Loading...
1/*
2 * Created: Tue Feb 2 08:37:54 1999 by faith@valinux.com
3 *
4 * Copyright 1999 Precision Insight, Inc., Cedar Park, Texas.
5 * Copyright 2000 VA Linux Systems, Inc., Sunnyvale, California.
6 * All Rights Reserved.
7 *
8 * Author Rickard E. (Rik) Faith <faith@valinux.com>
9 * Author Gareth Hughes <gareth@valinux.com>
10 *
11 * Permission is hereby granted, free of charge, to any person obtaining a
12 * copy of this software and associated documentation files (the "Software"),
13 * to deal in the Software without restriction, including without limitation
14 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
15 * and/or sell copies of the Software, and to permit persons to whom the
16 * Software is furnished to do so, subject to the following conditions:
17 *
18 * The above copyright notice and this permission notice (including the next
19 * paragraph) shall be included in all copies or substantial portions of the
20 * Software.
21 *
22 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
23 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
24 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
25 * VA LINUX SYSTEMS AND/OR ITS SUPPLIERS BE LIABLE FOR ANY CLAIM, DAMAGES OR
26 * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
27 * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
28 * OTHER DEALINGS IN THE SOFTWARE.
29 */
30
31#include <linux/slab.h>
32
33#include <drm/drm_auth.h>
34#include <drm/drm_drv.h>
35#include <drm/drm_file.h>
36#include <drm/drm_lease.h>
37#include <drm/drm_print.h>
38
39#include "drm_internal.h"
40
41/**
42 * DOC: master and authentication
43 *
44 * &struct drm_master is used to track groups of clients with open
45 * primary device nodes. For every &struct drm_file which has had at
46 * least once successfully became the device master (either through the
47 * SET_MASTER IOCTL, or implicitly through opening the primary device node when
48 * no one else is the current master that time) there exists one &drm_master.
49 * This is noted in &drm_file.is_master. All other clients have just a pointer
50 * to the &drm_master they are associated with.
51 *
52 * In addition only one &drm_master can be the current master for a &drm_device.
53 * It can be switched through the DROP_MASTER and SET_MASTER IOCTL, or
54 * implicitly through closing/opening the primary device node. See also
55 * drm_is_current_master().
56 *
57 * Clients can authenticate against the current master (if it matches their own)
58 * using the GETMAGIC and AUTHMAGIC IOCTLs. Together with exchanging masters,
59 * this allows controlled access to the device for an entire group of mutually
60 * trusted clients.
61 */
62
63static bool drm_is_current_master_locked(struct drm_file *fpriv)
64{
65 lockdep_assert_once(lockdep_is_held(&fpriv->master_lookup_lock) ||
66 lockdep_is_held(&fpriv->minor->dev->master_mutex));
67
68 return fpriv->is_master && drm_lease_owner(fpriv->master) == fpriv->minor->dev->master;
69}
70
71/**
72 * drm_is_current_master - checks whether @priv is the current master
73 * @fpriv: DRM file private
74 *
75 * Checks whether @fpriv is current master on its device. This decides whether a
76 * client is allowed to run DRM_MASTER IOCTLs.
77 *
78 * Most of the modern IOCTL which require DRM_MASTER are for kernel modesetting
79 * - the current master is assumed to own the non-shareable display hardware.
80 */
81bool drm_is_current_master(struct drm_file *fpriv)
82{
83 bool ret;
84
85 spin_lock(&fpriv->master_lookup_lock);
86 ret = drm_is_current_master_locked(fpriv);
87 spin_unlock(&fpriv->master_lookup_lock);
88
89 return ret;
90}
91EXPORT_SYMBOL(drm_is_current_master);
92
93int drm_getmagic(struct drm_device *dev, void *data, struct drm_file *file_priv)
94{
95 struct drm_auth *auth = data;
96 int ret = 0;
97
98 mutex_lock(&dev->master_mutex);
99 if (!file_priv->magic) {
100 ret = idr_alloc(&file_priv->master->magic_map, file_priv,
101 1, 0, GFP_KERNEL);
102 if (ret >= 0)
103 file_priv->magic = ret;
104 }
105 auth->magic = file_priv->magic;
106 mutex_unlock(&dev->master_mutex);
107
108 drm_dbg_core(dev, "%u\n", auth->magic);
109
110 return ret < 0 ? ret : 0;
111}
112
113int drm_authmagic(struct drm_device *dev, void *data,
114 struct drm_file *file_priv)
115{
116 struct drm_auth *auth = data;
117 struct drm_file *file;
118
119 drm_dbg_core(dev, "%u\n", auth->magic);
120
121 mutex_lock(&dev->master_mutex);
122 file = idr_find(&file_priv->master->magic_map, auth->magic);
123 if (file) {
124 file->authenticated = 1;
125 idr_replace(&file_priv->master->magic_map, NULL, auth->magic);
126 }
127 mutex_unlock(&dev->master_mutex);
128
129 return file ? 0 : -EINVAL;
130}
131
132struct drm_master *drm_master_create(struct drm_device *dev)
133{
134 struct drm_master *master;
135
136 master = kzalloc(sizeof(*master), GFP_KERNEL);
137 if (!master)
138 return NULL;
139
140 kref_init(&master->refcount);
141 idr_init_base(&master->magic_map, 1);
142 master->dev = dev;
143
144 /* initialize the tree of output resource lessees */
145 INIT_LIST_HEAD(&master->lessees);
146 INIT_LIST_HEAD(&master->lessee_list);
147 idr_init(&master->leases);
148 idr_init_base(&master->lessee_idr, 1);
149
150 return master;
151}
152
153static void drm_set_master(struct drm_device *dev, struct drm_file *fpriv,
154 bool new_master)
155{
156 dev->master = drm_master_get(fpriv->master);
157 if (dev->driver->master_set)
158 dev->driver->master_set(dev, fpriv, new_master);
159
160 fpriv->was_master = true;
161}
162
163static int drm_new_set_master(struct drm_device *dev, struct drm_file *fpriv)
164{
165 struct drm_master *old_master;
166 struct drm_master *new_master;
167
168 lockdep_assert_held_once(&dev->master_mutex);
169
170 WARN_ON(fpriv->is_master);
171 old_master = fpriv->master;
172 new_master = drm_master_create(dev);
173 if (!new_master)
174 return -ENOMEM;
175 spin_lock(&fpriv->master_lookup_lock);
176 fpriv->master = new_master;
177 spin_unlock(&fpriv->master_lookup_lock);
178
179 fpriv->is_master = 1;
180 fpriv->authenticated = 1;
181
182 drm_set_master(dev, fpriv, true);
183
184 if (old_master)
185 drm_master_put(&old_master);
186
187 return 0;
188}
189
190/*
191 * In the olden days the SET/DROP_MASTER ioctls used to return EACCES when
192 * CAP_SYS_ADMIN was not set. This was used to prevent rogue applications
193 * from becoming master and/or failing to release it.
194 *
195 * At the same time, the first client (for a given VT) is _always_ master.
196 * Thus in order for the ioctls to succeed, one had to _explicitly_ run the
197 * application as root or flip the setuid bit.
198 *
199 * If the CAP_SYS_ADMIN was missing, no other client could become master...
200 * EVER :-( Leading to a) the graphics session dying badly or b) a completely
201 * locked session.
202 *
203 *
204 * As some point systemd-logind was introduced to orchestrate and delegate
205 * master as applicable. It does so by opening the fd and passing it to users
206 * while in itself logind a) does the set/drop master per users' request and
207 * b) * implicitly drops master on VT switch.
208 *
209 * Even though logind looks like the future, there are a few issues:
210 * - some platforms don't have equivalent (Android, CrOS, some BSDs) so
211 * root is required _solely_ for SET/DROP MASTER.
212 * - applications may not be updated to use it,
213 * - any client which fails to drop master* can DoS the application using
214 * logind, to a varying degree.
215 *
216 * * Either due missing CAP_SYS_ADMIN or simply not calling DROP_MASTER.
217 *
218 *
219 * Here we implement the next best thing:
220 * - ensure the logind style of fd passing works unchanged, and
221 * - allow a client to drop/set master, iff it is/was master at a given point
222 * in time.
223 *
224 * Note: DROP_MASTER cannot be free for all, as an arbitrator user could:
225 * - DoS/crash the arbitrator - details would be implementation specific
226 * - open the node, become master implicitly and cause issues
227 *
228 * As a result this fixes the following when using root-less build w/o logind
229 * - startx
230 * - weston
231 * - various compositors based on wlroots
232 */
233static int
234drm_master_check_perm(struct drm_device *dev, struct drm_file *file_priv)
235{
236 if (file_priv->was_master &&
237 rcu_access_pointer(file_priv->pid) == task_tgid(current))
238 return 0;
239
240 if (!capable(CAP_SYS_ADMIN))
241 return -EACCES;
242
243 return 0;
244}
245
246int drm_setmaster_ioctl(struct drm_device *dev, void *data,
247 struct drm_file *file_priv)
248{
249 int ret;
250
251 mutex_lock(&dev->master_mutex);
252
253 ret = drm_master_check_perm(dev, file_priv);
254 if (ret)
255 goto out_unlock;
256
257 if (drm_is_current_master_locked(file_priv))
258 goto out_unlock;
259
260 if (dev->master) {
261 ret = -EBUSY;
262 goto out_unlock;
263 }
264
265 if (!file_priv->master) {
266 ret = -EINVAL;
267 goto out_unlock;
268 }
269
270 if (!file_priv->is_master) {
271 ret = drm_new_set_master(dev, file_priv);
272 goto out_unlock;
273 }
274
275 if (file_priv->master->lessor != NULL) {
276 drm_dbg_lease(dev,
277 "Attempt to set lessee %d as master\n",
278 file_priv->master->lessee_id);
279 ret = -EINVAL;
280 goto out_unlock;
281 }
282
283 drm_set_master(dev, file_priv, false);
284out_unlock:
285 mutex_unlock(&dev->master_mutex);
286 return ret;
287}
288
289static void drm_drop_master(struct drm_device *dev,
290 struct drm_file *fpriv)
291{
292 if (dev->driver->master_drop)
293 dev->driver->master_drop(dev, fpriv);
294 drm_master_put(&dev->master);
295}
296
297int drm_dropmaster_ioctl(struct drm_device *dev, void *data,
298 struct drm_file *file_priv)
299{
300 int ret;
301
302 mutex_lock(&dev->master_mutex);
303
304 ret = drm_master_check_perm(dev, file_priv);
305 if (ret)
306 goto out_unlock;
307
308 if (!drm_is_current_master_locked(file_priv)) {
309 ret = -EINVAL;
310 goto out_unlock;
311 }
312
313 if (!dev->master) {
314 ret = -EINVAL;
315 goto out_unlock;
316 }
317
318 if (file_priv->master->lessor != NULL) {
319 drm_dbg_lease(dev,
320 "Attempt to drop lessee %d as master\n",
321 file_priv->master->lessee_id);
322 ret = -EINVAL;
323 goto out_unlock;
324 }
325
326 drm_drop_master(dev, file_priv);
327out_unlock:
328 mutex_unlock(&dev->master_mutex);
329 return ret;
330}
331
332int drm_master_open(struct drm_file *file_priv)
333{
334 struct drm_device *dev = file_priv->minor->dev;
335 int ret = 0;
336
337 /* if there is no current master make this fd it, but do not create
338 * any master object for render clients
339 */
340 mutex_lock(&dev->master_mutex);
341 if (!dev->master) {
342 ret = drm_new_set_master(dev, file_priv);
343 } else {
344 spin_lock(&file_priv->master_lookup_lock);
345 file_priv->master = drm_master_get(dev->master);
346 spin_unlock(&file_priv->master_lookup_lock);
347 }
348 mutex_unlock(&dev->master_mutex);
349
350 return ret;
351}
352
353void drm_master_release(struct drm_file *file_priv)
354{
355 struct drm_device *dev = file_priv->minor->dev;
356 struct drm_master *master;
357
358 mutex_lock(&dev->master_mutex);
359 master = file_priv->master;
360 if (file_priv->magic)
361 idr_remove(&file_priv->master->magic_map, file_priv->magic);
362
363 if (!drm_is_current_master_locked(file_priv))
364 goto out;
365
366 if (dev->master == file_priv->master)
367 drm_drop_master(dev, file_priv);
368out:
369 if (drm_core_check_feature(dev, DRIVER_MODESET) && file_priv->is_master) {
370 /* Revoke any leases held by this or lessees, but only if
371 * this is the "real" master
372 */
373 drm_lease_revoke(master);
374 }
375
376 /* drop the master reference held by the file priv */
377 if (file_priv->master)
378 drm_master_put(&file_priv->master);
379 mutex_unlock(&dev->master_mutex);
380}
381
382/**
383 * drm_master_get - reference a master pointer
384 * @master: &struct drm_master
385 *
386 * Increments the reference count of @master and returns a pointer to @master.
387 */
388struct drm_master *drm_master_get(struct drm_master *master)
389{
390 kref_get(&master->refcount);
391 return master;
392}
393EXPORT_SYMBOL(drm_master_get);
394
395/**
396 * drm_file_get_master - reference &drm_file.master of @file_priv
397 * @file_priv: DRM file private
398 *
399 * Increments the reference count of @file_priv's &drm_file.master and returns
400 * the &drm_file.master. If @file_priv has no &drm_file.master, returns NULL.
401 *
402 * Master pointers returned from this function should be unreferenced using
403 * drm_master_put().
404 */
405struct drm_master *drm_file_get_master(struct drm_file *file_priv)
406{
407 struct drm_master *master = NULL;
408
409 spin_lock(&file_priv->master_lookup_lock);
410 if (!file_priv->master)
411 goto unlock;
412 master = drm_master_get(file_priv->master);
413
414unlock:
415 spin_unlock(&file_priv->master_lookup_lock);
416 return master;
417}
418EXPORT_SYMBOL(drm_file_get_master);
419
420static void drm_master_destroy(struct kref *kref)
421{
422 struct drm_master *master = container_of(kref, struct drm_master, refcount);
423 struct drm_device *dev = master->dev;
424
425 if (drm_core_check_feature(dev, DRIVER_MODESET))
426 drm_lease_destroy(master);
427
428 idr_destroy(&master->magic_map);
429 idr_destroy(&master->leases);
430 idr_destroy(&master->lessee_idr);
431
432 kfree(master->unique);
433 kfree(master);
434}
435
436/**
437 * drm_master_put - unreference and clear a master pointer
438 * @master: pointer to a pointer of &struct drm_master
439 *
440 * This decrements the &drm_master behind @master and sets it to NULL.
441 */
442void drm_master_put(struct drm_master **master)
443{
444 kref_put(&(*master)->refcount, drm_master_destroy);
445 *master = NULL;
446}
447EXPORT_SYMBOL(drm_master_put);
448
449/* Used by drm_client and drm_fb_helper */
450bool drm_master_internal_acquire(struct drm_device *dev)
451{
452 mutex_lock(&dev->master_mutex);
453 if (dev->master) {
454 mutex_unlock(&dev->master_mutex);
455 return false;
456 }
457
458 return true;
459}
460EXPORT_SYMBOL(drm_master_internal_acquire);
461
462/* Used by drm_client and drm_fb_helper */
463void drm_master_internal_release(struct drm_device *dev)
464{
465 mutex_unlock(&dev->master_mutex);
466}
467EXPORT_SYMBOL(drm_master_internal_release);
1/*
2 * Created: Tue Feb 2 08:37:54 1999 by faith@valinux.com
3 *
4 * Copyright 1999 Precision Insight, Inc., Cedar Park, Texas.
5 * Copyright 2000 VA Linux Systems, Inc., Sunnyvale, California.
6 * All Rights Reserved.
7 *
8 * Author Rickard E. (Rik) Faith <faith@valinux.com>
9 * Author Gareth Hughes <gareth@valinux.com>
10 *
11 * Permission is hereby granted, free of charge, to any person obtaining a
12 * copy of this software and associated documentation files (the "Software"),
13 * to deal in the Software without restriction, including without limitation
14 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
15 * and/or sell copies of the Software, and to permit persons to whom the
16 * Software is furnished to do so, subject to the following conditions:
17 *
18 * The above copyright notice and this permission notice (including the next
19 * paragraph) shall be included in all copies or substantial portions of the
20 * Software.
21 *
22 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
23 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
24 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
25 * VA LINUX SYSTEMS AND/OR ITS SUPPLIERS BE LIABLE FOR ANY CLAIM, DAMAGES OR
26 * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
27 * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
28 * OTHER DEALINGS IN THE SOFTWARE.
29 */
30
31#include <drm/drmP.h>
32#include "drm_internal.h"
33#include "drm_legacy.h"
34
35/**
36 * DOC: master and authentication
37 *
38 * struct &drm_master is used to track groups of clients with open
39 * primary/legacy device nodes. For every struct &drm_file which has had at
40 * least once successfully became the device master (either through the
41 * SET_MASTER IOCTL, or implicitly through opening the primary device node when
42 * no one else is the current master that time) there exists one &drm_master.
43 * This is noted in the is_master member of &drm_file. All other clients have
44 * just a pointer to the &drm_master they are associated with.
45 *
46 * In addition only one &drm_master can be the current master for a &drm_device.
47 * It can be switched through the DROP_MASTER and SET_MASTER IOCTL, or
48 * implicitly through closing/openeing the primary device node. See also
49 * drm_is_current_master().
50 *
51 * Clients can authenticate against the current master (if it matches their own)
52 * using the GETMAGIC and AUTHMAGIC IOCTLs. Together with exchanging masters,
53 * this allows controlled access to the device for an entire group of mutually
54 * trusted clients.
55 */
56
57int drm_getmagic(struct drm_device *dev, void *data, struct drm_file *file_priv)
58{
59 struct drm_auth *auth = data;
60 int ret = 0;
61
62 mutex_lock(&dev->master_mutex);
63 if (!file_priv->magic) {
64 ret = idr_alloc(&file_priv->master->magic_map, file_priv,
65 1, 0, GFP_KERNEL);
66 if (ret >= 0)
67 file_priv->magic = ret;
68 }
69 auth->magic = file_priv->magic;
70 mutex_unlock(&dev->master_mutex);
71
72 DRM_DEBUG("%u\n", auth->magic);
73
74 return ret < 0 ? ret : 0;
75}
76
77int drm_authmagic(struct drm_device *dev, void *data,
78 struct drm_file *file_priv)
79{
80 struct drm_auth *auth = data;
81 struct drm_file *file;
82
83 DRM_DEBUG("%u\n", auth->magic);
84
85 mutex_lock(&dev->master_mutex);
86 file = idr_find(&file_priv->master->magic_map, auth->magic);
87 if (file) {
88 file->authenticated = 1;
89 idr_replace(&file_priv->master->magic_map, NULL, auth->magic);
90 }
91 mutex_unlock(&dev->master_mutex);
92
93 return file ? 0 : -EINVAL;
94}
95
96static struct drm_master *drm_master_create(struct drm_device *dev)
97{
98 struct drm_master *master;
99
100 master = kzalloc(sizeof(*master), GFP_KERNEL);
101 if (!master)
102 return NULL;
103
104 kref_init(&master->refcount);
105 spin_lock_init(&master->lock.spinlock);
106 init_waitqueue_head(&master->lock.lock_queue);
107 idr_init(&master->magic_map);
108 master->dev = dev;
109
110 return master;
111}
112
113static int drm_set_master(struct drm_device *dev, struct drm_file *fpriv,
114 bool new_master)
115{
116 int ret = 0;
117
118 dev->master = drm_master_get(fpriv->master);
119 if (dev->driver->master_set) {
120 ret = dev->driver->master_set(dev, fpriv, new_master);
121 if (unlikely(ret != 0)) {
122 drm_master_put(&dev->master);
123 }
124 }
125
126 return ret;
127}
128
129static int drm_new_set_master(struct drm_device *dev, struct drm_file *fpriv)
130{
131 struct drm_master *old_master;
132 int ret;
133
134 lockdep_assert_held_once(&dev->master_mutex);
135
136 old_master = fpriv->master;
137 fpriv->master = drm_master_create(dev);
138 if (!fpriv->master) {
139 fpriv->master = old_master;
140 return -ENOMEM;
141 }
142
143 if (dev->driver->master_create) {
144 ret = dev->driver->master_create(dev, fpriv->master);
145 if (ret)
146 goto out_err;
147 }
148 fpriv->is_master = 1;
149 fpriv->authenticated = 1;
150
151 ret = drm_set_master(dev, fpriv, true);
152 if (ret)
153 goto out_err;
154
155 if (old_master)
156 drm_master_put(&old_master);
157
158 return 0;
159
160out_err:
161 /* drop references and restore old master on failure */
162 drm_master_put(&fpriv->master);
163 fpriv->master = old_master;
164
165 return ret;
166}
167
168int drm_setmaster_ioctl(struct drm_device *dev, void *data,
169 struct drm_file *file_priv)
170{
171 int ret = 0;
172
173 mutex_lock(&dev->master_mutex);
174 if (drm_is_current_master(file_priv))
175 goto out_unlock;
176
177 if (dev->master) {
178 ret = -EINVAL;
179 goto out_unlock;
180 }
181
182 if (!file_priv->master) {
183 ret = -EINVAL;
184 goto out_unlock;
185 }
186
187 if (!file_priv->is_master) {
188 ret = drm_new_set_master(dev, file_priv);
189 goto out_unlock;
190 }
191
192 ret = drm_set_master(dev, file_priv, false);
193out_unlock:
194 mutex_unlock(&dev->master_mutex);
195 return ret;
196}
197
198static void drm_drop_master(struct drm_device *dev,
199 struct drm_file *fpriv)
200{
201 if (dev->driver->master_drop)
202 dev->driver->master_drop(dev, fpriv);
203 drm_master_put(&dev->master);
204}
205
206int drm_dropmaster_ioctl(struct drm_device *dev, void *data,
207 struct drm_file *file_priv)
208{
209 int ret = -EINVAL;
210
211 mutex_lock(&dev->master_mutex);
212 if (!drm_is_current_master(file_priv))
213 goto out_unlock;
214
215 if (!dev->master)
216 goto out_unlock;
217
218 ret = 0;
219 drm_drop_master(dev, file_priv);
220out_unlock:
221 mutex_unlock(&dev->master_mutex);
222 return ret;
223}
224
225int drm_master_open(struct drm_file *file_priv)
226{
227 struct drm_device *dev = file_priv->minor->dev;
228 int ret = 0;
229
230 /* if there is no current master make this fd it, but do not create
231 * any master object for render clients */
232 mutex_lock(&dev->master_mutex);
233 if (!dev->master)
234 ret = drm_new_set_master(dev, file_priv);
235 else
236 file_priv->master = drm_master_get(dev->master);
237 mutex_unlock(&dev->master_mutex);
238
239 return ret;
240}
241
242void drm_master_release(struct drm_file *file_priv)
243{
244 struct drm_device *dev = file_priv->minor->dev;
245 struct drm_master *master = file_priv->master;
246
247 mutex_lock(&dev->master_mutex);
248 if (file_priv->magic)
249 idr_remove(&file_priv->master->magic_map, file_priv->magic);
250
251 if (!drm_is_current_master(file_priv))
252 goto out;
253
254 if (drm_core_check_feature(dev, DRIVER_LEGACY)) {
255 /*
256 * Since the master is disappearing, so is the
257 * possibility to lock.
258 */
259 mutex_lock(&dev->struct_mutex);
260 if (master->lock.hw_lock) {
261 if (dev->sigdata.lock == master->lock.hw_lock)
262 dev->sigdata.lock = NULL;
263 master->lock.hw_lock = NULL;
264 master->lock.file_priv = NULL;
265 wake_up_interruptible_all(&master->lock.lock_queue);
266 }
267 mutex_unlock(&dev->struct_mutex);
268 }
269
270 if (dev->master == file_priv->master)
271 drm_drop_master(dev, file_priv);
272out:
273 /* drop the master reference held by the file priv */
274 if (file_priv->master)
275 drm_master_put(&file_priv->master);
276 mutex_unlock(&dev->master_mutex);
277}
278
279/**
280 * drm_is_current_master - checks whether @priv is the current master
281 * @fpriv: DRM file private
282 *
283 * Checks whether @fpriv is current master on its device. This decides whether a
284 * client is allowed to run DRM_MASTER IOCTLs.
285 *
286 * Most of the modern IOCTL which require DRM_MASTER are for kernel modesetting
287 * - the current master is assumed to own the non-shareable display hardware.
288 */
289bool drm_is_current_master(struct drm_file *fpriv)
290{
291 return fpriv->is_master && fpriv->master == fpriv->minor->dev->master;
292}
293EXPORT_SYMBOL(drm_is_current_master);
294
295/**
296 * drm_master_get - reference a master pointer
297 * @master: struct &drm_master
298 *
299 * Increments the reference count of @master and returns a pointer to @master.
300 */
301struct drm_master *drm_master_get(struct drm_master *master)
302{
303 kref_get(&master->refcount);
304 return master;
305}
306EXPORT_SYMBOL(drm_master_get);
307
308static void drm_master_destroy(struct kref *kref)
309{
310 struct drm_master *master = container_of(kref, struct drm_master, refcount);
311 struct drm_device *dev = master->dev;
312
313 if (dev->driver->master_destroy)
314 dev->driver->master_destroy(dev, master);
315
316 drm_legacy_master_rmmaps(dev, master);
317
318 idr_destroy(&master->magic_map);
319 kfree(master->unique);
320 kfree(master);
321}
322
323/**
324 * drm_master_put - unreference and clear a master pointer
325 * @master: pointer to a pointer of struct &drm_master
326 *
327 * This decrements the &drm_master behind @master and sets it to NULL.
328 */
329void drm_master_put(struct drm_master **master)
330{
331 kref_put(&(*master)->refcount, drm_master_destroy);
332 *master = NULL;
333}
334EXPORT_SYMBOL(drm_master_put);