completion.c | Explore in Territory

// SPDX-License-Identifier: GPL-2.0

/*
 * Generic wait-for-completion handler;
 *
 * It differs from semaphores in that their default case is the opposite,
 * wait_for_completion default blocks whereas semaphore default non-block. The
 * interface also makes it easy to 'complete' multiple waiting threads,
 * something which isn't entirely natural for semaphores.
 *
 * But more importantly, the primitive documents the usage. Semaphores would
 * typically be used for exclusion which gives rise to priority inversion.
 * Waiting for completion is a typically sync point, but not an exclusion point.
 */

static void complete_with_flags(struct completion *x, int wake_flags)
{ … }

void complete_on_current_cpu(struct completion *x)
{ … }

/**
 * complete: - signals a single thread waiting on this completion
 * @x:  holds the state of this particular completion
 *
 * This will wake up a single thread waiting on this completion. Threads will be
 * awakened in the same order in which they were queued.
 *
 * See also complete_all(), wait_for_completion() and related routines.
 *
 * If this function wakes up a task, it executes a full memory barrier before
 * accessing the task state.
 */
void complete(struct completion *x)
{ … }
EXPORT_SYMBOL(…);

/**
 * complete_all: - signals all threads waiting on this completion
 * @x:  holds the state of this particular completion
 *
 * This will wake up all threads waiting on this particular completion event.
 *
 * If this function wakes up a task, it executes a full memory barrier before
 * accessing the task state.
 *
 * Since complete_all() sets the completion of @x permanently to done
 * to allow multiple waiters to finish, a call to reinit_completion()
 * must be used on @x if @x is to be used again. The code must make
 * sure that all waiters have woken and finished before reinitializing
 * @x. Also note that the function completion_done() can not be used
 * to know if there are still waiters after complete_all() has been called.
 */
void complete_all(struct completion *x)
{ … }
EXPORT_SYMBOL(…);

static inline long __sched
do_wait_for_common(struct completion *x,
		   long (*action)(long), long timeout, int state)
{ … }

static inline long __sched
__wait_for_common(struct completion *x,
		  long (*action)(long), long timeout, int state)
{ … }

static long __sched
wait_for_common(struct completion *x, long timeout, int state)
{ … }

static long __sched
wait_for_common_io(struct completion *x, long timeout, int state)
{ … }

/**
 * wait_for_completion: - waits for completion of a task
 * @x:  holds the state of this particular completion
 *
 * This waits to be signaled for completion of a specific task. It is NOT
 * interruptible and there is no timeout.
 *
 * See also similar routines (i.e. wait_for_completion_timeout()) with timeout
 * and interrupt capability. Also see complete().
 */
void __sched wait_for_completion(struct completion *x)
{ … }
EXPORT_SYMBOL(…);

/**
 * wait_for_completion_timeout: - waits for completion of a task (w/timeout)
 * @x:  holds the state of this particular completion
 * @timeout:  timeout value in jiffies
 *
 * This waits for either a completion of a specific task to be signaled or for a
 * specified timeout to expire. The timeout is in jiffies. It is not
 * interruptible.
 *
 * Return: 0 if timed out, and positive (at least 1, or number of jiffies left
 * till timeout) if completed.
 */
unsigned long __sched
wait_for_completion_timeout(struct completion *x, unsigned long timeout)
{ … }
EXPORT_SYMBOL(…);

/**
 * wait_for_completion_io: - waits for completion of a task
 * @x:  holds the state of this particular completion
 *
 * This waits to be signaled for completion of a specific task. It is NOT
 * interruptible and there is no timeout. The caller is accounted as waiting
 * for IO (which traditionally means blkio only).
 */
void __sched wait_for_completion_io(struct completion *x)
{ … }
EXPORT_SYMBOL(…);

/**
 * wait_for_completion_io_timeout: - waits for completion of a task (w/timeout)
 * @x:  holds the state of this particular completion
 * @timeout:  timeout value in jiffies
 *
 * This waits for either a completion of a specific task to be signaled or for a
 * specified timeout to expire. The timeout is in jiffies. It is not
 * interruptible. The caller is accounted as waiting for IO (which traditionally
 * means blkio only).
 *
 * Return: 0 if timed out, and positive (at least 1, or number of jiffies left
 * till timeout) if completed.
 */
unsigned long __sched
wait_for_completion_io_timeout(struct completion *x, unsigned long timeout)
{ … }
EXPORT_SYMBOL(…);

/**
 * wait_for_completion_interruptible: - waits for completion of a task (w/intr)
 * @x:  holds the state of this particular completion
 *
 * This waits for completion of a specific task to be signaled. It is
 * interruptible.
 *
 * Return: -ERESTARTSYS if interrupted, 0 if completed.
 */
int __sched wait_for_completion_interruptible(struct completion *x)
{ … }
EXPORT_SYMBOL(…);

/**
 * wait_for_completion_interruptible_timeout: - waits for completion (w/(to,intr))
 * @x:  holds the state of this particular completion
 * @timeout:  timeout value in jiffies
 *
 * This waits for either a completion of a specific task to be signaled or for a
 * specified timeout to expire. It is interruptible. The timeout is in jiffies.
 *
 * Return: -ERESTARTSYS if interrupted, 0 if timed out, positive (at least 1,
 * or number of jiffies left till timeout) if completed.
 */
long __sched
wait_for_completion_interruptible_timeout(struct completion *x,
					  unsigned long timeout)
{ … }
EXPORT_SYMBOL(…);

/**
 * wait_for_completion_killable: - waits for completion of a task (killable)
 * @x:  holds the state of this particular completion
 *
 * This waits to be signaled for completion of a specific task. It can be
 * interrupted by a kill signal.
 *
 * Return: -ERESTARTSYS if interrupted, 0 if completed.
 */
int __sched wait_for_completion_killable(struct completion *x)
{ … }
EXPORT_SYMBOL(…);

int __sched wait_for_completion_state(struct completion *x, unsigned int state)
{ … }
EXPORT_SYMBOL(…);

/**
 * wait_for_completion_killable_timeout: - waits for completion of a task (w/(to,killable))
 * @x:  holds the state of this particular completion
 * @timeout:  timeout value in jiffies
 *
 * This waits for either a completion of a specific task to be
 * signaled or for a specified timeout to expire. It can be
 * interrupted by a kill signal. The timeout is in jiffies.
 *
 * Return: -ERESTARTSYS if interrupted, 0 if timed out, positive (at least 1,
 * or number of jiffies left till timeout) if completed.
 */
long __sched
wait_for_completion_killable_timeout(struct completion *x,
				     unsigned long timeout)
{ … }
EXPORT_SYMBOL(…);

/**
 *	try_wait_for_completion - try to decrement a completion without blocking
 *	@x:	completion structure
 *
 *	Return: 0 if a decrement cannot be done without blocking
 *		 1 if a decrement succeeded.
 *
 *	If a completion is being used as a counting completion,
 *	attempt to decrement the counter without blocking. This
 *	enables us to avoid waiting if the resource the completion
 *	is protecting is not available.
 */
bool try_wait_for_completion(struct completion *x)
{ … }
EXPORT_SYMBOL(…);

/**
 *	completion_done - Test to see if a completion has any waiters
 *	@x:	completion structure
 *
 *	Return: 0 if there are waiters (wait_for_completion() in progress)
 *		 1 if there are no waiters.
 *
 *	Note, this will always return true if complete_all() was called on @X.
 */
bool completion_done(struct completion *x)
{ … }
EXPORT_SYMBOL(…);
linux/kernel/sched/completion.c
