xref: /openbmc/linux/include/rdma/uverbs_ioctl.h (revision 2359ccdd)
1 /*
2  * Copyright (c) 2017, Mellanox Technologies inc.  All rights reserved.
3  *
4  * This software is available to you under a choice of one of two
5  * licenses.  You may choose to be licensed under the terms of the GNU
6  * General Public License (GPL) Version 2, available from the file
7  * COPYING in the main directory of this source tree, or the
8  * OpenIB.org BSD license below:
9  *
10  *     Redistribution and use in source and binary forms, with or
11  *     without modification, are permitted provided that the following
12  *     conditions are met:
13  *
14  *      - Redistributions of source code must retain the above
15  *        copyright notice, this list of conditions and the following
16  *        disclaimer.
17  *
18  *      - Redistributions in binary form must reproduce the above
19  *        copyright notice, this list of conditions and the following
20  *        disclaimer in the documentation and/or other materials
21  *        provided with the distribution.
22  *
23  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
24  * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
25  * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
26  * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
27  * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
28  * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
29  * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
30  * SOFTWARE.
31  */
32 
33 #ifndef _UVERBS_IOCTL_
34 #define _UVERBS_IOCTL_
35 
36 #include <rdma/uverbs_types.h>
37 #include <linux/uaccess.h>
38 #include <rdma/rdma_user_ioctl.h>
39 #include <rdma/ib_user_ioctl_verbs.h>
40 #include <rdma/ib_user_ioctl_cmds.h>
41 
42 /*
43  * =======================================
44  *	Verbs action specifications
45  * =======================================
46  */
47 
48 enum uverbs_attr_type {
49 	UVERBS_ATTR_TYPE_NA,
50 	UVERBS_ATTR_TYPE_PTR_IN,
51 	UVERBS_ATTR_TYPE_PTR_OUT,
52 	UVERBS_ATTR_TYPE_IDR,
53 	UVERBS_ATTR_TYPE_FD,
54 	UVERBS_ATTR_TYPE_ENUM_IN,
55 };
56 
57 enum uverbs_obj_access {
58 	UVERBS_ACCESS_READ,
59 	UVERBS_ACCESS_WRITE,
60 	UVERBS_ACCESS_NEW,
61 	UVERBS_ACCESS_DESTROY
62 };
63 
64 enum {
65 	UVERBS_ATTR_SPEC_F_MANDATORY	= 1U << 0,
66 	/* Support extending attributes by length, validate all unknown size == zero  */
67 	UVERBS_ATTR_SPEC_F_MIN_SZ_OR_ZERO = 1U << 1,
68 };
69 
70 /* Specification of a single attribute inside the ioctl message */
71 struct uverbs_attr_spec {
72 	union {
73 		/* Header shared by all following union members - to reduce space. */
74 		struct {
75 			enum uverbs_attr_type		type;
76 			/* Combination of bits from enum UVERBS_ATTR_SPEC_F_XXXX */
77 			u8				flags;
78 		};
79 		struct {
80 			enum uverbs_attr_type		type;
81 			/* Combination of bits from enum UVERBS_ATTR_SPEC_F_XXXX */
82 			u8				flags;
83 			/* Current known size to kernel */
84 			u16				len;
85 			/* User isn't allowed to provide something < min_len */
86 			u16				min_len;
87 		} ptr;
88 		struct {
89 			enum uverbs_attr_type		type;
90 			/* Combination of bits from enum UVERBS_ATTR_SPEC_F_XXXX */
91 			u8				flags;
92 			/*
93 			 * higher bits mean the namespace and lower bits mean
94 			 * the type id within the namespace.
95 			 */
96 			u16			obj_type;
97 			u8			access;
98 		} obj;
99 		struct {
100 			enum uverbs_attr_type		type;
101 			/* Combination of bits from enum UVERBS_ATTR_SPEC_F_XXXX */
102 			u8				flags;
103 			u8				num_elems;
104 			/*
105 			 * The enum attribute can select one of the attributes
106 			 * contained in the ids array. Currently only PTR_IN
107 			 * attributes are supported in the ids array.
108 			 */
109 			const struct uverbs_attr_spec	*ids;
110 		} enum_def;
111 	};
112 };
113 
114 struct uverbs_attr_spec_hash {
115 	size_t				num_attrs;
116 	unsigned long			*mandatory_attrs_bitmask;
117 	struct uverbs_attr_spec		attrs[0];
118 };
119 
120 struct uverbs_attr_bundle;
121 struct ib_uverbs_file;
122 
123 enum {
124 	/*
125 	 * Action marked with this flag creates a context (or root for all
126 	 * objects).
127 	 */
128 	UVERBS_ACTION_FLAG_CREATE_ROOT = 1U << 0,
129 };
130 
131 struct uverbs_method_spec {
132 	/* Combination of bits from enum UVERBS_ACTION_FLAG_XXXX */
133 	u32						flags;
134 	size_t						num_buckets;
135 	size_t						num_child_attrs;
136 	int (*handler)(struct ib_device *ib_dev, struct ib_uverbs_file *ufile,
137 		       struct uverbs_attr_bundle *ctx);
138 	struct uverbs_attr_spec_hash		*attr_buckets[0];
139 };
140 
141 struct uverbs_method_spec_hash {
142 	size_t					num_methods;
143 	struct uverbs_method_spec		*methods[0];
144 };
145 
146 struct uverbs_object_spec {
147 	const struct uverbs_obj_type		*type_attrs;
148 	size_t					num_buckets;
149 	struct uverbs_method_spec_hash		*method_buckets[0];
150 };
151 
152 struct uverbs_object_spec_hash {
153 	size_t					num_objects;
154 	struct uverbs_object_spec		*objects[0];
155 };
156 
157 struct uverbs_root_spec {
158 	size_t					num_buckets;
159 	struct uverbs_object_spec_hash		*object_buckets[0];
160 };
161 
162 /*
163  * =======================================
164  *	Verbs definitions
165  * =======================================
166  */
167 
168 struct uverbs_attr_def {
169 	u16                           id;
170 	struct uverbs_attr_spec       attr;
171 };
172 
173 struct uverbs_method_def {
174 	u16                                  id;
175 	/* Combination of bits from enum UVERBS_ACTION_FLAG_XXXX */
176 	u32				     flags;
177 	size_t				     num_attrs;
178 	const struct uverbs_attr_def * const (*attrs)[];
179 	int (*handler)(struct ib_device *ib_dev, struct ib_uverbs_file *ufile,
180 		       struct uverbs_attr_bundle *ctx);
181 };
182 
183 struct uverbs_object_def {
184 	u16					 id;
185 	const struct uverbs_obj_type	        *type_attrs;
186 	size_t				         num_methods;
187 	const struct uverbs_method_def * const (*methods)[];
188 };
189 
190 struct uverbs_object_tree_def {
191 	size_t					 num_objects;
192 	const struct uverbs_object_def * const (*objects)[];
193 };
194 
195 #define UA_FLAGS(_flags)  .flags = _flags
196 #define __UVERBS_ATTR0(_id, _type, _fld, _attr, ...)              \
197 	((const struct uverbs_attr_def)				  \
198 	 {.id = _id, .attr = {{._fld = {.type = _type, _attr, .flags = 0, } }, } })
199 #define __UVERBS_ATTR1(_id, _type, _fld, _attr, _extra1, ...)      \
200 	((const struct uverbs_attr_def)				  \
201 	 {.id = _id, .attr = {{._fld = {.type = _type, _attr, _extra1 } },} })
202 #define __UVERBS_ATTR2(_id, _type, _fld, _attr, _extra1, _extra2)    \
203 	((const struct uverbs_attr_def)				  \
204 	 {.id = _id, .attr = {{._fld = {.type = _type, _attr, _extra1, _extra2 } },} })
205 #define __UVERBS_ATTR(_id, _type, _fld, _attr, _extra1, _extra2, _n, ...)	\
206 	__UVERBS_ATTR##_n(_id, _type, _fld, _attr, _extra1, _extra2)
207 
208 #define UVERBS_ATTR_TYPE(_type)					\
209 	.min_len = sizeof(_type), .len = sizeof(_type)
210 #define UVERBS_ATTR_STRUCT(_type, _last)			\
211 	.min_len = ((uintptr_t)(&((_type *)0)->_last + 1)), .len = sizeof(_type)
212 #define UVERBS_ATTR_SIZE(_min_len, _len)			\
213 	.min_len = _min_len, .len = _len
214 
215 /*
216  * In new compiler, UVERBS_ATTR could be simplified by declaring it as
217  * [_id] = {.type = _type, .len = _len, ##__VA_ARGS__}
218  * But since we support older compilers too, we need the more complex code.
219  */
220 #define UVERBS_ATTR(_id, _type, _fld, _attr, ...)			\
221 	__UVERBS_ATTR(_id, _type, _fld, _attr, ##__VA_ARGS__, 2, 1, 0)
222 #define UVERBS_ATTR_PTR_IN_SZ(_id, _len, ...)				\
223 	UVERBS_ATTR(_id, UVERBS_ATTR_TYPE_PTR_IN, ptr, _len, ##__VA_ARGS__)
224 /* If sizeof(_type) <= sizeof(u64), this will be inlined rather than a pointer */
225 #define UVERBS_ATTR_PTR_IN(_id, _type, ...)				\
226 	UVERBS_ATTR_PTR_IN_SZ(_id, _type, ##__VA_ARGS__)
227 #define UVERBS_ATTR_PTR_OUT_SZ(_id, _len, ...)				\
228 	UVERBS_ATTR(_id, UVERBS_ATTR_TYPE_PTR_OUT, ptr, _len, ##__VA_ARGS__)
229 #define UVERBS_ATTR_PTR_OUT(_id, _type, ...)				\
230 	UVERBS_ATTR_PTR_OUT_SZ(_id, _type, ##__VA_ARGS__)
231 #define UVERBS_ATTR_ENUM_IN(_id, _enum_arr, ...)			\
232 	UVERBS_ATTR(_id, UVERBS_ATTR_TYPE_ENUM_IN, enum_def,		\
233 		    .ids = (_enum_arr),					\
234 		    .num_elems = ARRAY_SIZE(_enum_arr), ##__VA_ARGS__)
235 
236 /*
237  * In new compiler, UVERBS_ATTR_IDR (and FD) could be simplified by declaring
238  * it as
239  * {.id = _id,								\
240  *  .attr {.type = __obj_class,						\
241  *         .obj = {.obj_type = _idr_type,				\
242  *                       .access = _access                              \
243  *                }, ##__VA_ARGS__ } }
244  * But since we support older compilers too, we need the more complex code.
245  */
246 #define ___UVERBS_ATTR_OBJ0(_id, _obj_class, _obj_type, _access, ...)\
247 	((const struct uverbs_attr_def)					\
248 	{.id = _id,							\
249 	 .attr = { {.obj = {.type = _obj_class, .obj_type = _obj_type,	\
250 			    .access = _access, .flags = 0 } }, } })
251 #define ___UVERBS_ATTR_OBJ1(_id, _obj_class, _obj_type, _access, _flags)\
252 	((const struct uverbs_attr_def)					\
253 	{.id = _id,							\
254 	.attr = { {.obj = {.type = _obj_class, .obj_type = _obj_type,	\
255 			   .access = _access, _flags} }, } })
256 #define ___UVERBS_ATTR_OBJ(_id, _obj_class, _obj_type, _access, _flags, \
257 			   _n, ...)					\
258 	___UVERBS_ATTR_OBJ##_n(_id, _obj_class, _obj_type, _access, _flags)
259 #define __UVERBS_ATTR_OBJ(_id, _obj_class, _obj_type, _access, ...)	\
260 	___UVERBS_ATTR_OBJ(_id, _obj_class, _obj_type, _access,		\
261 			   ##__VA_ARGS__, 1, 0)
262 #define UVERBS_ATTR_IDR(_id, _idr_type, _access, ...)			 \
263 	__UVERBS_ATTR_OBJ(_id, UVERBS_ATTR_TYPE_IDR, _idr_type, _access,\
264 			  ##__VA_ARGS__)
265 #define UVERBS_ATTR_FD(_id, _fd_type, _access, ...)			\
266 	__UVERBS_ATTR_OBJ(_id, UVERBS_ATTR_TYPE_FD, _fd_type,		\
267 			  (_access) + BUILD_BUG_ON_ZERO(		\
268 				(_access) != UVERBS_ACCESS_NEW &&	\
269 				(_access) != UVERBS_ACCESS_READ),	\
270 			  ##__VA_ARGS__)
271 #define DECLARE_UVERBS_ATTR_SPEC(_name, ...)				\
272 	const struct uverbs_attr_def _name = __VA_ARGS__
273 
274 #define DECLARE_UVERBS_ENUM(_name, ...)					\
275 	const struct uverbs_enum_spec _name = {				\
276 		.len = ARRAY_SIZE(((struct uverbs_attr_spec[]){__VA_ARGS__})),\
277 		.ids = {__VA_ARGS__},					\
278 	}
279 #define _UVERBS_METHOD_ATTRS_SZ(...)					\
280 	(sizeof((const struct uverbs_attr_def * const []){__VA_ARGS__}) /\
281 	 sizeof(const struct uverbs_attr_def *))
282 #define _UVERBS_METHOD(_id, _handler, _flags, ...)			\
283 	((const struct uverbs_method_def) {				\
284 	 .id = _id,							\
285 	 .flags = _flags,						\
286 	 .handler = _handler,						\
287 	 .num_attrs = _UVERBS_METHOD_ATTRS_SZ(__VA_ARGS__),		\
288 	 .attrs = &(const struct uverbs_attr_def * const []){__VA_ARGS__} })
289 #define DECLARE_UVERBS_METHOD(_name, _id, _handler, ...)		\
290 	const struct uverbs_method_def _name =				\
291 		_UVERBS_METHOD(_id, _handler, 0, ##__VA_ARGS__)
292 #define DECLARE_UVERBS_CTX_METHOD(_name, _id, _handler, _flags, ...)	\
293 	const struct uverbs_method_def _name =				\
294 		_UVERBS_METHOD(_id, _handler,				\
295 			       UVERBS_ACTION_FLAG_CREATE_ROOT,		\
296 			       ##__VA_ARGS__)
297 #define _UVERBS_OBJECT_METHODS_SZ(...)					\
298 	(sizeof((const struct uverbs_method_def * const []){__VA_ARGS__}) / \
299 	 sizeof(const struct uverbs_method_def *))
300 #define _UVERBS_OBJECT(_id, _type_attrs, ...)				\
301 	((const struct uverbs_object_def) {				\
302 	 .id = _id,							\
303 	 .type_attrs = _type_attrs,					\
304 	 .num_methods = _UVERBS_OBJECT_METHODS_SZ(__VA_ARGS__),		\
305 	 .methods = &(const struct uverbs_method_def * const []){__VA_ARGS__} })
306 #define DECLARE_UVERBS_OBJECT(_name, _id, _type_attrs, ...)		\
307 	const struct uverbs_object_def _name =				\
308 		_UVERBS_OBJECT(_id, _type_attrs, ##__VA_ARGS__)
309 #define _UVERBS_TREE_OBJECTS_SZ(...)					\
310 	(sizeof((const struct uverbs_object_def * const []){__VA_ARGS__}) / \
311 	 sizeof(const struct uverbs_object_def *))
312 #define _UVERBS_OBJECT_TREE(...)					\
313 	((const struct uverbs_object_tree_def) {			\
314 	 .num_objects = _UVERBS_TREE_OBJECTS_SZ(__VA_ARGS__),		\
315 	 .objects = &(const struct uverbs_object_def * const []){__VA_ARGS__} })
316 #define DECLARE_UVERBS_OBJECT_TREE(_name, ...)				\
317 	const struct uverbs_object_tree_def _name =			\
318 		_UVERBS_OBJECT_TREE(__VA_ARGS__)
319 
320 /* =================================================
321  *              Parsing infrastructure
322  * =================================================
323  */
324 
325 struct uverbs_ptr_attr {
326 	u64		data;
327 	u16		len;
328 	/* Combination of bits from enum UVERBS_ATTR_F_XXXX */
329 	u16		flags;
330 	u8		enum_id;
331 };
332 
333 struct uverbs_obj_attr {
334 	/* pointer to the kernel descriptor -> type, access, etc */
335 	const struct uverbs_obj_type	*type;
336 	struct ib_uobject		*uobject;
337 	/* fd or id in idr of this object */
338 	int				id;
339 };
340 
341 struct uverbs_attr {
342 	/*
343 	 * pointer to the user-space given attribute, in order to write the
344 	 * new uobject's id or update flags.
345 	 */
346 	struct ib_uverbs_attr __user	*uattr;
347 	union {
348 		struct uverbs_ptr_attr	ptr_attr;
349 		struct uverbs_obj_attr	obj_attr;
350 	};
351 };
352 
353 struct uverbs_attr_bundle_hash {
354 	/* if bit i is set, it means attrs[i] contains valid information */
355 	unsigned long *valid_bitmap;
356 	size_t num_attrs;
357 	/*
358 	 * arrays of attributes, each element corresponds to the specification
359 	 * of the attribute in the same index.
360 	 */
361 	struct uverbs_attr *attrs;
362 };
363 
364 struct uverbs_attr_bundle {
365 	size_t				num_buckets;
366 	struct uverbs_attr_bundle_hash  hash[];
367 };
368 
369 static inline bool uverbs_attr_is_valid_in_hash(const struct uverbs_attr_bundle_hash *attrs_hash,
370 						unsigned int idx)
371 {
372 	return test_bit(idx, attrs_hash->valid_bitmap);
373 }
374 
375 static inline bool uverbs_attr_is_valid(const struct uverbs_attr_bundle *attrs_bundle,
376 					unsigned int idx)
377 {
378 	u16 idx_bucket = idx >>	UVERBS_ID_NS_SHIFT;
379 
380 	if (attrs_bundle->num_buckets <= idx_bucket)
381 		return false;
382 
383 	return uverbs_attr_is_valid_in_hash(&attrs_bundle->hash[idx_bucket],
384 					    idx & ~UVERBS_ID_NS_MASK);
385 }
386 
387 #define IS_UVERBS_COPY_ERR(_ret)		((_ret) && (_ret) != -ENOENT)
388 
389 static inline const struct uverbs_attr *uverbs_attr_get(const struct uverbs_attr_bundle *attrs_bundle,
390 							u16 idx)
391 {
392 	u16 idx_bucket = idx >>	UVERBS_ID_NS_SHIFT;
393 
394 	if (!uverbs_attr_is_valid(attrs_bundle, idx))
395 		return ERR_PTR(-ENOENT);
396 
397 	return &attrs_bundle->hash[idx_bucket].attrs[idx & ~UVERBS_ID_NS_MASK];
398 }
399 
400 static inline int uverbs_attr_get_enum_id(const struct uverbs_attr_bundle *attrs_bundle,
401 					  u16 idx)
402 {
403 	const struct uverbs_attr *attr = uverbs_attr_get(attrs_bundle, idx);
404 
405 	if (IS_ERR(attr))
406 		return PTR_ERR(attr);
407 
408 	return attr->ptr_attr.enum_id;
409 }
410 
411 static inline void *uverbs_attr_get_obj(const struct uverbs_attr_bundle *attrs_bundle,
412 					u16 idx)
413 {
414 	struct ib_uobject *uobj =
415 		uverbs_attr_get(attrs_bundle, idx)->obj_attr.uobject;
416 
417 	if (IS_ERR(uobj))
418 		return uobj;
419 
420 	return uobj->object;
421 }
422 
423 static inline int uverbs_copy_to(const struct uverbs_attr_bundle *attrs_bundle,
424 				 size_t idx, const void *from, size_t size)
425 {
426 	const struct uverbs_attr *attr = uverbs_attr_get(attrs_bundle, idx);
427 	u16 flags;
428 	size_t min_size;
429 
430 	if (IS_ERR(attr))
431 		return PTR_ERR(attr);
432 
433 	min_size = min_t(size_t, attr->ptr_attr.len, size);
434 	if (copy_to_user(u64_to_user_ptr(attr->ptr_attr.data), from, min_size))
435 		return -EFAULT;
436 
437 	flags = attr->ptr_attr.flags | UVERBS_ATTR_F_VALID_OUTPUT;
438 	if (put_user(flags, &attr->uattr->flags))
439 		return -EFAULT;
440 
441 	return 0;
442 }
443 
444 static inline bool uverbs_attr_ptr_is_inline(const struct uverbs_attr *attr)
445 {
446 	return attr->ptr_attr.len <= sizeof(attr->ptr_attr.data);
447 }
448 
449 static inline int _uverbs_copy_from(void *to,
450 				    const struct uverbs_attr_bundle *attrs_bundle,
451 				    size_t idx,
452 				    size_t size)
453 {
454 	const struct uverbs_attr *attr = uverbs_attr_get(attrs_bundle, idx);
455 
456 	if (IS_ERR(attr))
457 		return PTR_ERR(attr);
458 
459 	/*
460 	 * Validation ensures attr->ptr_attr.len >= size. If the caller is
461 	 * using UVERBS_ATTR_SPEC_F_MIN_SZ_OR_ZERO then it must call
462 	 * uverbs_copy_from_or_zero.
463 	 */
464 	if (unlikely(size < attr->ptr_attr.len))
465 		return -EINVAL;
466 
467 	if (uverbs_attr_ptr_is_inline(attr))
468 		memcpy(to, &attr->ptr_attr.data, attr->ptr_attr.len);
469 	else if (copy_from_user(to, u64_to_user_ptr(attr->ptr_attr.data),
470 				attr->ptr_attr.len))
471 		return -EFAULT;
472 
473 	return 0;
474 }
475 
476 static inline int _uverbs_copy_from_or_zero(void *to,
477 					    const struct uverbs_attr_bundle *attrs_bundle,
478 					    size_t idx,
479 					    size_t size)
480 {
481 	const struct uverbs_attr *attr = uverbs_attr_get(attrs_bundle, idx);
482 	size_t min_size;
483 
484 	if (IS_ERR(attr))
485 		return PTR_ERR(attr);
486 
487 	min_size = min_t(size_t, size, attr->ptr_attr.len);
488 
489 	if (uverbs_attr_ptr_is_inline(attr))
490 		memcpy(to, &attr->ptr_attr.data, min_size);
491 	else if (copy_from_user(to, u64_to_user_ptr(attr->ptr_attr.data),
492 				min_size))
493 		return -EFAULT;
494 
495 	if (size > min_size)
496 		memset(to + min_size, 0, size - min_size);
497 
498 	return 0;
499 }
500 
501 #define uverbs_copy_from(to, attrs_bundle, idx)				      \
502 	_uverbs_copy_from(to, attrs_bundle, idx, sizeof(*to))
503 
504 #define uverbs_copy_from_or_zero(to, attrs_bundle, idx)			      \
505 	_uverbs_copy_from_or_zero(to, attrs_bundle, idx, sizeof(*to))
506 
507 /* =================================================
508  *	 Definitions -> Specs infrastructure
509  * =================================================
510  */
511 
512 /*
513  * uverbs_alloc_spec_tree - Merges different common and driver specific feature
514  *	into one parsing tree that every uverbs command will be parsed upon.
515  *
516  * @num_trees: Number of trees in the array @trees.
517  * @trees: Array of pointers to tree root definitions to merge. Each such tree
518  *	   possibly contains objects, methods and attributes definitions.
519  *
520  * Returns:
521  *	uverbs_root_spec *: The root of the merged parsing tree.
522  *	On error, we return an error code. Error is checked via IS_ERR.
523  *
524  * The following merges could take place:
525  * a. Two trees representing the same method with different handler
526  *	-> We take the handler of the tree that its handler != NULL
527  *	   and its index in the trees array is greater. The incentive for that
528  *	   is that developers are expected to first merge common trees and then
529  *	   merge trees that gives specialized the behaviour.
530  * b. Two trees representing the same object with different
531  *    type_attrs (struct uverbs_obj_type):
532  *	-> We take the type_attrs of the tree that its type_attr != NULL
533  *	   and its index in the trees array is greater. This could be used
534  *	   in order to override the free function, allocation size, etc.
535  * c. Two trees representing the same method attribute (same id but possibly
536  *    different attributes):
537  *	-> ERROR (-ENOENT), we believe that's not the programmer's intent.
538  *
539  * An object without any methods is considered invalid and will abort the
540  * function with -ENOENT error.
541  */
542 #if IS_ENABLED(CONFIG_INFINIBAND_USER_ACCESS)
543 struct uverbs_root_spec *uverbs_alloc_spec_tree(unsigned int num_trees,
544 						const struct uverbs_object_tree_def **trees);
545 void uverbs_free_spec_tree(struct uverbs_root_spec *root);
546 #else
547 static inline struct uverbs_root_spec *uverbs_alloc_spec_tree(unsigned int num_trees,
548 							      const struct uverbs_object_tree_def **trees)
549 {
550 	return NULL;
551 }
552 
553 static inline void uverbs_free_spec_tree(struct uverbs_root_spec *root)
554 {
555 }
556 #endif
557 
558 #endif
559