NAME
pthread_mutex_getprioceiling(), pthread_mutex_setprioceiling() — get or set the prioceiling of a mutex.
SYNOPSIS
#include <pthread.h>
int pthread_mutex_getprioceiling(
pthread_mutex_t *__restrict mutex,
int *__restrict prioceiling
);
int pthread_mutex_setprioceiling(
pthread_mutex_t *__restrict mutex,
int prioceiling,
int *__restrict old_ceiling
);
PARAMETERS
- mutex
Pointer to the mutex whose
prioceiling
attribute is to be set/retrieved.
- prioceiling
This parameter either points to the memory location where the
prioceiling
attribute of
mutex
is to be returned (get function) or
specifies the new value of the
prioceiling
attribute for
mutex
(set function).
- old_ceiling
This parameter points to the memory location where the old
prioceiling
attribute of
mutex
is to be returned (set function only).
DESCRIPTION
The
pthread_mutex_setprioceiling()
function will first lock
mutex.
If the mutex is currently locked, the calling thread will block until the
mutex can be locked.
Once the mutex has been locked, the
prioceiling
attribute of
mutex
will be changed to the value specified in the
prioceiling
parameter and
mutex
will be unlocked.
The old priority ceiling for the mutex will be returned in
old_prioceiling.
The
pthread_mutex_getprioceiling()
function returns the current value of the
prioceiling
attribute for
mutex
in the
prioceiling
parameter.
Be sure to check for the definition of
_POSIX_THREAD_PRIO_PROTECT
before using these functions.
Not all systems will support these functions.
RETURN VALUE
Upon successful completion,
pthread_mutex_getprioceiling()
and
pthread_mutex_setprioceiling()
return zero. Otherwise, an error number is returned to indicate the error
(the
errno
variable is not set).
ERRORS
If any of the following occur, the
pthread_mutex_getprioceiling()
and
pthread_mutex_setprioceiling()
functions return the corresponding error number:
- ENOSYS
_POSIX_THREAD_PRIO_PROTECT
is not defined and these functions are not supported.
For each of the following conditions, if the condition is detected, the
pthread_mutex_getprioceiling()
and
pthread_mutex_setprioceiling()
functions return the corresponding error number:
- EINVAL
The priority value
prioceiling
is not a legal value.
- EINVAL
mutex
is not a valid mutex.
- ENOSYS
The prioceiling protocol is not supported for mutexes.
- EPERM
The caller does not have the appropriate privileges to
change priority ceiling for
mutex.
- EFAULT
mutex
parameter points to an illegal address.
AUTHOR
pthread_mutex_getprioceiling()
and
pthread_mutex_setprioceiling()
were derived from the IEEE POSIX P1003.1c standard.
STANDARDS CONFORMANCE
pthread_mutex_getprioceiling(): POSIX 1003.1c.
pthread_mutex_setprioceiling(): POSIX 1003.1c.
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