[GitHub/mt8127/android_kernel_alcatel_ttab.git] / drivers / char / drm / drm_lock.c

/**
 * \file drm_lock.c
 * IOCTLs for locking
 *
 * \author Rickard E. (Rik) Faith <faith@valinux.com>
 * \author Gareth Hughes <gareth@valinux.com>
 */

/*
 * Created: Tue Feb  2 08:37:54 1999 by faith@valinux.com
 *
 * Copyright 1999 Precision Insight, Inc., Cedar Park, Texas.
 * Copyright 2000 VA Linux Systems, Inc., Sunnyvale, California.
 * 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, sublicense,
 * 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 NONINFRINGEMENT.  IN NO EVENT SHALL
 * VA LINUX SYSTEMS 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.
 */

#include "drmP.h"

static int drm_notifier(void *priv);

/**
 * Lock ioctl.
 *
 * \param inode device inode.
 * \param file_priv DRM file private.
 * \param cmd command.
 * \param arg user argument, pointing to a drm_lock structure.
 * \return zero on success or negative number on failure.
 *
 * Add the current task to the lock wait queue, and attempt to take to lock.
 */
int drm_lock(struct inode *inode, struct drm_file *file_priv,
	     unsigned int cmd, unsigned long arg)
{
	struct drm_device *dev = file_priv->head->dev;
	DECLARE_WAITQUEUE(entry, current);
	struct drm_lock lock;
	int ret = 0;

	++file_priv->lock_count;

	if (copy_from_user(&lock, (struct drm_lock __user *) arg, sizeof(lock)))
		return -EFAULT;

	if (lock.context == DRM_KERNEL_CONTEXT) {
		DRM_ERROR("Process %d using kernel context %d\n",
			  current->pid, lock.context);
		return -EINVAL;
	}

	DRM_DEBUG("%d (pid %d) requests lock (0x%08x), flags = 0x%08x\n",
		  lock.context, current->pid,
		  dev->lock.hw_lock->lock, lock.flags);

	if (drm_core_check_feature(dev, DRIVER_DMA_QUEUE))
		if (lock.context < 0)
			return -EINVAL;

	add_wait_queue(&dev->lock.lock_queue, &entry);
	spin_lock(&dev->lock.spinlock);
	dev->lock.user_waiters++;
	spin_unlock(&dev->lock.spinlock);
	for (;;) {
		__set_current_state(TASK_INTERRUPTIBLE);
		if (!dev->lock.hw_lock) {
			/* Device has been unregistered */
			ret = -EINTR;
			break;
		}
		if (drm_lock_take(&dev->lock, lock.context)) {
			dev->lock.file_priv = file_priv;
			dev->lock.lock_time = jiffies;
			atomic_inc(&dev->counts[_DRM_STAT_LOCKS]);
			break;	/* Got lock */
		}

		/* Contention */
		schedule();
		if (signal_pending(current)) {
			ret = -ERESTARTSYS;
			break;
		}
	}
	spin_lock(&dev->lock.spinlock);
	dev->lock.user_waiters--;
	spin_unlock(&dev->lock.spinlock);
	__set_current_state(TASK_RUNNING);
	remove_wait_queue(&dev->lock.lock_queue, &entry);

	DRM_DEBUG( "%d %s\n", lock.context, ret ? "interrupted" : "has lock" );
	if (ret) return ret;

	sigemptyset(&dev->sigmask);
	sigaddset(&dev->sigmask, SIGSTOP);
	sigaddset(&dev->sigmask, SIGTSTP);
	sigaddset(&dev->sigmask, SIGTTIN);
	sigaddset(&dev->sigmask, SIGTTOU);
	dev->sigdata.context = lock.context;
	dev->sigdata.lock = dev->lock.hw_lock;
	block_all_signals(drm_notifier, &dev->sigdata, &dev->sigmask);

	if (dev->driver->dma_ready && (lock.flags & _DRM_LOCK_READY))
		dev->driver->dma_ready(dev);

	if (dev->driver->dma_quiescent && (lock.flags & _DRM_LOCK_QUIESCENT)) {
		if (dev->driver->dma_quiescent(dev)) {
			DRM_DEBUG("%d waiting for DMA quiescent\n", lock.context);
			return -EBUSY;
		}
	}

	if (dev->driver->kernel_context_switch &&
	    dev->last_context != lock.context) {
		dev->driver->kernel_context_switch(dev, dev->last_context,
						   lock.context);
	}

	return 0;
}

/**
 * Unlock ioctl.
 *
 * \param inode device inode.
 * \param file_priv DRM file private.
 * \param cmd command.
 * \param arg user argument, pointing to a drm_lock structure.
 * \return zero on success or negative number on failure.
 *
 * Transfer and free the lock.
 */
int drm_unlock(struct inode *inode, struct drm_file *file_priv,
	       unsigned int cmd, unsigned long arg)
{
	struct drm_device *dev = file_priv->head->dev;
	struct drm_lock lock;
	unsigned long irqflags;

	if (copy_from_user(&lock, (struct drm_lock __user *) arg, sizeof(lock)))
		return -EFAULT;

	if (lock.context == DRM_KERNEL_CONTEXT) {
		DRM_ERROR("Process %d using kernel context %d\n",
			  current->pid, lock.context);
		return -EINVAL;
	}

	spin_lock_irqsave(&dev->tasklet_lock, irqflags);

	if (dev->locked_tasklet_func) {
		dev->locked_tasklet_func(dev);

		dev->locked_tasklet_func = NULL;
	}

	spin_unlock_irqrestore(&dev->tasklet_lock, irqflags);

	atomic_inc(&dev->counts[_DRM_STAT_UNLOCKS]);

	/* kernel_context_switch isn't used by any of the x86 drm
	 * modules but is required by the Sparc driver.
	 */
	if (dev->driver->kernel_context_switch_unlock)
		dev->driver->kernel_context_switch_unlock(dev);
	else {
		if (drm_lock_free(&dev->lock,lock.context)) {
			/* FIXME: Should really bail out here. */
		}
	}

	unblock_all_signals();
	return 0;
}

/**
 * Take the heavyweight lock.
 *
 * \param lock lock pointer.
 * \param context locking context.
 * \return one if the lock is held, or zero otherwise.
 *
 * Attempt to mark the lock as held by the given context, via the \p cmpxchg instruction.
 */
int drm_lock_take(struct drm_lock_data *lock_data,
		  unsigned int context)
{
	unsigned int old, new, prev;
	volatile unsigned int *lock = &lock_data->hw_lock->lock;

	spin_lock(&lock_data->spinlock);
	do {
		old = *lock;
		if (old & _DRM_LOCK_HELD)
			new = old | _DRM_LOCK_CONT;
		else {
			new = context | _DRM_LOCK_HELD |
				((lock_data->user_waiters + lock_data->kernel_waiters > 1) ?
				 _DRM_LOCK_CONT : 0);
		}
		prev = cmpxchg(lock, old, new);
	} while (prev != old);
	spin_unlock(&lock_data->spinlock);

	if (_DRM_LOCKING_CONTEXT(old) == context) {
		if (old & _DRM_LOCK_HELD) {
			if (context != DRM_KERNEL_CONTEXT) {
				DRM_ERROR("%d holds heavyweight lock\n",
					  context);
			}
			return 0;
		}
	}

	if ((_DRM_LOCKING_CONTEXT(new)) == context && (new & _DRM_LOCK_HELD)) {
		/* Have lock */
		return 1;
	}
	return 0;
}

/**
 * This takes a lock forcibly and hands it to context.	Should ONLY be used
 * inside *_unlock to give lock to kernel before calling *_dma_schedule.
 *
 * \param dev DRM device.
 * \param lock lock pointer.
 * \param context locking context.
 * \return always one.
 *
 * Resets the lock file pointer.
 * Marks the lock as held by the given context, via the \p cmpxchg instruction.
 */
static int drm_lock_transfer(struct drm_lock_data *lock_data,
			     unsigned int context)
{
	unsigned int old, new, prev;
	volatile unsigned int *lock = &lock_data->hw_lock->lock;

	lock_data->file_priv = NULL;
	do {
		old = *lock;
		new = context | _DRM_LOCK_HELD;
		prev = cmpxchg(lock, old, new);
	} while (prev != old);
	return 1;
}

/**
 * Free lock.
 *
 * \param dev DRM device.
 * \param lock lock.
 * \param context context.
 *
 * Resets the lock file pointer.
 * Marks the lock as not held, via the \p cmpxchg instruction. Wakes any task
 * waiting on the lock queue.
 */
int drm_lock_free(struct drm_lock_data *lock_data, unsigned int context)
{
	unsigned int old, new, prev;
	volatile unsigned int *lock = &lock_data->hw_lock->lock;

	spin_lock(&lock_data->spinlock);
	if (lock_data->kernel_waiters != 0) {
		drm_lock_transfer(lock_data, 0);
		lock_data->idle_has_lock = 1;
		spin_unlock(&lock_data->spinlock);
		return 1;
	}
	spin_unlock(&lock_data->spinlock);

	do {
		old = *lock;
		new = _DRM_LOCKING_CONTEXT(old);
		prev = cmpxchg(lock, old, new);
	} while (prev != old);

	if (_DRM_LOCK_IS_HELD(old) && _DRM_LOCKING_CONTEXT(old) != context) {
		DRM_ERROR("%d freed heavyweight lock held by %d\n",
			  context, _DRM_LOCKING_CONTEXT(old));
		return 1;
	}
	wake_up_interruptible(&lock_data->lock_queue);
	return 0;
}

/**
 * If we get here, it means that the process has called DRM_IOCTL_LOCK
 * without calling DRM_IOCTL_UNLOCK.
 *
 * If the lock is not held, then let the signal proceed as usual.  If the lock
 * is held, then set the contended flag and keep the signal blocked.
 *
 * \param priv pointer to a drm_sigdata structure.
 * \return one if the signal should be delivered normally, or zero if the
 * signal should be blocked.
 */
static int drm_notifier(void *priv)
{
	struct drm_sigdata *s = (struct drm_sigdata *) priv;
	unsigned int old, new, prev;

	/* Allow signal delivery if lock isn't held */
	if (!s->lock || !_DRM_LOCK_IS_HELD(s->lock->lock)
	    || _DRM_LOCKING_CONTEXT(s->lock->lock) != s->context)
		return 1;

	/* Otherwise, set flag to force call to
	   drmUnlock */
	do {
		old = s->lock->lock;
		new = old | _DRM_LOCK_CONT;
		prev = cmpxchg(&s->lock->lock, old, new);
	} while (prev != old);
	return 0;
}

/**
 * This function returns immediately and takes the hw lock
 * with the kernel context if it is free, otherwise it gets the highest priority when and if
 * it is eventually released.
 *
 * This guarantees that the kernel will _eventually_ have the lock _unless_ it is held
 * by a blocked process. (In the latter case an explicit wait for the hardware lock would cause
 * a deadlock, which is why the "idlelock" was invented).
 *
 * This should be sufficient to wait for GPU idle without
 * having to worry about starvation.
 */

void drm_idlelock_take(struct drm_lock_data *lock_data)
{
	int ret = 0;

	spin_lock(&lock_data->spinlock);
	lock_data->kernel_waiters++;
	if (!lock_data->idle_has_lock) {

		spin_unlock(&lock_data->spinlock);
		ret = drm_lock_take(lock_data, DRM_KERNEL_CONTEXT);
		spin_lock(&lock_data->spinlock);

		if (ret == 1)
			lock_data->idle_has_lock = 1;
	}
	spin_unlock(&lock_data->spinlock);
}
EXPORT_SYMBOL(drm_idlelock_take);

void drm_idlelock_release(struct drm_lock_data *lock_data)
{
	unsigned int old, prev;
	volatile unsigned int *lock = &lock_data->hw_lock->lock;

	spin_lock(&lock_data->spinlock);
	if (--lock_data->kernel_waiters == 0) {
		if (lock_data->idle_has_lock) {
			do {
				old = *lock;
				prev = cmpxchg(lock, old, DRM_KERNEL_CONTEXT);
			} while (prev != old);
			wake_up_interruptible(&lock_data->lock_queue);
			lock_data->idle_has_lock = 0;
		}
	}
	spin_unlock(&lock_data->spinlock);
}
EXPORT_SYMBOL(drm_idlelock_release);


int drm_i_have_hw_lock(struct drm_file *file_priv)
{
	DRM_DEVICE;

	return (file_priv->lock_count && dev->lock.hw_lock &&
		_DRM_LOCK_IS_HELD(dev->lock.hw_lock->lock) &&
		dev->lock.file_priv == file_priv);
}

EXPORT_SYMBOL(drm_i_have_hw_lock);
Commit	Line	Data
1da177e4	1	/**
b5e89ed5	2	* \file drm_lock.c
1da177e4	3	* IOCTLs for locking
b5e89ed5	4	*
1da177e4 LT	5	* \author Rickard E. (Rik) Faith <faith@valinux.com>
	6	* \author Gareth Hughes <gareth@valinux.com>
	7	*/
	8
	9	/*
	10	* Created: Tue Feb 2 08:37:54 1999 by faith@valinux.com
	11	*
	12	* Copyright 1999 Precision Insight, Inc., Cedar Park, Texas.
	13	* Copyright 2000 VA Linux Systems, Inc., Sunnyvale, California.
	14	* All Rights Reserved.
	15	*
	16	* Permission is hereby granted, free of charge, to any person obtaining a
	17	* copy of this software and associated documentation files (the "Software"),
	18	* to deal in the Software without restriction, including without limitation
	19	* the rights to use, copy, modify, merge, publish, distribute, sublicense,
	20	* and/or sell copies of the Software, and to permit persons to whom the
	21	* Software is furnished to do so, subject to the following conditions:
	22	*
	23	* The above copyright notice and this permission notice (including the next
	24	* paragraph) shall be included in all copies or substantial portions of the
	25	* Software.
	26	*
	27	* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
	28	* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
	29	* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
	30	* VA LINUX SYSTEMS AND/OR ITS SUPPLIERS BE LIABLE FOR ANY CLAIM, DAMAGES OR
	31	* OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
	32	* ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
	33	* OTHER DEALINGS IN THE SOFTWARE.
	34	*/
	35
	36	#include "drmP.h"
	37
c94f7029 DA	38	static int drm_notifier(void *priv);
c94f7029 DA	39
b5e89ed5	40	/**
1da177e4 LT	41	* Lock ioctl.
	42	*
	43	* \param inode device inode.
6c340eac	44	* \param file_priv DRM file private.
1da177e4 LT	45	* \param cmd command.
	46	* \param arg user argument, pointing to a drm_lock structure.
	47	* \return zero on success or negative number on failure.
	48	*
	49	* Add the current task to the lock wait queue, and attempt to take to lock.
	50	*/
6c340eac	51	int drm_lock(struct inode inode, struct drm_file file_priv,
b5e89ed5	52	unsigned int cmd, unsigned long arg)
1da177e4	53	{
6c340eac	54	struct drm_device *dev = file_priv->head->dev;
b5e89ed5	55	DECLARE_WAITQUEUE(entry, current);
c60ce623	56	struct drm_lock lock;
b5e89ed5	57	int ret = 0;
1da177e4	58
6c340eac	59	++file_priv->lock_count;
1da177e4	60
c60ce623	61	if (copy_from_user(&lock, (struct drm_lock __user *) arg, sizeof(lock)))
1da177e4 LT	62	return -EFAULT;
1da177e4 LT	63
b5e89ed5 DA	64	if (lock.context == DRM_KERNEL_CONTEXT) {
	65	DRM_ERROR("Process %d using kernel context %d\n",
	66	current->pid, lock.context);
	67	return -EINVAL;
	68	}
1da177e4	69
b5e89ed5 DA	70	DRM_DEBUG("%d (pid %d) requests lock (0x%08x), flags = 0x%08x\n",
	71	lock.context, current->pid,
	72	dev->lock.hw_lock->lock, lock.flags);
1da177e4 LT	73
1da177e4 LT	74	if (drm_core_check_feature(dev, DRIVER_DMA_QUEUE))
b5e89ed5	75	if (lock.context < 0)
1da177e4 LT	76	return -EINVAL;
1da177e4 LT	77
b5e89ed5	78	add_wait_queue(&dev->lock.lock_queue, &entry);
040ac320 TH	79	spin_lock(&dev->lock.spinlock);
	80	dev->lock.user_waiters++;
	81	spin_unlock(&dev->lock.spinlock);
1da177e4 LT	82	for (;;) {
1da177e4 LT	83	__set_current_state(TASK_INTERRUPTIBLE);
b5e89ed5	84	if (!dev->lock.hw_lock) {
1da177e4 LT	85	/* Device has been unregistered */
	86	ret = -EINTR;
	87	break;
	88	}
040ac320	89	if (drm_lock_take(&dev->lock, lock.context)) {
6c340eac	90	dev->lock.file_priv = file_priv;
1da177e4	91	dev->lock.lock_time = jiffies;
b5e89ed5 DA	92	atomic_inc(&dev->counts[_DRM_STAT_LOCKS]);
b5e89ed5 DA	93	break; /* Got lock */
1da177e4	94	}
b5e89ed5	95
1da177e4 LT	96	/* Contention */
1da177e4 LT	97	schedule();
b5e89ed5	98	if (signal_pending(current)) {
1da177e4 LT	99	ret = -ERESTARTSYS;
	100	break;
	101	}
	102	}
040ac320 TH	103	spin_lock(&dev->lock.spinlock);
	104	dev->lock.user_waiters--;
	105	spin_unlock(&dev->lock.spinlock);
1da177e4	106	__set_current_state(TASK_RUNNING);
b5e89ed5	107	remove_wait_queue(&dev->lock.lock_queue, &entry);
1da177e4	108
040ac320 TH	109	DRM_DEBUG( "%d %s\n", lock.context, ret ? "interrupted" : "has lock" );
040ac320 TH	110	if (ret) return ret;
d985c108	111
b5e89ed5 DA	112	sigemptyset(&dev->sigmask);
	113	sigaddset(&dev->sigmask, SIGSTOP);
	114	sigaddset(&dev->sigmask, SIGTSTP);
	115	sigaddset(&dev->sigmask, SIGTTIN);
	116	sigaddset(&dev->sigmask, SIGTTOU);
1da177e4	117	dev->sigdata.context = lock.context;
b5e89ed5 DA	118	dev->sigdata.lock = dev->lock.hw_lock;
	119	block_all_signals(drm_notifier, &dev->sigdata, &dev->sigmask);
	120
1da177e4 LT	121	if (dev->driver->dma_ready && (lock.flags & _DRM_LOCK_READY))
1da177e4 LT	122	dev->driver->dma_ready(dev);
b5e89ed5	123
d985c108 DA	124	if (dev->driver->dma_quiescent && (lock.flags & _DRM_LOCK_QUIESCENT)) {
d985c108 DA	125	if (dev->driver->dma_quiescent(dev)) {
cf65f162	126	DRM_DEBUG("%d waiting for DMA quiescent\n", lock.context);
20caafa6	127	return -EBUSY;
d985c108 DA	128	}
d985c108 DA	129	}
b5e89ed5 DA	130
b5e89ed5 DA	131	if (dev->driver->kernel_context_switch &&
1da177e4	132	dev->last_context != lock.context) {
b5e89ed5 DA	133	dev->driver->kernel_context_switch(dev, dev->last_context,
b5e89ed5 DA	134	lock.context);
1da177e4	135	}
040ac320	136
d985c108	137	return 0;
1da177e4 LT	138	}
1da177e4 LT	139
b5e89ed5	140	/**
1da177e4 LT	141	* Unlock ioctl.
	142	*
	143	* \param inode device inode.
6c340eac	144	* \param file_priv DRM file private.
1da177e4 LT	145	* \param cmd command.
	146	* \param arg user argument, pointing to a drm_lock structure.
	147	* \return zero on success or negative number on failure.
	148	*
	149	* Transfer and free the lock.
	150	*/
6c340eac	151	int drm_unlock(struct inode inode, struct drm_file file_priv,
b5e89ed5	152	unsigned int cmd, unsigned long arg)
1da177e4	153	{
6c340eac	154	struct drm_device *dev = file_priv->head->dev;
c60ce623	155	struct drm_lock lock;
5c2df2bf	156	unsigned long irqflags;
1da177e4	157
c60ce623	158	if (copy_from_user(&lock, (struct drm_lock __user *) arg, sizeof(lock)))
1da177e4 LT	159	return -EFAULT;
1da177e4 LT	160
b5e89ed5 DA	161	if (lock.context == DRM_KERNEL_CONTEXT) {
	162	DRM_ERROR("Process %d using kernel context %d\n",
	163	current->pid, lock.context);
1da177e4 LT	164	return -EINVAL;
	165	}
	166
2e54a007 MD	167	spin_lock_irqsave(&dev->tasklet_lock, irqflags);
	168
	169	if (dev->locked_tasklet_func) {
	170	dev->locked_tasklet_func(dev);
	171
	172	dev->locked_tasklet_func = NULL;
	173	}
	174
	175	spin_unlock_irqrestore(&dev->tasklet_lock, irqflags);
	176
b5e89ed5	177	atomic_inc(&dev->counts[_DRM_STAT_UNLOCKS]);
1da177e4 LT	178
	179	/* kernel_context_switch isn't used by any of the x86 drm
	180	* modules but is required by the Sparc driver.
	181	*/
	182	if (dev->driver->kernel_context_switch_unlock)
0c4dd906	183	dev->driver->kernel_context_switch_unlock(dev);
1da177e4	184	else {
040ac320 TH	185	if (drm_lock_free(&dev->lock,lock.context)) {
040ac320 TH	186	/* FIXME: Should really bail out here. */
1da177e4 LT	187	}
	188	}
	189
	190	unblock_all_signals();
	191	return 0;
	192	}
	193
	194	/**
	195	* Take the heavyweight lock.
	196	*
	197	* \param lock lock pointer.
	198	* \param context locking context.
	199	* \return one if the lock is held, or zero otherwise.
	200	*
	201	* Attempt to mark the lock as held by the given context, via the \p cmpxchg instruction.
	202	*/
55910517	203	int drm_lock_take(struct drm_lock_data *lock_data,
040ac320	204	unsigned int context)
1da177e4 LT	205	{
1da177e4 LT	206	unsigned int old, new, prev;
040ac320	207	volatile unsigned int *lock = &lock_data->hw_lock->lock;
1da177e4	208
040ac320	209	spin_lock(&lock_data->spinlock);
1da177e4 LT	210	do {
1da177e4 LT	211	old = *lock;
b5e89ed5 DA	212	if (old & _DRM_LOCK_HELD)
b5e89ed5 DA	213	new = old \| _DRM_LOCK_CONT;
040ac320 TH	214	else {
	215	new = context \| _DRM_LOCK_HELD \|
	216	((lock_data->user_waiters + lock_data->kernel_waiters > 1) ?
	217	_DRM_LOCK_CONT : 0);
	218	}
1da177e4 LT	219	prev = cmpxchg(lock, old, new);
1da177e4 LT	220	} while (prev != old);
040ac320 TH	221	spin_unlock(&lock_data->spinlock);
040ac320 TH	222
1da177e4 LT	223	if (_DRM_LOCKING_CONTEXT(old) == context) {
	224	if (old & _DRM_LOCK_HELD) {
	225	if (context != DRM_KERNEL_CONTEXT) {
	226	DRM_ERROR("%d holds heavyweight lock\n",
	227	context);
	228	}
	229	return 0;
	230	}
	231	}
040ac320 TH	232
040ac320 TH	233	if ((_DRM_LOCKING_CONTEXT(new)) == context && (new & _DRM_LOCK_HELD)) {
b5e89ed5	234	/* Have lock */
1da177e4 LT	235	return 1;
	236	}
	237	return 0;
	238	}
	239
	240	/**
	241	* This takes a lock forcibly and hands it to context. Should ONLY be used
b5e89ed5 DA	242	* inside _unlock to give lock to kernel before calling _dma_schedule.
b5e89ed5 DA	243	*
1da177e4 LT	244	* \param dev DRM device.
	245	* \param lock lock pointer.
	246	* \param context locking context.
	247	* \return always one.
	248	*
	249	* Resets the lock file pointer.
	250	* Marks the lock as held by the given context, via the \p cmpxchg instruction.
	251	*/
55910517	252	static int drm_lock_transfer(struct drm_lock_data *lock_data,
c94f7029	253	unsigned int context)
1da177e4 LT	254	{
1da177e4 LT	255	unsigned int old, new, prev;
040ac320	256	volatile unsigned int *lock = &lock_data->hw_lock->lock;
1da177e4	257
6c340eac	258	lock_data->file_priv = NULL;
1da177e4	259	do {
b5e89ed5 DA	260	old = *lock;
b5e89ed5 DA	261	new = context \| _DRM_LOCK_HELD;
1da177e4 LT	262	prev = cmpxchg(lock, old, new);
	263	} while (prev != old);
	264	return 1;
	265	}
	266
	267	/**
	268	* Free lock.
b5e89ed5	269	*
1da177e4 LT	270	* \param dev DRM device.
	271	* \param lock lock.
	272	* \param context context.
b5e89ed5	273	*
1da177e4 LT	274	* Resets the lock file pointer.
	275	* Marks the lock as not held, via the \p cmpxchg instruction. Wakes any task
	276	* waiting on the lock queue.
	277	*/
55910517	278	int drm_lock_free(struct drm_lock_data *lock_data, unsigned int context)
1da177e4 LT	279	{
1da177e4 LT	280	unsigned int old, new, prev;
040ac320 TH	281	volatile unsigned int *lock = &lock_data->hw_lock->lock;
	282
	283	spin_lock(&lock_data->spinlock);
	284	if (lock_data->kernel_waiters != 0) {
	285	drm_lock_transfer(lock_data, 0);
	286	lock_data->idle_has_lock = 1;
	287	spin_unlock(&lock_data->spinlock);
	288	return 1;
	289	}
	290	spin_unlock(&lock_data->spinlock);
1da177e4	291
1da177e4	292	do {
b5e89ed5	293	old = *lock;
040ac320	294	new = _DRM_LOCKING_CONTEXT(old);
1da177e4 LT	295	prev = cmpxchg(lock, old, new);
1da177e4 LT	296	} while (prev != old);
040ac320	297
1da177e4 LT	298	if (_DRM_LOCK_IS_HELD(old) && _DRM_LOCKING_CONTEXT(old) != context) {
1da177e4 LT	299	DRM_ERROR("%d freed heavyweight lock held by %d\n",
b5e89ed5	300	context, _DRM_LOCKING_CONTEXT(old));
1da177e4 LT	301	return 1;
1da177e4 LT	302	}
040ac320	303	wake_up_interruptible(&lock_data->lock_queue);
1da177e4 LT	304	return 0;
	305	}
	306
	307	/**
	308	* If we get here, it means that the process has called DRM_IOCTL_LOCK
	309	* without calling DRM_IOCTL_UNLOCK.
	310	*
	311	* If the lock is not held, then let the signal proceed as usual. If the lock
	312	* is held, then set the contended flag and keep the signal blocked.
	313	*
	314	* \param priv pointer to a drm_sigdata structure.
	315	* \return one if the signal should be delivered normally, or zero if the
	316	* signal should be blocked.
	317	*/
c94f7029	318	static int drm_notifier(void *priv)
1da177e4	319	{
55910517	320	struct drm_sigdata s = (struct drm_sigdata ) priv;
b5e89ed5	321	unsigned int old, new, prev;
1da177e4	322
b5e89ed5	323	/* Allow signal delivery if lock isn't held */
1da177e4	324	if (!s->lock \|\| !_DRM_LOCK_IS_HELD(s->lock->lock)
b5e89ed5 DA	325	\|\| _DRM_LOCKING_CONTEXT(s->lock->lock) != s->context)
b5e89ed5 DA	326	return 1;
1da177e4	327
b5e89ed5 DA	328	/* Otherwise, set flag to force call to
b5e89ed5 DA	329	drmUnlock */
1da177e4	330	do {
b5e89ed5 DA	331	old = s->lock->lock;
b5e89ed5 DA	332	new = old \| _DRM_LOCK_CONT;
1da177e4 LT	333	prev = cmpxchg(&s->lock->lock, old, new);
	334	} while (prev != old);
	335	return 0;
	336	}
040ac320 TH	337
	338	/**
	339	* This function returns immediately and takes the hw lock
	340	* with the kernel context if it is free, otherwise it gets the highest priority when and if
	341	* it is eventually released.
	342	*
	343	* This guarantees that the kernel will _eventually_ have the lock _unless_ it is held
	344	* by a blocked process. (In the latter case an explicit wait for the hardware lock would cause
	345	* a deadlock, which is why the "idlelock" was invented).
	346	*
	347	* This should be sufficient to wait for GPU idle without
	348	* having to worry about starvation.
	349	*/
	350
55910517	351	void drm_idlelock_take(struct drm_lock_data *lock_data)
040ac320 TH	352	{
	353	int ret = 0;
	354
	355	spin_lock(&lock_data->spinlock);
	356	lock_data->kernel_waiters++;
	357	if (!lock_data->idle_has_lock) {
	358
	359	spin_unlock(&lock_data->spinlock);
	360	ret = drm_lock_take(lock_data, DRM_KERNEL_CONTEXT);
	361	spin_lock(&lock_data->spinlock);
	362
	363	if (ret == 1)
	364	lock_data->idle_has_lock = 1;
	365	}
	366	spin_unlock(&lock_data->spinlock);
	367	}
	368	EXPORT_SYMBOL(drm_idlelock_take);
	369
55910517	370	void drm_idlelock_release(struct drm_lock_data *lock_data)
040ac320 TH	371	{
	372	unsigned int old, prev;
	373	volatile unsigned int *lock = &lock_data->hw_lock->lock;
	374
	375	spin_lock(&lock_data->spinlock);
	376	if (--lock_data->kernel_waiters == 0) {
	377	if (lock_data->idle_has_lock) {
	378	do {
	379	old = *lock;
	380	prev = cmpxchg(lock, old, DRM_KERNEL_CONTEXT);
	381	} while (prev != old);
	382	wake_up_interruptible(&lock_data->lock_queue);
	383	lock_data->idle_has_lock = 0;
	384	}
	385	}
	386	spin_unlock(&lock_data->spinlock);
	387	}
	388	EXPORT_SYMBOL(drm_idlelock_release);
	389
	390
6c340eac	391	int drm_i_have_hw_lock(struct drm_file *file_priv)
040ac320 TH	392	{
	393	DRM_DEVICE;
	394
6c340eac	395	return (file_priv->lock_count && dev->lock.hw_lock &&
040ac320	396	_DRM_LOCK_IS_HELD(dev->lock.hw_lock->lock) &&
6c340eac	397	dev->lock.file_priv == file_priv);
040ac320 TH	398	}
	399
	400	EXPORT_SYMBOL(drm_i_have_hw_lock);