[linux-2.6-block.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 <linux/export.h>
#include <drm/drmP.h>
#include "drm_legacy.h"
#include "drm_internal.h"

static int drm_lock_take(struct drm_lock_data *lock_data, unsigned int context);

/**
 * 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_legacy_lock(struct drm_device *dev, void *data,
		    struct drm_file *file_priv)
{
	DECLARE_WAITQUEUE(entry, current);
	struct drm_lock *lock = data;
	struct drm_master *master = file_priv->master;
	int ret = 0;

	if (drm_core_check_feature(dev, DRIVER_MODESET))
		return -EINVAL;

	++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),
		  master->lock.hw_lock->lock, lock->flags);

	add_wait_queue(&master->lock.lock_queue, &entry);
	spin_lock_bh(&master->lock.spinlock);
	master->lock.user_waiters++;
	spin_unlock_bh(&master->lock.spinlock);

	for (;;) {
		__set_current_state(TASK_INTERRUPTIBLE);
		if (!master->lock.hw_lock) {
			/* Device has been unregistered */
			send_sig(SIGTERM, current, 0);
			ret = -EINTR;
			break;
		}
		if (drm_lock_take(&master->lock, lock->context)) {
			master->lock.file_priv = file_priv;
			master->lock.lock_time = jiffies;
			break;	/* Got lock */
		}

		/* Contention */
		mutex_unlock(&drm_global_mutex);
		schedule();
		mutex_lock(&drm_global_mutex);
		if (signal_pending(current)) {
			ret = -EINTR;
			break;
		}
	}
	spin_lock_bh(&master->lock.spinlock);
	master->lock.user_waiters--;
	spin_unlock_bh(&master->lock.spinlock);
	__set_current_state(TASK_RUNNING);
	remove_wait_queue(&master->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->is_master) {
		dev->sigdata.context = lock->context;
		dev->sigdata.lock = master->lock.hw_lock;
	}

	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;
		}
	}

	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_legacy_unlock(struct drm_device *dev, void *data, struct drm_file *file_priv)
{
	struct drm_lock *lock = data;
	struct drm_master *master = file_priv->master;

	if (drm_core_check_feature(dev, DRIVER_MODESET))
		return -EINVAL;

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

	if (drm_legacy_lock_free(&master->lock, lock->context)) {
		/* FIXME: Should really bail out here. */
	}

	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.
 */
static
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;
}

/**
 * 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_legacy_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;
}

/**
 * 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_legacy_idlelock_take(struct drm_lock_data *lock_data)
{
	int ret;

	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_legacy_idlelock_take);

void drm_legacy_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_legacy_idlelock_release);

int drm_legacy_i_have_hw_lock(struct drm_device *dev,
			      struct drm_file *file_priv)
{
	struct drm_master *master = file_priv->master;
	return (file_priv->lock_count && master->lock.hw_lock &&
		_DRM_LOCK_IS_HELD(master->lock.hw_lock->lock) &&
		master->lock.file_priv == file_priv);
}
Commit	Line	Data
	1	/**
	2	* \file drm_lock.c
	3	* IOCTLs for locking
	4	*
	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 <linux/export.h>
	37	#include <drm/drmP.h>
	38	#include "drm_legacy.h"
	39	#include "drm_internal.h"
	40
	41	static int drm_lock_take(struct drm_lock_data *lock_data, unsigned int context);
	42
	43	/**
	44	* Lock ioctl.
	45	*
	46	* \param inode device inode.
	47	* \param file_priv DRM file private.
	48	* \param cmd command.
	49	* \param arg user argument, pointing to a drm_lock structure.
	50	* \return zero on success or negative number on failure.
	51	*
	52	* Add the current task to the lock wait queue, and attempt to take to lock.
	53	*/
	54	int drm_legacy_lock(struct drm_device dev, void data,
	55	struct drm_file *file_priv)
	56	{
	57	DECLARE_WAITQUEUE(entry, current);
	58	struct drm_lock *lock = data;
	59	struct drm_master *master = file_priv->master;
	60	int ret = 0;
	61
	62	if (drm_core_check_feature(dev, DRIVER_MODESET))
	63	return -EINVAL;
	64
	65	++file_priv->lock_count;
	66
	67	if (lock->context == DRM_KERNEL_CONTEXT) {
	68	DRM_ERROR("Process %d using kernel context %d\n",
	69	task_pid_nr(current), lock->context);
	70	return -EINVAL;
	71	}
	72
	73	DRM_DEBUG("%d (pid %d) requests lock (0x%08x), flags = 0x%08x\n",
	74	lock->context, task_pid_nr(current),
	75	master->lock.hw_lock->lock, lock->flags);
	76
	77	add_wait_queue(&master->lock.lock_queue, &entry);
	78	spin_lock_bh(&master->lock.spinlock);
	79	master->lock.user_waiters++;
	80	spin_unlock_bh(&master->lock.spinlock);
	81
	82	for (;;) {
	83	__set_current_state(TASK_INTERRUPTIBLE);
	84	if (!master->lock.hw_lock) {
	85	/* Device has been unregistered */
	86	send_sig(SIGTERM, current, 0);
	87	ret = -EINTR;
	88	break;
	89	}
	90	if (drm_lock_take(&master->lock, lock->context)) {
	91	master->lock.file_priv = file_priv;
	92	master->lock.lock_time = jiffies;
	93	break; /* Got lock */
	94	}
	95
	96	/* Contention */
	97	mutex_unlock(&drm_global_mutex);
	98	schedule();
	99	mutex_lock(&drm_global_mutex);
	100	if (signal_pending(current)) {
	101	ret = -EINTR;
	102	break;
	103	}
	104	}
	105	spin_lock_bh(&master->lock.spinlock);
	106	master->lock.user_waiters--;
	107	spin_unlock_bh(&master->lock.spinlock);
	108	__set_current_state(TASK_RUNNING);
	109	remove_wait_queue(&master->lock.lock_queue, &entry);
	110
	111	DRM_DEBUG("%d %s\n", lock->context,
	112	ret ? "interrupted" : "has lock");
	113	if (ret) return ret;
	114
	115	/* don't set the block all signals on the master process for now
	116	* really probably not the correct answer but lets us debug xkb
	117	* xserver for now */
	118	if (!file_priv->is_master) {
	119	dev->sigdata.context = lock->context;
	120	dev->sigdata.lock = master->lock.hw_lock;
	121	}
	122
	123	if (dev->driver->dma_quiescent && (lock->flags & _DRM_LOCK_QUIESCENT))
	124	{
	125	if (dev->driver->dma_quiescent(dev)) {
	126	DRM_DEBUG("%d waiting for DMA quiescent\n",
	127	lock->context);
	128	return -EBUSY;
	129	}
	130	}
	131
	132	return 0;
	133	}
	134
	135	/**
	136	* Unlock ioctl.
	137	*
	138	* \param inode device inode.
	139	* \param file_priv DRM file private.
	140	* \param cmd command.
	141	* \param arg user argument, pointing to a drm_lock structure.
	142	* \return zero on success or negative number on failure.
	143	*
	144	* Transfer and free the lock.
	145	*/
	146	int drm_legacy_unlock(struct drm_device dev, void data, struct drm_file *file_priv)
	147	{
	148	struct drm_lock *lock = data;
	149	struct drm_master *master = file_priv->master;
	150
	151	if (drm_core_check_feature(dev, DRIVER_MODESET))
	152	return -EINVAL;
	153
	154	if (lock->context == DRM_KERNEL_CONTEXT) {
	155	DRM_ERROR("Process %d using kernel context %d\n",
	156	task_pid_nr(current), lock->context);
	157	return -EINVAL;
	158	}
	159
	160	if (drm_legacy_lock_free(&master->lock, lock->context)) {
	161	/* FIXME: Should really bail out here. */
	162	}
	163
	164	return 0;
	165	}
	166
	167	/**
	168	* Take the heavyweight lock.
	169	*
	170	* \param lock lock pointer.
	171	* \param context locking context.
	172	* \return one if the lock is held, or zero otherwise.
	173	*
	174	* Attempt to mark the lock as held by the given context, via the \p cmpxchg instruction.
	175	*/
	176	static
	177	int drm_lock_take(struct drm_lock_data *lock_data,
	178	unsigned int context)
	179	{
	180	unsigned int old, new, prev;
	181	volatile unsigned int *lock = &lock_data->hw_lock->lock;
	182
	183	spin_lock_bh(&lock_data->spinlock);
	184	do {
	185	old = *lock;
	186	if (old & _DRM_LOCK_HELD)
	187	new = old \| _DRM_LOCK_CONT;
	188	else {
	189	new = context \| _DRM_LOCK_HELD \|
	190	((lock_data->user_waiters + lock_data->kernel_waiters > 1) ?
	191	_DRM_LOCK_CONT : 0);
	192	}
	193	prev = cmpxchg(lock, old, new);
	194	} while (prev != old);
	195	spin_unlock_bh(&lock_data->spinlock);
	196
	197	if (_DRM_LOCKING_CONTEXT(old) == context) {
	198	if (old & _DRM_LOCK_HELD) {
	199	if (context != DRM_KERNEL_CONTEXT) {
	200	DRM_ERROR("%d holds heavyweight lock\n",
	201	context);
	202	}
	203	return 0;
	204	}
	205	}
	206
	207	if ((_DRM_LOCKING_CONTEXT(new)) == context && (new & _DRM_LOCK_HELD)) {
	208	/* Have lock */
	209	return 1;
	210	}
	211	return 0;
	212	}
	213
	214	/**
	215	* This takes a lock forcibly and hands it to context. Should ONLY be used
	216	* inside _unlock to give lock to kernel before calling _dma_schedule.
	217	*
	218	* \param dev DRM device.
	219	* \param lock lock pointer.
	220	* \param context locking context.
	221	* \return always one.
	222	*
	223	* Resets the lock file pointer.
	224	* Marks the lock as held by the given context, via the \p cmpxchg instruction.
	225	*/
	226	static int drm_lock_transfer(struct drm_lock_data *lock_data,
	227	unsigned int context)
	228	{
	229	unsigned int old, new, prev;
	230	volatile unsigned int *lock = &lock_data->hw_lock->lock;
	231
	232	lock_data->file_priv = NULL;
	233	do {
	234	old = *lock;
	235	new = context \| _DRM_LOCK_HELD;
	236	prev = cmpxchg(lock, old, new);
	237	} while (prev != old);
	238	return 1;
	239	}
	240
	241	/**
	242	* Free lock.
	243	*
	244	* \param dev DRM device.
	245	* \param lock lock.
	246	* \param context context.
	247	*
	248	* Resets the lock file pointer.
	249	* Marks the lock as not held, via the \p cmpxchg instruction. Wakes any task
	250	* waiting on the lock queue.
	251	*/
	252	int drm_legacy_lock_free(struct drm_lock_data *lock_data, unsigned int context)
	253	{
	254	unsigned int old, new, prev;
	255	volatile unsigned int *lock = &lock_data->hw_lock->lock;
	256
	257	spin_lock_bh(&lock_data->spinlock);
	258	if (lock_data->kernel_waiters != 0) {
	259	drm_lock_transfer(lock_data, 0);
	260	lock_data->idle_has_lock = 1;
	261	spin_unlock_bh(&lock_data->spinlock);
	262	return 1;
	263	}
	264	spin_unlock_bh(&lock_data->spinlock);
	265
	266	do {
	267	old = *lock;
	268	new = _DRM_LOCKING_CONTEXT(old);
	269	prev = cmpxchg(lock, old, new);
	270	} while (prev != old);
	271
	272	if (_DRM_LOCK_IS_HELD(old) && _DRM_LOCKING_CONTEXT(old) != context) {
	273	DRM_ERROR("%d freed heavyweight lock held by %d\n",
	274	context, _DRM_LOCKING_CONTEXT(old));
	275	return 1;
	276	}
	277	wake_up_interruptible(&lock_data->lock_queue);
	278	return 0;
	279	}
	280
	281	/**
	282	* This function returns immediately and takes the hw lock
	283	* with the kernel context if it is free, otherwise it gets the highest priority when and if
	284	* it is eventually released.
	285	*
	286	* This guarantees that the kernel will _eventually_ have the lock _unless_ it is held
	287	* by a blocked process. (In the latter case an explicit wait for the hardware lock would cause
	288	* a deadlock, which is why the "idlelock" was invented).
	289	*
	290	* This should be sufficient to wait for GPU idle without
	291	* having to worry about starvation.
	292	*/
	293
	294	void drm_legacy_idlelock_take(struct drm_lock_data *lock_data)
	295	{
	296	int ret;
	297
	298	spin_lock_bh(&lock_data->spinlock);
	299	lock_data->kernel_waiters++;
	300	if (!lock_data->idle_has_lock) {
	301
	302	spin_unlock_bh(&lock_data->spinlock);
	303	ret = drm_lock_take(lock_data, DRM_KERNEL_CONTEXT);
	304	spin_lock_bh(&lock_data->spinlock);
	305
	306	if (ret == 1)
	307	lock_data->idle_has_lock = 1;
	308	}
	309	spin_unlock_bh(&lock_data->spinlock);
	310	}
	311	EXPORT_SYMBOL(drm_legacy_idlelock_take);
	312
	313	void drm_legacy_idlelock_release(struct drm_lock_data *lock_data)
	314	{
	315	unsigned int old, prev;
	316	volatile unsigned int *lock = &lock_data->hw_lock->lock;
	317
	318	spin_lock_bh(&lock_data->spinlock);
	319	if (--lock_data->kernel_waiters == 0) {
	320	if (lock_data->idle_has_lock) {
	321	do {
	322	old = *lock;
	323	prev = cmpxchg(lock, old, DRM_KERNEL_CONTEXT);
	324	} while (prev != old);
	325	wake_up_interruptible(&lock_data->lock_queue);
	326	lock_data->idle_has_lock = 0;
	327	}
	328	}
	329	spin_unlock_bh(&lock_data->spinlock);
	330	}
	331	EXPORT_SYMBOL(drm_legacy_idlelock_release);
	332
	333	int drm_legacy_i_have_hw_lock(struct drm_device *dev,
	334	struct drm_file *file_priv)
	335	{
	336	struct drm_master *master = file_priv->master;
	337	return (file_priv->lock_count && master->lock.hw_lock &&
	338	_DRM_LOCK_IS_HELD(master->lock.hw_lock->lock) &&
	339	master->lock.file_priv == file_priv);
	340	}