summaryrefslogtreecommitdiff
path: root/drivers/infiniband/core/uverbs_ioctl_merge.c
blob: 0f88a1919d51b0ddfdd087ca4007d4891e1188be (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
/*
 * Copyright (c) 2017, Mellanox Technologies inc.  All rights reserved.
 *
 * This software is available to you under a choice of one of two
 * licenses.  You may choose to be licensed under the terms of the GNU
 * General Public License (GPL) Version 2, available from the file
 * COPYING in the main directory of this source tree, or the
 * OpenIB.org BSD license below:
 *
 *     Redistribution and use in source and binary forms, with or
 *     without modification, are permitted provided that the following
 *     conditions are met:
 *
 *      - Redistributions of source code must retain the above
 *        copyright notice, this list of conditions and the following
 *        disclaimer.
 *
 *      - Redistributions in binary form must reproduce the above
 *        copyright notice, this list of conditions and the following
 *        disclaimer in the documentation and/or other materials
 *        provided with the distribution.
 *
 * 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 THE AUTHORS OR COPYRIGHT HOLDERS
 * 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 <rdma/uverbs_ioctl.h>
#include <rdma/rdma_user_ioctl.h>
#include <linux/bitops.h>
#include "uverbs.h"

#define UVERBS_NUM_NS (UVERBS_ID_NS_MASK >> UVERBS_ID_NS_SHIFT)
#define GET_NS_ID(idx) (((idx) & UVERBS_ID_NS_MASK) >> UVERBS_ID_NS_SHIFT)
#define GET_ID(idx) ((idx) & ~UVERBS_ID_NS_MASK)

#define _for_each_element(elem, tmpi, tmpj, hashes, num_buckets_offset,	       \
			  buckets_offset)				       \
	for (tmpj = 0,							       \
	     elem = (*(const void ***)((hashes)[tmpi] +			       \
				       (buckets_offset)))[0];	               \
	     tmpj < *(size_t *)((hashes)[tmpi] + (num_buckets_offset));        \
	     tmpj++)						               \
		if ((elem = ((*(const void ***)(hashes[tmpi] +		       \
						(buckets_offset)))[tmpj])))

/*
 * Iterate all elements of a few @hashes. The number of given hashes is
 * indicated by @num_hashes. The offset of the number of buckets in the hash is
 * represented by @num_buckets_offset, while the offset of the buckets array in
 * the hash structure is represented by @buckets_offset. tmpi and tmpj are two
 * short (or int) based indices that are given by the user. tmpi iterates over
 * the different hashes. @elem points the current element in the hashes[tmpi]
 * bucket we are looping on. To be honest, @hashes representation isn't exactly
 * a hash, but more a collection of elements. These elements' ids are treated
 * in a hash like manner, where the first upper bits are the bucket number.
 * These elements are later mapped into a perfect-hash.
 */
#define for_each_element(elem, tmpi, tmpj, hashes, num_hashes,                 \
			 num_buckets_offset, buckets_offset)		       \
	for (tmpi = 0; tmpi < (num_hashes); tmpi++)		               \
		_for_each_element(elem, tmpi, tmpj, hashes, num_buckets_offset,\
				  buckets_offset)

#define get_elements_iterators_entry_above(iters, num_elements, elements,     \
					  num_objects_fld, objects_fld, bucket,\
					  min_id)			       \
	get_elements_above_id((const void **)iters, num_elements,       \
				     (const void **)(elements),		       \
				     offsetof(typeof(**elements),	       \
					      num_objects_fld),		       \
				     offsetof(typeof(**elements), objects_fld),\
				     offsetof(typeof(***(*elements)->objects_fld), id),\
				     bucket, min_id)

#define get_objects_above_id(iters, num_trees, trees, bucket, min_id)	       \
	get_elements_iterators_entry_above(iters, num_trees, trees,	       \
					   num_objects, objects, bucket, min_id)

#define get_methods_above_id(method_iters, num_iters, iters, bucket, min_id)\
	get_elements_iterators_entry_above(method_iters, num_iters, iters,     \
					   num_methods, methods, bucket, min_id)

#define get_attrs_above_id(attrs_iters, num_iters, iters, bucket, min_id)\
	get_elements_iterators_entry_above(attrs_iters, num_iters, iters,      \
					   num_attrs, attrs, bucket, min_id)

/*
 * get_elements_above_id get a few hashes represented by @elements and
 * @num_elements. The hashes fields are described by @num_offset, @data_offset
 * and @id_offset in the same way as required by for_each_element. The function
 * returns an array of @iters, represents an array of elements in the hashes
 * buckets, which their ids are the smallest ids in all hashes but are all
 * larger than the id given by min_id. Elements are only added to the iters
 * array if their id belongs to the bucket @bucket. The number of elements in
 * the returned array is returned by the function. @min_id is also updated to
 * reflect the new min_id of all elements in iters.
 */
static size_t get_elements_above_id(const void **iters,
				    unsigned int num_elements,
				    const void **elements,
				    size_t num_offset,
				    size_t data_offset,
				    size_t id_offset,
				    u16 bucket,
				    short *min_id)
{
	size_t num_iters = 0;
	short min = SHRT_MAX;
	const void *elem;
	int i, j, last_stored = -1;
	unsigned int equal_min = 0;

	for_each_element(elem, i, j, elements, num_elements, num_offset,
			 data_offset) {
		u16 id = *(u16 *)(elem + id_offset);

		if (GET_NS_ID(id) != bucket)
			continue;

		if (GET_ID(id) < *min_id ||
		    (min != SHRT_MAX && GET_ID(id) > min))
			continue;

		/*
		 * We first iterate all hashes represented by @elements. When
		 * we do, we try to find an element @elem in the bucket @bucket
		 * which its id is min. Since we can't ensure the user sorted
		 * the elements in increasing order, we override this hash's
		 * minimal id element we found, if a new element with a smaller
		 * id was just found.
		 */
		iters[last_stored == i ? num_iters - 1 : num_iters++] = elem;
		last_stored = i;
		if (min == GET_ID(id))
			equal_min++;
		else
			equal_min = 1;
		min = GET_ID(id);
	}

	/*
	 * We only insert to our iters array an element, if its id is smaller
	 * than all previous ids. Therefore, the final iters array is sorted so
	 * that smaller ids are in the end of the array.
	 * Therefore, we need to clean the beginning of the array to make sure
	 * all ids of final elements are equal to min.
	 */
	memmove(iters, iters + num_iters - equal_min, sizeof(*iters) * equal_min);

	*min_id = min;
	return equal_min;
}

#define find_max_element_entry_id(num_elements, elements, num_objects_fld, \
				  objects_fld, bucket)			   \
	find_max_element_id(num_elements, (const void **)(elements),	   \
			    offsetof(typeof(**elements), num_objects_fld),    \
			    offsetof(typeof(**elements), objects_fld),	      \
			    offsetof(typeof(***(*elements)->objects_fld), id),\
			    bucket)

static short find_max_element_ns_id(unsigned int num_elements,
				    const void **elements,
				    size_t num_offset,
				    size_t data_offset,
				    size_t id_offset)
{
	short max_ns = SHRT_MIN;
	const void *elem;
	int i, j;

	for_each_element(elem, i, j, elements, num_elements, num_offset,
			 data_offset) {
		u16 id = *(u16 *)(elem + id_offset);

		if (GET_NS_ID(id) > max_ns)
			max_ns = GET_NS_ID(id);
	}

	return max_ns;
}

static short find_max_element_id(unsigned int num_elements,
				 const void **elements,
				 size_t num_offset,
				 size_t data_offset,
				 size_t id_offset,
				 u16 bucket)
{
	short max_id = SHRT_MIN;
	const void *elem;
	int i, j;

	for_each_element(elem, i, j, elements, num_elements, num_offset,
			 data_offset) {
		u16 id = *(u16 *)(elem + id_offset);

		if (GET_NS_ID(id) == bucket &&
		    GET_ID(id) > max_id)
			max_id = GET_ID(id);
	}
	return max_id;
}

#define find_max_element_entry_id(num_elements, elements, num_objects_fld,   \
				  objects_fld, bucket)			      \
	find_max_element_id(num_elements, (const void **)(elements),	      \
			    offsetof(typeof(**elements), num_objects_fld),    \
			    offsetof(typeof(**elements), objects_fld),	      \
			    offsetof(typeof(***(*elements)->objects_fld), id),\
			    bucket)

#define find_max_element_ns_entry_id(num_elements, elements,		    \
				     num_objects_fld, objects_fld)	    \
	find_max_element_ns_id(num_elements, (const void **)(elements),	    \
			      offsetof(typeof(**elements), num_objects_fld),\
			      offsetof(typeof(**elements), objects_fld),    \
			      offsetof(typeof(***(*elements)->objects_fld), id))

/*
 * find_max_xxxx_ns_id gets a few elements. Each element is described by an id
 * which its upper bits represents a namespace. It finds the max namespace. This
 * could be used in order to know how many buckets do we need to allocate. If no
 * elements exist, SHRT_MIN is returned. Namespace represents here different
 * buckets. The common example is "common bucket" and "driver bucket".
 *
 * find_max_xxxx_id gets a few elements and a bucket. Each element is described
 * by an id which its upper bits represent a namespace. It returns the max id
 * which is contained in the same namespace defined in @bucket. This could be
 * used in order to know how many elements do we need to allocate in the bucket.
 * If no elements exist, SHRT_MIN is returned.
 */

#define find_max_object_id(num_trees, trees, bucket)			\
		find_max_element_entry_id(num_trees, trees, num_objects,\
					  objects, bucket)
#define find_max_object_ns_id(num_trees, trees)			\
		find_max_element_ns_entry_id(num_trees, trees,		\
					     num_objects, objects)

#define find_max_method_id(num_iters, iters, bucket)			\
		find_max_element_entry_id(num_iters, iters, num_methods,\
					  methods, bucket)
#define find_max_method_ns_id(num_iters, iters)			\
		find_max_element_ns_entry_id(num_iters, iters,		\
					     num_methods, methods)

#define find_max_attr_id(num_iters, iters, bucket)			\
		find_max_element_entry_id(num_iters, iters, num_attrs,  \
					  attrs, bucket)
#define find_max_attr_ns_id(num_iters, iters)				\
		find_max_element_ns_entry_id(num_iters, iters,		\
					     num_attrs, attrs)

static void free_method(struct uverbs_method_spec *method)
{
	unsigned int i;

	if (!method)
		return;

	for (i = 0; i < method->num_buckets; i++)
		kfree(method->attr_buckets[i]);

	kfree(method);
}

#define IS_ATTR_OBJECT(attr) ((attr)->type == UVERBS_ATTR_TYPE_IDR || \
			      (attr)->type == UVERBS_ATTR_TYPE_FD)

/*
 * This function gets array of size @num_method_defs which contains pointers to
 * method definitions @method_defs. The function allocates an
 * uverbs_method_spec structure and initializes its number of buckets and the
 * elements in buckets to the correct attributes. While doing that, it
 * validates that there aren't conflicts between attributes of different
 * method_defs.
 */
static struct uverbs_method_spec *build_method_with_attrs(const struct uverbs_method_def **method_defs,
							  size_t num_method_defs)
{
	int bucket_idx;
	int max_attr_buckets = 0;
	size_t num_attr_buckets = 0;
	int res = 0;
	struct uverbs_method_spec *method = NULL;
	const struct uverbs_attr_def **attr_defs;
	unsigned int num_of_singularities = 0;

	max_attr_buckets = find_max_attr_ns_id(num_method_defs, method_defs);
	if (max_attr_buckets >= 0)
		num_attr_buckets = max_attr_buckets + 1;

	method = kzalloc(sizeof(*method) +
			 num_attr_buckets * sizeof(*method->attr_buckets),
			 GFP_KERNEL);
	if (!method)
		return ERR_PTR(-ENOMEM);

	method->num_buckets = num_attr_buckets;
	attr_defs = kcalloc(num_method_defs, sizeof(*attr_defs), GFP_KERNEL);
	if (!attr_defs) {
		res = -ENOMEM;
		goto free_method;
	}
	for (bucket_idx = 0; bucket_idx < method->num_buckets; bucket_idx++) {
		short min_id = SHRT_MIN;
		int attr_max_bucket = 0;
		struct uverbs_attr_spec_hash *hash = NULL;

		attr_max_bucket = find_max_attr_id(num_method_defs, method_defs,
						   bucket_idx);
		if (attr_max_bucket < 0)
			continue;

		hash = kzalloc(sizeof(*hash) +
			       ALIGN(sizeof(*hash->attrs) * (attr_max_bucket + 1),
				     sizeof(long)) +
			       BITS_TO_LONGS(attr_max_bucket + 1) * sizeof(long),
			       GFP_KERNEL);
		if (!hash) {
			res = -ENOMEM;
			goto free;
		}
		hash->num_attrs = attr_max_bucket + 1;
		method->num_child_attrs += hash->num_attrs;
		hash->mandatory_attrs_bitmask = (void *)(hash + 1) +
						 ALIGN(sizeof(*hash->attrs) *
						       (attr_max_bucket + 1),
						       sizeof(long));

		method->attr_buckets[bucket_idx] = hash;

		do {
			size_t			 num_attr_defs;
			struct uverbs_attr_spec	*attr;
			bool attr_obj_with_special_access;

			num_attr_defs =
				get_attrs_above_id(attr_defs,
						   num_method_defs,
						   method_defs,
						   bucket_idx,
						   &min_id);
			/* Last attr in bucket */
			if (!num_attr_defs)
				break;

			if (num_attr_defs > 1) {
				/*
				 * We don't allow two attribute definitions for
				 * the same attribute. This is usually a
				 * programmer error. If required, it's better to
				 * just add a new attribute to capture the new
				 * semantics.
				 */
				res = -EEXIST;
				goto free;
			}

			attr = &hash->attrs[min_id];
			memcpy(attr, &attr_defs[0]->attr, sizeof(*attr));

			attr_obj_with_special_access = IS_ATTR_OBJECT(attr) &&
				   (attr->obj.access == UVERBS_ACCESS_NEW ||
				    attr->obj.access == UVERBS_ACCESS_DESTROY);
			num_of_singularities +=  !!attr_obj_with_special_access;
			if (WARN(num_of_singularities > 1,
				 "ib_uverbs: Method contains more than one object attr (%d) with new/destroy access\n",
				 min_id) ||
			    WARN(attr_obj_with_special_access &&
				 !(attr->flags & UVERBS_ATTR_SPEC_F_MANDATORY),
				 "ib_uverbs: Tried to merge attr (%d) but it's an object with new/destroy access but isn't mandatory\n",
				 min_id) ||
			    WARN(IS_ATTR_OBJECT(attr) &&
				 attr->flags & UVERBS_ATTR_SPEC_F_MIN_SZ_OR_ZERO,
				 "ib_uverbs: Tried to merge attr (%d) but it's an object with min_sz flag\n",
				 min_id)) {
				res = -EINVAL;
				goto free;
			}

			if (attr->flags & UVERBS_ATTR_SPEC_F_MANDATORY)
				set_bit(min_id, hash->mandatory_attrs_bitmask);
			min_id++;

		} while (1);
	}
	kfree(attr_defs);
	return method;

free:
	kfree(attr_defs);
free_method:
	free_method(method);
	return ERR_PTR(res);
}

static void free_object(struct uverbs_object_spec *object)
{
	unsigned int i, j;

	if (!object)
		return;

	for (i = 0; i < object->num_buckets; i++) {
		struct uverbs_method_spec_hash	*method_buckets =
			object->method_buckets[i];

		if (!method_buckets)
			continue;

		for (j = 0; j < method_buckets->num_methods; j++)
			free_method(method_buckets->methods[j]);

		kfree(method_buckets);
	}

	kfree(object);
}

/*
 * This function gets array of size @num_object_defs which contains pointers to
 * object definitions @object_defs. The function allocated an
 * uverbs_object_spec structure and initialize its number of buckets and the
 * elements in buckets to the correct methods. While doing that, it
 * sorts out the correct relationship between conflicts in the same method.
 */
static struct uverbs_object_spec *build_object_with_methods(const struct uverbs_object_def **object_defs,
							    size_t num_object_defs)
{
	u16 bucket_idx;
	int max_method_buckets = 0;
	u16 num_method_buckets = 0;
	int res = 0;
	struct uverbs_object_spec *object = NULL;
	const struct uverbs_method_def **method_defs;

	max_method_buckets = find_max_method_ns_id(num_object_defs, object_defs);
	if (max_method_buckets >= 0)
		num_method_buckets = max_method_buckets + 1;

	object = kzalloc(sizeof(*object) +
			 num_method_buckets *
			 sizeof(*object->method_buckets), GFP_KERNEL);
	if (!object)
		return ERR_PTR(-ENOMEM);

	object->num_buckets = num_method_buckets;
	method_defs = kcalloc(num_object_defs, sizeof(*method_defs), GFP_KERNEL);
	if (!method_defs) {
		res = -ENOMEM;
		goto free_object;
	}

	for (bucket_idx = 0; bucket_idx < object->num_buckets; bucket_idx++) {
		short min_id = SHRT_MIN;
		int methods_max_bucket = 0;
		struct uverbs_method_spec_hash *hash = NULL;

		methods_max_bucket = find_max_method_id(num_object_defs, object_defs,
							bucket_idx);
		if (methods_max_bucket < 0)
			continue;

		hash = kzalloc(sizeof(*hash) +
			       sizeof(*hash->methods) * (methods_max_bucket + 1),
			       GFP_KERNEL);
		if (!hash) {
			res = -ENOMEM;
			goto free;
		}

		hash->num_methods = methods_max_bucket + 1;
		object->method_buckets[bucket_idx] = hash;

		do {
			size_t				num_method_defs;
			struct uverbs_method_spec	*method;
			int i;

			num_method_defs =
				get_methods_above_id(method_defs,
						     num_object_defs,
						     object_defs,
						     bucket_idx,
						     &min_id);
			/* Last method in bucket */
			if (!num_method_defs)
				break;

			method = build_method_with_attrs(method_defs,
							 num_method_defs);
			if (IS_ERR(method)) {
				res = PTR_ERR(method);
				goto free;
			}

			/*
			 * The last tree which is given as an argument to the
			 * merge overrides previous method handler.
			 * Therefore, we iterate backwards and search for the
			 * first handler which != NULL. This also defines the
			 * set of flags used for this handler.
			 */
			for (i = num_method_defs - 1;
			     i >= 0 && !method_defs[i]->handler; i--)
				;
			hash->methods[min_id++] = method;
			/* NULL handler isn't allowed */
			if (WARN(i < 0,
				 "ib_uverbs: tried to merge function id %d, but all handlers are NULL\n",
				 min_id)) {
				res = -EINVAL;
				goto free;
			}
			method->handler = method_defs[i]->handler;
			method->flags = method_defs[i]->flags;

		} while (1);
	}
	kfree(method_defs);
	return object;

free:
	kfree(method_defs);
free_object:
	free_object(object);
	return ERR_PTR(res);
}

void uverbs_free_spec_tree(struct uverbs_root_spec *root)
{
	unsigned int i, j;

	if (!root)
		return;

	for (i = 0; i < root->num_buckets; i++) {
		struct uverbs_object_spec_hash *object_hash =
			root->object_buckets[i];

		if (!object_hash)
			continue;

		for (j = 0; j < object_hash->num_objects; j++)
			free_object(object_hash->objects[j]);

		kfree(object_hash);
	}

	kfree(root);
}
EXPORT_SYMBOL(uverbs_free_spec_tree);

struct uverbs_root_spec *uverbs_alloc_spec_tree(unsigned int num_trees,
						const struct uverbs_object_tree_def **trees)
{
	u16 bucket_idx;
	short max_object_buckets = 0;
	size_t num_objects_buckets = 0;
	struct uverbs_root_spec *root_spec = NULL;
	const struct uverbs_object_def **object_defs;
	int i;
	int res = 0;

	max_object_buckets = find_max_object_ns_id(num_trees, trees);
	/*
	 * Devices which don't want to support ib_uverbs, should just allocate
	 * an empty parsing tree. Every user-space command won't hit any valid
	 * entry in the parsing tree and thus will fail.
	 */
	if (max_object_buckets >= 0)
		num_objects_buckets = max_object_buckets + 1;

	root_spec = kzalloc(sizeof(*root_spec) +
			    num_objects_buckets * sizeof(*root_spec->object_buckets),
			    GFP_KERNEL);
	if (!root_spec)
		return ERR_PTR(-ENOMEM);
	root_spec->num_buckets = num_objects_buckets;

	object_defs = kcalloc(num_trees, sizeof(*object_defs),
			      GFP_KERNEL);
	if (!object_defs) {
		res = -ENOMEM;
		goto free_root;
	}

	for (bucket_idx = 0; bucket_idx < root_spec->num_buckets; bucket_idx++) {
		short min_id = SHRT_MIN;
		short objects_max_bucket;
		struct uverbs_object_spec_hash *hash = NULL;

		objects_max_bucket = find_max_object_id(num_trees, trees,
							bucket_idx);
		if (objects_max_bucket < 0)
			continue;

		hash = kzalloc(sizeof(*hash) +
			       sizeof(*hash->objects) * (objects_max_bucket + 1),
			       GFP_KERNEL);
		if (!hash) {
			res = -ENOMEM;
			goto free;
		}
		hash->num_objects = objects_max_bucket + 1;
		root_spec->object_buckets[bucket_idx] = hash;

		do {
			size_t				num_object_defs;
			struct uverbs_object_spec	*object;

			num_object_defs = get_objects_above_id(object_defs,
							       num_trees,
							       trees,
							       bucket_idx,
							       &min_id);
			/* Last object in bucket */
			if (!num_object_defs)
				break;

			object = build_object_with_methods(object_defs,
							   num_object_defs);
			if (IS_ERR(object)) {
				res = PTR_ERR(object);
				goto free;
			}

			/*
			 * The last tree which is given as an argument to the
			 * merge overrides previous object's type_attrs.
			 * Therefore, we iterate backwards and search for the
			 * first type_attrs which != NULL.
			 */
			for (i = num_object_defs - 1;
			     i >= 0 && !object_defs[i]->type_attrs; i--)
				;
			/*
			 * NULL is a valid type_attrs. It means an object we
			 * can't instantiate (like DEVICE).
			 */
			object->type_attrs = i < 0 ? NULL :
				object_defs[i]->type_attrs;

			hash->objects[min_id++] = object;
		} while (1);
	}

	kfree(object_defs);
	return root_spec;

free:
	kfree(object_defs);
free_root:
	uverbs_free_spec_tree(root_spec);
	return ERR_PTR(res);
}
EXPORT_SYMBOL(uverbs_alloc_spec_tree);