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/* Copyright (c) 2008-2009, 2011, 2013-2014 The Linux Foundation.
* All rights reserved.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 and
* only version 2 as published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
*/
#ifndef __LINUX_REMOTE_SPINLOCK_H
#define __LINUX_REMOTE_SPINLOCK_H
#include <linux/spinlock.h>
#include <linux/mutex.h>
#include <asm/remote_spinlock.h>
/* Grabbing a local spin lock before going for a remote lock has several
* advantages:
* 1. Get calls to preempt enable/disable and IRQ save/restore for free.
* 2. For UP kernel, there is no overhead.
* 3. Reduces the possibility of executing the remote spin lock code. This is
* especially useful when the remote CPUs' mutual exclusion instructions
* don't work with the local CPUs' instructions. In such cases, one has to
* use software based mutex algorithms (e.g. Lamport's bakery algorithm)
* which could get expensive when the no. of contending CPUs is high.
* 4. In the case of software based mutex algorithm the exection time will be
* smaller since the no. of contending CPUs is reduced by having just one
* contender for all the local CPUs.
* 5. Get most of the spin lock debug features for free.
* 6. The code will continue to work "gracefully" even when the remote spin
* lock code is stubbed out for debug purposes or when there is no remote
* CPU in some board/machine types.
*/
typedef struct {
spinlock_t local;
_remote_spinlock_t remote;
} remote_spinlock_t;
#define remote_spin_lock_init(lock, id) \
({ \
spin_lock_init(&((lock)->local)); \
_remote_spin_lock_init(id, &((lock)->remote)); \
})
#define remote_spin_lock(lock) \
do { \
spin_lock(&((lock)->local)); \
_remote_spin_lock(&((lock)->remote)); \
} while (0)
#define remote_spin_unlock(lock) \
do { \
_remote_spin_unlock(&((lock)->remote)); \
spin_unlock(&((lock)->local)); \
} while (0)
#define remote_spin_lock_irqsave(lock, flags) \
do { \
spin_lock_irqsave(&((lock)->local), flags); \
_remote_spin_lock(&((lock)->remote)); \
} while (0)
#define remote_spin_unlock_irqrestore(lock, flags) \
do { \
_remote_spin_unlock(&((lock)->remote)); \
spin_unlock_irqrestore(&((lock)->local), flags); \
} while (0)
#define remote_spin_trylock(lock) \
({ \
spin_trylock(&((lock)->local)) \
? _remote_spin_trylock(&((lock)->remote)) \
? 1 \
: ({ spin_unlock(&((lock)->local)); 0; }) \
: 0; \
})
#define remote_spin_trylock_irqsave(lock, flags) \
({ \
spin_trylock_irqsave(&((lock)->local), flags) \
? _remote_spin_trylock(&((lock)->remote)) \
? 1 \
: ({ spin_unlock_irqrestore(&((lock)->local), flags); \
0; }) \
: 0; \
})
#define remote_spin_lock_rlock_id(lock, tid) \
_remote_spin_lock_rlock_id(&((lock)->remote), tid)
#define remote_spin_unlock_rlock(lock) \
_remote_spin_unlock_rlock(&((lock)->remote))
#define remote_spin_release(lock, pid) \
_remote_spin_release(&((lock)->remote), pid)
#define remote_spin_release_all(pid) \
_remote_spin_release_all(pid)
#define remote_spin_owner(lock) \
_remote_spin_owner(&((lock)->remote))
typedef struct {
struct mutex local;
_remote_mutex_t remote;
} remote_mutex_t;
#define remote_mutex_init(lock, id) \
({ \
mutex_init(&((lock)->local)); \
_remote_mutex_init(id, &((lock)->remote)); \
})
#define remote_mutex_lock(lock) \
do { \
mutex_lock(&((lock)->local)); \
_remote_mutex_lock(&((lock)->remote)); \
} while (0)
#define remote_mutex_trylock(lock) \
({ \
mutex_trylock(&((lock)->local)) \
? _remote_mutex_trylock(&((lock)->remote)) \
? 1 \
: ({mutex_unlock(&((lock)->local)); 0; }) \
: 0; \
})
#define remote_mutex_unlock(lock) \
do { \
_remote_mutex_unlock(&((lock)->remote)); \
mutex_unlock(&((lock)->local)); \
} while (0)
#endif
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