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pthread_mutex_unlock

Section: C Library Functions (3)
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NAME

pthread_mutex_unlock - Unlocks the specified mutex.  

LIBRARY

DECthreads POSIX 1003.1c Library (libpthread.so)  

SYNOPSIS

#include <pthread.h>

int pthread_mutex_unlock(
                       pthread_mutex_t   *mutex);  

STANDARDS

Interfaces documented on this reference page conform to industry standards as follows:

IEEE Std 1003.1c-1995, POSIX System Application Program Interface  

PARAMETERS

Mutex to be unlocked.  

DESCRIPTION

This routine unlocks the mutex specified by the mutex argument.

This routine behaves as follows, based on the type of the specified mutex: For a normal, default, or errorcheck mutex: if the mutex is owned by the calling thread, it is unlocked with no current owner. Further, for a normal or default mutex: if the mutex is not locked or is locked by another thread, this routine can also return [EPERM], but this is not guaranteed. For an errorcheck mutex: if the mutex is not locked or is locked by another thread, this routine returns [EPERM]. For a recursive mutex: if the mutex is owned by the calling thread, the lock count is decremented. The mutex remains locked and owned until the lock count reaches zero (0). When the lock count reaches zero, the mutex becomes unlocked with no current owner.

If one or more threads are waiting to lock the specified mutex, and the mutex becomes unlocked, this routine causes one thread to unblock and to try to acquire the mutex. The scheduling policy is used to determine which thread to unblock. For the SCHED_FIFO and SCHED_RR policies, a blocked thread is chosen in priority order, using first-in/first-out within priorities. Note that the mutex might not be acquired by the awakened thread if any other running thread attempts to lock the mutex first.

On Tru64 UNIX, if a signal is delivered to a thread waiting for a mutex, upon return from the signal handler, the thread resumes waiting for the mutex as if it was not interrupted.

 

RETURN VALUES

If an error condition occurs, this routine returns an integer value indicating the type of error. Possible return values are as follows: Successful completion. The value specified for mutex is invalid. The calling thread does not own the mutex.  

ERRORS

None  

RELATED INFORMATION

Functions: pthread_mutexattr_settype(3), pthread_mutex_destroy(3), pthread_mutex_init(3), pthread_mutex_lock(3), pthread_mutex_trylock(3)

Manuals: Guide to DECthreads and Programmer's Guide

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Index

NAME
LIBRARY
SYNOPSIS
STANDARDS
PARAMETERS
DESCRIPTION
RETURN VALUES
ERRORS
RELATED INFORMATION

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Time: 02:41:41 GMT, October 02, 2010