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/**************************************************************************

 *

 * Copyright (c) 2007-2009 VMware, Inc., Palo Alto, CA., USA

 * All Rights Reserved.

 *

 * Permission is hereby granted, free of charge, to any person obtaining a

 * copy of this software and associated documentation files (the

 * "Software"), to deal in the Software without restriction, including

 * without limitation the rights to use, copy, modify, merge, publish,

 * distribute, sub license, and/or sell copies of the Software, and to

 * permit persons to whom the Software is furnished to do so, subject to

 * the following conditions:

 *

 * The above copyright notice and this permission notice (including the

 * next paragraph) shall be included in all copies or substantial portions

 * of the Software.

 *

 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR

 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,

 * FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT. IN NO EVENT SHALL

 * THE COPYRIGHT HOLDERS, AUTHORS AND/OR ITS SUPPLIERS BE LIABLE FOR ANY CLAIM,

 * DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR

 * OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE

 * USE OR OTHER DEALINGS IN THE SOFTWARE.

 *

 **************************************************************************/

/*

 * Authors: Thomas Hellstrom 

 */

#include 

#include 

#include 

//#include 

#include 

#include 

#include 

#include 

#define TTM_WRITE_LOCK_PENDING    (1 << 0)

#define TTM_VT_LOCK_PENDING       (1 << 1)

#define TTM_SUSPEND_LOCK_PENDING  (1 << 2)

#define TTM_VT_LOCK               (1 << 3)

#define TTM_SUSPEND_LOCK          (1 << 4)

void ttm_lock_init(struct ttm_lock *lock)

{

	spin_lock_init(&lock->lock);

	init_waitqueue_head(&lock->queue);

	lock->rw = 0;

	lock->flags = 0;

}

EXPORT_SYMBOL(ttm_lock_init);

void ttm_read_unlock(struct ttm_lock *lock)

{

	spin_lock(&lock->lock);

	if (--lock->rw == 0)

		wake_up_all(&lock->queue);

	spin_unlock(&lock->lock);

}

EXPORT_SYMBOL(ttm_read_unlock);

static bool __ttm_read_lock(struct ttm_lock *lock)

{

	bool locked = false;

	spin_lock(&lock->lock);

	if (lock->rw >= 0 && lock->flags == 0) {

		++lock->rw;

		locked = true;

	}

	spin_unlock(&lock->lock);

	return locked;

}

int ttm_read_lock(struct ttm_lock *lock, bool interruptible)

{

	int ret = 0;

	if (interruptible)

		ret = wait_event_interruptible(lock->queue,

					       __ttm_read_lock(lock));

	else

		wait_event(lock->queue, __ttm_read_lock(lock));

	return ret;

}

EXPORT_SYMBOL(ttm_read_lock);

static bool __ttm_read_trylock(struct ttm_lock *lock, bool *locked)

{

	bool block = true;

	*locked = false;

	spin_lock(&lock->lock);

	if (lock->rw >= 0 && lock->flags == 0) {

		++lock->rw;

		block = false;

		*locked = true;

	} else if (lock->flags == 0) {

		block = false;

	}

	spin_unlock(&lock->lock);

	return !block;

}

int ttm_read_trylock(struct ttm_lock *lock, bool interruptible)

{

	int ret = 0;

	bool locked;

	if (interruptible)

		ret = wait_event_interruptible

			(lock->queue, __ttm_read_trylock(lock, &locked));

	else

		wait_event(lock->queue, __ttm_read_trylock(lock, &locked));

	if (unlikely(ret != 0)) {

		BUG_ON(locked);

		return ret;

	}

	return (locked) ? 0 : -EBUSY;

}

void ttm_write_unlock(struct ttm_lock *lock)

{

	spin_lock(&lock->lock);

	lock->rw = 0;

	wake_up_all(&lock->queue);

	spin_unlock(&lock->lock);

}

EXPORT_SYMBOL(ttm_write_unlock);

static bool __ttm_write_lock(struct ttm_lock *lock)

{

	bool locked = false;

	spin_lock(&lock->lock);

	if (lock->rw == 0 && ((lock->flags & ~TTM_WRITE_LOCK_PENDING) == 0)) {

		lock->rw = -1;

		lock->flags &= ~TTM_WRITE_LOCK_PENDING;

		locked = true;

	} else {

		lock->flags |= TTM_WRITE_LOCK_PENDING;

	}

	spin_unlock(&lock->lock);

	return locked;

}

int ttm_write_lock(struct ttm_lock *lock, bool interruptible)

{

	int ret = 0;

	if (interruptible) {

		ret = wait_event_interruptible(lock->queue,

					       __ttm_write_lock(lock));

		if (unlikely(ret != 0)) {

			spin_lock(&lock->lock);

			lock->flags &= ~TTM_WRITE_LOCK_PENDING;

			wake_up_all(&lock->queue);

			spin_unlock(&lock->lock);

		}

	} else

		wait_event(lock->queue, __ttm_read_lock(lock));

	return ret;

}

EXPORT_SYMBOL(ttm_write_lock);

static int __ttm_vt_unlock(struct ttm_lock *lock)

{

	int ret = 0;

	spin_lock(&lock->lock);

	if (unlikely(!(lock->flags & TTM_VT_LOCK)))

		ret = -EINVAL;

	lock->flags &= ~TTM_VT_LOCK;

	wake_up_all(&lock->queue);

	spin_unlock(&lock->lock);

	return ret;

}

static void ttm_vt_lock_remove(struct ttm_base_object **p_base)

{

	struct ttm_base_object *base = *p_base;

	struct ttm_lock *lock = container_of(base, struct ttm_lock, base);

	int ret;

	*p_base = NULL;

	ret = __ttm_vt_unlock(lock);

	BUG_ON(ret != 0);

}

static bool __ttm_vt_lock(struct ttm_lock *lock)

{

	bool locked = false;

	spin_lock(&lock->lock);

	if (lock->rw == 0) {

		lock->flags &= ~TTM_VT_LOCK_PENDING;

		lock->flags |= TTM_VT_LOCK;

		locked = true;

	} else {

		lock->flags |= TTM_VT_LOCK_PENDING;

	}

	spin_unlock(&lock->lock);

	return locked;

}

int ttm_vt_lock(struct ttm_lock *lock,

		bool interruptible,

		struct ttm_object_file *tfile)

{

	int ret = 0;

	if (interruptible) {

		ret = wait_event_interruptible(lock->queue,

					       __ttm_vt_lock(lock));

		if (unlikely(ret != 0)) {

			spin_lock(&lock->lock);

			lock->flags &= ~TTM_VT_LOCK_PENDING;

			wake_up_all(&lock->queue);

			spin_unlock(&lock->lock);

			return ret;

		}

	} else

		wait_event(lock->queue, __ttm_vt_lock(lock));

	/*

	 * Add a base-object, the destructor of which will

	 * make sure the lock is released if the client dies

	 * while holding it.

	 */

	ret = ttm_base_object_init(tfile, &lock->base, false,

				   ttm_lock_type, &ttm_vt_lock_remove, NULL);

	if (ret)

		(void)__ttm_vt_unlock(lock);

	else

		lock->vt_holder = tfile;

	return ret;

}

EXPORT_SYMBOL(ttm_vt_lock);

int ttm_vt_unlock(struct ttm_lock *lock)

{

	return ttm_ref_object_base_unref(lock->vt_holder,

					 lock->base.hash.key, TTM_REF_USAGE);

}

EXPORT_SYMBOL(ttm_vt_unlock);

void ttm_suspend_unlock(struct ttm_lock *lock)

{

	spin_lock(&lock->lock);

	lock->flags &= ~TTM_SUSPEND_LOCK;

	wake_up_all(&lock->queue);

	spin_unlock(&lock->lock);

}

EXPORT_SYMBOL(ttm_suspend_unlock);

static bool __ttm_suspend_lock(struct ttm_lock *lock)

{

	bool locked = false;

	spin_lock(&lock->lock);

	if (lock->rw == 0) {

		lock->flags &= ~TTM_SUSPEND_LOCK_PENDING;

		lock->flags |= TTM_SUSPEND_LOCK;

		locked = true;

	} else {

		lock->flags |= TTM_SUSPEND_LOCK_PENDING;

	}

	spin_unlock(&lock->lock);

	return locked;

}

void ttm_suspend_lock(struct ttm_lock *lock)

{

	wait_event(lock->queue, __ttm_suspend_lock(lock));

}

EXPORT_SYMBOL(ttm_suspend_lock);