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Technical Reference: Base Operating System and Extensions, Volume 1

pthread_mutexattr_getkind_np Subroutine


Returns the value of the kind attribute of a mutex attributes object.


Threads Library (libpthreads.a)


#include <pthread.h>

int pthread_mutexattr_getkind_np ( attr, kind)
pthread_mutexattr_t *attr;
int *kind;


The pthread_mutexattr_getkind_np subroutine returns the value of the kind attribute of the mutex attributes object attr. This attribute specifies the kind of the mutex created with this attributes object. It may have one of the following values:

MUTEX_FAST_NP Denotes a fast mutex. A fast mutex can be locked only once. If the same thread unlocks twice the same fast mutex, the thread will deadlock. Any thread can unlock a fast mutex. A fast mutex is not compatible with the priority inheritance protocol.
MUTEX_RECURSIVE_NP Denotes a recursive mutex. A recursive mutex can be locked more than once by the same thread without causing that thread to deadlock. The thread must then unlock the mutex as many times as it locked it. Only the thread that locked a recursive mutex can unlock it. A recursive mutex must not be used with condition variables.
MUTEX_NONRECURSIVE_NP Denotes the default non-recursive POSIX compliant mutex.

  1. The pthread.h header file must be the first included file of each source file using the threads library. Otherwise, the -D_THREAD_SAFE compilation flag should be used, or the cc_r compiler used. In this case, the flag is automatically set.
  2. The pthread_mutexattr_getkind_np subroutine is not portable.


attr Specifies the mutex attributes object.
kind Points to where the kind attribute value will be stored.

Return Values

Upon successful completion, the value of the kind attribute is returned via the kind parameter, and 0 is returned. Otherwise, an error code is returned.

Error Codes

The pthread_mutexattr_getkind_np subroutine is unsuccessful if the following is true:

EINVAL The attr parameter is not valid.

Implementation Specifics

This subroutine is part of the Base Operating System (BOS) Runtime.

This subroutine is not POSIX compliant and is provided only for compatibility with DCE threads. It should not be used when writing new applications.

Related Information

The pthread_mutexattr_setkind_np (pthread_mutexattr_setkind_np Subroutine) subroutine.

Using Mutexes in AIX 5L Version 5.1 General Programming Concepts: Writing and Debugging Programs.

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