-for-completion handler data structures.
   8  * See kernel/sched.c for details.
   9  */
  10
  11 #include <linux/wait.h>
  12
  13 /**
  14  * struct completion - structure used to maintain state for a "completion"
  15  *
  16  * This is the opaque structure used to maintain the state for a "completion".
  17  * Completions currently use a FIFO to queue threads that have to wait for
  18  * the "completion" event.
  19  *
  20  * See also:  complete(), wait_for_completion() (and friends _timeout,
  21  * _interruptible, _interruptible_timeout, and _killable), init_completion(),
  22  * and macros DECLARE_COMPLETION(), DECLARE_COMPLETION_ONSTACK(), and
  23  * INIT_COMPLETION().
  24  */
  25 struct completion {
  26         unsigned int done;
  27         wait_queue_head_t wait;
  28 };
  29
  30 #define COMPLETION_INITIALIZER(work) \
  31         { 0, __WAIT_QUEUE_HEAD_INITIALIZER((work).wait) }
  32
  33 #define COMPLETION_INITIALIZER_ONSTACK(work) \
  34         ({ init_completion(&work); work; })
  35
  36 /**
  37  * DECLARE_COMPLETION: - declare and initialize a completion structure
  38  * @work:  identifier for the completion structure
  39  *
  40  * This macro declares and initializes a completion structure. Generally used
  41  * for static declarations. You should use the _ONSTACK variant for automatic
  42  * variables.
  43  */
  44 #define DECLARE_COMPLETION(work) \
  45         struct completion work = COMPLETION_INITIALIZER(work)
  46
  47 /*
  48  * Lockdep needs to run a non-constant initializer for on-stack
  49  * completions - so we use the _ONSTACK() variant for those that
  50  * are on the kernel stack:
  51  */
  52 /**
  53  * DECLARE_COMPLETION_ONSTACK: - declare and initialize a completion structure
  54  * @work:  identifier for the completion structure
  55  *
  56  * This macro declares and initializes a completion structure on the kernel
  57  * stack.
  58  */
  59 #ifdef CONFIG_LOCKDEP
  60 # define DECLARE_COMPLETION_ONSTACK(work) \
  61         struct completion work = COMPLETION_INITIALIZER_ONSTACK(work)
  62 #else
  63 # define DECLARE_COMPLETION_ONSTACK(work) DECLARE_COMPLETION(work)
  64 #endif
  65
  66 /**
  67  * init_completion: - Initialize a dynamically allocated completion
  68  * @x:  completion structure that is to be initialized
  69  *
  70  * This inline function will initialize a dynamically created completion
  71  * structure.
  72  */
  73 static inline void init_completion(struct completion *x)
  74 {
  75         x->done = 0;
  76         init_waitqueue_head(&x->wait);
  77 }
  78
  79 extern void wait_for_completion(struct completion *);
  80 extern int wait_for_completion_interruptible(struct completion *x);
  81 extern int wait_for_completion_killable(struct completion *x);
  82 extern unsigned long wait_for_completion_timeout(struct completion *x,
  83                                                    unsigned long timeout);
  84 extern unsigned long wait_for_completion_interruptible_timeout(
  85                         struct completion *x, unsigned long timeout);
  86 extern bool try_wait_for_completion(struct completion *x);
  87 extern bool completion_done(struct completion *x);
  88
  89 extern void complete(struct completion *);
  90 extern void complete_all(struct completion *);
  91
  92 /**
  93  * INIT_COMPLETION: - reinitialize a completion structure
  94  * @x:  completion structure to be reinitialized
  95  *
  96  * This macro should be used to reinitialize a completion structure so it can
  97  * be reused. This is especially important after complete_all() is used.
  98  */
  99 #define INIT_COMPLETION(x)      ((x).done = 0)
 100
 101
 102 #endif