[mirror_ubuntu-focal-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 <linux/export.h>
#include <linux/sched/signal.h>

#include <drm/drm.h>
#include <drm/drm_drv.h>
#include <drm/drm_file.h>
#include <drm/drm_print.h>

#include "drm_internal.h"
#include "drm_legacy.h"

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

/**
 * 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;
}

static 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;
}

/**
 * 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_LEGACY))
		return -EOPNOTSUPP;

	++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 ? master->lock.hw_lock->lock : -1,
		  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 (!drm_is_current_master(file_priv)) {
		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_LEGACY))
		return -EOPNOTSUPP;

	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;
}

/**
 * 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);

static 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);
}

void drm_legacy_lock_release(struct drm_device *dev, struct file *filp)
{
	struct drm_file *file_priv = filp->private_data;

	/* if the master has gone away we can't do anything with the lock */
	if (!dev->master)
		return;

	if (drm_legacy_i_have_hw_lock(dev, file_priv)) {
		DRM_DEBUG("File %p released, freeing lock for context %d\n",
			  filp, _DRM_LOCKING_CONTEXT(file_priv->master->lock.hw_lock->lock));
		drm_legacy_lock_free(&file_priv->master->lock,
				     _DRM_LOCKING_CONTEXT(file_priv->master->lock.hw_lock->lock));
	}
}

void drm_legacy_lock_master_cleanup(struct drm_device *dev, struct drm_master *master)
{
	if (!drm_core_check_feature(dev, DRIVER_LEGACY))
		return;

	/*
	 * Since the master is disappearing, so is the
	 * possibility to lock.
	 */	mutex_lock(&dev->struct_mutex);
	if (master->lock.hw_lock) {
		if (dev->sigdata.lock == master->lock.hw_lock)
			dev->sigdata.lock = NULL;
		master->lock.hw_lock = NULL;
		master->lock.file_priv = NULL;
		wake_up_interruptible_all(&master->lock.lock_queue);
	}
	mutex_unlock(&dev->struct_mutex);
}
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
5c2a5ce6	36	#include <linux/export.h>
3f07c014 IM	37	#include <linux/sched/signal.h>
3f07c014 IM	38
0500c04e SR	39	#include <drm/drm.h>
	40	#include <drm/drm_drv.h>
	41	#include <drm/drm_file.h>
	42	#include <drm/drm_print.h>
	43
44af3f5c	44	#include "drm_internal.h"
0500c04e	45	#include "drm_legacy.h"
1da177e4	46
4ac5ec40 DV	47	static int drm_lock_take(struct drm_lock_data *lock_data, unsigned int context);
4ac5ec40 DV	48
1a75a222 DV	49	/**
	50	* Take the heavyweight lock.
	51	*
	52	* \param lock lock pointer.
	53	* \param context locking context.
	54	* \return one if the lock is held, or zero otherwise.
	55	*
	56	* Attempt to mark the lock as held by the given context, via the \p cmpxchg instruction.
	57	*/
	58	static
	59	int drm_lock_take(struct drm_lock_data *lock_data,
	60	unsigned int context)
	61	{
	62	unsigned int old, new, prev;
	63	volatile unsigned int *lock = &lock_data->hw_lock->lock;
	64
	65	spin_lock_bh(&lock_data->spinlock);
	66	do {
	67	old = *lock;
	68	if (old & _DRM_LOCK_HELD)
	69	new = old \| _DRM_LOCK_CONT;
	70	else {
	71	new = context \| _DRM_LOCK_HELD \|
	72	((lock_data->user_waiters + lock_data->kernel_waiters > 1) ?
	73	_DRM_LOCK_CONT : 0);
	74	}
	75	prev = cmpxchg(lock, old, new);
	76	} while (prev != old);
	77	spin_unlock_bh(&lock_data->spinlock);
	78
	79	if (_DRM_LOCKING_CONTEXT(old) == context) {
	80	if (old & _DRM_LOCK_HELD) {
	81	if (context != DRM_KERNEL_CONTEXT) {
	82	DRM_ERROR("%d holds heavyweight lock\n",
	83	context);
	84	}
	85	return 0;
	86	}
	87	}
	88
	89	if ((_DRM_LOCKING_CONTEXT(new)) == context && (new & _DRM_LOCK_HELD)) {
	90	/* Have lock */
	91	return 1;
	92	}
	93	return 0;
	94	}
	95
	96	/**
	97	* This takes a lock forcibly and hands it to context. Should ONLY be used
	98	* inside _unlock to give lock to kernel before calling _dma_schedule.
	99	*
	100	* \param dev DRM device.
	101	* \param lock lock pointer.
	102	* \param context locking context.
	103	* \return always one.
	104	*
	105	* Resets the lock file pointer.
	106	* Marks the lock as held by the given context, via the \p cmpxchg instruction.
	107	*/
	108	static int drm_lock_transfer(struct drm_lock_data *lock_data,
	109	unsigned int context)
	110	{
	111	unsigned int old, new, prev;
	112	volatile unsigned int *lock = &lock_data->hw_lock->lock;
113
114	lock_data->file_priv = NULL;
115	do {
116	old = *lock;
117	new = context \| _DRM_LOCK_HELD;
118	prev = cmpxchg(lock, old, new);
119	} while (prev != old);
120	return 1;
121	}
122
123	static int drm_legacy_lock_free(struct drm_lock_data *lock_data,
124	unsigned int context)
125	{
126	unsigned int old, new, prev;
127	volatile unsigned int *lock = &lock_data->hw_lock->lock;
128
129	spin_lock_bh(&lock_data->spinlock);
130	if (lock_data->kernel_waiters != 0) {
131	drm_lock_transfer(lock_data, 0);
132	lock_data->idle_has_lock = 1;
133	spin_unlock_bh(&lock_data->spinlock);
134	return 1;
135	}
136	spin_unlock_bh(&lock_data->spinlock);
137
138	do {
139	old = *lock;
140	new = _DRM_LOCKING_CONTEXT(old);
141	prev = cmpxchg(lock, old, new);
142	} while (prev != old);
143
144	if (_DRM_LOCK_IS_HELD(old) && _DRM_LOCKING_CONTEXT(old) != context) {
145	DRM_ERROR("%d freed heavyweight lock held by %d\n",
146	context, _DRM_LOCKING_CONTEXT(old));
147	return 1;
148	}
149	wake_up_interruptible(&lock_data->lock_queue);
150	return 0;
151	}
152
b5e89ed5	153	/**
1da177e4 LT	154	* Lock ioctl.
	155	*
	156	* \param inode device inode.
6c340eac	157	* \param file_priv DRM file private.
1da177e4 LT	158	* \param cmd command.
	159	* \param arg user argument, pointing to a drm_lock structure.
	160	* \return zero on success or negative number on failure.
	161	*
	162	* Add the current task to the lock wait queue, and attempt to take to lock.
	163	*/
bb6d822e DH	164	int drm_legacy_lock(struct drm_device dev, void data,
bb6d822e DH	165	struct drm_file *file_priv)
1da177e4	166	{
b5e89ed5	167	DECLARE_WAITQUEUE(entry, current);
c153f45f	168	struct drm_lock *lock = data;
7c1c2871	169	struct drm_master *master = file_priv->master;
b5e89ed5	170	int ret = 0;
1da177e4	171
fa538645	172	if (!drm_core_check_feature(dev, DRIVER_LEGACY))
69fdf420	173	return -EOPNOTSUPP;
da168d81	174
6c340eac	175	++file_priv->lock_count;
1da177e4	176
c153f45f	177	if (lock->context == DRM_KERNEL_CONTEXT) {
b5e89ed5	178	DRM_ERROR("Process %d using kernel context %d\n",
ba25f9dc	179	task_pid_nr(current), lock->context);
b5e89ed5 DA	180	return -EINVAL;
b5e89ed5 DA	181	}
1da177e4	182
b5e89ed5	183	DRM_DEBUG("%d (pid %d) requests lock (0x%08x), flags = 0x%08x\n",
ba25f9dc	184	lock->context, task_pid_nr(current),
a2ec1c13 CW	185	master->lock.hw_lock ? master->lock.hw_lock->lock : -1,
a2ec1c13 CW	186	lock->flags);
1da177e4	187
7c1c2871 DA	188	add_wait_queue(&master->lock.lock_queue, &entry);
	189	spin_lock_bh(&master->lock.spinlock);
	190	master->lock.user_waiters++;
	191	spin_unlock_bh(&master->lock.spinlock);
	192
1da177e4 LT	193	for (;;) {
1da177e4 LT	194	__set_current_state(TASK_INTERRUPTIBLE);
7c1c2871	195	if (!master->lock.hw_lock) {
1da177e4	196	/* Device has been unregistered */
fda714c2	197	send_sig(SIGTERM, current, 0);
1da177e4 LT	198	ret = -EINTR;
	199	break;
	200	}
7c1c2871 DA	201	if (drm_lock_take(&master->lock, lock->context)) {
	202	master->lock.file_priv = file_priv;
	203	master->lock.lock_time = jiffies;
b5e89ed5	204	break; /* Got lock */
1da177e4	205	}
b5e89ed5	206
1da177e4	207	/* Contention */
08f2e669	208	mutex_unlock(&drm_global_mutex);
1da177e4	209	schedule();
08f2e669	210	mutex_lock(&drm_global_mutex);
b5e89ed5	211	if (signal_pending(current)) {
4d77c88e	212	ret = -EINTR;
1da177e4 LT	213	break;
	214	}
	215	}
7c1c2871 DA	216	spin_lock_bh(&master->lock.spinlock);
	217	master->lock.user_waiters--;
	218	spin_unlock_bh(&master->lock.spinlock);
1da177e4	219	__set_current_state(TASK_RUNNING);
7c1c2871	220	remove_wait_queue(&master->lock.lock_queue, &entry);
1da177e4	221
c153f45f EA	222	DRM_DEBUG("%d %s\n", lock->context,
c153f45f EA	223	ret ? "interrupted" : "has lock");
040ac320	224	if (ret) return ret;
d985c108	225
3e5fc80a DA	226	/* don't set the block all signals on the master process for now
	227	* really probably not the correct answer but lets us debug xkb
	228	* xserver for now */
b3ac9f25	229	if (!drm_is_current_master(file_priv)) {
3e5fc80a	230	dev->sigdata.context = lock->context;
7c1c2871	231	dev->sigdata.lock = master->lock.hw_lock;
3e5fc80a	232	}
b5e89ed5	233
c153f45f EA	234	if (dev->driver->dma_quiescent && (lock->flags & _DRM_LOCK_QUIESCENT))
c153f45f EA	235	{
d985c108	236	if (dev->driver->dma_quiescent(dev)) {
c153f45f EA	237	DRM_DEBUG("%d waiting for DMA quiescent\n",
c153f45f EA	238	lock->context);
20caafa6	239	return -EBUSY;
d985c108 DA	240	}
d985c108 DA	241	}
b5e89ed5	242
d985c108	243	return 0;
1da177e4 LT	244	}
1da177e4 LT	245
b5e89ed5	246	/**
1da177e4 LT	247	* Unlock ioctl.
	248	*
	249	* \param inode device inode.
6c340eac	250	* \param file_priv DRM file private.
1da177e4 LT	251	* \param cmd command.
	252	* \param arg user argument, pointing to a drm_lock structure.
	253	* \return zero on success or negative number on failure.
	254	*
	255	* Transfer and free the lock.
	256	*/
bb6d822e	257	int drm_legacy_unlock(struct drm_device dev, void data, struct drm_file *file_priv)
1da177e4	258	{
c153f45f	259	struct drm_lock *lock = data;
45ff46c5	260	struct drm_master *master = file_priv->master;
1da177e4	261
fa538645	262	if (!drm_core_check_feature(dev, DRIVER_LEGACY))
69fdf420	263	return -EOPNOTSUPP;
da168d81	264
c153f45f	265	if (lock->context == DRM_KERNEL_CONTEXT) {
b5e89ed5	266	DRM_ERROR("Process %d using kernel context %d\n",
ba25f9dc	267	task_pid_nr(current), lock->context);
1da177e4 LT	268	return -EINVAL;
	269	}
	270
bb6d822e	271	if (drm_legacy_lock_free(&master->lock, lock->context)) {
45ff46c5 DV	272	/* FIXME: Should really bail out here. */
	273	}
	274
1da177e4 LT	275	return 0;
	276	}
	277
040ac320 TH	278	/**
	279	* This function returns immediately and takes the hw lock
	280	* with the kernel context if it is free, otherwise it gets the highest priority when and if
	281	* it is eventually released.
	282	*
	283	* This guarantees that the kernel will _eventually_ have the lock _unless_ it is held
	284	* by a blocked process. (In the latter case an explicit wait for the hardware lock would cause
	285	* a deadlock, which is why the "idlelock" was invented).
	286	*
	287	* This should be sufficient to wait for GPU idle without
	288	* having to worry about starvation.
	289	*/
	290
bb6d822e	291	void drm_legacy_idlelock_take(struct drm_lock_data *lock_data)
040ac320	292	{
4a1b0714	293	int ret;
040ac320	294
f116cc56	295	spin_lock_bh(&lock_data->spinlock);
040ac320 TH	296	lock_data->kernel_waiters++;
	297	if (!lock_data->idle_has_lock) {
	298
f116cc56	299	spin_unlock_bh(&lock_data->spinlock);
040ac320	300	ret = drm_lock_take(lock_data, DRM_KERNEL_CONTEXT);
f116cc56	301	spin_lock_bh(&lock_data->spinlock);
040ac320 TH	302
	303	if (ret == 1)
	304	lock_data->idle_has_lock = 1;
	305	}
f116cc56	306	spin_unlock_bh(&lock_data->spinlock);
040ac320	307	}
bb6d822e	308	EXPORT_SYMBOL(drm_legacy_idlelock_take);
040ac320	309
bb6d822e	310	void drm_legacy_idlelock_release(struct drm_lock_data *lock_data)
040ac320 TH	311	{
	312	unsigned int old, prev;
	313	volatile unsigned int *lock = &lock_data->hw_lock->lock;
	314
f116cc56	315	spin_lock_bh(&lock_data->spinlock);
040ac320 TH	316	if (--lock_data->kernel_waiters == 0) {
	317	if (lock_data->idle_has_lock) {
	318	do {
	319	old = *lock;
	320	prev = cmpxchg(lock, old, DRM_KERNEL_CONTEXT);
	321	} while (prev != old);
	322	wake_up_interruptible(&lock_data->lock_queue);
	323	lock_data->idle_has_lock = 0;
	324	}
	325	}
f116cc56	326	spin_unlock_bh(&lock_data->spinlock);
040ac320	327	}
bb6d822e	328	EXPORT_SYMBOL(drm_legacy_idlelock_release);
040ac320	329
1a75a222 DV	330	static int drm_legacy_i_have_hw_lock(struct drm_device *dev,
1a75a222 DV	331	struct drm_file *file_priv)
040ac320	332	{
7c1c2871 DA	333	struct drm_master *master = file_priv->master;
	334	return (file_priv->lock_count && master->lock.hw_lock &&
	335	_DRM_LOCK_IS_HELD(master->lock.hw_lock->lock) &&
	336	master->lock.file_priv == file_priv);
040ac320	337	}
1a75a222 DV	338
	339	void drm_legacy_lock_release(struct drm_device dev, struct file filp)
	340	{
	341	struct drm_file *file_priv = filp->private_data;
	342
	343	/* if the master has gone away we can't do anything with the lock */
95c081c1	344	if (!dev->master)
1a75a222 DV	345	return;
	346
	347	if (drm_legacy_i_have_hw_lock(dev, file_priv)) {
	348	DRM_DEBUG("File %p released, freeing lock for context %d\n",
	349	filp, _DRM_LOCKING_CONTEXT(file_priv->master->lock.hw_lock->lock));
	350	drm_legacy_lock_free(&file_priv->master->lock,
	351	_DRM_LOCKING_CONTEXT(file_priv->master->lock.hw_lock->lock));
	352	}
	353	}
058ca50c DA	354
	355	void drm_legacy_lock_master_cleanup(struct drm_device dev, struct drm_master master)
	356	{
	357	if (!drm_core_check_feature(dev, DRIVER_LEGACY))
	358	return;
	359
	360	/*
	361	* Since the master is disappearing, so is the
	362	* possibility to lock.
	363	*/ mutex_lock(&dev->struct_mutex);
	364	if (master->lock.hw_lock) {
	365	if (dev->sigdata.lock == master->lock.hw_lock)
	366	dev->sigdata.lock = NULL;
	367	master->lock.hw_lock = NULL;
	368	master->lock.file_priv = NULL;
	369	wake_up_interruptible_all(&master->lock.lock_queue);
	370	}
	371	mutex_unlock(&dev->struct_mutex);
	372	}