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 69struct 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 */ 87extern 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 */ 96extern 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 */ 108extern 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 */ 125extern 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 */ 134extern 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 */ 146extern 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 */ 155extern 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 */ 164extern 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 */ 173extern 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 */ 187extern 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 */ 199extern 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 */ 208extern 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 */ 220extern 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 */ 239static 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