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 <linux/wait.h> 53#include <linux/atomic.h> 54 55#include "ttm_object.h" 56 57/** 58 * struct ttm_lock 59 * 60 * @base: ttm base object used solely to release the lock if the client 61 * holding the lock dies. 62 * @queue: Queue for processes waiting for lock change-of-status. 63 * @lock: Spinlock protecting some lock members. 64 * @rw: Read-write lock counter. Protected by @lock. 65 * @flags: Lock state. Protected by @lock. 66 * @kill_takers: Boolean whether to kill takers of the lock. 67 * @signal: Signal to send when kill_takers is true. 68 */ 69 70struct ttm_lock { 71 struct ttm_base_object base; 72 wait_queue_head_t queue; 73 spinlock_t lock; 74 int32_t rw; 75 uint32_t flags; 76 bool kill_takers; 77 int signal; 78 struct ttm_object_file *vt_holder; 79}; 80 81 82/** 83 * ttm_lock_init 84 * 85 * @lock: Pointer to a struct ttm_lock 86 * Initializes the lock. 87 */ 88extern void ttm_lock_init(struct ttm_lock *lock); 89 90/** 91 * ttm_read_unlock 92 * 93 * @lock: Pointer to a struct ttm_lock 94 * 95 * Releases a read lock. 96 */ 97extern void ttm_read_unlock(struct ttm_lock *lock); 98 99/** 100 * ttm_read_lock 101 * 102 * @lock: Pointer to a struct ttm_lock 103 * @interruptible: Interruptible sleeping while waiting for a lock. 104 * 105 * Takes the lock in read mode. 106 * Returns: 107 * -ERESTARTSYS If interrupted by a signal and interruptible is true. 108 */ 109extern int ttm_read_lock(struct ttm_lock *lock, bool interruptible); 110 111/** 112 * ttm_read_trylock 113 * 114 * @lock: Pointer to a struct ttm_lock 115 * @interruptible: Interruptible sleeping while waiting for a lock. 116 * 117 * Tries to take the lock in read mode. If the lock is already held 118 * in write mode, the function will return -EBUSY. If the lock is held 119 * in vt or suspend mode, the function will sleep until these modes 120 * are unlocked. 121 * 122 * Returns: 123 * -EBUSY The lock was already held in write mode. 124 * -ERESTARTSYS If interrupted by a signal and interruptible is true. 125 */ 126extern int ttm_read_trylock(struct ttm_lock *lock, bool interruptible); 127 128/** 129 * ttm_write_unlock 130 * 131 * @lock: Pointer to a struct ttm_lock 132 * 133 * Releases a write lock. 134 */ 135extern void ttm_write_unlock(struct ttm_lock *lock); 136 137/** 138 * ttm_write_lock 139 * 140 * @lock: Pointer to a struct ttm_lock 141 * @interruptible: Interruptible sleeping while waiting for a lock. 142 * 143 * Takes the lock in write mode. 144 * Returns: 145 * -ERESTARTSYS If interrupted by a signal and interruptible is true. 146 */ 147extern int ttm_write_lock(struct ttm_lock *lock, bool interruptible); 148 149/** 150 * ttm_lock_downgrade 151 * 152 * @lock: Pointer to a struct ttm_lock 153 * 154 * Downgrades a write lock to a read lock. 155 */ 156extern void ttm_lock_downgrade(struct ttm_lock *lock); 157 158/** 159 * ttm_suspend_lock 160 * 161 * @lock: Pointer to a struct ttm_lock 162 * 163 * Takes the lock in suspend mode. Excludes read and write mode. 164 */ 165extern void ttm_suspend_lock(struct ttm_lock *lock); 166 167/** 168 * ttm_suspend_unlock 169 * 170 * @lock: Pointer to a struct ttm_lock 171 * 172 * Releases a suspend lock 173 */ 174extern void ttm_suspend_unlock(struct ttm_lock *lock); 175 176/** 177 * ttm_vt_lock 178 * 179 * @lock: Pointer to a struct ttm_lock 180 * @interruptible: Interruptible sleeping while waiting for a lock. 181 * @tfile: Pointer to a struct ttm_object_file to register the lock with. 182 * 183 * Takes the lock in vt mode. 184 * Returns: 185 * -ERESTARTSYS If interrupted by a signal and interruptible is true. 186 * -ENOMEM: Out of memory when locking. 187 */ 188extern int ttm_vt_lock(struct ttm_lock *lock, bool interruptible, 189 struct ttm_object_file *tfile); 190 191/** 192 * ttm_vt_unlock 193 * 194 * @lock: Pointer to a struct ttm_lock 195 * 196 * Releases a vt lock. 197 * Returns: 198 * -EINVAL If the lock was not held. 199 */ 200extern int ttm_vt_unlock(struct ttm_lock *lock); 201 202/** 203 * ttm_write_unlock 204 * 205 * @lock: Pointer to a struct ttm_lock 206 * 207 * Releases a write lock. 208 */ 209extern void ttm_write_unlock(struct ttm_lock *lock); 210 211/** 212 * ttm_write_lock 213 * 214 * @lock: Pointer to a struct ttm_lock 215 * @interruptible: Interruptible sleeping while waiting for a lock. 216 * 217 * Takes the lock in write mode. 218 * Returns: 219 * -ERESTARTSYS If interrupted by a signal and interruptible is true. 220 */ 221extern int ttm_write_lock(struct ttm_lock *lock, bool interruptible); 222 223/** 224 * ttm_lock_set_kill 225 * 226 * @lock: Pointer to a struct ttm_lock 227 * @val: Boolean whether to kill processes taking the lock. 228 * @signal: Signal to send to the process taking the lock. 229 * 230 * The kill-when-taking-lock functionality is used to kill processes that keep 231 * on using the TTM functionality when its resources has been taken down, for 232 * example when the X server exits. A typical sequence would look like this: 233 * - X server takes lock in write mode. 234 * - ttm_lock_set_kill() is called with @val set to true. 235 * - As part of X server exit, TTM resources are taken down. 236 * - X server releases the lock on file release. 237 * - Another dri client wants to render, takes the lock and is killed. 238 * 239 */ 240static inline void ttm_lock_set_kill(struct ttm_lock *lock, bool val, 241 int signal) 242{ 243 lock->kill_takers = val; 244 if (val) 245 lock->signal = signal; 246} 247 248#endif 249