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$FreeBSD: src/lib/libpthread/man/pthread_mutexattr.3,v 1.8 2002/09/16 19:29:29 mini Exp $
.Dd June 12, 2016 .Dt PTHREAD_MUTEXATTR 3 .Os .Sh NAME .Nm pthread_mutexattr_init , .Nm pthread_mutexattr_destroy , .Nm pthread_mutexattr_setprioceiling , .Nm pthread_mutexattr_getprioceiling , .Nm pthread_mutexattr_setprotocol , .Nm pthread_mutexattr_getprotocol , .Nm pthread_mutexattr_settype , .Nm pthread_mutexattr_gettype , .Nm pthread_mutexattr_getpshared , .Nm pthread_mutexattr_setpshared .Nd mutex attribute operations .Sh LIBRARY .Lb libpthread .Sh SYNOPSIS n pthread.h .Ft int .Fn pthread_mutexattr_init "pthread_mutexattr_t *attr" .Ft int .Fn pthread_mutexattr_destroy "pthread_mutexattr_t *attr" .Ft int .Fn pthread_mutexattr_setprioceiling \ "pthread_mutexattr_t *attr" "int prioceiling" .Ft int .Fn pthread_mutexattr_getprioceiling \ "pthread_mutexattr_t *attr" "int *prioceiling" .Ft int .Fn pthread_mutexattr_setprotocol \ "pthread_mutexattr_t *attr" "int protocol" .Ft int .Fn pthread_mutexattr_getprotocol \ "pthread_mutexattr_t *attr" "int *protocol" .Ft int .Fn pthread_mutexattr_settype "pthread_mutexattr_t *attr" "int type" .Ft int .Fn pthread_mutexattr_gettype \ "pthread_mutexattr_t * restrict attr" "int * restrict type" .Ft int .Fn pthread_mutexattr_getpshared \ "const pthread_mutexattr_t * restrict attr" "int * restrict pshared" .Ft int .Fn pthread_mutexattr_setpshared \ "pthread_mutexattr_t * attr" "int pshared" .Sh DESCRIPTION Mutex attributes are used to specify parameters to .Fn pthread_mutex_init . Like with thread attributes, one attribute object can be used in multiple calls to .Xr pthread_mutex_init 3 , with or without modifications between calls.
p The .Fn pthread_mutexattr_init function initializes .Fa attr with all the default mutex attributes.
p The .Fn pthread_mutexattr_destroy function destroys .Fa attr .
p The .Fn pthread_mutexattr_settype functions set the mutex .Fa type value of the attribute. Valid mutex types are: l -tag -width "XXX" -offset 2n t Dv PTHREAD_MUTEX_NORMAL This type of mutex does not check for usage errors. It will deadlock if reentered, and result in undefined behavior if a locked mutex is unlocked by another thread. Attempts to unlock an already unlocked .Dv PTHREAD_MUTEX_NORMAL mutex will result in undefined behavior. t Dv PTHREAD_MUTEX_ERRORCHECK These mutexes do check for usage errors. If an attempt is made to relock a .Dv PTHREAD_MUTEX_ERRORCHECK mutex without first dropping the lock, an error will be returned. If a thread attempts to unlock a .Dv PTHREAD_MUTEX_ERRORCHECK mutex that is locked by another thread, an error will be returned. If a thread attempts to unlock a .Dv PTHREAD_MUTEX_ERRORCHECK thread that is unlocked, an error will be returned. t Dv PTHREAD_MUTEX_RECURSIVE These mutexes allow recursive locking. An attempt to relock a .Dv PTHREAD_MUTEX_RECURSIVE mutex that is already locked by the same thread succeeds. An equivalent number of .Xr pthread_mutex_unlock 3 calls are needed before the mutex will wake another thread waiting on this lock. If a thread attempts to unlock a .Dv PTHREAD_MUTEX_RECURSIVE mutex that is locked by another thread, an error will be returned. If a thread attempts to unlock a .Dv PTHREAD_MUTEX_RECURSIVE thread that is unlocked, an error will be returned.
p It is advised that .Dv PTHREAD_MUTEX_RECURSIVE mutexes are not used with condition variables. This is because of the implicit unlocking done by .Xr pthread_cond_wait 3 and .Xr pthread_cond_timedwait 3 . t Dv PTHREAD_MUTEX_DEFAULT Also this type of mutex will cause undefined behavior if reentered. Unlocking a .Dv PTHREAD_MUTEX_DEFAULT mutex locked by another thread will result in undefined behavior. Attempts to unlock an already unlocked .Dv PTHREAD_MUTEX_DEFAULT mutex will result in undefined behavior.
p This is the default mutex type for .Fn pthread_mutexattr_init . .El
p The .Fn pthread_mutexattr_gettype functions copy the type value of the attribute to the location pointed to by the second parameter.
p The .Fn pthread_mutexattr_getpshared function obtains the value of the process-shared attribute from the attributes object referenced by .Fa attr .
p The .Fn pthread_mutexattr_setpshared function is used to set the process-shared attribute in an initialised attributes object referenced by .Fa attr .
p The .Fn pthread_mutexattr_getprotocol and .Fn pthread_mutexattr_setprotocol functions shall get and set the protocol attribute of a mutex attributes object pointed to by .Fa attr which was previously created by the function .Fn pthread_mutexattr_init .
p The .Fn pthread_mutexattr_getprioceiling and .Fn pthread_mutexattr_setprioceiling functions, shall get and set the priority ceiling attribute of a mutex attributes object pointed to by .Fa attr which was previously created by the function .Fn pthread_mutexattr_init . .Sh RETURN VALUES If successful, these functions return 0. Otherwise, an error number is returned to indicate the error. .Sh ERRORS The .Fn pthread_mutexattr_init function shall fail if: l -tag -width Er t Bq Er ENOMEM Insufficient memory exists to initialize the mutex attributes object. .El
p The .Fn pthread_mutexattr_settype function shall fail if: l -tag -width Er t Bq Er EINVAL The value specified either by .Fa type or .Fa attr is invalid. .El
p No error numbers are defined for the .Fn pthread_mutexattr_destroy and .Fn pthread_mutexattr_gettype functions.
p .Fn pthread_mutexattr_setprioceiling may fail if: l -tag -width Er t Bq Er EINVAL Invalid value for .Fa attr , or invalid value for .Fa prioceiling . .El
p .Fn pthread_mutexattr_getprioceiling may fail if: l -tag -width Er t Bq Er EINVAL Invalid value for .Fa attr . .El
p .Fn pthread_mutexattr_setprotocol may fail if: l -tag -width Er t Bq Er EINVAL Invalid value for .Fa attr , or invalid value for .Fa protocol . .El
p .Fn pthread_mutexattr_getprotocol may fail if: l -tag -width Er t Bq Er EINVAL Invalid value for .Fa attr . .El
p .Fn pthread_mutexattr_getpshared and .Fn pthread_mutexattr_setpshared may fail if: l -tag -width Er t Bq Er EINVAL the value specified by .Fa attr is invalid. .El .Sh SEE ALSO .Xr pthread_mutex_init 3 .Sh STANDARDS These functions conform to .St -p1003.1-2001 . .Sh BUGS The .Fn pthread_mutexattr_getpshared and .Fn pthread_mutexattr_setpshared functions are hidden by default since only thread shared attributes are supported.
Indexes created Sat Sep 20 22:09:52 GMT 2025