[mirror_ubuntu-artful-kernel.git] / drivers / gpu / 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 drm_device *dev, void *data, struct drm_file *file_priv)
{
	DECLARE_WAITQUEUE(entry, current);
	struct drm_lock *lock = data;
	int ret = 0;

	++file_priv->lock_count;

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

	DRM_DEBUG("%d (pid %d) requests lock (0x%08x), flags = 0x%08x\n",
		  lock->context, task_pid_nr(current),
		  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_bh(&dev->lock.spinlock);
	dev->lock.user_waiters++;
	spin_unlock_bh(&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_bh(&dev->lock.spinlock);
	dev->lock.user_waiters--;
	spin_unlock_bh(&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;

	/* don't set the block all signals on the master process for now 
	 * really probably not the correct answer but lets us debug xkb
 	 * xserver for now */
	if (!file_priv->master) {
		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 drm_device *dev, void *data, struct drm_file *file_priv)
{
	struct drm_lock *lock = data;

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

	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_bh(&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_bh(&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;
}
EXPORT_SYMBOL(drm_lock_take);

/**
 * 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_bh(&lock_data->spinlock);
	if (lock_data->kernel_waiters != 0) {
		drm_lock_transfer(lock_data, 0);
		lock_data->idle_has_lock = 1;
		spin_unlock_bh(&lock_data->spinlock);
		return 1;
	}
	spin_unlock_bh(&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;
}
EXPORT_SYMBOL(drm_lock_free);

/**
 * 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_bh(&lock_data->spinlock);
	lock_data->kernel_waiters++;
	if (!lock_data->idle_has_lock) {

		spin_unlock_bh(&lock_data->spinlock);
		ret = drm_lock_take(lock_data, DRM_KERNEL_CONTEXT);
		spin_lock_bh(&lock_data->spinlock);

		if (ret == 1)
			lock_data->idle_has_lock = 1;
	}
	spin_unlock_bh(&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_bh(&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_bh(&lock_data->spinlock);
}
EXPORT_SYMBOL(drm_idlelock_release);


int drm_i_have_hw_lock(struct drm_device *dev, struct drm_file *file_priv)
{
	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	*/
c153f45f	51	int drm_lock(struct drm_device dev, void data, struct drm_file *file_priv)
1da177e4	52	{
b5e89ed5	53	DECLARE_WAITQUEUE(entry, current);
c153f45f	54	struct drm_lock *lock = data;
b5e89ed5	55	int ret = 0;
1da177e4	56
6c340eac	57	++file_priv->lock_count;
1da177e4	58
c153f45f	59	if (lock->context == DRM_KERNEL_CONTEXT) {
b5e89ed5	60	DRM_ERROR("Process %d using kernel context %d\n",
ba25f9dc	61	task_pid_nr(current), lock->context);
b5e89ed5 DA	62	return -EINVAL;
b5e89ed5 DA	63	}
1da177e4	64
b5e89ed5	65	DRM_DEBUG("%d (pid %d) requests lock (0x%08x), flags = 0x%08x\n",
ba25f9dc	66	lock->context, task_pid_nr(current),
c153f45f	67	dev->lock.hw_lock->lock, lock->flags);
1da177e4 LT	68
1da177e4 LT	69	if (drm_core_check_feature(dev, DRIVER_DMA_QUEUE))
c153f45f	70	if (lock->context < 0)
1da177e4 LT	71	return -EINVAL;
1da177e4 LT	72
b5e89ed5	73	add_wait_queue(&dev->lock.lock_queue, &entry);
f116cc56	74	spin_lock_bh(&dev->lock.spinlock);
040ac320	75	dev->lock.user_waiters++;
f116cc56	76	spin_unlock_bh(&dev->lock.spinlock);
1da177e4 LT	77	for (;;) {
1da177e4 LT	78	__set_current_state(TASK_INTERRUPTIBLE);
b5e89ed5	79	if (!dev->lock.hw_lock) {
1da177e4 LT	80	/* Device has been unregistered */
	81	ret = -EINTR;
	82	break;
	83	}
c153f45f	84	if (drm_lock_take(&dev->lock, lock->context)) {
6c340eac	85	dev->lock.file_priv = file_priv;
1da177e4	86	dev->lock.lock_time = jiffies;
b5e89ed5 DA	87	atomic_inc(&dev->counts[_DRM_STAT_LOCKS]);
b5e89ed5 DA	88	break; /* Got lock */
1da177e4	89	}
b5e89ed5	90
1da177e4 LT	91	/* Contention */
1da177e4 LT	92	schedule();
b5e89ed5	93	if (signal_pending(current)) {
1da177e4 LT	94	ret = -ERESTARTSYS;
	95	break;
	96	}
	97	}
f116cc56	98	spin_lock_bh(&dev->lock.spinlock);
040ac320	99	dev->lock.user_waiters--;
f116cc56	100	spin_unlock_bh(&dev->lock.spinlock);
1da177e4	101	__set_current_state(TASK_RUNNING);
b5e89ed5	102	remove_wait_queue(&dev->lock.lock_queue, &entry);
1da177e4	103
c153f45f EA	104	DRM_DEBUG("%d %s\n", lock->context,
c153f45f EA	105	ret ? "interrupted" : "has lock");
040ac320	106	if (ret) return ret;
d985c108	107
3e5fc80a DA	108	/* don't set the block all signals on the master process for now
	109	* really probably not the correct answer but lets us debug xkb
	110	* xserver for now */
	111	if (!file_priv->master) {
	112	sigemptyset(&dev->sigmask);
	113	sigaddset(&dev->sigmask, SIGSTOP);
	114	sigaddset(&dev->sigmask, SIGTSTP);
	115	sigaddset(&dev->sigmask, SIGTTIN);
	116	sigaddset(&dev->sigmask, SIGTTOU);
	117	dev->sigdata.context = lock->context;
	118	dev->sigdata.lock = dev->lock.hw_lock;
	119	block_all_signals(drm_notifier, &dev->sigdata, &dev->sigmask);
	120	}
b5e89ed5	121
c153f45f	122	if (dev->driver->dma_ready && (lock->flags & _DRM_LOCK_READY))
1da177e4	123	dev->driver->dma_ready(dev);
b5e89ed5	124
c153f45f EA	125	if (dev->driver->dma_quiescent && (lock->flags & _DRM_LOCK_QUIESCENT))
c153f45f EA	126	{
d985c108	127	if (dev->driver->dma_quiescent(dev)) {
c153f45f EA	128	DRM_DEBUG("%d waiting for DMA quiescent\n",
c153f45f EA	129	lock->context);
20caafa6	130	return -EBUSY;
d985c108 DA	131	}
d985c108 DA	132	}
b5e89ed5 DA	133
b5e89ed5 DA	134	if (dev->driver->kernel_context_switch &&
c153f45f	135	dev->last_context != lock->context) {
b5e89ed5	136	dev->driver->kernel_context_switch(dev, dev->last_context,
c153f45f	137	lock->context);
1da177e4	138	}
040ac320	139
d985c108	140	return 0;
1da177e4 LT	141	}
1da177e4 LT	142
b5e89ed5	143	/**
1da177e4 LT	144	* Unlock ioctl.
	145	*
	146	* \param inode device inode.
6c340eac	147	* \param file_priv DRM file private.
1da177e4 LT	148	* \param cmd command.
	149	* \param arg user argument, pointing to a drm_lock structure.
	150	* \return zero on success or negative number on failure.
	151	*
	152	* Transfer and free the lock.
	153	*/
c153f45f	154	int drm_unlock(struct drm_device dev, void data, struct drm_file *file_priv)
1da177e4	155	{
c153f45f	156	struct drm_lock *lock = data;
1da177e4	157
c153f45f	158	if (lock->context == DRM_KERNEL_CONTEXT) {
b5e89ed5	159	DRM_ERROR("Process %d using kernel context %d\n",
ba25f9dc	160	task_pid_nr(current), lock->context);
1da177e4 LT	161	return -EINVAL;
	162	}
	163
b5e89ed5	164	atomic_inc(&dev->counts[_DRM_STAT_UNLOCKS]);
1da177e4 LT	165
	166	/* kernel_context_switch isn't used by any of the x86 drm
	167	* modules but is required by the Sparc driver.
	168	*/
	169	if (dev->driver->kernel_context_switch_unlock)
0c4dd906	170	dev->driver->kernel_context_switch_unlock(dev);
1da177e4	171	else {
c153f45f	172	if (drm_lock_free(&dev->lock,lock->context)) {
040ac320	173	/* FIXME: Should really bail out here. */
1da177e4 LT	174	}
	175	}
	176
	177	unblock_all_signals();
	178	return 0;
	179	}
	180
	181	/**
	182	* Take the heavyweight lock.
	183	*
	184	* \param lock lock pointer.
	185	* \param context locking context.
	186	* \return one if the lock is held, or zero otherwise.
	187	*
	188	* Attempt to mark the lock as held by the given context, via the \p cmpxchg instruction.
	189	*/
55910517	190	int drm_lock_take(struct drm_lock_data *lock_data,
040ac320	191	unsigned int context)
1da177e4 LT	192	{
1da177e4 LT	193	unsigned int old, new, prev;
040ac320	194	volatile unsigned int *lock = &lock_data->hw_lock->lock;
1da177e4	195
f116cc56	196	spin_lock_bh(&lock_data->spinlock);
1da177e4 LT	197	do {
1da177e4 LT	198	old = *lock;
b5e89ed5 DA	199	if (old & _DRM_LOCK_HELD)
b5e89ed5 DA	200	new = old \| _DRM_LOCK_CONT;
040ac320 TH	201	else {
	202	new = context \| _DRM_LOCK_HELD \|
	203	((lock_data->user_waiters + lock_data->kernel_waiters > 1) ?
	204	_DRM_LOCK_CONT : 0);
	205	}
1da177e4 LT	206	prev = cmpxchg(lock, old, new);
1da177e4 LT	207	} while (prev != old);
f116cc56	208	spin_unlock_bh(&lock_data->spinlock);
040ac320	209
1da177e4 LT	210	if (_DRM_LOCKING_CONTEXT(old) == context) {
	211	if (old & _DRM_LOCK_HELD) {
	212	if (context != DRM_KERNEL_CONTEXT) {
	213	DRM_ERROR("%d holds heavyweight lock\n",
	214	context);
	215	}
	216	return 0;
	217	}
	218	}
040ac320 TH	219
040ac320 TH	220	if ((_DRM_LOCKING_CONTEXT(new)) == context && (new & _DRM_LOCK_HELD)) {
b5e89ed5	221	/* Have lock */
1da177e4 LT	222	return 1;
	223	}
	224	return 0;
	225	}
9e44af79	226	EXPORT_SYMBOL(drm_lock_take);
1da177e4 LT	227
	228	/**
	229	* This takes a lock forcibly and hands it to context. Should ONLY be used
b5e89ed5 DA	230	* inside _unlock to give lock to kernel before calling _dma_schedule.
b5e89ed5 DA	231	*
1da177e4 LT	232	* \param dev DRM device.
	233	* \param lock lock pointer.
	234	* \param context locking context.
	235	* \return always one.
	236	*
	237	* Resets the lock file pointer.
	238	* Marks the lock as held by the given context, via the \p cmpxchg instruction.
	239	*/
55910517	240	static int drm_lock_transfer(struct drm_lock_data *lock_data,
c94f7029	241	unsigned int context)
1da177e4 LT	242	{
1da177e4 LT	243	unsigned int old, new, prev;
040ac320	244	volatile unsigned int *lock = &lock_data->hw_lock->lock;
1da177e4	245
6c340eac	246	lock_data->file_priv = NULL;
1da177e4	247	do {
b5e89ed5 DA	248	old = *lock;
b5e89ed5 DA	249	new = context \| _DRM_LOCK_HELD;
1da177e4 LT	250	prev = cmpxchg(lock, old, new);
	251	} while (prev != old);
	252	return 1;
	253	}
	254
	255	/**
	256	* Free lock.
b5e89ed5	257	*
1da177e4 LT	258	* \param dev DRM device.
	259	* \param lock lock.
	260	* \param context context.
b5e89ed5	261	*
1da177e4 LT	262	* Resets the lock file pointer.
	263	* Marks the lock as not held, via the \p cmpxchg instruction. Wakes any task
	264	* waiting on the lock queue.
	265	*/
55910517	266	int drm_lock_free(struct drm_lock_data *lock_data, unsigned int context)
1da177e4 LT	267	{
1da177e4 LT	268	unsigned int old, new, prev;
040ac320 TH	269	volatile unsigned int *lock = &lock_data->hw_lock->lock;
040ac320 TH	270
f116cc56	271	spin_lock_bh(&lock_data->spinlock);
040ac320 TH	272	if (lock_data->kernel_waiters != 0) {
	273	drm_lock_transfer(lock_data, 0);
	274	lock_data->idle_has_lock = 1;
f116cc56	275	spin_unlock_bh(&lock_data->spinlock);
040ac320 TH	276	return 1;
040ac320 TH	277	}
f116cc56	278	spin_unlock_bh(&lock_data->spinlock);
1da177e4	279
1da177e4	280	do {
b5e89ed5	281	old = *lock;
040ac320	282	new = _DRM_LOCKING_CONTEXT(old);
1da177e4 LT	283	prev = cmpxchg(lock, old, new);
1da177e4 LT	284	} while (prev != old);
040ac320	285
1da177e4 LT	286	if (_DRM_LOCK_IS_HELD(old) && _DRM_LOCKING_CONTEXT(old) != context) {
1da177e4 LT	287	DRM_ERROR("%d freed heavyweight lock held by %d\n",
b5e89ed5	288	context, _DRM_LOCKING_CONTEXT(old));
1da177e4 LT	289	return 1;
1da177e4 LT	290	}
040ac320	291	wake_up_interruptible(&lock_data->lock_queue);
1da177e4 LT	292	return 0;
1da177e4 LT	293	}
9e44af79	294	EXPORT_SYMBOL(drm_lock_free);
1da177e4 LT	295
	296	/**
	297	* If we get here, it means that the process has called DRM_IOCTL_LOCK
	298	* without calling DRM_IOCTL_UNLOCK.
	299	*
	300	* If the lock is not held, then let the signal proceed as usual. If the lock
	301	* is held, then set the contended flag and keep the signal blocked.
	302	*
	303	* \param priv pointer to a drm_sigdata structure.
	304	* \return one if the signal should be delivered normally, or zero if the
	305	* signal should be blocked.
	306	*/
c94f7029	307	static int drm_notifier(void *priv)
1da177e4	308	{
55910517	309	struct drm_sigdata s = (struct drm_sigdata ) priv;
b5e89ed5	310	unsigned int old, new, prev;
1da177e4	311
b5e89ed5	312	/* Allow signal delivery if lock isn't held */
1da177e4	313	if (!s->lock \|\| !_DRM_LOCK_IS_HELD(s->lock->lock)
b5e89ed5 DA	314	\|\| _DRM_LOCKING_CONTEXT(s->lock->lock) != s->context)
b5e89ed5 DA	315	return 1;
1da177e4	316
b5e89ed5 DA	317	/* Otherwise, set flag to force call to
b5e89ed5 DA	318	drmUnlock */
1da177e4	319	do {
b5e89ed5 DA	320	old = s->lock->lock;
b5e89ed5 DA	321	new = old \| _DRM_LOCK_CONT;
1da177e4 LT	322	prev = cmpxchg(&s->lock->lock, old, new);
	323	} while (prev != old);
	324	return 0;
	325	}
040ac320 TH	326
	327	/**
	328	* This function returns immediately and takes the hw lock
	329	* with the kernel context if it is free, otherwise it gets the highest priority when and if
	330	* it is eventually released.
	331	*
	332	* This guarantees that the kernel will _eventually_ have the lock _unless_ it is held
	333	* by a blocked process. (In the latter case an explicit wait for the hardware lock would cause
	334	* a deadlock, which is why the "idlelock" was invented).
	335	*
	336	* This should be sufficient to wait for GPU idle without
	337	* having to worry about starvation.
	338	*/
	339
55910517	340	void drm_idlelock_take(struct drm_lock_data *lock_data)
040ac320 TH	341	{
	342	int ret = 0;
	343
f116cc56	344	spin_lock_bh(&lock_data->spinlock);
040ac320 TH	345	lock_data->kernel_waiters++;
	346	if (!lock_data->idle_has_lock) {
	347
f116cc56	348	spin_unlock_bh(&lock_data->spinlock);
040ac320	349	ret = drm_lock_take(lock_data, DRM_KERNEL_CONTEXT);
f116cc56	350	spin_lock_bh(&lock_data->spinlock);
040ac320 TH	351
	352	if (ret == 1)
	353	lock_data->idle_has_lock = 1;
	354	}
f116cc56	355	spin_unlock_bh(&lock_data->spinlock);
040ac320 TH	356	}
	357	EXPORT_SYMBOL(drm_idlelock_take);
	358
55910517	359	void drm_idlelock_release(struct drm_lock_data *lock_data)
040ac320 TH	360	{
	361	unsigned int old, prev;
	362	volatile unsigned int *lock = &lock_data->hw_lock->lock;
	363
f116cc56	364	spin_lock_bh(&lock_data->spinlock);
040ac320 TH	365	if (--lock_data->kernel_waiters == 0) {
	366	if (lock_data->idle_has_lock) {
	367	do {
	368	old = *lock;
	369	prev = cmpxchg(lock, old, DRM_KERNEL_CONTEXT);
	370	} while (prev != old);
	371	wake_up_interruptible(&lock_data->lock_queue);
	372	lock_data->idle_has_lock = 0;
	373	}
	374	}
f116cc56	375	spin_unlock_bh(&lock_data->spinlock);
040ac320 TH	376	}
	377	EXPORT_SYMBOL(drm_idlelock_release);
	378
	379
c153f45f	380	int drm_i_have_hw_lock(struct drm_device dev, struct drm_file file_priv)
040ac320	381	{
6c340eac	382	return (file_priv->lock_count && dev->lock.hw_lock &&
040ac320	383	_DRM_LOCK_IS_HELD(dev->lock.hw_lock->lock) &&
6c340eac	384	dev->lock.file_priv == file_priv);
040ac320 TH	385	}
	386
	387	EXPORT_SYMBOL(drm_i_have_hw_lock);