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1 jermar 1
/*
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 * Copyright (C) 2001-2004 Jakub Jermar
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 * All rights reserved.
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 *
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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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 *
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 * - 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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 * - 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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 * - The name of the author may not be used to endorse or promote products
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 *   derived from this software without specific prior written permission.
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 *
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 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
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 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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 */
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#ifndef __SPINLOCK_H__
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#define __SPINLOCK_H__
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#include <arch/types.h>
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#include <typedefs.h>
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#include <preemption.h>
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#include <atomic.h>
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#include <debug.h>
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#ifdef CONFIG_SMP
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struct spinlock {
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#ifdef CONFIG_DEBUG_SPINLOCK
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    char *name;
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#endif
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    atomic_t val;
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};
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/*
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 * SPINLOCK_DECLARE is to be used for dynamically allocated spinlocks,
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 * where the lock gets initialized in run time.
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 */
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#define SPINLOCK_DECLARE(slname)    spinlock_t slname
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/*
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 * SPINLOCK_INITIALIZE is to be used for statically allocated spinlocks.
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 * It declares and initializes the lock.
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 */
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#ifdef CONFIG_DEBUG_SPINLOCK
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#define SPINLOCK_INITIALIZE(slname)     \
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    spinlock_t slname = {       \
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        .name = #slname,    \
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        .val = { 0 }        \
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    }
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#else
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#define SPINLOCK_INITIALIZE(slname)     \
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    spinlock_t slname = {       \
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        .val = { 0 }        \
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    }
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#endif
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extern void spinlock_initialize(spinlock_t *sl, char *name);
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extern int spinlock_trylock(spinlock_t *sl);
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extern void spinlock_lock_debug(spinlock_t *sl);
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#ifdef CONFIG_DEBUG_SPINLOCK
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#  define spinlock_lock(x) spinlock_lock_debug(x)
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#else
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#  define spinlock_lock(x) atomic_lock_arch(&(x)->val)
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#endif
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/** Unlock spinlock
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 *
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 * Unlock spinlock.
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 *
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 * @param sl Pointer to spinlock_t structure.
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 */
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static inline void spinlock_unlock(spinlock_t *sl)
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{
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    ASSERT(atomic_get(&sl->val) != 0);
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    /*
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     * Prevent critical section code from bleeding out this way down.
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     */
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    CS_LEAVE_BARRIER();
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    atomic_set(&sl->val,0);
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    preemption_enable();
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}
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#else
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/* On UP systems, spinlocks are effectively left out. */
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#define SPINLOCK_DECLARE(name)
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#define SPINLOCK_INITIALIZE(name)
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#define spinlock_initialize(x,name)
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#define spinlock_lock(x)        preemption_disable()
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#define spinlock_trylock(x)         (preemption_disable(), 1)
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#define spinlock_unlock(x)      preemption_enable()
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#endif
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#endif