b5c99d4306
.Vt type var No = Dv INITIALIZER; to provide examples of static initialization in SYNOPSIS section. .Va macro does the wrong thing (check groff PostScript output) and the need for .Pp kludge (now dropped) should have been an indication too. While here move static initialization example to be right after the declaration of *_init().
218 lines
6.9 KiB
Groff
218 lines
6.9 KiB
Groff
.\" $NetBSD: pthread_mutex.3,v 1.6 2012/11/12 23:11:05 uwe Exp $
|
|
.\"
|
|
.\" Copyright (c) 2002, 2010 The NetBSD Foundation, Inc.
|
|
.\" All rights reserved.
|
|
.\"
|
|
.\" Redistribution and use in source and binary forms, with or without
|
|
.\" modification, are permitted provided that the following conditions
|
|
.\" are met:
|
|
.\" 1. Redistributions of source code must retain the above copyright
|
|
.\" notice, this list of conditions and the following disclaimer.
|
|
.\" 2. Redistributions in binary form must reproduce the above copyright
|
|
.\" notice, this list of conditions and the following disclaimer in the
|
|
.\" documentation and/or other materials provided with the distribution.
|
|
.\"
|
|
.\" THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
|
|
.\" ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
|
|
.\" TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
|
|
.\" PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
|
|
.\" BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
|
|
.\" CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
|
|
.\" SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
|
|
.\" INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
|
|
.\" CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
|
|
.\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
|
|
.\" POSSIBILITY OF SUCH DAMAGE.
|
|
.\"
|
|
.\" Copyright (c) 1997 Brian Cully <shmit@kublai.com>
|
|
.\" All rights reserved.
|
|
.\"
|
|
.\" Redistribution and use in source and binary forms, with or without
|
|
.\" modification, are permitted provided that the following conditions
|
|
.\" are met:
|
|
.\" 1. Redistributions of source code must retain the above copyright
|
|
.\" notice, this list of conditions and the following disclaimer.
|
|
.\" 2. Redistributions in binary form must reproduce the above copyright
|
|
.\" notice, this list of conditions and the following disclaimer in the
|
|
.\" documentation and/or other materials provided with the distribution.
|
|
.\" 3. Neither the name of the author nor the names of any co-contributors
|
|
.\" may be used to endorse or promote products derived from this software
|
|
.\" without specific prior written permission.
|
|
.\"
|
|
.\" THIS SOFTWARE IS PROVIDED BY JOHN BIRRELL AND CONTRIBUTORS ``AS IS'' AND
|
|
.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
|
|
.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
|
|
.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
|
|
.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
|
|
.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
|
|
.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
|
|
.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
|
|
.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
|
|
.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
|
|
.\" SUCH DAMAGE.
|
|
.\"
|
|
.\" ----------------------------------------------------------------------------
|
|
.Dd July 8, 2010
|
|
.Dt PTHREAD_MUTEX 3
|
|
.Os
|
|
.Sh NAME
|
|
.Nm pthread_mutex
|
|
.Nd mutual exclusion primitives
|
|
.Sh LIBRARY
|
|
.Lb libpthread
|
|
.\" ----------------------------------------------------------------------------
|
|
.Sh SYNOPSIS
|
|
.In pthread.h
|
|
.Ft int
|
|
.Fn pthread_mutex_init "pthread_mutex_t * restrict mutex" \
|
|
"const pthread_mutexattr_t * restrict attr"
|
|
.Vt pthread_mutex_t mutex No = Dv PTHREAD_MUTEX_INITIALIZER;
|
|
.Ft int
|
|
.Fn pthread_mutex_destroy "pthread_mutex_t *mutex"
|
|
.Ft int
|
|
.Fn pthread_mutex_lock "pthread_mutex_t *mutex"
|
|
.Ft int
|
|
.Fn pthread_mutex_trylock "pthread_mutex_t *mutex"
|
|
.Ft int
|
|
.Fn pthread_mutex_unlock "pthread_mutex_t *mutex"
|
|
.\" ----------------------------------------------------------------------------
|
|
.Sh DESCRIPTION
|
|
The
|
|
.Fn pthread_mutex_init
|
|
function creates a new mutex, with attributes specified with
|
|
.Fa attr .
|
|
If
|
|
.Fa attr
|
|
is
|
|
.Dv NULL ,
|
|
the default attributes are used.
|
|
.Pp
|
|
The macro
|
|
.Dv PTHREAD_MUTEX_INITIALIZER
|
|
can be used to initialize a mutex when the default attributes are
|
|
appropriate and the mutex can be statically allocated.
|
|
The behavior is similar to
|
|
.Fn pthread_mutex_init
|
|
with
|
|
.Fa attr
|
|
specified as
|
|
.Dv NULL ,
|
|
except that no error checking is done.
|
|
.Pp
|
|
.\" -----
|
|
The
|
|
.Fn pthread_mutex_destroy
|
|
function frees the resources allocated for
|
|
.Fa mutex .
|
|
It is possible to reinitialize a destroyed mutex, but undefined
|
|
behavior may follow if the destroyed object is otherwise referenced.
|
|
.Pp
|
|
.\" -----
|
|
The
|
|
.Fn pthread_mutex_lock
|
|
function locks
|
|
.Fa mutex .
|
|
If the mutex is already locked, the calling thread will block until the
|
|
mutex becomes available.
|
|
The error conditions may vary depending on the type of the mutex; see
|
|
.Xr pthread_mutexattr 3
|
|
for additional details.
|
|
.Pp
|
|
The
|
|
.Fn pthread_mutex_trylock
|
|
function locks
|
|
.Fa mutex .
|
|
If the mutex is already locked,
|
|
.Fn pthread_mutex_trylock
|
|
will not block waiting for the mutex, but will return an error condition.
|
|
.Pp
|
|
.\" -----
|
|
The
|
|
.Fn pthread_mutex_unlock
|
|
function unlocks an acquired
|
|
.Fa mutex .
|
|
When operating with the default mutex type,
|
|
undefined behavior follows if a thread tries to unlock a mutex
|
|
that has not been locked by it, or if a thread tries to release
|
|
a mutex that is already unlocked.
|
|
.\" ----------------------------------------------------------------------------
|
|
.Sh RETURN VALUES
|
|
Upon success all described functions return zero.
|
|
Otherwise, an error number will be returned to indicate the error.
|
|
.Sh ERRORS
|
|
.Fn pthread_mutex_init
|
|
may fail if:
|
|
.Bl -tag -width Er
|
|
.It Bq Er EAGAIN
|
|
The system lacks the resources to initialize another mutex.
|
|
.It Bq Er EINVAL
|
|
The value specified by
|
|
.Fa attr
|
|
is invalid.
|
|
.It Bq Er ENOMEM
|
|
The process cannot allocate enough memory to initialize another mutex.
|
|
.El
|
|
.Pp
|
|
.\" -----
|
|
.Fn pthread_mutex_destroy
|
|
may fail if:
|
|
.Bl -tag -width Er
|
|
.It Bq Er EBUSY
|
|
.Fa Mutex
|
|
is locked by another thread.
|
|
.It Bq Er EINVAL
|
|
The value specified by
|
|
.Fa mutex
|
|
is invalid.
|
|
.El
|
|
.Pp
|
|
.\" -----
|
|
.Fn pthread_mutex_lock
|
|
may fail if:
|
|
.Bl -tag -width Er
|
|
.It Bq Er EDEADLK
|
|
A deadlock would occur if the thread blocked waiting for
|
|
.Fa mutex .
|
|
.It Bq Er EINVAL
|
|
The value specified by
|
|
.Fa mutex
|
|
is invalid.
|
|
.El
|
|
.Pp
|
|
.Fn pthread_mutex_trylock
|
|
may fail if:
|
|
.Bl -tag -width Er
|
|
.It Bq Er EBUSY
|
|
.Fa Mutex
|
|
is already locked.
|
|
.It Bq Er EINVAL
|
|
The value specified by
|
|
.Fa mutex
|
|
is invalid.
|
|
.El
|
|
.Pp
|
|
.\" -----
|
|
.Fn pthread_mutex_unlock
|
|
may fail if:
|
|
.Bl -tag -width Er
|
|
.It Bq Er EINVAL
|
|
The value specified by
|
|
.Fa mutex
|
|
is invalid.
|
|
.It Bq Er EPERM
|
|
The current thread does not hold a lock on
|
|
.Fa mutex .
|
|
.El
|
|
.\" ----------------------------------------------------------------------------
|
|
.Sh SEE ALSO
|
|
.Xr pthread 3 ,
|
|
.Xr pthread_barrier 3 ,
|
|
.Xr pthread_cond 3 ,
|
|
.Xr pthread_mutexattr 3 ,
|
|
.Xr pthread_rwlock 3 ,
|
|
.Xr pthread_spin 3
|
|
.\" ----------------------------------------------------------------------------
|
|
.Sh STANDARDS
|
|
These functions conform to
|
|
.St -p1003.1-2001 .
|