Set Mutex's Robust Attribute

pthread_mutexattr_setrobust_np(3T)

pthread_mutexattr_setrobust_np(3T) sets the robust attribute of a mutex attribute object.

#include <pthread.h>

int pthread_mutexattr_setrobust_np(pthread_mutexatt_t *attr, int *robustness);

pthread_mutexattr_setrobust_np() applies only if the symbol _POSIX_THREAD_PRIO_INHERIT is defined.

attr points to the mutex attribute object previously created by a call to pthread_mutexattr_init().

robustness defines the behavior when the owner of the mutex dies. The value of robustness, defined in pthread.h, is PTHREAD_MUTEX_ROBUST_NP or PTHREAD_MUTEX_STALLED_NP. The default value is PTHREAD_MUTEX_STALLED_NP.

• PTHREAD_MUTEX_ROBUST_NP

  When the owner of the mutex dies, all subsequent calls to pthread_mutex_lock() are blocked from progress in an unspecified manner.

• PTHREAD_MUTEX_STALLED_NP

  When the owner of the mutex dies, the mutex is unlocked. The next owner of this mutex acquires it with an error return of EOWNWERDEAD.

  ---

  Note -

  Your application must check the return code from pthread_mutex_lock() for a mutex of this type.

  ---

  • The new owner of this mutex should make the state protected by the mutex consistent; this state might have been left inconsistent when the previous owner died.

  • If the new owner is able to make the state consistent, call pthread_mutex_consistent_np() for the mutex, and unlock the mutex.

  • If the new owner is not able to make the state consistent, do not call pthread_mutex_consistent_np() for the mutex, but unlock the mutex.

    All waiters are woken up and all subsequent calls to pthread_mutex_lock() fail to acquire the mutex. The return code is ENOTRECOVERABLE. The mutex can be made consistent by calling pthread_mutex_destroy() to unitialize the mutex, and calling pthread_mutex_int() to reinitialize it.

  If the thread that acquire the lock with EOWNERDEAD died, the next owner acquires the lock with an EOWNERDEAD return code.

Return Values

On successful completion, pthread_mutexattr_setrobust_np() returns 0. Any other returned value indicates that an error occurred.

If any of the following conditions occurs, pthread_mutexattr_setrobust_np() fails and returns the corresponding value.

ENOSYS

The option _POSIX_THREAD_PRIO__INHERIT is not defined or the implementation does not support pthread_mutexattr_setrobust_np().

ENOTSUP

The value specified by robustness is not supported.

pthread_mutexattr_setrobust_np() might fail if:

EINVAL

The value specified by attr or robustness is invalid.