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 */ 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