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 /** @file ttm_lock.h
32 * This file implements a simple replacement for the buffer manager use
33 * of the DRM heavyweight hardware lock.
34 * The lock is a read-write lock. Taking it in read mode and write mode
35 * is relatively fast, and intended for in-kernel use only.
36 *
37 * The vt mode is used only when there is a need to block all
38 * user-space processes from validating buffers.
39 * It's allowed to leave kernel space with the vt lock held.
40 * If a user-space process dies while having the vt-lock,
41 * it will be released during the file descriptor release. The vt lock
42 * excludes write lock and read lock.
43 *
44 * The suspend mode is used to lock out all TTM users when preparing for
45 * and executing suspend operations.
46 *
47 */
48
49 #ifndef _TTM_LOCK_H_
50 #define _TTM_LOCK_H_
51
52 #include <ttm/ttm_object.h>
53 #include <linux/wait.h>
54 #include <linux/atomic.h>
55
56 /**
57 * struct ttm_lock
58 *
59 * @base: ttm base object used solely to release the lock if the client
60 * holding the lock dies.
61 * @queue: Queue for processes waiting for lock change-of-status.
62 * @lock: Spinlock protecting some lock members.
63 * @rw: Read-write lock counter. Protected by @lock.
64 * @flags: Lock state. Protected by @lock.
65 * @kill_takers: Boolean whether to kill takers of the lock.
66 * @signal: Signal to send when kill_takers is true.
67 */
68
69 struct ttm_lock {
70 struct ttm_base_object base;
71 wait_queue_head_t queue;
72 spinlock_t lock;
73 int32_t rw;
74 uint32_t flags;
75 bool kill_takers;
76 int signal;
77 struct ttm_object_file *vt_holder;
78 };
79
80
81 /**
82 * ttm_lock_init
83 *
84 * @lock: Pointer to a struct ttm_lock
85 * Initializes the lock.
86 */
87 extern void ttm_lock_init(struct ttm_lock *lock);
88
89 /**
90 * ttm_read_unlock
91 *
92 * @lock: Pointer to a struct ttm_lock
93 *
94 * Releases a read lock.
95 */
96 extern void ttm_read_unlock(struct ttm_lock *lock);
97
98 /**
99 * ttm_read_lock
100 *
101 * @lock: Pointer to a struct ttm_lock
102 * @interruptible: Interruptible sleeping while waiting for a lock.
103 *
104 * Takes the lock in read mode.
105 * Returns:
106 * -ERESTARTSYS If interrupted by a signal and interruptible is true.
107 */
108 extern int ttm_read_lock(struct ttm_lock *lock, bool interruptible);
109
110 /**
111 * ttm_read_trylock
112 *
113 * @lock: Pointer to a struct ttm_lock
114 * @interruptible: Interruptible sleeping while waiting for a lock.
115 *
116 * Tries to take the lock in read mode. If the lock is already held
117 * in write mode, the function will return -EBUSY. If the lock is held
118 * in vt or suspend mode, the function will sleep until these modes
119 * are unlocked.
120 *
121 * Returns:
122 * -EBUSY The lock was already held in write mode.
123 * -ERESTARTSYS If interrupted by a signal and interruptible is true.
124 */
125 extern int ttm_read_trylock(struct ttm_lock *lock, bool interruptible);
126
127 /**
128 * ttm_write_unlock
129 *
130 * @lock: Pointer to a struct ttm_lock
131 *
132 * Releases a write lock.
133 */
134 extern void ttm_write_unlock(struct ttm_lock *lock);
135
136 /**
137 * ttm_write_lock
138 *
139 * @lock: Pointer to a struct ttm_lock
140 * @interruptible: Interruptible sleeping while waiting for a lock.
141 *
142 * Takes the lock in write mode.
143 * Returns:
144 * -ERESTARTSYS If interrupted by a signal and interruptible is true.
145 */
146 extern int ttm_write_lock(struct ttm_lock *lock, bool interruptible);
147
148 /**
149 * ttm_lock_downgrade
150 *
151 * @lock: Pointer to a struct ttm_lock
152 *
153 * Downgrades a write lock to a read lock.
154 */
155 extern void ttm_lock_downgrade(struct ttm_lock *lock);
156
157 /**
158 * ttm_suspend_lock
159 *
160 * @lock: Pointer to a struct ttm_lock
161 *
162 * Takes the lock in suspend mode. Excludes read and write mode.
163 */
164 extern void ttm_suspend_lock(struct ttm_lock *lock);
165
166 /**
167 * ttm_suspend_unlock
168 *
169 * @lock: Pointer to a struct ttm_lock
170 *
171 * Releases a suspend lock
172 */
173 extern void ttm_suspend_unlock(struct ttm_lock *lock);
174
175 /**
176 * ttm_vt_lock
177 *
178 * @lock: Pointer to a struct ttm_lock
179 * @interruptible: Interruptible sleeping while waiting for a lock.
180 * @tfile: Pointer to a struct ttm_object_file to register the lock with.
181 *
182 * Takes the lock in vt mode.
183 * Returns:
184 * -ERESTARTSYS If interrupted by a signal and interruptible is true.
185 * -ENOMEM: Out of memory when locking.
186 */
187 extern int ttm_vt_lock(struct ttm_lock *lock, bool interruptible,
188 struct ttm_object_file *tfile);
189
190 /**
191 * ttm_vt_unlock
192 *
193 * @lock: Pointer to a struct ttm_lock
194 *
195 * Releases a vt lock.
196 * Returns:
197 * -EINVAL If the lock was not held.
198 */
199 extern int ttm_vt_unlock(struct ttm_lock *lock);
200
201 /**
202 * ttm_write_unlock
203 *
204 * @lock: Pointer to a struct ttm_lock
205 *
206 * Releases a write lock.
207 */
208 extern void ttm_write_unlock(struct ttm_lock *lock);
209
210 /**
211 * ttm_write_lock
212 *
213 * @lock: Pointer to a struct ttm_lock
214 * @interruptible: Interruptible sleeping while waiting for a lock.
215 *
216 * Takes the lock in write mode.
217 * Returns:
218 * -ERESTARTSYS If interrupted by a signal and interruptible is true.
219 */
220 extern int ttm_write_lock(struct ttm_lock *lock, bool interruptible);
221
222 /**
223 * ttm_lock_set_kill
224 *
225 * @lock: Pointer to a struct ttm_lock
226 * @val: Boolean whether to kill processes taking the lock.
227 * @signal: Signal to send to the process taking the lock.
228 *
229 * The kill-when-taking-lock functionality is used to kill processes that keep
230 * on using the TTM functionality when its resources has been taken down, for
231 * example when the X server exits. A typical sequence would look like this:
232 * - X server takes lock in write mode.
233 * - ttm_lock_set_kill() is called with @val set to true.
234 * - As part of X server exit, TTM resources are taken down.
235 * - X server releases the lock on file release.
236 * - Another dri client wants to render, takes the lock and is killed.
237 *
238 */
ttm_lock_set_kill(struct ttm_lock * lock,bool val,int signal)239 static inline void ttm_lock_set_kill(struct ttm_lock *lock, bool val,
240 int signal)
241 {
242 lock->kill_takers = val;
243 if (val)
244 lock->signal = signal;
245 }
246
247 #endif
248