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 <dev/drm2/drmP.h>
53 #include <dev/drm2/drm.h>
54 #include <dev/drm2/ttm/ttm_object.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 struct mtx lock;
72 int32_t rw;
73 uint32_t flags;
74 bool kill_takers;
75 int signal;
76 struct ttm_object_file *vt_holder;
77 };
78
79
80 /**
81 * ttm_lock_init
82 *
83 * @lock: Pointer to a struct ttm_lock
84 * Initializes the lock.
85 */
86 extern void ttm_lock_init(struct ttm_lock *lock);
87
88 /**
89 * ttm_read_unlock
90 *
91 * @lock: Pointer to a struct ttm_lock
92 *
93 * Releases a read lock.
94 */
95 extern void ttm_read_unlock(struct ttm_lock *lock);
96
97 /**
98 * ttm_read_lock
99 *
100 * @lock: Pointer to a struct ttm_lock
101 * @interruptible: Interruptible sleeping while waiting for a lock.
102 *
103 * Takes the lock in read mode.
104 * Returns:
105 * -ERESTARTSYS If interrupted by a signal and interruptible is true.
106 */
107 extern int ttm_read_lock(struct ttm_lock *lock, bool interruptible);
108
109 /**
110 * ttm_read_trylock
111 *
112 * @lock: Pointer to a struct ttm_lock
113 * @interruptible: Interruptible sleeping while waiting for a lock.
114 *
115 * Tries to take the lock in read mode. If the lock is already held
116 * in write mode, the function will return -EBUSY. If the lock is held
117 * in vt or suspend mode, the function will sleep until these modes
118 * are unlocked.
119 *
120 * Returns:
121 * -EBUSY The lock was already held in write mode.
122 * -ERESTARTSYS If interrupted by a signal and interruptible is true.
123 */
124 extern int ttm_read_trylock(struct ttm_lock *lock, bool interruptible);
125
126 /**
127 * ttm_lock_downgrade
128 *
129 * @lock: Pointer to a struct ttm_lock
130 *
131 * Downgrades a write lock to a read lock.
132 */
133 extern void ttm_lock_downgrade(struct ttm_lock *lock);
134
135 /**
136 * ttm_suspend_lock
137 *
138 * @lock: Pointer to a struct ttm_lock
139 *
140 * Takes the lock in suspend mode. Excludes read and write mode.
141 */
142 extern void ttm_suspend_lock(struct ttm_lock *lock);
143
144 /**
145 * ttm_suspend_unlock
146 *
147 * @lock: Pointer to a struct ttm_lock
148 *
149 * Releases a suspend lock
150 */
151 extern void ttm_suspend_unlock(struct ttm_lock *lock);
152
153 /**
154 * ttm_vt_lock
155 *
156 * @lock: Pointer to a struct ttm_lock
157 * @interruptible: Interruptible sleeping while waiting for a lock.
158 * @tfile: Pointer to a struct ttm_object_file to register the lock with.
159 *
160 * Takes the lock in vt mode.
161 * Returns:
162 * -ERESTARTSYS If interrupted by a signal and interruptible is true.
163 * -ENOMEM: Out of memory when locking.
164 */
165 extern int ttm_vt_lock(struct ttm_lock *lock, bool interruptible,
166 struct ttm_object_file *tfile);
167
168 /**
169 * ttm_vt_unlock
170 *
171 * @lock: Pointer to a struct ttm_lock
172 *
173 * Releases a vt lock.
174 * Returns:
175 * -EINVAL If the lock was not held.
176 */
177 extern int ttm_vt_unlock(struct ttm_lock *lock);
178
179 /**
180 * ttm_write_unlock
181 *
182 * @lock: Pointer to a struct ttm_lock
183 *
184 * Releases a write lock.
185 */
186 extern void ttm_write_unlock(struct ttm_lock *lock);
187
188 /**
189 * ttm_write_lock
190 *
191 * @lock: Pointer to a struct ttm_lock
192 * @interruptible: Interruptible sleeping while waiting for a lock.
193 *
194 * Takes the lock in write mode.
195 * Returns:
196 * -ERESTARTSYS If interrupted by a signal and interruptible is true.
197 */
198 extern int ttm_write_lock(struct ttm_lock *lock, bool interruptible);
199
200 void ttm_write_lock_downgrade(struct ttm_lock *lock);
201
202 /**
203 * ttm_lock_set_kill
204 *
205 * @lock: Pointer to a struct ttm_lock
206 * @val: Boolean whether to kill processes taking the lock.
207 * @signal: Signal to send to the process taking the lock.
208 *
209 * The kill-when-taking-lock functionality is used to kill processes that keep
210 * on using the TTM functionality when its resources has been taken down, for
211 * example when the X server exits. A typical sequence would look like this:
212 * - X server takes lock in write mode.
213 * - ttm_lock_set_kill() is called with @val set to true.
214 * - As part of X server exit, TTM resources are taken down.
215 * - X server releases the lock on file release.
216 * - Another dri client wants to render, takes the lock and is killed.
217 *
218 */
ttm_lock_set_kill(struct ttm_lock * lock,bool val,int signal)219 static inline void ttm_lock_set_kill(struct ttm_lock *lock, bool val,
220 int signal)
221 {
222 lock->kill_takers = val;
223 if (val)
224 lock->signal = signal;
225 }
226
227 #endif
228