1 /** 2 * \file drm_lock.c 3 * IOCTLs for locking 4 * 5 * \author Rickard E. (Rik) Faith <faith@valinux.com> 6 * \author Gareth Hughes <gareth@valinux.com> 7 */ 8 9 /* 10 * Created: Tue Feb 2 08:37:54 1999 by faith@valinux.com 11 * 12 * Copyright 1999 Precision Insight, Inc., Cedar Park, Texas. 13 * Copyright 2000 VA Linux Systems, Inc., Sunnyvale, California. 14 * All Rights Reserved. 15 * 16 * Permission is hereby granted, free of charge, to any person obtaining a 17 * copy of this software and associated documentation files (the "Software"), 18 * to deal in the Software without restriction, including without limitation 19 * the rights to use, copy, modify, merge, publish, distribute, sublicense, 20 * and/or sell copies of the Software, and to permit persons to whom the 21 * Software is furnished to do so, subject to the following conditions: 22 * 23 * The above copyright notice and this permission notice (including the next 24 * paragraph) shall be included in all copies or substantial portions of the 25 * Software. 26 * 27 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR 28 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, 29 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL 30 * VA LINUX SYSTEMS AND/OR ITS SUPPLIERS BE LIABLE FOR ANY CLAIM, DAMAGES OR 31 * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, 32 * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR 33 * OTHER DEALINGS IN THE SOFTWARE. 34 */ 35 36 #include <linux/export.h> 37 #include <drm/drmP.h> 38 #include "drm_legacy.h" 39 #include "drm_internal.h" 40 41 #if 0 42 static int drm_lock_take(struct drm_lock_data *lock_data, unsigned int context); 43 44 /** 45 * Take the heavyweight lock. 46 * 47 * \param lock lock pointer. 48 * \param context locking context. 49 * \return one if the lock is held, or zero otherwise. 50 * 51 * Attempt to mark the lock as held by the given context, via the \p cmpxchg instruction. 52 */ 53 static 54 int drm_lock_take(struct drm_lock_data *lock_data, 55 unsigned int context) 56 { 57 unsigned int old, new, prev; 58 volatile unsigned int *lock = &lock_data->hw_lock->lock; 59 60 spin_lock_bh(&lock_data->spinlock); 61 do { 62 old = *lock; 63 if (old & _DRM_LOCK_HELD) 64 new = old | _DRM_LOCK_CONT; 65 else { 66 new = context | _DRM_LOCK_HELD | 67 ((lock_data->user_waiters + lock_data->kernel_waiters > 1) ? 68 _DRM_LOCK_CONT : 0); 69 } 70 prev = cmpxchg(lock, old, new); 71 } while (prev != old); 72 spin_unlock_bh(&lock_data->spinlock); 73 74 if (_DRM_LOCKING_CONTEXT(old) == context) { 75 if (old & _DRM_LOCK_HELD) { 76 if (context != DRM_KERNEL_CONTEXT) { 77 DRM_ERROR("%d holds heavyweight lock\n", 78 context); 79 } 80 return 0; 81 } 82 } 83 84 if ((_DRM_LOCKING_CONTEXT(new)) == context && (new & _DRM_LOCK_HELD)) { 85 /* Have lock */ 86 return 1; 87 } 88 return 0; 89 } 90 91 /** 92 * This takes a lock forcibly and hands it to context. Should ONLY be used 93 * inside *_unlock to give lock to kernel before calling *_dma_schedule. 94 * 95 * \param dev DRM device. 96 * \param lock lock pointer. 97 * \param context locking context. 98 * \return always one. 99 * 100 * Resets the lock file pointer. 101 * Marks the lock as held by the given context, via the \p cmpxchg instruction. 102 */ 103 static int drm_lock_transfer(struct drm_lock_data *lock_data, 104 unsigned int context) 105 { 106 unsigned int old, new, prev; 107 volatile unsigned int *lock = &lock_data->hw_lock->lock; 108 109 lock_data->file_priv = NULL; 110 do { 111 old = *lock; 112 new = context | _DRM_LOCK_HELD; 113 prev = cmpxchg(lock, old, new); 114 } while (prev != old); 115 return 1; 116 } 117 118 static int drm_legacy_lock_free(struct drm_lock_data *lock_data, 119 unsigned int context) 120 { 121 unsigned int old, new, prev; 122 volatile unsigned int *lock = &lock_data->hw_lock->lock; 123 124 spin_lock_bh(&lock_data->spinlock); 125 if (lock_data->kernel_waiters != 0) { 126 drm_lock_transfer(lock_data, 0); 127 lock_data->idle_has_lock = 1; 128 spin_unlock_bh(&lock_data->spinlock); 129 return 1; 130 } 131 spin_unlock_bh(&lock_data->spinlock); 132 133 do { 134 old = *lock; 135 new = _DRM_LOCKING_CONTEXT(old); 136 prev = cmpxchg(lock, old, new); 137 } while (prev != old); 138 139 if (_DRM_LOCK_IS_HELD(old) && _DRM_LOCKING_CONTEXT(old) != context) { 140 DRM_ERROR("%d freed heavyweight lock held by %d\n", 141 context, _DRM_LOCKING_CONTEXT(old)); 142 return 1; 143 } 144 wake_up_interruptible(&lock_data->lock_queue); 145 return 0; 146 } 147 #endif 148 149 /** 150 * Lock ioctl. 151 * 152 * \param inode device inode. 153 * \param file_priv DRM file private. 154 * \param cmd command. 155 * \param arg user argument, pointing to a drm_lock structure. 156 * \return zero on success or negative number on failure. 157 * 158 * Add the current task to the lock wait queue, and attempt to take to lock. 159 */ 160 int drm_legacy_lock(struct drm_device *dev, void *data, 161 struct drm_file *file_priv) 162 { 163 #if 0 164 DECLARE_WAITQUEUE(entry, current); 165 struct drm_lock *lock = data; 166 struct drm_master *master = file_priv->master; 167 int ret = 0; 168 169 if (!drm_core_check_feature(dev, DRIVER_LEGACY)) 170 return -EINVAL; 171 172 ++file_priv->lock_count; 173 174 if (lock->context == DRM_KERNEL_CONTEXT) { 175 DRM_ERROR("Process %d using kernel context %d\n", 176 task_pid_nr(current), lock->context); 177 return -EINVAL; 178 } 179 180 DRM_DEBUG("%d (pid %d) requests lock (0x%08x), flags = 0x%08x\n", 181 lock->context, task_pid_nr(current), 182 master->lock.hw_lock->lock, lock->flags); 183 184 add_wait_queue(&master->lock.lock_queue, &entry); 185 spin_lock_bh(&master->lock.spinlock); 186 master->lock.user_waiters++; 187 spin_unlock_bh(&master->lock.spinlock); 188 189 for (;;) { 190 __set_current_state(TASK_INTERRUPTIBLE); 191 if (!master->lock.hw_lock) { 192 /* Device has been unregistered */ 193 send_sig(SIGTERM, current, 0); 194 ret = -EINTR; 195 break; 196 } 197 if (drm_lock_take(&master->lock, lock->context)) { 198 master->lock.file_priv = file_priv; 199 master->lock.lock_time = jiffies; 200 break; /* Got lock */ 201 } 202 203 /* Contention */ 204 mutex_unlock(&drm_global_mutex); 205 schedule(); 206 mutex_lock(&drm_global_mutex); 207 if (signal_pending(current)) { 208 ret = -EINTR; 209 break; 210 } 211 } 212 spin_lock_bh(&master->lock.spinlock); 213 master->lock.user_waiters--; 214 spin_unlock_bh(&master->lock.spinlock); 215 __set_current_state(TASK_RUNNING); 216 remove_wait_queue(&master->lock.lock_queue, &entry); 217 218 DRM_DEBUG("%d %s\n", lock->context, 219 ret ? "interrupted" : "has lock"); 220 if (ret) return ret; 221 222 /* don't set the block all signals on the master process for now 223 * really probably not the correct answer but lets us debug xkb 224 * xserver for now */ 225 if (!drm_is_current_master(file_priv)) { 226 dev->sigdata.context = lock->context; 227 dev->sigdata.lock = master->lock.hw_lock; 228 } 229 230 if (dev->driver->dma_quiescent && (lock->flags & _DRM_LOCK_QUIESCENT)) 231 { 232 if (dev->driver->dma_quiescent(dev)) { 233 DRM_DEBUG("%d waiting for DMA quiescent\n", 234 lock->context); 235 return -EBUSY; 236 } 237 } 238 #endif 239 240 return 0; 241 } 242 243 /** 244 * Unlock ioctl. 245 * 246 * \param inode device inode. 247 * \param file_priv DRM file private. 248 * \param cmd command. 249 * \param arg user argument, pointing to a drm_lock structure. 250 * \return zero on success or negative number on failure. 251 * 252 * Transfer and free the lock. 253 */ 254 int drm_legacy_unlock(struct drm_device *dev, void *data, struct drm_file *file_priv) 255 { 256 #if 0 257 struct drm_lock *lock = data; 258 struct drm_master *master = file_priv->master; 259 260 if (!drm_core_check_feature(dev, DRIVER_LEGACY)) 261 return -EINVAL; 262 263 if (lock->context == DRM_KERNEL_CONTEXT) { 264 DRM_ERROR("Process %d using kernel context %d\n", 265 task_pid_nr(current), lock->context); 266 return -EINVAL; 267 } 268 269 if (drm_legacy_lock_free(&master->lock, lock->context)) { 270 /* FIXME: Should really bail out here. */ 271 } 272 #endif 273 274 return 0; 275 } 276 277 #if 0 278 /** 279 * This function returns immediately and takes the hw lock 280 * with the kernel context if it is free, otherwise it gets the highest priority when and if 281 * it is eventually released. 282 * 283 * This guarantees that the kernel will _eventually_ have the lock _unless_ it is held 284 * by a blocked process. (In the latter case an explicit wait for the hardware lock would cause 285 * a deadlock, which is why the "idlelock" was invented). 286 * 287 * This should be sufficient to wait for GPU idle without 288 * having to worry about starvation. 289 */ 290 291 void drm_legacy_idlelock_take(struct drm_lock_data *lock_data) 292 { 293 int ret; 294 295 spin_lock_bh(&lock_data->spinlock); 296 lock_data->kernel_waiters++; 297 if (!lock_data->idle_has_lock) { 298 299 spin_unlock_bh(&lock_data->spinlock); 300 ret = drm_lock_take(lock_data, DRM_KERNEL_CONTEXT); 301 spin_lock_bh(&lock_data->spinlock); 302 303 if (ret == 1) 304 lock_data->idle_has_lock = 1; 305 } 306 spin_unlock_bh(&lock_data->spinlock); 307 } 308 EXPORT_SYMBOL(drm_legacy_idlelock_take); 309 310 void drm_legacy_idlelock_release(struct drm_lock_data *lock_data) 311 { 312 unsigned int old, prev; 313 volatile unsigned int *lock = &lock_data->hw_lock->lock; 314 315 spin_lock_bh(&lock_data->spinlock); 316 if (--lock_data->kernel_waiters == 0) { 317 if (lock_data->idle_has_lock) { 318 do { 319 old = *lock; 320 prev = cmpxchg(lock, old, DRM_KERNEL_CONTEXT); 321 } while (prev != old); 322 wake_up_interruptible(&lock_data->lock_queue); 323 lock_data->idle_has_lock = 0; 324 } 325 } 326 spin_unlock_bh(&lock_data->spinlock); 327 } 328 EXPORT_SYMBOL(drm_legacy_idlelock_release); 329 330 static int drm_legacy_i_have_hw_lock(struct drm_device *dev, 331 struct drm_file *file_priv) 332 { 333 struct drm_master *master = file_priv->master; 334 return (file_priv->lock_count && master->lock.hw_lock && 335 _DRM_LOCK_IS_HELD(master->lock.hw_lock->lock) && 336 master->lock.file_priv == file_priv); 337 } 338 #endif 339 340 void drm_legacy_lock_release(struct drm_device *dev, struct file *filp) 341 { 342 #if 0 343 struct drm_file *file_priv = filp->private_data; 344 345 /* if the master has gone away we can't do anything with the lock */ 346 if (!dev->master) 347 return; 348 349 if (drm_legacy_i_have_hw_lock(dev, file_priv)) { 350 DRM_DEBUG("File %p released, freeing lock for context %d\n", 351 filp, _DRM_LOCKING_CONTEXT(file_priv->master->lock.hw_lock->lock)); 352 drm_legacy_lock_free(&file_priv->master->lock, 353 _DRM_LOCKING_CONTEXT(file_priv->master->lock.hw_lock->lock)); 354 } 355 #endif 356 } 357