PTHREAD_MUTEXATTR_GETPRIOCEILING(3C) Standard C Library Functions


NAME


pthread_mutexattr_getprioceiling, pthread_mutexattr_setprioceiling - get
or set prioceiling attribute of mutex attribute object

SYNOPSIS


cc -mt [ flag... ] file... -lpthread [ library... ]
#include <pthread.h>

int pthread_mutexattr_getprioceiling(
const pthread_mutexattr_t *restrict attr,
int *restrict prioceiling);


int pthread_mutexattr_setprioceiling(pthread_mutexattr_t *attr,
int prioceiling);


DESCRIPTION


The pthread_mutexattr_getprioceiling() and
pthread_mutexattr_setprioceiling() functions, respectively, get and set
the priority ceiling attribute of a mutex attribute object pointed to by
attr, which was previously created by the pthread_mutexattr_init()
function.


The prioceiling attribute contains the priority ceiling of initialized
mutexes. The values of prioceiling must be within the range of priorities
defined by SCHED_FIFO.


The prioceiling attribute defines the priority ceiling of initialized
mutexes, which is the minimum priority level at which the critical
section guarded by the mutex is executed. In order to avoid priority
inversion, the priority ceiling of the mutex must be set to a priority
higher than or equal to the highest priority of all the threads that may
lock that mutex.


The ceiling value should be drawn from the range of priorities for the
SCHED_FIFO policy. When a thread acquires such a mutex, the policy of the
thread at mutex acquisition should match that from which the ceiling
value was derived (SCHED_FIFO, in this case). If a thread changes its
scheduling policy while holding a ceiling mutex, the behavior of
pthread_mutex_lock() and pthread_mutex_unlock() on this mutex is
undefined. See pthread_mutex_lock(3C).

RETURN VALUES


Upon successful completion, the pthread_mutexattr_getprioceiling() and
pthread_mutexattr_setprioceiling() functions return 0. Otherwise, an
error number is returned to indicate the error.

ERRORS


The pthread_mutexattr_setprioceiling() function will fail if:

EINVAL
The value specified by attr is NULL or prioceiling is invalid.


The pthread_mutexattr_getprioceiling() and
pthread_mutexattr_setprioceiling() functions may fail if:

EINVAL
The value specified by attr or prioceiling is invalid.


EPERM
The caller does not have the privilege to perform the
operation.


ATTRIBUTES


See attributes(5) for descriptions of the following attributes:


+--------------------+-------------------+
| ATTRIBUTE TYPE | ATTRIBUTE VALUE |
+--------------------+-------------------+
|Interface Stability | Committed |
+--------------------+-------------------+
|MT-Level | MT-Safe |
+--------------------+-------------------+
|Standard | See standards(5). |
+--------------------+-------------------+

SEE ALSO


pthread_cond_init(3C), pthread_create(3C), pthread_mutex_init(3C),
pthread_mutex_lock(3C), sched_get_priority_min(3C), attributes(5),
standards(5)


April 1, 2008
PTHREAD_MUTEXATTR_GETPRIOCEILING(3C)