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1/*
2 * Copyright (c) 2006-2009 VMware, Inc., Palo Alto, CA., USA
3 * Copyright (c) 2012 David Airlie <airlied@linux.ie>
4 * Copyright (c) 2013 David Herrmann <dh.herrmann@gmail.com>
5 *
6 * Permission is hereby granted, free of charge, to any person obtaining a
7 * copy of this software and associated documentation files (the "Software"),
8 * to deal in the Software without restriction, including without limitation
9 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
10 * and/or sell copies of the Software, and to permit persons to whom the
11 * Software is furnished to do so, subject to the following conditions:
12 *
13 * The above copyright notice and this permission notice shall be included in
14 * all copies or substantial portions of the Software.
15 *
16 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
17 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
18 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
19 * THE COPYRIGHT HOLDER(S) OR AUTHOR(S) BE LIABLE FOR ANY CLAIM, DAMAGES OR
20 * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
21 * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
22 * OTHER DEALINGS IN THE SOFTWARE.
23 */
24
25#include <drm/drmP.h>
26#include <drm/drm_mm.h>
27#include <drm/drm_vma_manager.h>
28#include <linux/fs.h>
29#include <linux/mm.h>
30#include <linux/module.h>
31#include <linux/rbtree.h>
32#include <linux/slab.h>
33#include <linux/spinlock.h>
34#include <linux/types.h>
35
36/**
37 * DOC: vma offset manager
38 *
39 * The vma-manager is responsible to map arbitrary driver-dependent memory
40 * regions into the linear user address-space. It provides offsets to the
41 * caller which can then be used on the address_space of the drm-device. It
42 * takes care to not overlap regions, size them appropriately and to not
43 * confuse mm-core by inconsistent fake vm_pgoff fields.
44 * Drivers shouldn't use this for object placement in VMEM. This manager should
45 * only be used to manage mappings into linear user-space VMs.
46 *
47 * We use drm_mm as backend to manage object allocations. But it is highly
48 * optimized for alloc/free calls, not lookups. Hence, we use an rb-tree to
49 * speed up offset lookups.
50 *
51 * You must not use multiple offset managers on a single address_space.
52 * Otherwise, mm-core will be unable to tear down memory mappings as the VM will
53 * no longer be linear.
54 *
55 * This offset manager works on page-based addresses. That is, every argument
56 * and return code (with the exception of drm_vma_node_offset_addr()) is given
57 * in number of pages, not number of bytes. That means, object sizes and offsets
58 * must always be page-aligned (as usual).
59 * If you want to get a valid byte-based user-space address for a given offset,
60 * please see drm_vma_node_offset_addr().
61 *
62 * Additionally to offset management, the vma offset manager also handles access
63 * management. For every open-file context that is allowed to access a given
64 * node, you must call drm_vma_node_allow(). Otherwise, an mmap() call on this
65 * open-file with the offset of the node will fail with -EACCES. To revoke
66 * access again, use drm_vma_node_revoke(). However, the caller is responsible
67 * for destroying already existing mappings, if required.
68 */
69
70/**
71 * drm_vma_offset_manager_init - Initialize new offset-manager
72 * @mgr: Manager object
73 * @page_offset: Offset of available memory area (page-based)
74 * @size: Size of available address space range (page-based)
75 *
76 * Initialize a new offset-manager. The offset and area size available for the
77 * manager are given as @page_offset and @size. Both are interpreted as
78 * page-numbers, not bytes.
79 *
80 * Adding/removing nodes from the manager is locked internally and protected
81 * against concurrent access. However, node allocation and destruction is left
82 * for the caller. While calling into the vma-manager, a given node must
83 * always be guaranteed to be referenced.
84 */
85void drm_vma_offset_manager_init(struct drm_vma_offset_manager *mgr,
86 unsigned long page_offset, unsigned long size)
87{
88 rwlock_init(&mgr->vm_lock);
89 mgr->vm_addr_space_rb = RB_ROOT;
90 drm_mm_init(&mgr->vm_addr_space_mm, page_offset, size);
91}
92EXPORT_SYMBOL(drm_vma_offset_manager_init);
93
94/**
95 * drm_vma_offset_manager_destroy() - Destroy offset manager
96 * @mgr: Manager object
97 *
98 * Destroy an object manager which was previously created via
99 * drm_vma_offset_manager_init(). The caller must remove all allocated nodes
100 * before destroying the manager. Otherwise, drm_mm will refuse to free the
101 * requested resources.
102 *
103 * The manager must not be accessed after this function is called.
104 */
105void drm_vma_offset_manager_destroy(struct drm_vma_offset_manager *mgr)
106{
107 /* take the lock to protect against buggy drivers */
108 write_lock(&mgr->vm_lock);
109 drm_mm_takedown(&mgr->vm_addr_space_mm);
110 write_unlock(&mgr->vm_lock);
111}
112EXPORT_SYMBOL(drm_vma_offset_manager_destroy);
113
114/**
115 * drm_vma_offset_lookup_locked() - Find node in offset space
116 * @mgr: Manager object
117 * @start: Start address for object (page-based)
118 * @pages: Size of object (page-based)
119 *
120 * Find a node given a start address and object size. This returns the _best_
121 * match for the given node. That is, @start may point somewhere into a valid
122 * region and the given node will be returned, as long as the node spans the
123 * whole requested area (given the size in number of pages as @pages).
124 *
125 * Note that before lookup the vma offset manager lookup lock must be acquired
126 * with drm_vma_offset_lock_lookup(). See there for an example. This can then be
127 * used to implement weakly referenced lookups using kref_get_unless_zero().
128 *
129 * Example:
130 * drm_vma_offset_lock_lookup(mgr);
131 * node = drm_vma_offset_lookup_locked(mgr);
132 * if (node)
133 * kref_get_unless_zero(container_of(node, sth, entr));
134 * drm_vma_offset_unlock_lookup(mgr);
135 *
136 * RETURNS:
137 * Returns NULL if no suitable node can be found. Otherwise, the best match
138 * is returned. It's the caller's responsibility to make sure the node doesn't
139 * get destroyed before the caller can access it.
140 */
141struct drm_vma_offset_node *drm_vma_offset_lookup_locked(struct drm_vma_offset_manager *mgr,
142 unsigned long start,
143 unsigned long pages)
144{
145 struct drm_vma_offset_node *node, *best;
146 struct rb_node *iter;
147 unsigned long offset;
148
149 iter = mgr->vm_addr_space_rb.rb_node;
150 best = NULL;
151
152 while (likely(iter)) {
153 node = rb_entry(iter, struct drm_vma_offset_node, vm_rb);
154 offset = node->vm_node.start;
155 if (start >= offset) {
156 iter = iter->rb_right;
157 best = node;
158 if (start == offset)
159 break;
160 } else {
161 iter = iter->rb_left;
162 }
163 }
164
165 /* verify that the node spans the requested area */
166 if (best) {
167 offset = best->vm_node.start + best->vm_node.size;
168 if (offset < start + pages)
169 best = NULL;
170 }
171
172 return best;
173}
174EXPORT_SYMBOL(drm_vma_offset_lookup_locked);
175
176/* internal helper to link @node into the rb-tree */
177static void _drm_vma_offset_add_rb(struct drm_vma_offset_manager *mgr,
178 struct drm_vma_offset_node *node)
179{
180 struct rb_node **iter = &mgr->vm_addr_space_rb.rb_node;
181 struct rb_node *parent = NULL;
182 struct drm_vma_offset_node *iter_node;
183
184 while (likely(*iter)) {
185 parent = *iter;
186 iter_node = rb_entry(*iter, struct drm_vma_offset_node, vm_rb);
187
188 if (node->vm_node.start < iter_node->vm_node.start)
189 iter = &(*iter)->rb_left;
190 else if (node->vm_node.start > iter_node->vm_node.start)
191 iter = &(*iter)->rb_right;
192 else
193 BUG();
194 }
195
196 rb_link_node(&node->vm_rb, parent, iter);
197 rb_insert_color(&node->vm_rb, &mgr->vm_addr_space_rb);
198}
199
200/**
201 * drm_vma_offset_add() - Add offset node to manager
202 * @mgr: Manager object
203 * @node: Node to be added
204 * @pages: Allocation size visible to user-space (in number of pages)
205 *
206 * Add a node to the offset-manager. If the node was already added, this does
207 * nothing and return 0. @pages is the size of the object given in number of
208 * pages.
209 * After this call succeeds, you can access the offset of the node until it
210 * is removed again.
211 *
212 * If this call fails, it is safe to retry the operation or call
213 * drm_vma_offset_remove(), anyway. However, no cleanup is required in that
214 * case.
215 *
216 * @pages is not required to be the same size as the underlying memory object
217 * that you want to map. It only limits the size that user-space can map into
218 * their address space.
219 *
220 * RETURNS:
221 * 0 on success, negative error code on failure.
222 */
223int drm_vma_offset_add(struct drm_vma_offset_manager *mgr,
224 struct drm_vma_offset_node *node, unsigned long pages)
225{
226 int ret;
227
228 write_lock(&mgr->vm_lock);
229
230 if (drm_mm_node_allocated(&node->vm_node)) {
231 ret = 0;
232 goto out_unlock;
233 }
234
235 ret = drm_mm_insert_node(&mgr->vm_addr_space_mm, &node->vm_node,
236 pages, 0, DRM_MM_SEARCH_DEFAULT);
237 if (ret)
238 goto out_unlock;
239
240 _drm_vma_offset_add_rb(mgr, node);
241
242out_unlock:
243 write_unlock(&mgr->vm_lock);
244 return ret;
245}
246EXPORT_SYMBOL(drm_vma_offset_add);
247
248/**
249 * drm_vma_offset_remove() - Remove offset node from manager
250 * @mgr: Manager object
251 * @node: Node to be removed
252 *
253 * Remove a node from the offset manager. If the node wasn't added before, this
254 * does nothing. After this call returns, the offset and size will be 0 until a
255 * new offset is allocated via drm_vma_offset_add() again. Helper functions like
256 * drm_vma_node_start() and drm_vma_node_offset_addr() will return 0 if no
257 * offset is allocated.
258 */
259void drm_vma_offset_remove(struct drm_vma_offset_manager *mgr,
260 struct drm_vma_offset_node *node)
261{
262 write_lock(&mgr->vm_lock);
263
264 if (drm_mm_node_allocated(&node->vm_node)) {
265 rb_erase(&node->vm_rb, &mgr->vm_addr_space_rb);
266 drm_mm_remove_node(&node->vm_node);
267 memset(&node->vm_node, 0, sizeof(node->vm_node));
268 }
269
270 write_unlock(&mgr->vm_lock);
271}
272EXPORT_SYMBOL(drm_vma_offset_remove);
273
274/**
275 * drm_vma_node_allow - Add open-file to list of allowed users
276 * @node: Node to modify
277 * @filp: Open file to add
278 *
279 * Add @filp to the list of allowed open-files for this node. If @filp is
280 * already on this list, the ref-count is incremented.
281 *
282 * The list of allowed-users is preserved across drm_vma_offset_add() and
283 * drm_vma_offset_remove() calls. You may even call it if the node is currently
284 * not added to any offset-manager.
285 *
286 * You must remove all open-files the same number of times as you added them
287 * before destroying the node. Otherwise, you will leak memory.
288 *
289 * This is locked against concurrent access internally.
290 *
291 * RETURNS:
292 * 0 on success, negative error code on internal failure (out-of-mem)
293 */
294int drm_vma_node_allow(struct drm_vma_offset_node *node, struct file *filp)
295{
296 struct rb_node **iter;
297 struct rb_node *parent = NULL;
298 struct drm_vma_offset_file *new, *entry;
299 int ret = 0;
300
301 /* Preallocate entry to avoid atomic allocations below. It is quite
302 * unlikely that an open-file is added twice to a single node so we
303 * don't optimize for this case. OOM is checked below only if the entry
304 * is actually used. */
305 new = kmalloc(sizeof(*entry), GFP_KERNEL);
306
307 write_lock(&node->vm_lock);
308
309 iter = &node->vm_files.rb_node;
310
311 while (likely(*iter)) {
312 parent = *iter;
313 entry = rb_entry(*iter, struct drm_vma_offset_file, vm_rb);
314
315 if (filp == entry->vm_filp) {
316 entry->vm_count++;
317 goto unlock;
318 } else if (filp > entry->vm_filp) {
319 iter = &(*iter)->rb_right;
320 } else {
321 iter = &(*iter)->rb_left;
322 }
323 }
324
325 if (!new) {
326 ret = -ENOMEM;
327 goto unlock;
328 }
329
330 new->vm_filp = filp;
331 new->vm_count = 1;
332 rb_link_node(&new->vm_rb, parent, iter);
333 rb_insert_color(&new->vm_rb, &node->vm_files);
334 new = NULL;
335
336unlock:
337 write_unlock(&node->vm_lock);
338 kfree(new);
339 return ret;
340}
341EXPORT_SYMBOL(drm_vma_node_allow);
342
343/**
344 * drm_vma_node_revoke - Remove open-file from list of allowed users
345 * @node: Node to modify
346 * @filp: Open file to remove
347 *
348 * Decrement the ref-count of @filp in the list of allowed open-files on @node.
349 * If the ref-count drops to zero, remove @filp from the list. You must call
350 * this once for every drm_vma_node_allow() on @filp.
351 *
352 * This is locked against concurrent access internally.
353 *
354 * If @filp is not on the list, nothing is done.
355 */
356void drm_vma_node_revoke(struct drm_vma_offset_node *node, struct file *filp)
357{
358 struct drm_vma_offset_file *entry;
359 struct rb_node *iter;
360
361 write_lock(&node->vm_lock);
362
363 iter = node->vm_files.rb_node;
364 while (likely(iter)) {
365 entry = rb_entry(iter, struct drm_vma_offset_file, vm_rb);
366 if (filp == entry->vm_filp) {
367 if (!--entry->vm_count) {
368 rb_erase(&entry->vm_rb, &node->vm_files);
369 kfree(entry);
370 }
371 break;
372 } else if (filp > entry->vm_filp) {
373 iter = iter->rb_right;
374 } else {
375 iter = iter->rb_left;
376 }
377 }
378
379 write_unlock(&node->vm_lock);
380}
381EXPORT_SYMBOL(drm_vma_node_revoke);
382
383/**
384 * drm_vma_node_is_allowed - Check whether an open-file is granted access
385 * @node: Node to check
386 * @filp: Open-file to check for
387 *
388 * Search the list in @node whether @filp is currently on the list of allowed
389 * open-files (see drm_vma_node_allow()).
390 *
391 * This is locked against concurrent access internally.
392 *
393 * RETURNS:
394 * true iff @filp is on the list
395 */
396bool drm_vma_node_is_allowed(struct drm_vma_offset_node *node,
397 struct file *filp)
398{
399 struct drm_vma_offset_file *entry;
400 struct rb_node *iter;
401
402 read_lock(&node->vm_lock);
403
404 iter = node->vm_files.rb_node;
405 while (likely(iter)) {
406 entry = rb_entry(iter, struct drm_vma_offset_file, vm_rb);
407 if (filp == entry->vm_filp)
408 break;
409 else if (filp > entry->vm_filp)
410 iter = iter->rb_right;
411 else
412 iter = iter->rb_left;
413 }
414
415 read_unlock(&node->vm_lock);
416
417 return iter;
418}
419EXPORT_SYMBOL(drm_vma_node_is_allowed);
1// SPDX-License-Identifier: GPL-2.0 OR MIT
2/*
3 * Copyright (c) 2006-2009 VMware, Inc., Palo Alto, CA., USA
4 * Copyright (c) 2012 David Airlie <airlied@linux.ie>
5 * Copyright (c) 2013 David Herrmann <dh.herrmann@gmail.com>
6 *
7 * Permission is hereby granted, free of charge, to any person obtaining a
8 * copy of this software and associated documentation files (the "Software"),
9 * to deal in the Software without restriction, including without limitation
10 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
11 * and/or sell copies of the Software, and to permit persons to whom the
12 * Software is furnished to do so, subject to the following conditions:
13 *
14 * The above copyright notice and this permission notice shall be included in
15 * all copies or substantial portions of the Software.
16 *
17 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
18 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
19 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
20 * THE COPYRIGHT HOLDER(S) OR AUTHOR(S) BE LIABLE FOR ANY CLAIM, DAMAGES OR
21 * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
22 * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
23 * OTHER DEALINGS IN THE SOFTWARE.
24 */
25
26#include <linux/mm.h>
27#include <linux/module.h>
28#include <linux/rbtree.h>
29#include <linux/slab.h>
30#include <linux/spinlock.h>
31#include <linux/types.h>
32
33#include <drm/drm_mm.h>
34#include <drm/drm_vma_manager.h>
35
36/**
37 * DOC: vma offset manager
38 *
39 * The vma-manager is responsible to map arbitrary driver-dependent memory
40 * regions into the linear user address-space. It provides offsets to the
41 * caller which can then be used on the address_space of the drm-device. It
42 * takes care to not overlap regions, size them appropriately and to not
43 * confuse mm-core by inconsistent fake vm_pgoff fields.
44 * Drivers shouldn't use this for object placement in VMEM. This manager should
45 * only be used to manage mappings into linear user-space VMs.
46 *
47 * We use drm_mm as backend to manage object allocations. But it is highly
48 * optimized for alloc/free calls, not lookups. Hence, we use an rb-tree to
49 * speed up offset lookups.
50 *
51 * You must not use multiple offset managers on a single address_space.
52 * Otherwise, mm-core will be unable to tear down memory mappings as the VM will
53 * no longer be linear.
54 *
55 * This offset manager works on page-based addresses. That is, every argument
56 * and return code (with the exception of drm_vma_node_offset_addr()) is given
57 * in number of pages, not number of bytes. That means, object sizes and offsets
58 * must always be page-aligned (as usual).
59 * If you want to get a valid byte-based user-space address for a given offset,
60 * please see drm_vma_node_offset_addr().
61 *
62 * Additionally to offset management, the vma offset manager also handles access
63 * management. For every open-file context that is allowed to access a given
64 * node, you must call drm_vma_node_allow(). Otherwise, an mmap() call on this
65 * open-file with the offset of the node will fail with -EACCES. To revoke
66 * access again, use drm_vma_node_revoke(). However, the caller is responsible
67 * for destroying already existing mappings, if required.
68 */
69
70/**
71 * drm_vma_offset_manager_init - Initialize new offset-manager
72 * @mgr: Manager object
73 * @page_offset: Offset of available memory area (page-based)
74 * @size: Size of available address space range (page-based)
75 *
76 * Initialize a new offset-manager. The offset and area size available for the
77 * manager are given as @page_offset and @size. Both are interpreted as
78 * page-numbers, not bytes.
79 *
80 * Adding/removing nodes from the manager is locked internally and protected
81 * against concurrent access. However, node allocation and destruction is left
82 * for the caller. While calling into the vma-manager, a given node must
83 * always be guaranteed to be referenced.
84 */
85void drm_vma_offset_manager_init(struct drm_vma_offset_manager *mgr,
86 unsigned long page_offset, unsigned long size)
87{
88 rwlock_init(&mgr->vm_lock);
89 drm_mm_init(&mgr->vm_addr_space_mm, page_offset, size);
90}
91EXPORT_SYMBOL(drm_vma_offset_manager_init);
92
93/**
94 * drm_vma_offset_manager_destroy() - Destroy offset manager
95 * @mgr: Manager object
96 *
97 * Destroy an object manager which was previously created via
98 * drm_vma_offset_manager_init(). The caller must remove all allocated nodes
99 * before destroying the manager. Otherwise, drm_mm will refuse to free the
100 * requested resources.
101 *
102 * The manager must not be accessed after this function is called.
103 */
104void drm_vma_offset_manager_destroy(struct drm_vma_offset_manager *mgr)
105{
106 drm_mm_takedown(&mgr->vm_addr_space_mm);
107}
108EXPORT_SYMBOL(drm_vma_offset_manager_destroy);
109
110/**
111 * drm_vma_offset_lookup_locked() - Find node in offset space
112 * @mgr: Manager object
113 * @start: Start address for object (page-based)
114 * @pages: Size of object (page-based)
115 *
116 * Find a node given a start address and object size. This returns the _best_
117 * match for the given node. That is, @start may point somewhere into a valid
118 * region and the given node will be returned, as long as the node spans the
119 * whole requested area (given the size in number of pages as @pages).
120 *
121 * Note that before lookup the vma offset manager lookup lock must be acquired
122 * with drm_vma_offset_lock_lookup(). See there for an example. This can then be
123 * used to implement weakly referenced lookups using kref_get_unless_zero().
124 *
125 * Example:
126 *
127 * ::
128 *
129 * drm_vma_offset_lock_lookup(mgr);
130 * node = drm_vma_offset_lookup_locked(mgr);
131 * if (node)
132 * kref_get_unless_zero(container_of(node, sth, entr));
133 * drm_vma_offset_unlock_lookup(mgr);
134 *
135 * RETURNS:
136 * Returns NULL if no suitable node can be found. Otherwise, the best match
137 * is returned. It's the caller's responsibility to make sure the node doesn't
138 * get destroyed before the caller can access it.
139 */
140struct drm_vma_offset_node *drm_vma_offset_lookup_locked(struct drm_vma_offset_manager *mgr,
141 unsigned long start,
142 unsigned long pages)
143{
144 struct drm_mm_node *node, *best;
145 struct rb_node *iter;
146 unsigned long offset;
147
148 iter = mgr->vm_addr_space_mm.interval_tree.rb_root.rb_node;
149 best = NULL;
150
151 while (likely(iter)) {
152 node = rb_entry(iter, struct drm_mm_node, rb);
153 offset = node->start;
154 if (start >= offset) {
155 iter = iter->rb_right;
156 best = node;
157 if (start == offset)
158 break;
159 } else {
160 iter = iter->rb_left;
161 }
162 }
163
164 /* verify that the node spans the requested area */
165 if (best) {
166 offset = best->start + best->size;
167 if (offset < start + pages)
168 best = NULL;
169 }
170
171 if (!best)
172 return NULL;
173
174 return container_of(best, struct drm_vma_offset_node, vm_node);
175}
176EXPORT_SYMBOL(drm_vma_offset_lookup_locked);
177
178/**
179 * drm_vma_offset_add() - Add offset node to manager
180 * @mgr: Manager object
181 * @node: Node to be added
182 * @pages: Allocation size visible to user-space (in number of pages)
183 *
184 * Add a node to the offset-manager. If the node was already added, this does
185 * nothing and return 0. @pages is the size of the object given in number of
186 * pages.
187 * After this call succeeds, you can access the offset of the node until it
188 * is removed again.
189 *
190 * If this call fails, it is safe to retry the operation or call
191 * drm_vma_offset_remove(), anyway. However, no cleanup is required in that
192 * case.
193 *
194 * @pages is not required to be the same size as the underlying memory object
195 * that you want to map. It only limits the size that user-space can map into
196 * their address space.
197 *
198 * RETURNS:
199 * 0 on success, negative error code on failure.
200 */
201int drm_vma_offset_add(struct drm_vma_offset_manager *mgr,
202 struct drm_vma_offset_node *node, unsigned long pages)
203{
204 int ret = 0;
205
206 write_lock(&mgr->vm_lock);
207
208 if (!drm_mm_node_allocated(&node->vm_node))
209 ret = drm_mm_insert_node(&mgr->vm_addr_space_mm,
210 &node->vm_node, pages);
211
212 write_unlock(&mgr->vm_lock);
213
214 return ret;
215}
216EXPORT_SYMBOL(drm_vma_offset_add);
217
218/**
219 * drm_vma_offset_remove() - Remove offset node from manager
220 * @mgr: Manager object
221 * @node: Node to be removed
222 *
223 * Remove a node from the offset manager. If the node wasn't added before, this
224 * does nothing. After this call returns, the offset and size will be 0 until a
225 * new offset is allocated via drm_vma_offset_add() again. Helper functions like
226 * drm_vma_node_start() and drm_vma_node_offset_addr() will return 0 if no
227 * offset is allocated.
228 */
229void drm_vma_offset_remove(struct drm_vma_offset_manager *mgr,
230 struct drm_vma_offset_node *node)
231{
232 write_lock(&mgr->vm_lock);
233
234 if (drm_mm_node_allocated(&node->vm_node)) {
235 drm_mm_remove_node(&node->vm_node);
236 memset(&node->vm_node, 0, sizeof(node->vm_node));
237 }
238
239 write_unlock(&mgr->vm_lock);
240}
241EXPORT_SYMBOL(drm_vma_offset_remove);
242
243/**
244 * drm_vma_node_allow - Add open-file to list of allowed users
245 * @node: Node to modify
246 * @tag: Tag of file to remove
247 *
248 * Add @tag to the list of allowed open-files for this node. If @tag is
249 * already on this list, the ref-count is incremented.
250 *
251 * The list of allowed-users is preserved across drm_vma_offset_add() and
252 * drm_vma_offset_remove() calls. You may even call it if the node is currently
253 * not added to any offset-manager.
254 *
255 * You must remove all open-files the same number of times as you added them
256 * before destroying the node. Otherwise, you will leak memory.
257 *
258 * This is locked against concurrent access internally.
259 *
260 * RETURNS:
261 * 0 on success, negative error code on internal failure (out-of-mem)
262 */
263int drm_vma_node_allow(struct drm_vma_offset_node *node, struct drm_file *tag)
264{
265 struct rb_node **iter;
266 struct rb_node *parent = NULL;
267 struct drm_vma_offset_file *new, *entry;
268 int ret = 0;
269
270 /* Preallocate entry to avoid atomic allocations below. It is quite
271 * unlikely that an open-file is added twice to a single node so we
272 * don't optimize for this case. OOM is checked below only if the entry
273 * is actually used. */
274 new = kmalloc(sizeof(*entry), GFP_KERNEL);
275
276 write_lock(&node->vm_lock);
277
278 iter = &node->vm_files.rb_node;
279
280 while (likely(*iter)) {
281 parent = *iter;
282 entry = rb_entry(*iter, struct drm_vma_offset_file, vm_rb);
283
284 if (tag == entry->vm_tag) {
285 entry->vm_count++;
286 goto unlock;
287 } else if (tag > entry->vm_tag) {
288 iter = &(*iter)->rb_right;
289 } else {
290 iter = &(*iter)->rb_left;
291 }
292 }
293
294 if (!new) {
295 ret = -ENOMEM;
296 goto unlock;
297 }
298
299 new->vm_tag = tag;
300 new->vm_count = 1;
301 rb_link_node(&new->vm_rb, parent, iter);
302 rb_insert_color(&new->vm_rb, &node->vm_files);
303 new = NULL;
304
305unlock:
306 write_unlock(&node->vm_lock);
307 kfree(new);
308 return ret;
309}
310EXPORT_SYMBOL(drm_vma_node_allow);
311
312/**
313 * drm_vma_node_revoke - Remove open-file from list of allowed users
314 * @node: Node to modify
315 * @tag: Tag of file to remove
316 *
317 * Decrement the ref-count of @tag in the list of allowed open-files on @node.
318 * If the ref-count drops to zero, remove @tag from the list. You must call
319 * this once for every drm_vma_node_allow() on @tag.
320 *
321 * This is locked against concurrent access internally.
322 *
323 * If @tag is not on the list, nothing is done.
324 */
325void drm_vma_node_revoke(struct drm_vma_offset_node *node,
326 struct drm_file *tag)
327{
328 struct drm_vma_offset_file *entry;
329 struct rb_node *iter;
330
331 write_lock(&node->vm_lock);
332
333 iter = node->vm_files.rb_node;
334 while (likely(iter)) {
335 entry = rb_entry(iter, struct drm_vma_offset_file, vm_rb);
336 if (tag == entry->vm_tag) {
337 if (!--entry->vm_count) {
338 rb_erase(&entry->vm_rb, &node->vm_files);
339 kfree(entry);
340 }
341 break;
342 } else if (tag > entry->vm_tag) {
343 iter = iter->rb_right;
344 } else {
345 iter = iter->rb_left;
346 }
347 }
348
349 write_unlock(&node->vm_lock);
350}
351EXPORT_SYMBOL(drm_vma_node_revoke);
352
353/**
354 * drm_vma_node_is_allowed - Check whether an open-file is granted access
355 * @node: Node to check
356 * @tag: Tag of file to remove
357 *
358 * Search the list in @node whether @tag is currently on the list of allowed
359 * open-files (see drm_vma_node_allow()).
360 *
361 * This is locked against concurrent access internally.
362 *
363 * RETURNS:
364 * true iff @filp is on the list
365 */
366bool drm_vma_node_is_allowed(struct drm_vma_offset_node *node,
367 struct drm_file *tag)
368{
369 struct drm_vma_offset_file *entry;
370 struct rb_node *iter;
371
372 read_lock(&node->vm_lock);
373
374 iter = node->vm_files.rb_node;
375 while (likely(iter)) {
376 entry = rb_entry(iter, struct drm_vma_offset_file, vm_rb);
377 if (tag == entry->vm_tag)
378 break;
379 else if (tag > entry->vm_tag)
380 iter = iter->rb_right;
381 else
382 iter = iter->rb_left;
383 }
384
385 read_unlock(&node->vm_lock);
386
387 return iter;
388}
389EXPORT_SYMBOL(drm_vma_node_is_allowed);