1 /**************************************************************************
2 *
3 * Copyright (c) 2007-2009 VMware, Inc., Palo Alto, CA., USA
4 * All Rights Reserved.
5 *
6 * Permission is hereby granted, free of charge, to any person obtaining a
7 * copy of this software and associated documentation files (the
8 * "Software"), to deal in the Software without restriction, including
9 * without limitation the rights to use, copy, modify, merge, publish,
10 * distribute, sub license, and/or sell copies of the Software, and to
11 * permit persons to whom the Software is furnished to do so, subject to
12 * the following conditions:
13 *
14 * The above copyright notice and this permission notice (including the
15 * next paragraph) shall be included in all copies or substantial portions
16 * of the Software.
17 *
18 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
19 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
20 * FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT. IN NO EVENT SHALL
21 * THE COPYRIGHT HOLDERS, AUTHORS AND/OR ITS SUPPLIERS BE LIABLE FOR ANY CLAIM,
22 * DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
23 * OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
24 * USE OR OTHER DEALINGS IN THE SOFTWARE.
25 *
26 **************************************************************************/
27 /*
28 * Authors: Thomas Hellstrom <thellstrom-at-vmware-dot-com>
29 */
30
31 #include <drm/ttm/ttm_lock.h>
32 #include <drm/ttm/ttm_module.h>
33 #include <linux/atomic.h>
34 #include <linux/errno.h>
35 #include <linux/wait.h>
36 #include <linux/sched.h>
37 #include <linux/module.h>
38
39 #define TTM_WRITE_LOCK_PENDING (1 << 0)
40 #define TTM_VT_LOCK_PENDING (1 << 1)
41 #define TTM_SUSPEND_LOCK_PENDING (1 << 2)
42 #define TTM_VT_LOCK (1 << 3)
43 #define TTM_SUSPEND_LOCK (1 << 4)
44
ttm_lock_init(struct ttm_lock * lock)45 void ttm_lock_init(struct ttm_lock *lock)
46 {
47 spin_lock_init(&lock->lock);
48 init_waitqueue_head(&lock->queue);
49 lock->rw = 0;
50 lock->flags = 0;
51 lock->kill_takers = false;
52 lock->signal = SIGKILL;
53 }
54 EXPORT_SYMBOL(ttm_lock_init);
55
ttm_read_unlock(struct ttm_lock * lock)56 void ttm_read_unlock(struct ttm_lock *lock)
57 {
58 spin_lock(&lock->lock);
59 if (--lock->rw == 0)
60 wake_up_all(&lock->queue);
61 spin_unlock(&lock->lock);
62 }
63 EXPORT_SYMBOL(ttm_read_unlock);
64
__ttm_read_lock(struct ttm_lock * lock)65 static bool __ttm_read_lock(struct ttm_lock *lock)
66 {
67 bool locked = false;
68
69 spin_lock(&lock->lock);
70 if (unlikely(lock->kill_takers)) {
71 send_sig(lock->signal, current, 0);
72 spin_unlock(&lock->lock);
73 return false;
74 }
75 if (lock->rw >= 0 && lock->flags == 0) {
76 ++lock->rw;
77 locked = true;
78 }
79 spin_unlock(&lock->lock);
80 return locked;
81 }
82
ttm_read_lock(struct ttm_lock * lock,bool interruptible)83 int ttm_read_lock(struct ttm_lock *lock, bool interruptible)
84 {
85 int ret = 0;
86
87 if (interruptible)
88 ret = wait_event_interruptible(lock->queue,
89 __ttm_read_lock(lock));
90 else
91 wait_event(lock->queue, __ttm_read_lock(lock));
92 return ret;
93 }
94 EXPORT_SYMBOL(ttm_read_lock);
95
__ttm_read_trylock(struct ttm_lock * lock,bool * locked)96 static bool __ttm_read_trylock(struct ttm_lock *lock, bool *locked)
97 {
98 bool block = true;
99
100 *locked = false;
101
102 spin_lock(&lock->lock);
103 if (unlikely(lock->kill_takers)) {
104 send_sig(lock->signal, current, 0);
105 spin_unlock(&lock->lock);
106 return false;
107 }
108 if (lock->rw >= 0 && lock->flags == 0) {
109 ++lock->rw;
110 block = false;
111 *locked = true;
112 } else if (lock->flags == 0) {
113 block = false;
114 }
115 spin_unlock(&lock->lock);
116
117 return !block;
118 }
119
ttm_read_trylock(struct ttm_lock * lock,bool interruptible)120 int ttm_read_trylock(struct ttm_lock *lock, bool interruptible)
121 {
122 int ret = 0;
123 bool locked;
124
125 if (interruptible)
126 ret = wait_event_interruptible
127 (lock->queue, __ttm_read_trylock(lock, &locked));
128 else
129 wait_event(lock->queue, __ttm_read_trylock(lock, &locked));
130
131 if (unlikely(ret != 0)) {
132 BUG_ON(locked);
133 return ret;
134 }
135
136 return (locked) ? 0 : -EBUSY;
137 }
138
ttm_write_unlock(struct ttm_lock * lock)139 void ttm_write_unlock(struct ttm_lock *lock)
140 {
141 spin_lock(&lock->lock);
142 lock->rw = 0;
143 wake_up_all(&lock->queue);
144 spin_unlock(&lock->lock);
145 }
146 EXPORT_SYMBOL(ttm_write_unlock);
147
__ttm_write_lock(struct ttm_lock * lock)148 static bool __ttm_write_lock(struct ttm_lock *lock)
149 {
150 bool locked = false;
151
152 spin_lock(&lock->lock);
153 if (unlikely(lock->kill_takers)) {
154 send_sig(lock->signal, current, 0);
155 spin_unlock(&lock->lock);
156 return false;
157 }
158 if (lock->rw == 0 && ((lock->flags & ~TTM_WRITE_LOCK_PENDING) == 0)) {
159 lock->rw = -1;
160 lock->flags &= ~TTM_WRITE_LOCK_PENDING;
161 locked = true;
162 } else {
163 lock->flags |= TTM_WRITE_LOCK_PENDING;
164 }
165 spin_unlock(&lock->lock);
166 return locked;
167 }
168
ttm_write_lock(struct ttm_lock * lock,bool interruptible)169 int ttm_write_lock(struct ttm_lock *lock, bool interruptible)
170 {
171 int ret = 0;
172
173 if (interruptible) {
174 ret = wait_event_interruptible(lock->queue,
175 __ttm_write_lock(lock));
176 if (unlikely(ret != 0)) {
177 spin_lock(&lock->lock);
178 lock->flags &= ~TTM_WRITE_LOCK_PENDING;
179 wake_up_all(&lock->queue);
180 spin_unlock(&lock->lock);
181 }
182 } else
183 wait_event(lock->queue, __ttm_write_lock(lock));
184
185 return ret;
186 }
187 EXPORT_SYMBOL(ttm_write_lock);
188
__ttm_vt_unlock(struct ttm_lock * lock)189 static int __ttm_vt_unlock(struct ttm_lock *lock)
190 {
191 int ret = 0;
192
193 spin_lock(&lock->lock);
194 if (unlikely(!(lock->flags & TTM_VT_LOCK)))
195 ret = -EINVAL;
196 lock->flags &= ~TTM_VT_LOCK;
197 wake_up_all(&lock->queue);
198 spin_unlock(&lock->lock);
199
200 return ret;
201 }
202
ttm_vt_lock_remove(struct ttm_base_object ** p_base)203 static void ttm_vt_lock_remove(struct ttm_base_object **p_base)
204 {
205 struct ttm_base_object *base = *p_base;
206 struct ttm_lock *lock = container_of(base, struct ttm_lock, base);
207 int ret;
208
209 *p_base = NULL;
210 ret = __ttm_vt_unlock(lock);
211 BUG_ON(ret != 0);
212 }
213
__ttm_vt_lock(struct ttm_lock * lock)214 static bool __ttm_vt_lock(struct ttm_lock *lock)
215 {
216 bool locked = false;
217
218 spin_lock(&lock->lock);
219 if (lock->rw == 0) {
220 lock->flags &= ~TTM_VT_LOCK_PENDING;
221 lock->flags |= TTM_VT_LOCK;
222 locked = true;
223 } else {
224 lock->flags |= TTM_VT_LOCK_PENDING;
225 }
226 spin_unlock(&lock->lock);
227 return locked;
228 }
229
ttm_vt_lock(struct ttm_lock * lock,bool interruptible,struct ttm_object_file * tfile)230 int ttm_vt_lock(struct ttm_lock *lock,
231 bool interruptible,
232 struct ttm_object_file *tfile)
233 {
234 int ret = 0;
235
236 if (interruptible) {
237 ret = wait_event_interruptible(lock->queue,
238 __ttm_vt_lock(lock));
239 if (unlikely(ret != 0)) {
240 spin_lock(&lock->lock);
241 lock->flags &= ~TTM_VT_LOCK_PENDING;
242 wake_up_all(&lock->queue);
243 spin_unlock(&lock->lock);
244 return ret;
245 }
246 } else
247 wait_event(lock->queue, __ttm_vt_lock(lock));
248
249 /*
250 * Add a base-object, the destructor of which will
251 * make sure the lock is released if the client dies
252 * while holding it.
253 */
254
255 ret = ttm_base_object_init(tfile, &lock->base, false,
256 ttm_lock_type, &ttm_vt_lock_remove, NULL);
257 if (ret)
258 (void)__ttm_vt_unlock(lock);
259 else
260 lock->vt_holder = tfile;
261
262 return ret;
263 }
264 EXPORT_SYMBOL(ttm_vt_lock);
265
ttm_vt_unlock(struct ttm_lock * lock)266 int ttm_vt_unlock(struct ttm_lock *lock)
267 {
268 return ttm_ref_object_base_unref(lock->vt_holder,
269 lock->base.hash.key, TTM_REF_USAGE);
270 }
271 EXPORT_SYMBOL(ttm_vt_unlock);
272
ttm_suspend_unlock(struct ttm_lock * lock)273 void ttm_suspend_unlock(struct ttm_lock *lock)
274 {
275 spin_lock(&lock->lock);
276 lock->flags &= ~TTM_SUSPEND_LOCK;
277 wake_up_all(&lock->queue);
278 spin_unlock(&lock->lock);
279 }
280 EXPORT_SYMBOL(ttm_suspend_unlock);
281
__ttm_suspend_lock(struct ttm_lock * lock)282 static bool __ttm_suspend_lock(struct ttm_lock *lock)
283 {
284 bool locked = false;
285
286 spin_lock(&lock->lock);
287 if (lock->rw == 0) {
288 lock->flags &= ~TTM_SUSPEND_LOCK_PENDING;
289 lock->flags |= TTM_SUSPEND_LOCK;
290 locked = true;
291 } else {
292 lock->flags |= TTM_SUSPEND_LOCK_PENDING;
293 }
294 spin_unlock(&lock->lock);
295 return locked;
296 }
297
ttm_suspend_lock(struct ttm_lock * lock)298 void ttm_suspend_lock(struct ttm_lock *lock)
299 {
300 wait_event(lock->queue, __ttm_suspend_lock(lock));
301 }
302 EXPORT_SYMBOL(ttm_suspend_lock);
303