96 lines
3.0 KiB
Groff
96 lines
3.0 KiB
Groff
.\" $NetBSD: pthread_spin_init.3,v 1.8 2008/05/26 08:45:55 wiz Exp $
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.\"
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.\" Copyright (c) 2002, 2008 The NetBSD Foundation, Inc.
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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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.Dd May 26, 2008
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.Dt PTHREAD_SPIN_INIT 3
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.Os
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.Sh NAME
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.Nm pthread_spin_init
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.Nd initialize 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_init "pthread_spinlock_t *lock" "int pshared"
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.Sh DESCRIPTION
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The
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.Fn pthread_spin_init
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function is used to initialize a spinlock.
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The
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.Fa pshared
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parameter is currently unused and all spinlocks exhibit the
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.Dv PTHREAD_PROCESS_SHARED
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property.
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.Pp
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The results of calling
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.Fn pthread_spin_init
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with an already initialized lock are undefined.
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.Sh RETURN VALUES
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If successful, the
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.Fn pthread_spin_init
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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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.Sh ERRORS
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The
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.Fn pthread_spin_init
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function shall fail if:
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.Bl -tag -width Er
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.It Bq Er ENOMEM
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Insufficient memory exists to initialize the lock.
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.El
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.Pp
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The
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.Fn pthread_spin_init
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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
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.Fa lock
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parameter was NULL or the
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.Fa pshared
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parameter was neither
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.Dv PTHREAD_PROCESS_SHARED
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nor
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.Dv PTHREAD_PROCESS_PRIVATE .
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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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.Xr pthread_spin_lock 3 ,
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.Xr pthread_spin_trylock 3 ,
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.Xr pthread_spin_unlock 3
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.Sh STANDARDS
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.Fn pthread_spin_init
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conforms to
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.St -p1003.1-2001 .
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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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