pthread_mutex_lock(3) Library Functions Manual pthread_mutex_lock(3)
NAME
pthread_mutex_lock - Locks an unlocked mutex.
LIBRARY
DECthreads POSIX 1003.1c Library (libpthread.so)
SYNOPSIS
#include <pthread.h>
int pthread_mutex_lock(
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 locked.
DESCRIPTION
This routine locks a mutex with behavior that depends upon the type of mutex, as follows: If a normal or default mutex is specified, a
deadlock can result if the current owner of the mutex calls this routine in an attempt to lock the mutex a second time. (The deadlock is
not detected or reported.) If a recursive mutex is specified, the current owner of the mutex can relock the same mutex without blocking.
The lock count is incremented for each recursive lock within the thread. If an errorcheck mutex is specified and the current owner tries
to lock the mutex a second time, this routine reports the [EDEADLK] error. If the mutex is locked by another thread, the calling thread
waits for the mutex to become available.
Use the pthread_mutexattr_settype(3) routine to set the type of the mutex to normal, default, recursive, or errorcheck. For more informa-
tion about types of mutexes, see the desciption of pthread_mutexattr_settype(3).
The thread that has locked a mutex becomes its current owner and remains its owner until the same thread has unlocked it. This routine
returns with the mutex in the locked state and with the current thread as the mutex's current owner.
A recursive or errorcheck mutex records the identity of the thread that locks it, allowing debuggers to display this information. In most
cases, normal and default mutexes do not record the owning thread's identity.
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. A deadlock condition is detected. The value specified by mutex is not a valid mutex.
ERRORS
None
RELATED INFORMATION
Functions: pthread_mutexattr_settype(3), pthread_mutex_destroy(3), pthread_mutex_init(3), pthread_mutex_trylock(3), pthread_mutex_unlock(3)
Manuals: Guide to DECthreads and Programmer's Guide
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pthread_mutex_lock(3)
