67 lines
2.6 KiB
C
67 lines
2.6 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://zfsonlinux.org/>.
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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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#ifndef _SPL_RWSEM_COMPAT_H
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#define _SPL_RWSEM_COMPAT_H
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#include <linux/rwsem.h>
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#if defined(RWSEM_SPINLOCK_IS_RAW)
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#define spl_rwsem_lock_irqsave(lk, fl) raw_spin_lock_irqsave(lk, fl)
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#define spl_rwsem_unlock_irqrestore(lk, fl) raw_spin_unlock_irqrestore(lk, fl)
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#define spl_rwsem_trylock_irqsave(lk, fl) raw_spin_trylock_irqsave(lk, fl)
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#else
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#define spl_rwsem_lock_irqsave(lk, fl) spin_lock_irqsave(lk, fl)
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#define spl_rwsem_unlock_irqrestore(lk, fl) spin_unlock_irqrestore(lk, fl)
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#define spl_rwsem_trylock_irqsave(lk, fl) spin_trylock_irqsave(lk, fl)
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#endif /* RWSEM_SPINLOCK_IS_RAW */
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/*
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* Prior to Linux 2.6.33 there existed a race condition in rwsem_is_locked().
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* The semaphore's activity was checked outside of the wait_lock which
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* could result in some readers getting the incorrect activity value.
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*
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* When a kernel without this fix is detected the SPL takes responsibility
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* for acquiring the wait_lock to avoid this race.
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*/
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#if defined(RWSEM_IS_LOCKED_TAKES_WAIT_LOCK)
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#define spl_rwsem_is_locked(rwsem) rwsem_is_locked(rwsem)
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#else
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static inline int
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spl_rwsem_is_locked(struct rw_semaphore *rwsem)
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{
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unsigned long flags;
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int rc = 1;
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if (spl_rwsem_trylock_irqsave(&rwsem->wait_lock, flags)) {
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rc = rwsem_is_locked(rwsem);
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spl_rwsem_unlock_irqrestore(&rwsem->wait_lock, flags);
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}
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return (rc);
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}
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#endif /* RWSEM_IS_LOCKED_TAKES_WAIT_LOCK */
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#endif /* _SPL_RWSEM_COMPAT_H */
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