PTHREAD_MUTEX_GETPRIOCEILING(3C) Standard C Library Functions
NAME
pthread_mutex_getprioceiling, pthread_mutex_setprioceiling - change
priority ceiling of a mutex
SYNOPSIS
cc -mt [
flag... ]
file... -lpthread [
library... ]
#include <pthread.h>
int pthread_mutex_getprioceiling(
const pthread_mutex_t *restrict mutex,
int *restrict prioceiling);
int pthread_mutex_setprioceiling(
pthread_mutex_t *restrict mutex,
int prioceiling,
int *restrict old_ceiling);
DESCRIPTION
The
pthread_mutex_getprioceiling() function returns the current
priority ceiling of the mutex.
The
pthread_mutex_setprioceiling() function either locks the mutex if
it is unlocked, or blocks until it can successfully lock the mutex,
then it changes the mutex's priority ceiling and releases the mutex.
When the change is successful, the previous value of the priority
ceiling is returned in
old_ceiling. The process of locking the mutex
need not adhere to the priority protect protocol.
If the
pthread_mutex_setprioceiling() function fails, the mutex
priority ceiling is not changed.
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).
The ceiling value should not be treated as a persistent value
resident in a
pthread_mutex_t that is valid across upgrades of
Solaris. The semantics of the actual ceiling value are determined by
the existing priority range for the
SCHED_FIFO policy, as returned
by the
sched_get_priority_min() and
sched_get_priority_max() functions (see
sched_get_priority_min(3C)) when called on the version
of Solaris on which the ceiling value is being utilized.
RETURN VALUES
Upon successful completion, the
pthread_mutex_getprioceiling() and
pthread_mutex_setprioceiling() functions return
0. Otherwise, an
error number is returned to indicate the error.
ERRORS
The
pthread_mutex_getprioceiling() and
pthread_mutex_setprioceiling() functions may fail if:
EINVAL The value specified by
mutex does not refer to a currently
existing mutex.
The
pthread_mutex_setprioceiling() function will fail if:
EINVAL The mutex was not initialized with its
protocol attribute
having the value of
PTHREAD_PRIO_PROTECT.
EINVAL The priority requested by
prioceiling is out of range.
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_mutex_init(3C),
pthread_mutex_lock(3C),
sched_get_priority_min(3C),
attributes(7),
standards(7) April 1, 2008
PTHREAD_MUTEX_GETPRIOCEILING(3C)
