716154c592
Updated AUTHORS, COPYING, DISCLAIMER, and INSTALL files. Added standardized headers to all source file to clearly indicate the copyright, license, and to give credit where credit is due.
78 lines
3.1 KiB
C
78 lines
3.1 KiB
C
/*****************************************************************************\
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* Copyright (C) 2007-2010 Lawrence Livermore National Security, LLC.
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* Copyright (C) 2007 The Regents of the University of California.
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* Produced at Lawrence Livermore National Laboratory (cf, DISCLAIMER).
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* Written by Brian Behlendorf <behlendorf1@llnl.gov>.
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* UCRL-CODE-235197
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*
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* This file is part of the SPL, Solaris Porting Layer.
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* For details, see <http://github.com/behlendorf/spl/>.
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*
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* The SPL is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License as published by the
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* Free Software Foundation; either version 2 of the License, or (at your
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* option) any later version.
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*
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* The SPL is distributed in the hope that it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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* for more details.
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*
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* You should have received a copy of the GNU General Public License along
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* with the SPL. If not, see <http://www.gnu.org/licenses/>.
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*****************************************************************************
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* Solaris Porting Layer (SPL) Mutex Implementation.
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\*****************************************************************************/
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#include <sys/mutex.h>
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#ifdef DEBUG_SUBSYSTEM
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#undef DEBUG_SUBSYSTEM
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#endif
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#define DEBUG_SUBSYSTEM S_MUTEX
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/*
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* While a standard mutex implementation has been available in the kernel
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* for quite some time. It was not until 2.6.29 and latter kernels that
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* adaptive mutexs were embraced and integrated with the scheduler. This
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* brought a significant performance improvement, but just as importantly
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* it added a lock owner to the generic mutex outside CONFIG_DEBUG_MUTEXES
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* builds. This is critical for correctly supporting the mutex_owner()
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* Solaris primitive. When the owner is available we use a pure Linux
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* mutex implementation. When the owner is not available we still use
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* Linux mutexs as a base but also reserve space for an owner field right
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* after the mutex structure.
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*
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* In the case when HAVE_MUTEX_OWNER is not defined your code may
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* still me able to leverage adaptive mutexs. As long as the task_curr()
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* symbol is exported this code will provide a poor mans adaptive mutex
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* implementation. However, this is not required and if the symbol is
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* unavailable we provide a standard mutex.
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*/
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#ifndef HAVE_MUTEX_OWNER
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#ifdef HAVE_TASK_CURR
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/*
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* mutex_spin_max = { 0, -1, 1-MAX_INT }
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* 0: Never spin when trying to acquire lock
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* -1: Spin until acquired or holder yields without dropping lock
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* 1-MAX_INT: Spin for N attempts before sleeping for lock
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*/
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int mutex_spin_max = 0;
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module_param(mutex_spin_max, int, 0644);
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MODULE_PARM_DESC(mutex_spin_max, "Spin a maximum of N times to acquire lock");
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int
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spl_mutex_spin_max(void)
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{
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return mutex_spin_max;
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}
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EXPORT_SYMBOL(spl_mutex_spin_max);
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#endif /* HAVE_TASK_CURR */
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#endif /* !HAVE_MUTEX_OWNER */
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int spl_mutex_init(void) { return 0; }
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void spl_mutex_fini(void) { }
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