summaryrefslogtreecommitdiff
path: root/drivers/gpu/drm/drm_lease.c
blob: 825abe38201acfe6aecd742f89b2b5b3e9165df0 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * Copyright © 2017 Keith Packard <keithp@keithp.com>
 */
#include <linux/file.h>
#include <linux/uaccess.h>

#include <drm/drm_auth.h>
#include <drm/drm_crtc_helper.h>
#include <drm/drm_drv.h>
#include <drm/drm_file.h>
#include <drm/drm_lease.h>
#include <drm/drm_print.h>

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

#define drm_for_each_lessee(lessee, lessor) \
	list_for_each_entry((lessee), &(lessor)->lessees, lessee_list)

static uint64_t drm_lease_idr_object;

/**
 * drm_lease_owner - return ancestor owner drm_master
 * @master: drm_master somewhere within tree of lessees and lessors
 *
 * RETURN:
 *
 * drm_master at the top of the tree (i.e, with lessor NULL
 */
struct drm_master *drm_lease_owner(struct drm_master *master)
{
	while (master->lessor != NULL)
		master = master->lessor;
	return master;
}

/**
 * _drm_find_lessee - find lessee by id (idr_mutex held)
 * @master: drm_master of lessor
 * @lessee_id: id
 *
 * RETURN:
 *
 * drm_master of the lessee if valid, NULL otherwise
 */

static struct drm_master*
_drm_find_lessee(struct drm_master *master, int lessee_id)
{
	lockdep_assert_held(&master->dev->mode_config.idr_mutex);
	return idr_find(&drm_lease_owner(master)->lessee_idr, lessee_id);
}

/**
 * _drm_lease_held_master - check to see if an object is leased (or owned) by master (idr_mutex held)
 * @master: the master to check the lease status of
 * @id: the id to check
 *
 * Checks if the specified master holds a lease on the object. Return
 * value:
 *
 *	true		'master' holds a lease on (or owns) the object
 *	false		'master' does not hold a lease.
 */
static int _drm_lease_held_master(struct drm_master *master, int id)
{
	lockdep_assert_held(&master->dev->mode_config.idr_mutex);
	if (master->lessor)
		return idr_find(&master->leases, id) != NULL;
	return true;
}

/**
 * _drm_has_leased - check to see if an object has been leased (idr_mutex held)
 * @master: the master to check the lease status of
 * @id: the id to check
 *
 * Checks if any lessee of 'master' holds a lease on 'id'. Return
 * value:
 *
 *	true		Some lessee holds a lease on the object.
 *	false		No lessee has a lease on the object.
 */
static bool _drm_has_leased(struct drm_master *master, int id)
{
	struct drm_master *lessee;

	lockdep_assert_held(&master->dev->mode_config.idr_mutex);
	drm_for_each_lessee(lessee, master)
		if (_drm_lease_held_master(lessee, id))
			return true;
	return false;
}

/**
 * _drm_lease_held - check drm_mode_object lease status (idr_mutex held)
 * @file_priv: the master drm_file
 * @id: the object id
 *
 * Checks if the specified master holds a lease on the object. Return
 * value:
 *
 *	true		'master' holds a lease on (or owns) the object
 *	false		'master' does not hold a lease.
 */
bool _drm_lease_held(struct drm_file *file_priv, int id)
{
	if (!file_priv || !file_priv->master)
		return true;

	return _drm_lease_held_master(file_priv->master, id);
}

/**
 * drm_lease_held - check drm_mode_object lease status (idr_mutex not held)
 * @file_priv: the master drm_file
 * @id: the object id
 *
 * Checks if the specified master holds a lease on the object. Return
 * value:
 *
 *	true		'master' holds a lease on (or owns) the object
 *	false		'master' does not hold a lease.
 */
bool drm_lease_held(struct drm_file *file_priv, int id)
{
	struct drm_master *master;
	bool ret;

	if (!file_priv || !file_priv->master || !file_priv->master->lessor)
		return true;

	master = file_priv->master;
	mutex_lock(&master->dev->mode_config.idr_mutex);
	ret = _drm_lease_held_master(master, id);
	mutex_unlock(&master->dev->mode_config.idr_mutex);
	return ret;
}

/**
 * drm_lease_filter_crtcs - restricted crtc set to leased values (idr_mutex not held)
 * @file_priv: requestor file
 * @crtcs_in: bitmask of crtcs to check
 *
 * Reconstructs a crtc mask based on the crtcs which are visible
 * through the specified file.
 */
uint32_t drm_lease_filter_crtcs(struct drm_file *file_priv, uint32_t crtcs_in)
{
	struct drm_master *master;
	struct drm_device *dev;
	struct drm_crtc *crtc;
	int count_in, count_out;
	uint32_t crtcs_out = 0;

	if (!file_priv || !file_priv->master || !file_priv->master->lessor)
		return crtcs_in;

	master = file_priv->master;
	dev = master->dev;

	count_in = count_out = 0;
	mutex_lock(&master->dev->mode_config.idr_mutex);
	list_for_each_entry(crtc, &dev->mode_config.crtc_list, head) {
		if (_drm_lease_held_master(master, crtc->base.id)) {
			uint32_t mask_in = 1ul << count_in;
			if ((crtcs_in & mask_in) != 0) {
				uint32_t mask_out = 1ul << count_out;
				crtcs_out |= mask_out;
			}
			count_out++;
		}
		count_in++;
	}
	mutex_unlock(&master->dev->mode_config.idr_mutex);
	return crtcs_out;
}

/*
 * drm_lease_create - create a new drm_master with leased objects (idr_mutex not held)
 * @lessor: lease holder (or owner) of objects
 * @leases: objects to lease to the new drm_master
 *
 * Uses drm_master_create to allocate a new drm_master, then checks to
 * make sure all of the desired objects can be leased, atomically
 * leasing them to the new drmmaster.
 *
 * 	ERR_PTR(-EACCES)	some other master holds the title to any object
 * 	ERR_PTR(-ENOENT)	some object is not a valid DRM object for this device
 * 	ERR_PTR(-EBUSY)		some other lessee holds title to this object
 *	ERR_PTR(-EEXIST)	same object specified more than once in the provided list
 *	ERR_PTR(-ENOMEM)	allocation failed
 */
static struct drm_master *drm_lease_create(struct drm_master *lessor, struct idr *leases)
{
	struct drm_device *dev = lessor->dev;
	int error;
	struct drm_master *lessee;
	int object;
	int id;
	void *entry;

	DRM_DEBUG_LEASE("lessor %d\n", lessor->lessee_id);

	lessee = drm_master_create(lessor->dev);
	if (!lessee) {
		DRM_DEBUG_LEASE("drm_master_create failed\n");
		return ERR_PTR(-ENOMEM);
	}

	mutex_lock(&dev->mode_config.idr_mutex);

	idr_for_each_entry(leases, entry, object) {
		error = 0;
		if (!idr_find(&dev->mode_config.object_idr, object))
			error = -ENOENT;
		else if (_drm_has_leased(lessor, object))
			error = -EBUSY;

		if (error != 0) {
			DRM_DEBUG_LEASE("object %d failed %d\n", object, error);
			goto out_lessee;
		}
	}

	/* Insert the new lessee into the tree */
	id = idr_alloc(&(drm_lease_owner(lessor)->lessee_idr), lessee, 1, 0, GFP_KERNEL);
	if (id < 0) {
		error = id;
		goto out_lessee;
	}

	lessee->lessee_id = id;
	lessee->lessor = drm_master_get(lessor);
	list_add_tail(&lessee->lessee_list, &lessor->lessees);

	/* Move the leases over */
	lessee->leases = *leases;
	DRM_DEBUG_LEASE("new lessee %d %p, lessor %d %p\n", lessee->lessee_id, lessee, lessor->lessee_id, lessor);

	mutex_unlock(&dev->mode_config.idr_mutex);
	return lessee;

out_lessee:
	mutex_unlock(&dev->mode_config.idr_mutex);

	drm_master_put(&lessee);

	return ERR_PTR(error);
}

/**
 * drm_lease_destroy - a master is going away (idr_mutex not held)
 * @master: the drm_master being destroyed
 *
 * All lessees will have been destroyed as they
 * hold a reference on their lessor. Notify any
 * lessor for this master so that it can check
 * the list of lessees.
 */
void drm_lease_destroy(struct drm_master *master)
{
	struct drm_device *dev = master->dev;

	mutex_lock(&dev->mode_config.idr_mutex);

	DRM_DEBUG_LEASE("drm_lease_destroy %d\n", master->lessee_id);

	/* This master is referenced by all lessees, hence it cannot be destroyed
	 * until all of them have been
	 */
	WARN_ON(!list_empty(&master->lessees));

	/* Remove this master from the lessee idr in the owner */
	if (master->lessee_id != 0) {
		DRM_DEBUG_LEASE("remove master %d from device list of lessees\n", master->lessee_id);
		idr_remove(&(drm_lease_owner(master)->lessee_idr), master->lessee_id);
	}

	/* Remove this master from any lessee list it may be on */
	list_del(&master->lessee_list);

	mutex_unlock(&dev->mode_config.idr_mutex);

	if (master->lessor) {
		/* Tell the master to check the lessee list */
		drm_sysfs_lease_event(dev);
		drm_master_put(&master->lessor);
	}

	DRM_DEBUG_LEASE("drm_lease_destroy done %d\n", master->lessee_id);
}

/**
 * _drm_lease_revoke - revoke access to all leased objects (idr_mutex held)
 * @top: the master losing its lease
 */
static void _drm_lease_revoke(struct drm_master *top)
{
	int object;
	void *entry;
	struct drm_master *master = top;

	lockdep_assert_held(&top->dev->mode_config.idr_mutex);

	/*
	 * Walk the tree starting at 'top' emptying all leases. Because
	 * the tree is fully connected, we can do this without recursing
	 */
	for (;;) {
		DRM_DEBUG_LEASE("revoke leases for %p %d\n", master, master->lessee_id);

		/* Evacuate the lease */
		idr_for_each_entry(&master->leases, entry, object)
			idr_remove(&master->leases, object);

		/* Depth-first list walk */

		/* Down */
		if (!list_empty(&master->lessees)) {
			master = list_first_entry(&master->lessees, struct drm_master, lessee_list);
		} else {
			/* Up */
			while (master != top && master == list_last_entry(&master->lessor->lessees, struct drm_master, lessee_list))
				master = master->lessor;

			if (master == top)
				break;

			/* Over */
			master = list_next_entry(master, lessee_list);
		}
	}
}

/**
 * drm_lease_revoke - revoke access to all leased objects (idr_mutex not held)
 * @top: the master losing its lease
 */
void drm_lease_revoke(struct drm_master *top)
{
	mutex_lock(&top->dev->mode_config.idr_mutex);
	_drm_lease_revoke(top);
	mutex_unlock(&top->dev->mode_config.idr_mutex);
}

static int validate_lease(struct drm_device *dev,
			  int object_count,
			  struct drm_mode_object **objects,
			  bool universal_planes)
{
	int o;
	int has_crtc = -1;
	int has_connector = -1;
	int has_plane = -1;

	/* we want to confirm that there is at least one crtc, plane
	   connector object. */

	for (o = 0; o < object_count; o++) {
		if (objects[o]->type == DRM_MODE_OBJECT_CRTC && has_crtc == -1) {
			has_crtc = o;
		}
		if (objects[o]->type == DRM_MODE_OBJECT_CONNECTOR && has_connector == -1)
			has_connector = o;

		if (universal_planes) {
			if (objects[o]->type == DRM_MODE_OBJECT_PLANE && has_plane == -1)
				has_plane = o;
		}
	}
	if (has_crtc == -1 || has_connector == -1)
		return -EINVAL;
	if (universal_planes && has_plane == -1)
		return -EINVAL;
	return 0;
}

static int fill_object_idr(struct drm_device *dev,
			   struct drm_file *lessor_priv,
			   struct idr *leases,
			   int object_count,
			   u32 *object_ids)
{
	struct drm_mode_object **objects;
	u32 o;
	int ret;
	bool universal_planes = READ_ONCE(lessor_priv->universal_planes);

	objects = kcalloc(object_count, sizeof(struct drm_mode_object *),
			  GFP_KERNEL);
	if (!objects)
		return -ENOMEM;

	/* step one - get references to all the mode objects
	   and check for validity. */
	for (o = 0; o < object_count; o++) {
		objects[o] = drm_mode_object_find(dev, lessor_priv,
						  object_ids[o],
						  DRM_MODE_OBJECT_ANY);
		if (!objects[o]) {
			ret = -ENOENT;
			goto out_free_objects;
		}

		if (!drm_mode_object_lease_required(objects[o]->type)) {
			DRM_DEBUG_KMS("invalid object for lease\n");
			ret = -EINVAL;
			goto out_free_objects;
		}
	}

	ret = validate_lease(dev, object_count, objects, universal_planes);
	if (ret) {
		DRM_DEBUG_LEASE("lease validation failed\n");
		goto out_free_objects;
	}

	/* add their IDs to the lease request - taking into account
	   universal planes */
	for (o = 0; o < object_count; o++) {
		struct drm_mode_object *obj = objects[o];
		u32 object_id = objects[o]->id;
		DRM_DEBUG_LEASE("Adding object %d to lease\n", object_id);

		/*
		 * We're using an IDR to hold the set of leased
		 * objects, but we don't need to point at the object's
		 * data structure from the lease as the main object_idr
		 * will be used to actually find that. Instead, all we
		 * really want is a 'leased/not-leased' result, for
		 * which any non-NULL pointer will work fine.
		 */
		ret = idr_alloc(leases, &drm_lease_idr_object , object_id, object_id + 1, GFP_KERNEL);
		if (ret < 0) {
			DRM_DEBUG_LEASE("Object %d cannot be inserted into leases (%d)\n",
					object_id, ret);
			goto out_free_objects;
		}
		if (obj->type == DRM_MODE_OBJECT_CRTC && !universal_planes) {
			struct drm_crtc *crtc = obj_to_crtc(obj);
			ret = idr_alloc(leases, &drm_lease_idr_object, crtc->primary->base.id, crtc->primary->base.id + 1, GFP_KERNEL);
			if (ret < 0) {
				DRM_DEBUG_LEASE("Object primary plane %d cannot be inserted into leases (%d)\n",
						object_id, ret);
				goto out_free_objects;
			}
			if (crtc->cursor) {
				ret = idr_alloc(leases, &drm_lease_idr_object, crtc->cursor->base.id, crtc->cursor->base.id + 1, GFP_KERNEL);
				if (ret < 0) {
					DRM_DEBUG_LEASE("Object cursor plane %d cannot be inserted into leases (%d)\n",
							object_id, ret);
					goto out_free_objects;
				}
			}
		}
	}

	ret = 0;
out_free_objects:
	for (o = 0; o < object_count; o++) {
		if (objects[o])
			drm_mode_object_put(objects[o]);
	}
	kfree(objects);
	return ret;
}

/**
 * drm_mode_create_lease_ioctl - create a new lease
 * @dev: the drm device
 * @data: pointer to struct drm_mode_create_lease
 * @lessor_priv: the file being manipulated
 *
 * The master associated with the specified file will have a lease
 * created containing the objects specified in the ioctl structure.
 * A file descriptor will be allocated for that and returned to the
 * application.
 */
int drm_mode_create_lease_ioctl(struct drm_device *dev,
				void *data, struct drm_file *lessor_priv)
{
	struct drm_mode_create_lease *cl = data;
	size_t object_count;
	int ret = 0;
	struct idr leases;
	struct drm_master *lessor = lessor_priv->master;
	struct drm_master *lessee = NULL;
	struct file *lessee_file = NULL;
	struct file *lessor_file = lessor_priv->filp;
	struct drm_file *lessee_priv;
	int fd = -1;
	uint32_t *object_ids;

	/* Can't lease without MODESET */
	if (!drm_core_check_feature(dev, DRIVER_MODESET))
		return -EOPNOTSUPP;

	/* Do not allow sub-leases */
	if (lessor->lessor) {
		DRM_DEBUG_LEASE("recursive leasing not allowed\n");
		return -EINVAL;
	}

	/* need some objects */
	if (cl->object_count == 0) {
		DRM_DEBUG_LEASE("no objects in lease\n");
		return -EINVAL;
	}

	if (cl->flags && (cl->flags & ~(O_CLOEXEC | O_NONBLOCK))) {
		DRM_DEBUG_LEASE("invalid flags\n");
		return -EINVAL;
	}

	object_count = cl->object_count;

	object_ids = memdup_user(u64_to_user_ptr(cl->object_ids),
			array_size(object_count, sizeof(__u32)));
	if (IS_ERR(object_ids))
		return PTR_ERR(object_ids);

	idr_init(&leases);

	/* fill and validate the object idr */
	ret = fill_object_idr(dev, lessor_priv, &leases,
			      object_count, object_ids);
	kfree(object_ids);
	if (ret) {
		DRM_DEBUG_LEASE("lease object lookup failed: %i\n", ret);
		idr_destroy(&leases);
		return ret;
	}

	/* Allocate a file descriptor for the lease */
	fd = get_unused_fd_flags(cl->flags & (O_CLOEXEC | O_NONBLOCK));
	if (fd < 0) {
		idr_destroy(&leases);
		return fd;
	}

	DRM_DEBUG_LEASE("Creating lease\n");
	/* lessee will take the ownership of leases */
	lessee = drm_lease_create(lessor, &leases);

	if (IS_ERR(lessee)) {
		ret = PTR_ERR(lessee);
		idr_destroy(&leases);
		goto out_leases;
	}

	/* Clone the lessor file to create a new file for us */
	DRM_DEBUG_LEASE("Allocating lease file\n");
	lessee_file = file_clone_open(lessor_file);
	if (IS_ERR(lessee_file)) {
		ret = PTR_ERR(lessee_file);
		goto out_lessee;
	}

	lessee_priv = lessee_file->private_data;
	/* Change the file to a master one */
	drm_master_put(&lessee_priv->master);
	lessee_priv->master = lessee;
	lessee_priv->is_master = 1;
	lessee_priv->authenticated = 1;

	/* Pass fd back to userspace */
	DRM_DEBUG_LEASE("Returning fd %d id %d\n", fd, lessee->lessee_id);
	cl->fd = fd;
	cl->lessee_id = lessee->lessee_id;

	/* Hook up the fd */
	fd_install(fd, lessee_file);

	DRM_DEBUG_LEASE("drm_mode_create_lease_ioctl succeeded\n");
	return 0;

out_lessee:
	drm_master_put(&lessee);

out_leases:
	put_unused_fd(fd);

	DRM_DEBUG_LEASE("drm_mode_create_lease_ioctl failed: %d\n", ret);
	return ret;
}

/**
 * drm_mode_list_lessees_ioctl - list lessee ids
 * @dev: the drm device
 * @data: pointer to struct drm_mode_list_lessees
 * @lessor_priv: the file being manipulated
 *
 * Starting from the master associated with the specified file,
 * the master with the provided lessee_id is found, and then
 * an array of lessee ids associated with leases from that master
 * are returned.
 */

int drm_mode_list_lessees_ioctl(struct drm_device *dev,
			       void *data, struct drm_file *lessor_priv)
{
	struct drm_mode_list_lessees *arg = data;
	__u32 __user *lessee_ids = (__u32 __user *) (uintptr_t) (arg->lessees_ptr);
	__u32 count_lessees = arg->count_lessees;
	struct drm_master *lessor = lessor_priv->master, *lessee;
	int count;
	int ret = 0;

	if (arg->pad)
		return -EINVAL;

	/* Can't lease without MODESET */
	if (!drm_core_check_feature(dev, DRIVER_MODESET))
		return -EOPNOTSUPP;

	DRM_DEBUG_LEASE("List lessees for %d\n", lessor->lessee_id);

	mutex_lock(&dev->mode_config.idr_mutex);

	count = 0;
	drm_for_each_lessee(lessee, lessor) {
		/* Only list un-revoked leases */
		if (!idr_is_empty(&lessee->leases)) {
			if (count_lessees > count) {
				DRM_DEBUG_LEASE("Add lessee %d\n", lessee->lessee_id);
				ret = put_user(lessee->lessee_id, lessee_ids + count);
				if (ret)
					break;
			}
			count++;
		}
	}

	DRM_DEBUG_LEASE("Lessor leases to %d\n", count);
	if (ret == 0)
		arg->count_lessees = count;

	mutex_unlock(&dev->mode_config.idr_mutex);

	return ret;
}

/**
 * drm_mode_get_lease_ioctl - list leased objects
 * @dev: the drm device
 * @data: pointer to struct drm_mode_get_lease
 * @lessee_priv: the file being manipulated
 *
 * Return the list of leased objects for the specified lessee
 */

int drm_mode_get_lease_ioctl(struct drm_device *dev,
			     void *data, struct drm_file *lessee_priv)
{
	struct drm_mode_get_lease *arg = data;
	__u32 __user *object_ids = (__u32 __user *) (uintptr_t) (arg->objects_ptr);
	__u32 count_objects = arg->count_objects;
	struct drm_master *lessee = lessee_priv->master;
	struct idr *object_idr;
	int count;
	void *entry;
	int object;
	int ret = 0;

	if (arg->pad)
		return -EINVAL;

	/* Can't lease without MODESET */
	if (!drm_core_check_feature(dev, DRIVER_MODESET))
		return -EOPNOTSUPP;

	DRM_DEBUG_LEASE("get lease for %d\n", lessee->lessee_id);

	mutex_lock(&dev->mode_config.idr_mutex);

	if (lessee->lessor == NULL)
		/* owner can use all objects */
		object_idr = &lessee->dev->mode_config.object_idr;
	else
		/* lessee can only use allowed object */
		object_idr = &lessee->leases;

	count = 0;
	idr_for_each_entry(object_idr, entry, object) {
		if (count_objects > count) {
			DRM_DEBUG_LEASE("adding object %d\n", object);
			ret = put_user(object, object_ids + count);
			if (ret)
				break;
		}
		count++;
	}

	DRM_DEBUG("lease holds %d objects\n", count);
	if (ret == 0)
		arg->count_objects = count;

	mutex_unlock(&dev->mode_config.idr_mutex);

	return ret;
}

/**
 * drm_mode_revoke_lease_ioctl - revoke lease
 * @dev: the drm device
 * @data: pointer to struct drm_mode_revoke_lease
 * @lessor_priv: the file being manipulated
 *
 * This removes all of the objects from the lease without
 * actually getting rid of the lease itself; that way all
 * references to it still work correctly
 */
int drm_mode_revoke_lease_ioctl(struct drm_device *dev,
				void *data, struct drm_file *lessor_priv)
{
	struct drm_mode_revoke_lease *arg = data;
	struct drm_master *lessor = lessor_priv->master;
	struct drm_master *lessee;
	int ret = 0;

	DRM_DEBUG_LEASE("revoke lease for %d\n", arg->lessee_id);

	/* Can't lease without MODESET */
	if (!drm_core_check_feature(dev, DRIVER_MODESET))
		return -EOPNOTSUPP;

	mutex_lock(&dev->mode_config.idr_mutex);

	lessee = _drm_find_lessee(lessor, arg->lessee_id);

	/* No such lessee */
	if (!lessee) {
		ret = -ENOENT;
		goto fail;
	}

	/* Lease is not held by lessor */
	if (lessee->lessor != lessor) {
		ret = -EACCES;
		goto fail;
	}

	_drm_lease_revoke(lessee);

fail:
	mutex_unlock(&dev->mode_config.idr_mutex);

	return ret;
}