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(7) for descriptions of the following attributes:


+--------------------+-------------------+
| ATTRIBUTE TYPE | ATTRIBUTE VALUE |
+--------------------+-------------------+
|Interface Stability | Committed |
+--------------------+-------------------+
|MT-Level | MT-Safe |
+--------------------+-------------------+
|Standard | See standards(7). |
+--------------------+-------------------+

SEE ALSO

pthread_cond_init(3C), pthread_create(3C), pthread_mutex_init(3C),
pthread_mutex_lock(3C), sched_get_priority_min(3C), attributes(7),
standards(7)

April 1, 2008
PTHREAD_MUTEXATTR_GETPRIOCEILING(3C)