PTHREAD_MUTEXATTR(3) FreeBSD Library Functions Manual PTHREAD_MUTEXATTR(3)
NAME
pthread_mutexattr_init, pthread_mutexattr_destroy,
pthread_mutexattr_setprioceiling, pthread_mutexattr_getprioceiling,
pthread_mutexattr_setprotocol, pthread_mutexattr_getprotocol,
pthread_mutexattr_setpshared, pthread_mutexattr_getpshared,
pthread_mutexattr_setrobust, pthread_mutexattr_getrobust,
pthread_mutexattr_settype, pthread_mutexattr_gettype - mutex attribute
operations
LIBRARY
POSIX Threads Library (libpthread, -lpthread)
SYNOPSIS
#include <pthread.h>
int
pthread_mutexattr_init(pthread_mutexattr_t *attr);
int
pthread_mutexattr_destroy(pthread_mutexattr_t *attr);
int
pthread_mutexattr_setprioceiling(pthread_mutexattr_t *attr,
int prioceiling);
int
pthread_mutexattr_getprioceiling(const pthread_mutexattr_t *attr,
int *prioceiling);
int
pthread_mutexattr_setprotocol(pthread_mutexattr_t *attr, int protocol);
int
pthread_mutexattr_getprotocol(const pthread_mutexattr_t *restrict attr,
int *restrict protocol);
int
pthread_mutexattr_setpshared(pthread_mutexattr_t *attr, int shared);
int
pthread_mutexattr_getpshared(const pthread_mutexattr_t *attr,
int *shared);
int
pthread_mutexattr_setrobust(pthread_mutexattr_t *attr, int robust);
int
pthread_mutexattr_getrobust(pthread_mutexattr_t *attr, int *robust);
int
pthread_mutexattr_settype(pthread_mutexattr_t *attr, int type);
int
pthread_mutexattr_gettype(const pthread_mutexattr_t *restrict attr,
int *restrict type);
DESCRIPTION
Mutex attributes are used to specify parameters to pthread_mutex_init().
One attribute object can be used in multiple calls to
pthread_mutex_init(), with or without modifications between calls.
The pthread_mutexattr_init() function initializes attr with all the
default mutex attributes.
The pthread_mutexattr_destroy() function destroys attr.
The pthread_mutexattr_setprioceiling() function sets the priority ceiling
for the mutex, used by threads executed under the PTHREAD_PRIO_PROTECT
protocol.
The pthread_mutexattr_setprotocol() function specifies the protocol to be
followed in utilizing mutexes. The protocol argument can take one of the
following values:
PTHREAD_PRIO_NONE Priority and scheduling of the thread owning this
mutex is not affected by its mutex ownership.
PTHREAD_PRIO_INHERIT Request priority-inheritance protocol, where the
thread owning the mutex is executed at the highest
priority among priorities of all threads waiting on
any mutex owned by this thread.
PTHREAD_PRIO_PROTECT Request priority-inheritance protocol, where the
thread owning the mutex is executed at highest
priority among priorities or priority ceilings of
all threads waiting on any mutex owned by this
thread.
The pthread_mutexattr_setrobust() function specifies robustness attribute
of the mutex. Possible values for the robust argument are
PTHREAD_MUTEX_STALLED No special actions are taken if the thread owning
the mutex is terminated without unlocking the
mutex lock. This can lead to deadlocks if no
other thread can unlock the mutex. This is the
default value.
PTHREAD_MUTEX_ROBUST If the process containing the owning thread of a
robust mutex, or owning thread, terminates while
holding the mutex lock, the next thread that
acquires the mutex is notified about the
termination by the return value EOWNERDEAD from
the locking function. Then, either
pthread_mutex_consistent(3) can be used to repair
the mutex lock state, or pthread_mutex_unlock(3)
can unlock the mutex lock but also put it an
unusable state, where all further attempts to
acquire it result in the ENOTRECOVERABLE error.
The pthread_mutexattr_settype() function sets the type of the mutex. The
type affects the behavior of calls which lock and unlock the mutex. The
possible values for the type argument are
PTHREAD_MUTEX_NORMAL Both recursive locking, and unlocking when the
lock is not owned by the current thread, cause
an error to be returned from the corresponding
functions. This matches
PTHREAD_MUTEX_ERRORCHECK but somewhat
contradicts the behavior mandated by POSIX.
PTHREAD_MUTEX_ERRORCHECK Both recursive locking, and unlocking when the
lock is not owned by the current thread, cause
an error returned from the corresponding
functions.
PTHREAD_MUTEX_RECURSIVE Recursive locking is allowed. Attempt to
unlock when current thread is not an owner of
the lock causes an error to be returned.
PTHREAD_MUTEX_DEFAULT The FreeBSD implementation maps this type to
PTHREAD_MUTEX_ERRORCHECK type.
The pthread_mutexattr_get*() functions copy the value of the attribute
that corresponds to each function name to the location pointed to by the
second function parameter.
RETURN VALUES
If successful, these functions return 0. Otherwise, an error number is
returned to indicate the error.
ERRORS
The pthread_mutexattr_init() function will fail if:
[ENOMEM] Out of memory.
The pthread_mutexattr_destroy() function will fail if:
[EINVAL] Invalid value for attr.
The pthread_mutexattr_setprioceiling() function will fail if:
[EINVAL] Invalid value for attr, or invalid value for
prioceiling.
The pthread_mutexattr_getprioceiling() function will fail if:
[EINVAL] Invalid value for attr.
The pthread_mutexattr_setprotocol() function will fail if:
[EINVAL] Invalid value for attr, or invalid value for protocol.
The pthread_mutexattr_getprotocol() function will fail if:
[EINVAL] Invalid value for attr.
The pthread_mutexattr_setpshared() function will fail if:
[EINVAL] Invalid value for attr, or invalid value for shared.
The pthread_mutexattr_getpshared() function will fail if:
[EINVAL] Invalid value for attr.
The pthread_mutexattr_settype() function will fail if:
[EINVAL] Invalid value for attr, or invalid value for type.
The pthread_mutexattr_gettype() function will fail if:
[EINVAL] Invalid value for attr.
The pthread_mutexattr_setrobust() function will fail if:
[EINVAL] Invalid value for attr, or invalid value for robust.
The pthread_mutexattr_getrobust() function will fail if:
[EINVAL] Invalid value for attr.
SEE ALSO
pthread_mutex_init(3)
STANDARDS
The pthread_mutexattr_init() and pthread_mutexattr_destroy() functions
conform to ISO/IEC 9945-1:1996 ("POSIX.1")
The pthread_mutexattr_setprioceiling(),
pthread_mutexattr_getprioceiling(), pthread_mutexattr_setprotocol(),
pthread_mutexattr_getprotocol(), pthread_mutexattr_setpshared(),
pthread_mutexattr_getpshared(), pthread_mutexattr_settype(), and
pthread_mutexattr_gettype() functions conform to Version 2 of the Single
UNIX Specification ("SUSv2"). The pthread_mutexattr_setrobust() and
pthread_mutexattr_getrobust() functions conform to Version 4 of the
Single UNIX Specification ("SUSv4").
FreeBSD 13.1-RELEASE-p6 October 1, 2021 FreeBSD 13.1-RELEASE-p6
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