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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#include "drm_legacy.h"
41
42/**
43 * DOC: master and authentication
44 *
45 * &struct drm_master is used to track groups of clients with open
46 * primary/legacy device nodes. For every &struct drm_file which has had at
47 * least once successfully became the device master (either through the
48 * SET_MASTER IOCTL, or implicitly through opening the primary device node when
49 * no one else is the current master that time) there exists one &drm_master.
50 * This is noted in &drm_file.is_master. All other clients have just a pointer
51 * to the &drm_master they are associated with.
52 *
53 * In addition only one &drm_master can be the current master for a &drm_device.
54 * It can be switched through the DROP_MASTER and SET_MASTER IOCTL, or
55 * implicitly through closing/opening the primary device node. See also
56 * drm_is_current_master().
57 *
58 * Clients can authenticate against the current master (if it matches their own)
59 * using the GETMAGIC and AUTHMAGIC IOCTLs. Together with exchanging masters,
60 * this allows controlled access to the device for an entire group of mutually
61 * trusted clients.
62 */
63
64static bool drm_is_current_master_locked(struct drm_file *fpriv)
65{
66 lockdep_assert_once(lockdep_is_held(&fpriv->master_lookup_lock) ||
67 lockdep_is_held(&fpriv->minor->dev->master_mutex));
68
69 return fpriv->is_master && drm_lease_owner(fpriv->master) == fpriv->minor->dev->master;
70}
71
72/**
73 * drm_is_current_master - checks whether @priv is the current master
74 * @fpriv: DRM file private
75 *
76 * Checks whether @fpriv is current master on its device. This decides whether a
77 * client is allowed to run DRM_MASTER IOCTLs.
78 *
79 * Most of the modern IOCTL which require DRM_MASTER are for kernel modesetting
80 * - the current master is assumed to own the non-shareable display hardware.
81 */
82bool drm_is_current_master(struct drm_file *fpriv)
83{
84 bool ret;
85
86 spin_lock(&fpriv->master_lookup_lock);
87 ret = drm_is_current_master_locked(fpriv);
88 spin_unlock(&fpriv->master_lookup_lock);
89
90 return ret;
91}
92EXPORT_SYMBOL(drm_is_current_master);
93
94int drm_getmagic(struct drm_device *dev, void *data, struct drm_file *file_priv)
95{
96 struct drm_auth *auth = data;
97 int ret = 0;
98
99 mutex_lock(&dev->master_mutex);
100 if (!file_priv->magic) {
101 ret = idr_alloc(&file_priv->master->magic_map, file_priv,
102 1, 0, GFP_KERNEL);
103 if (ret >= 0)
104 file_priv->magic = ret;
105 }
106 auth->magic = file_priv->magic;
107 mutex_unlock(&dev->master_mutex);
108
109 drm_dbg_core(dev, "%u\n", auth->magic);
110
111 return ret < 0 ? ret : 0;
112}
113
114int drm_authmagic(struct drm_device *dev, void *data,
115 struct drm_file *file_priv)
116{
117 struct drm_auth *auth = data;
118 struct drm_file *file;
119
120 drm_dbg_core(dev, "%u\n", auth->magic);
121
122 mutex_lock(&dev->master_mutex);
123 file = idr_find(&file_priv->master->magic_map, auth->magic);
124 if (file) {
125 file->authenticated = 1;
126 idr_replace(&file_priv->master->magic_map, NULL, auth->magic);
127 }
128 mutex_unlock(&dev->master_mutex);
129
130 return file ? 0 : -EINVAL;
131}
132
133struct drm_master *drm_master_create(struct drm_device *dev)
134{
135 struct drm_master *master;
136
137 master = kzalloc(sizeof(*master), GFP_KERNEL);
138 if (!master)
139 return NULL;
140
141 kref_init(&master->refcount);
142 drm_master_legacy_init(master);
143 idr_init_base(&master->magic_map, 1);
144 master->dev = dev;
145
146 /* initialize the tree of output resource lessees */
147 INIT_LIST_HEAD(&master->lessees);
148 INIT_LIST_HEAD(&master->lessee_list);
149 idr_init(&master->leases);
150 idr_init_base(&master->lessee_idr, 1);
151
152 return master;
153}
154
155static void drm_set_master(struct drm_device *dev, struct drm_file *fpriv,
156 bool new_master)
157{
158 dev->master = drm_master_get(fpriv->master);
159 if (dev->driver->master_set)
160 dev->driver->master_set(dev, fpriv, new_master);
161
162 fpriv->was_master = true;
163}
164
165static int drm_new_set_master(struct drm_device *dev, struct drm_file *fpriv)
166{
167 struct drm_master *old_master;
168 struct drm_master *new_master;
169
170 lockdep_assert_held_once(&dev->master_mutex);
171
172 WARN_ON(fpriv->is_master);
173 old_master = fpriv->master;
174 new_master = drm_master_create(dev);
175 if (!new_master)
176 return -ENOMEM;
177 spin_lock(&fpriv->master_lookup_lock);
178 fpriv->master = new_master;
179 spin_unlock(&fpriv->master_lookup_lock);
180
181 fpriv->is_master = 1;
182 fpriv->authenticated = 1;
183
184 drm_set_master(dev, fpriv, true);
185
186 if (old_master)
187 drm_master_put(&old_master);
188
189 return 0;
190}
191
192/*
193 * In the olden days the SET/DROP_MASTER ioctls used to return EACCES when
194 * CAP_SYS_ADMIN was not set. This was used to prevent rogue applications
195 * from becoming master and/or failing to release it.
196 *
197 * At the same time, the first client (for a given VT) is _always_ master.
198 * Thus in order for the ioctls to succeed, one had to _explicitly_ run the
199 * application as root or flip the setuid bit.
200 *
201 * If the CAP_SYS_ADMIN was missing, no other client could become master...
202 * EVER :-( Leading to a) the graphics session dying badly or b) a completely
203 * locked session.
204 *
205 *
206 * As some point systemd-logind was introduced to orchestrate and delegate
207 * master as applicable. It does so by opening the fd and passing it to users
208 * while in itself logind a) does the set/drop master per users' request and
209 * b) * implicitly drops master on VT switch.
210 *
211 * Even though logind looks like the future, there are a few issues:
212 * - some platforms don't have equivalent (Android, CrOS, some BSDs) so
213 * root is required _solely_ for SET/DROP MASTER.
214 * - applications may not be updated to use it,
215 * - any client which fails to drop master* can DoS the application using
216 * logind, to a varying degree.
217 *
218 * * Either due missing CAP_SYS_ADMIN or simply not calling DROP_MASTER.
219 *
220 *
221 * Here we implement the next best thing:
222 * - ensure the logind style of fd passing works unchanged, and
223 * - allow a client to drop/set master, iff it is/was master at a given point
224 * in time.
225 *
226 * Note: DROP_MASTER cannot be free for all, as an arbitrator user could:
227 * - DoS/crash the arbitrator - details would be implementation specific
228 * - open the node, become master implicitly and cause issues
229 *
230 * As a result this fixes the following when using root-less build w/o logind
231 * - startx
232 * - weston
233 * - various compositors based on wlroots
234 */
235static int
236drm_master_check_perm(struct drm_device *dev, struct drm_file *file_priv)
237{
238 if (file_priv->pid == task_pid(current) && file_priv->was_master)
239 return 0;
240
241 if (!capable(CAP_SYS_ADMIN))
242 return -EACCES;
243
244 return 0;
245}
246
247int drm_setmaster_ioctl(struct drm_device *dev, void *data,
248 struct drm_file *file_priv)
249{
250 int ret;
251
252 mutex_lock(&dev->master_mutex);
253
254 ret = drm_master_check_perm(dev, file_priv);
255 if (ret)
256 goto out_unlock;
257
258 if (drm_is_current_master_locked(file_priv))
259 goto out_unlock;
260
261 if (dev->master) {
262 ret = -EBUSY;
263 goto out_unlock;
264 }
265
266 if (!file_priv->master) {
267 ret = -EINVAL;
268 goto out_unlock;
269 }
270
271 if (!file_priv->is_master) {
272 ret = drm_new_set_master(dev, file_priv);
273 goto out_unlock;
274 }
275
276 if (file_priv->master->lessor != NULL) {
277 drm_dbg_lease(dev,
278 "Attempt to set lessee %d as master\n",
279 file_priv->master->lessee_id);
280 ret = -EINVAL;
281 goto out_unlock;
282 }
283
284 drm_set_master(dev, file_priv, false);
285out_unlock:
286 mutex_unlock(&dev->master_mutex);
287 return ret;
288}
289
290static void drm_drop_master(struct drm_device *dev,
291 struct drm_file *fpriv)
292{
293 if (dev->driver->master_drop)
294 dev->driver->master_drop(dev, fpriv);
295 drm_master_put(&dev->master);
296}
297
298int drm_dropmaster_ioctl(struct drm_device *dev, void *data,
299 struct drm_file *file_priv)
300{
301 int ret;
302
303 mutex_lock(&dev->master_mutex);
304
305 ret = drm_master_check_perm(dev, file_priv);
306 if (ret)
307 goto out_unlock;
308
309 if (!drm_is_current_master_locked(file_priv)) {
310 ret = -EINVAL;
311 goto out_unlock;
312 }
313
314 if (!dev->master) {
315 ret = -EINVAL;
316 goto out_unlock;
317 }
318
319 if (file_priv->master->lessor != NULL) {
320 drm_dbg_lease(dev,
321 "Attempt to drop lessee %d as master\n",
322 file_priv->master->lessee_id);
323 ret = -EINVAL;
324 goto out_unlock;
325 }
326
327 drm_drop_master(dev, file_priv);
328out_unlock:
329 mutex_unlock(&dev->master_mutex);
330 return ret;
331}
332
333int drm_master_open(struct drm_file *file_priv)
334{
335 struct drm_device *dev = file_priv->minor->dev;
336 int ret = 0;
337
338 /* if there is no current master make this fd it, but do not create
339 * any master object for render clients
340 */
341 mutex_lock(&dev->master_mutex);
342 if (!dev->master) {
343 ret = drm_new_set_master(dev, file_priv);
344 } else {
345 spin_lock(&file_priv->master_lookup_lock);
346 file_priv->master = drm_master_get(dev->master);
347 spin_unlock(&file_priv->master_lookup_lock);
348 }
349 mutex_unlock(&dev->master_mutex);
350
351 return ret;
352}
353
354void drm_master_release(struct drm_file *file_priv)
355{
356 struct drm_device *dev = file_priv->minor->dev;
357 struct drm_master *master;
358
359 mutex_lock(&dev->master_mutex);
360 master = file_priv->master;
361 if (file_priv->magic)
362 idr_remove(&file_priv->master->magic_map, file_priv->magic);
363
364 if (!drm_is_current_master_locked(file_priv))
365 goto out;
366
367 drm_legacy_lock_master_cleanup(dev, master);
368
369 if (dev->master == file_priv->master)
370 drm_drop_master(dev, file_priv);
371out:
372 if (drm_core_check_feature(dev, DRIVER_MODESET) && file_priv->is_master) {
373 /* Revoke any leases held by this or lessees, but only if
374 * this is the "real" master
375 */
376 drm_lease_revoke(master);
377 }
378
379 /* drop the master reference held by the file priv */
380 if (file_priv->master)
381 drm_master_put(&file_priv->master);
382 mutex_unlock(&dev->master_mutex);
383}
384
385/**
386 * drm_master_get - reference a master pointer
387 * @master: &struct drm_master
388 *
389 * Increments the reference count of @master and returns a pointer to @master.
390 */
391struct drm_master *drm_master_get(struct drm_master *master)
392{
393 kref_get(&master->refcount);
394 return master;
395}
396EXPORT_SYMBOL(drm_master_get);
397
398/**
399 * drm_file_get_master - reference &drm_file.master of @file_priv
400 * @file_priv: DRM file private
401 *
402 * Increments the reference count of @file_priv's &drm_file.master and returns
403 * the &drm_file.master. If @file_priv has no &drm_file.master, returns NULL.
404 *
405 * Master pointers returned from this function should be unreferenced using
406 * drm_master_put().
407 */
408struct drm_master *drm_file_get_master(struct drm_file *file_priv)
409{
410 struct drm_master *master = NULL;
411
412 spin_lock(&file_priv->master_lookup_lock);
413 if (!file_priv->master)
414 goto unlock;
415 master = drm_master_get(file_priv->master);
416
417unlock:
418 spin_unlock(&file_priv->master_lookup_lock);
419 return master;
420}
421EXPORT_SYMBOL(drm_file_get_master);
422
423static void drm_master_destroy(struct kref *kref)
424{
425 struct drm_master *master = container_of(kref, struct drm_master, refcount);
426 struct drm_device *dev = master->dev;
427
428 if (drm_core_check_feature(dev, DRIVER_MODESET))
429 drm_lease_destroy(master);
430
431 drm_legacy_master_rmmaps(dev, master);
432
433 idr_destroy(&master->magic_map);
434 idr_destroy(&master->leases);
435 idr_destroy(&master->lessee_idr);
436
437 kfree(master->unique);
438 kfree(master);
439}
440
441/**
442 * drm_master_put - unreference and clear a master pointer
443 * @master: pointer to a pointer of &struct drm_master
444 *
445 * This decrements the &drm_master behind @master and sets it to NULL.
446 */
447void drm_master_put(struct drm_master **master)
448{
449 kref_put(&(*master)->refcount, drm_master_destroy);
450 *master = NULL;
451}
452EXPORT_SYMBOL(drm_master_put);
453
454/* Used by drm_client and drm_fb_helper */
455bool drm_master_internal_acquire(struct drm_device *dev)
456{
457 mutex_lock(&dev->master_mutex);
458 if (dev->master) {
459 mutex_unlock(&dev->master_mutex);
460 return false;
461 }
462
463 return true;
464}
465EXPORT_SYMBOL(drm_master_internal_acquire);
466
467/* Used by drm_client and drm_fb_helper */
468void drm_master_internal_release(struct drm_device *dev)
469{
470 mutex_unlock(&dev->master_mutex);
471}
472EXPORT_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);