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)