1 /* $NetBSD: ttm_lock.h,v 1.3 2022/02/17 01:21:02 riastradh Exp $ */ 2 3 /************************************************************************** 4 * 5 * Copyright (c) 2007-2009 VMware, Inc., Palo Alto, CA., USA 6 * All Rights Reserved. 7 * 8 * Permission is hereby granted, free of charge, to any person obtaining a 9 * copy of this software and associated documentation files (the 10 * "Software"), to deal in the Software without restriction, including 11 * without limitation the rights to use, copy, modify, merge, publish, 12 * distribute, sub license, and/or sell copies of the Software, and to 13 * permit persons to whom the Software is furnished to do so, subject to 14 * the following conditions: 15 * 16 * The above copyright notice and this permission notice (including the 17 * next paragraph) shall be included in all copies or substantial portions 18 * of the Software. 19 * 20 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR 21 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, 22 * FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT. IN NO EVENT SHALL 23 * THE COPYRIGHT HOLDERS, AUTHORS AND/OR ITS SUPPLIERS BE LIABLE FOR ANY CLAIM, 24 * DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR 25 * OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE 26 * USE OR OTHER DEALINGS IN THE SOFTWARE. 27 * 28 **************************************************************************/ 29 /* 30 * Authors: Thomas Hellstrom <thellstrom-at-vmware-dot-com> 31 */ 32 33 /** @file ttm_lock.h 34 * This file implements a simple replacement for the buffer manager use 35 * of the DRM heavyweight hardware lock. 36 * The lock is a read-write lock. Taking it in read mode and write mode 37 * is relatively fast, and intended for in-kernel use only. 38 * 39 * The vt mode is used only when there is a need to block all 40 * user-space processes from validating buffers. 41 * It's allowed to leave kernel space with the vt lock held. 42 * If a user-space process dies while having the vt-lock, 43 * it will be released during the file descriptor release. The vt lock 44 * excludes write lock and read lock. 45 * 46 * The suspend mode is used to lock out all TTM users when preparing for 47 * and executing suspend operations. 48 * 49 */ 50 51 #ifndef _TTM_LOCK_H_ 52 #define _TTM_LOCK_H_ 53 54 #include <linux/atomic.h> 55 #include <linux/wait.h> 56 57 #include "ttm_object.h" 58 59 #ifdef __NetBSD__ 60 #include "drm_wait_netbsd.h" /* XXX */ 61 #endif 62 63 /** 64 * struct ttm_lock 65 * 66 * @base: ttm base object used solely to release the lock if the client 67 * holding the lock dies. 68 * @queue: Queue for processes waiting for lock change-of-status. 69 * @lock: Spinlock protecting some lock members. 70 * @rw: Read-write lock counter. Protected by @lock. 71 * @flags: Lock state. Protected by @lock. 72 */ 73 74 struct ttm_lock { 75 struct ttm_base_object base; 76 drm_waitqueue_t queue; 77 spinlock_t lock; 78 int32_t rw; 79 uint32_t flags; 80 }; 81 82 83 /** 84 * ttm_lock_init 85 * 86 * @lock: Pointer to a struct ttm_lock 87 * Initializes the lock. 88 */ 89 extern void ttm_lock_init(struct ttm_lock *lock); 90 91 /** 92 * ttm_read_unlock 93 * 94 * @lock: Pointer to a struct ttm_lock 95 * 96 * Releases a read lock. 97 */ 98 extern void ttm_read_unlock(struct ttm_lock *lock); 99 100 /** 101 * ttm_read_lock 102 * 103 * @lock: Pointer to a struct ttm_lock 104 * @interruptible: Interruptible sleeping while waiting for a lock. 105 * 106 * Takes the lock in read mode. 107 * Returns: 108 * -ERESTARTSYS If interrupted by a signal and interruptible is true. 109 */ 110 extern int ttm_read_lock(struct ttm_lock *lock, bool interruptible); 111 112 /** 113 * ttm_read_trylock 114 * 115 * @lock: Pointer to a struct ttm_lock 116 * @interruptible: Interruptible sleeping while waiting for a lock. 117 * 118 * Tries to take the lock in read mode. If the lock is already held 119 * in write mode, the function will return -EBUSY. If the lock is held 120 * in vt or suspend mode, the function will sleep until these modes 121 * are unlocked. 122 * 123 * Returns: 124 * -EBUSY The lock was already held in write mode. 125 * -ERESTARTSYS If interrupted by a signal and interruptible is true. 126 */ 127 extern int ttm_read_trylock(struct ttm_lock *lock, bool interruptible); 128 129 /** 130 * ttm_write_unlock 131 * 132 * @lock: Pointer to a struct ttm_lock 133 * 134 * Releases a write lock. 135 */ 136 extern void ttm_write_unlock(struct ttm_lock *lock); 137 138 /** 139 * ttm_write_lock 140 * 141 * @lock: Pointer to a struct ttm_lock 142 * @interruptible: Interruptible sleeping while waiting for a lock. 143 * 144 * Takes the lock in write mode. 145 * Returns: 146 * -ERESTARTSYS If interrupted by a signal and interruptible is true. 147 */ 148 extern int ttm_write_lock(struct ttm_lock *lock, bool interruptible); 149 150 /** 151 * ttm_lock_downgrade 152 * 153 * @lock: Pointer to a struct ttm_lock 154 * 155 * Downgrades a write lock to a read lock. 156 */ 157 extern void ttm_lock_downgrade(struct ttm_lock *lock); 158 159 /** 160 * ttm_suspend_lock 161 * 162 * @lock: Pointer to a struct ttm_lock 163 * 164 * Takes the lock in suspend mode. Excludes read and write mode. 165 */ 166 extern void ttm_suspend_lock(struct ttm_lock *lock); 167 168 /** 169 * ttm_suspend_unlock 170 * 171 * @lock: Pointer to a struct ttm_lock 172 * 173 * Releases a suspend lock 174 */ 175 extern void ttm_suspend_unlock(struct ttm_lock *lock); 176 177 /** 178 * ttm_vt_lock 179 * 180 * @lock: Pointer to a struct ttm_lock 181 * @interruptible: Interruptible sleeping while waiting for a lock. 182 * @tfile: Pointer to a struct ttm_object_file to register the lock with. 183 * 184 * Takes the lock in vt mode. 185 * Returns: 186 * -ERESTARTSYS If interrupted by a signal and interruptible is true. 187 * -ENOMEM: Out of memory when locking. 188 */ 189 extern int ttm_vt_lock(struct ttm_lock *lock, bool interruptible, 190 struct ttm_object_file *tfile); 191 192 /** 193 * ttm_vt_unlock 194 * 195 * @lock: Pointer to a struct ttm_lock 196 * 197 * Releases a vt lock. 198 * Returns: 199 * -EINVAL If the lock was not held. 200 */ 201 extern int ttm_vt_unlock(struct ttm_lock *lock); 202 203 /** 204 * ttm_write_unlock 205 * 206 * @lock: Pointer to a struct ttm_lock 207 * 208 * Releases a write lock. 209 */ 210 extern void ttm_write_unlock(struct ttm_lock *lock); 211 212 /** 213 * ttm_write_lock 214 * 215 * @lock: Pointer to a struct ttm_lock 216 * @interruptible: Interruptible sleeping while waiting for a lock. 217 * 218 * Takes the lock in write mode. 219 * Returns: 220 * -ERESTARTSYS If interrupted by a signal and interruptible is true. 221 */ 222 extern int ttm_write_lock(struct ttm_lock *lock, bool interruptible); 223 224 #endif 225