1 /* SPDX-License-Identifier: GPL-2.0 OR MIT */
2 /**************************************************************************
3 *
4 * Copyright (c) 2007-2009 VMware, Inc., Palo Alto, CA., USA
5 * All Rights Reserved.
6 *
7 * Permission is hereby granted, free of charge, to any person obtaining a
8 * copy of this software and associated documentation files (the
9 * "Software"), to deal in the Software without restriction, including
10 * without limitation the rights to use, copy, modify, merge, publish,
11 * distribute, sub license, and/or sell copies of the Software, and to
12 * permit persons to whom the Software is furnished to do so, subject to
13 * the following conditions:
14 *
15 * The above copyright notice and this permission notice (including the
16 * next paragraph) shall be included in all copies or substantial portions
17 * of the Software.
18 *
19 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
20 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
21 * FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT. IN NO EVENT SHALL
22 * THE COPYRIGHT HOLDERS, AUTHORS AND/OR ITS SUPPLIERS BE LIABLE FOR ANY CLAIM,
23 * DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
24 * OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
25 * USE OR OTHER DEALINGS IN THE SOFTWARE.
26 *
27 **************************************************************************/
28 /*
29 * Authors: Thomas Hellstrom <thellstrom-at-vmware-dot-com>
30 */
31
32 #include <linux/atomic.h>
33 #include <linux/errno.h>
34 #include <linux/wait.h>
35 #include <linux/sched/signal.h>
36 #include "ttm_lock.h"
37 #include "ttm_object.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 }
52
ttm_read_unlock(struct ttm_lock * lock)53 void ttm_read_unlock(struct ttm_lock *lock)
54 {
55 spin_lock(&lock->lock);
56 if (--lock->rw == 0)
57 wake_up_all(&lock->queue);
58 spin_unlock(&lock->lock);
59 }
60
__ttm_read_lock(struct ttm_lock * lock)61 static bool __ttm_read_lock(struct ttm_lock *lock)
62 {
63 bool locked = false;
64
65 spin_lock(&lock->lock);
66 if (lock->rw >= 0 && lock->flags == 0) {
67 ++lock->rw;
68 locked = true;
69 }
70 spin_unlock(&lock->lock);
71 return locked;
72 }
73
ttm_read_lock(struct ttm_lock * lock,bool interruptible)74 int ttm_read_lock(struct ttm_lock *lock, bool interruptible)
75 {
76 int ret = 0;
77
78 if (interruptible)
79 ret = wait_event_interruptible(lock->queue,
80 __ttm_read_lock(lock));
81 else
82 wait_event(lock->queue, __ttm_read_lock(lock));
83 return ret;
84 }
85
__ttm_read_trylock(struct ttm_lock * lock,bool * locked)86 static bool __ttm_read_trylock(struct ttm_lock *lock, bool *locked)
87 {
88 bool block = true;
89
90 *locked = false;
91
92 spin_lock(&lock->lock);
93 if (lock->rw >= 0 && lock->flags == 0) {
94 ++lock->rw;
95 block = false;
96 *locked = true;
97 } else if (lock->flags == 0) {
98 block = false;
99 }
100 spin_unlock(&lock->lock);
101
102 return !block;
103 }
104
ttm_read_trylock(struct ttm_lock * lock,bool interruptible)105 int ttm_read_trylock(struct ttm_lock *lock, bool interruptible)
106 {
107 int ret = 0;
108 bool locked;
109
110 if (interruptible)
111 ret = wait_event_interruptible
112 (lock->queue, __ttm_read_trylock(lock, &locked));
113 else
114 wait_event(lock->queue, __ttm_read_trylock(lock, &locked));
115
116 if (unlikely(ret != 0)) {
117 BUG_ON(locked);
118 return ret;
119 }
120
121 return (locked) ? 0 : -EBUSY;
122 }
123
ttm_write_unlock(struct ttm_lock * lock)124 void ttm_write_unlock(struct ttm_lock *lock)
125 {
126 spin_lock(&lock->lock);
127 lock->rw = 0;
128 wake_up_all(&lock->queue);
129 spin_unlock(&lock->lock);
130 }
131
__ttm_write_lock(struct ttm_lock * lock)132 static bool __ttm_write_lock(struct ttm_lock *lock)
133 {
134 bool locked = false;
135
136 spin_lock(&lock->lock);
137 if (lock->rw == 0 && ((lock->flags & ~TTM_WRITE_LOCK_PENDING) == 0)) {
138 lock->rw = -1;
139 lock->flags &= ~TTM_WRITE_LOCK_PENDING;
140 locked = true;
141 } else {
142 lock->flags |= TTM_WRITE_LOCK_PENDING;
143 }
144 spin_unlock(&lock->lock);
145 return locked;
146 }
147
ttm_write_lock(struct ttm_lock * lock,bool interruptible)148 int ttm_write_lock(struct ttm_lock *lock, bool interruptible)
149 {
150 int ret = 0;
151
152 if (interruptible) {
153 ret = wait_event_interruptible(lock->queue,
154 __ttm_write_lock(lock));
155 if (unlikely(ret != 0)) {
156 spin_lock(&lock->lock);
157 lock->flags &= ~TTM_WRITE_LOCK_PENDING;
158 wake_up_all(&lock->queue);
159 spin_unlock(&lock->lock);
160 }
161 } else
162 wait_event(lock->queue, __ttm_write_lock(lock));
163
164 return ret;
165 }
166
ttm_suspend_unlock(struct ttm_lock * lock)167 void ttm_suspend_unlock(struct ttm_lock *lock)
168 {
169 spin_lock(&lock->lock);
170 lock->flags &= ~TTM_SUSPEND_LOCK;
171 wake_up_all(&lock->queue);
172 spin_unlock(&lock->lock);
173 }
174
__ttm_suspend_lock(struct ttm_lock * lock)175 static bool __ttm_suspend_lock(struct ttm_lock *lock)
176 {
177 bool locked = false;
178
179 spin_lock(&lock->lock);
180 if (lock->rw == 0) {
181 lock->flags &= ~TTM_SUSPEND_LOCK_PENDING;
182 lock->flags |= TTM_SUSPEND_LOCK;
183 locked = true;
184 } else {
185 lock->flags |= TTM_SUSPEND_LOCK_PENDING;
186 }
187 spin_unlock(&lock->lock);
188 return locked;
189 }
190
ttm_suspend_lock(struct ttm_lock * lock)191 void ttm_suspend_lock(struct ttm_lock *lock)
192 {
193 wait_event(lock->queue, __ttm_suspend_lock(lock));
194 }
195