Unlocking a Mutex

Use pthread_mutex_unlock(3C) to unlock the mutex pointed to by mutex.

pthread_mutex_unlock Syntax

int pthread_mutex_unlock(pthread_mutex_t *mutex); 

#include <pthread.h>

pthread_mutex_t mutex;
int ret;

ret = pthread_mutex_unlock(&mutex); /* release the mutex */

pthread_mutex_unlock() releases the mutex object referenced by mutex. The manner in which a mutex is released is dependent upon the mutex's type attribute. If threads are blocked on the mutex object when pthread_mutex_unlock() is called and the mutex becomes available, the scheduling policy determines which thread acquires the mutex. For PTHREAD_MUTEX_RECURSIVE mutexes, the mutex becomes available when the count reaches zero and the calling thread no longer has any locks on this mutex.

pthread_mutex_unlock Return Values

pthread_mutex_unlock() returns zero after completing successfully. Any other return value indicates that an error occurred. When the following condition occurs, the function fails and returns the corresponding value.

EPERM

Description:

The current thread does not own the mutex.