2008-05-26 12:45:55 +04:00
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.\" $NetBSD: pthread_spin_unlock.3,v 1.8 2008/05/26 08:45:55 wiz Exp $
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2003-06-04 01:31:36 +04:00
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.\"
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2008-05-26 04:31:08 +04:00
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.\" Copyright (c) 2002, 2008 The NetBSD Foundation, Inc.
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2003-06-04 01:31:36 +04:00
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.\" All rights reserved.
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\" THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
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.\" ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
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.\" TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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.\" PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
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.\" BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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.\" CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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.\" SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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.\" INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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.\" CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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.\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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.\" POSSIBILITY OF SUCH DAMAGE.
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.\"
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2008-05-26 04:31:08 +04:00
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.Dd May 26, 2008
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2003-06-04 01:31:36 +04:00
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.Dt PTHREAD_SPIN_UNLOCK 3
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.Os
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.Sh NAME
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.Nm pthread_spin_unlock
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.Nd release a spin lock
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.Sh LIBRARY
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.Lb libpthread
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.Sh SYNOPSIS
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.In pthread.h
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.Ft int
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.Fn pthread_spin_unlock "pthread_spinlock_t *lock"
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.Sh DESCRIPTION
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The
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.Fn pthread_spin_unlock
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function is used to release the read/write lock previously obtained by
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.Fn pthread_spin_lock
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or
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.Fn pthread_spin_trylock .
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.Sh RETURN VALUES
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If successful, the
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.Fn pthread_spin_unlock
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2005-06-17 22:26:53 +04:00
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function will return zero.
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Otherwise an error number will be returned to indicate the error.
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2003-06-04 01:31:36 +04:00
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.Pp
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The results are undefined if
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.Fa lock
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is not held by the calling thread.
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.Sh ERRORS
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The
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.Fn pthread_spin_unlock
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function may fail if:
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.Bl -tag -width Er
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.It Bq Er EINVAL
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The value specified by
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.Fa lock
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is invalid.
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.El
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.Sh SEE ALSO
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.Xr pthread_spin_destroy 3 ,
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2003-07-04 12:41:25 +04:00
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.Xr pthread_spin_init 3 ,
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2003-06-04 01:31:36 +04:00
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.Xr pthread_spin_lock 3 ,
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2003-07-04 12:41:25 +04:00
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.Xr pthread_spin_trylock 3
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2003-06-04 01:31:36 +04:00
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.Sh STANDARDS
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.Fn pthread_rwlock_unlock
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conforms to
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.St -p1003.1-2001 .
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2008-05-26 12:45:55 +04:00
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.Sh CAVEATS
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Applications using spinlocks are vulnerable to the effects of priority
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inversion.
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Applications using real-time threads
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.Pq Dv SCHED_FIFO , SCHED_RR
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should not use these interfaces.
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Outside carefully controlled environments, priority inversion with spinlocks
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can lead to system deadlock.
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Mutexes are preferable in nearly every possible use case.
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