pthread_mutexattr_getrobust

Synopsis

#include <pthread.h>

int pthread_mutexattr_getrobust(const pthread_mutexattr_t *restrict attr,
                                int *restrict robust);

int pthread_mutexattr_setrobust(pthread_mutexattr_t *attr, int robust);

Status

Implemented

Conformance

IEEE Std 1003.1-2017

Description

The pthread_mutexattr_getrobust() and pthread_mutexattr_setrobust() functions, respectively, shall get and set the mutex robust attribute. This attribute is set in the robust parameter. Valid values for robust include:

  • PTHREAD_MUTEX_STALLED - No special actions are taken if the owner of the mutex is terminated while holding the mutex lock. This can lead to deadlocks if no other thread can unlock the mutex. This is the default value.

  • PTHREAD_MUTEX_ROBUST - If the process containing the owning thread of a robust mutex terminates while holding the mutex lock, the next thread that acquires the mutex shall be notified about the termination by the return value EOWNERDEAD from the locking function. If the owning thread of a robust mutex terminates while holding the mutex lock, the next thread that attempts to acquire the mutex may be notified about the termination by the return value EOWNERDEAD. The notified thread can then attempt to make the state protected by the mutex consistent again, and if successful can mark the mutex state as consistent by calling pthread_mutex_consistent(). After a subsequent successful call to pthread_mutex_unlock(), the mutex lock shall be released and can be used normally by other threads. If the mutex is unlocked without a call to pthread_mutex_consistent(), it shall be in a permanently unusable state and all attempts to lock the mutex shall fail with the error ENOTRECOVERABLE. The only permissible operation on such a mutex is pthread_mutex_destroy().

Phoenix-RTOS notifies the next owner with EOWNERDEAD whenever the owning thread of a robust mutex terminates while holding the mutex lock, also when its process has not terminated.

The behavior is undefined if the value specified by the attr argument to pthread_mutexattr_getrobust() or pthread_mutexattr_setrobust() does not refer to an initialized mutex attributes object.

Return value

Upon successful completion, the pthread_mutexattr_getrobust() function shall return zero and store the value of the robust attribute of attr into the object referenced by the robust parameter. Otherwise, an error value shall be returned to indicate the error. If successful, the pthread_mutexattr_setrobust() function shall return zero; otherwise, an error number shall be returned to indicate the error.

Errors

The pthread_mutexattr_setrobust() function shall fail if:

  • EINVAL - The value of robust is invalid.

These functions shall not return an error code of EINTR.

POSIX deviations

No POSIX deviations discovered.