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 "drmP.h" 37 38 static int drm_notifier(void *priv); 39 40 /** 41 * Lock ioctl. 42 * 43 * \param inode device inode. 44 * \param file_priv DRM file private. 45 * \param cmd command. 46 * \param arg user argument, pointing to a drm_lock structure. 47 * \return zero on success or negative number on failure. 48 * 49 * Add the current task to the lock wait queue, and attempt to take to lock. 50 */ 51 int drm_lock(struct drm_device *dev, void *data, struct drm_file *file_priv) 52 { 53 DECLARE_WAITQUEUE(entry, current); 54 struct drm_lock *lock = data; 55 int ret = 0; 56 57 ++file_priv->lock_count; 58 59 if (lock->context == DRM_KERNEL_CONTEXT) { 60 DRM_ERROR("Process %d using kernel context %d\n", 61 task_pid_nr(current), lock->context); 62 return -EINVAL; 63 } 64 65 DRM_DEBUG("%d (pid %d) requests lock (0x%08x), flags = 0x%08x\n", 66 lock->context, task_pid_nr(current), 67 dev->lock.hw_lock->lock, lock->flags); 68 69 if (drm_core_check_feature(dev, DRIVER_DMA_QUEUE)) 70 if (lock->context < 0) 71 return -EINVAL; 72 73 add_wait_queue(&dev->lock.lock_queue, &entry); 74 spin_lock_bh(&dev->lock.spinlock); 75 dev->lock.user_waiters++; 76 spin_unlock_bh(&dev->lock.spinlock); 77 for (;;) { 78 __set_current_state(TASK_INTERRUPTIBLE); 79 if (!dev->lock.hw_lock) { 80 /* Device has been unregistered */ 81 ret = -EINTR; 82 break; 83 } 84 if (drm_lock_take(&dev->lock, lock->context)) { 85 dev->lock.file_priv = file_priv; 86 dev->lock.lock_time = jiffies; 87 atomic_inc(&dev->counts[_DRM_STAT_LOCKS]); 88 break; /* Got lock */ 89 } 90 91 /* Contention */ 92 schedule(); 93 if (signal_pending(current)) { 94 ret = -ERESTARTSYS; 95 break; 96 } 97 } 98 spin_lock_bh(&dev->lock.spinlock); 99 dev->lock.user_waiters--; 100 spin_unlock_bh(&dev->lock.spinlock); 101 __set_current_state(TASK_RUNNING); 102 remove_wait_queue(&dev->lock.lock_queue, &entry); 103 104 DRM_DEBUG("%d %s\n", lock->context, 105 ret ? "interrupted" : "has lock"); 106 if (ret) return ret; 107 108 sigemptyset(&dev->sigmask); 109 sigaddset(&dev->sigmask, SIGSTOP); 110 sigaddset(&dev->sigmask, SIGTSTP); 111 sigaddset(&dev->sigmask, SIGTTIN); 112 sigaddset(&dev->sigmask, SIGTTOU); 113 dev->sigdata.context = lock->context; 114 dev->sigdata.lock = dev->lock.hw_lock; 115 block_all_signals(drm_notifier, &dev->sigdata, &dev->sigmask); 116 117 if (dev->driver->dma_ready && (lock->flags & _DRM_LOCK_READY)) 118 dev->driver->dma_ready(dev); 119 120 if (dev->driver->dma_quiescent && (lock->flags & _DRM_LOCK_QUIESCENT)) 121 { 122 if (dev->driver->dma_quiescent(dev)) { 123 DRM_DEBUG("%d waiting for DMA quiescent\n", 124 lock->context); 125 return -EBUSY; 126 } 127 } 128 129 if (dev->driver->kernel_context_switch && 130 dev->last_context != lock->context) { 131 dev->driver->kernel_context_switch(dev, dev->last_context, 132 lock->context); 133 } 134 135 return 0; 136 } 137 138 /** 139 * Unlock ioctl. 140 * 141 * \param inode device inode. 142 * \param file_priv DRM file private. 143 * \param cmd command. 144 * \param arg user argument, pointing to a drm_lock structure. 145 * \return zero on success or negative number on failure. 146 * 147 * Transfer and free the lock. 148 */ 149 int drm_unlock(struct drm_device *dev, void *data, struct drm_file *file_priv) 150 { 151 struct drm_lock *lock = data; 152 unsigned long irqflags; 153 154 if (lock->context == DRM_KERNEL_CONTEXT) { 155 DRM_ERROR("Process %d using kernel context %d\n", 156 task_pid_nr(current), lock->context); 157 return -EINVAL; 158 } 159 160 spin_lock_irqsave(&dev->tasklet_lock, irqflags); 161 162 if (dev->locked_tasklet_func) { 163 dev->locked_tasklet_func(dev); 164 165 dev->locked_tasklet_func = NULL; 166 } 167 168 spin_unlock_irqrestore(&dev->tasklet_lock, irqflags); 169 170 atomic_inc(&dev->counts[_DRM_STAT_UNLOCKS]); 171 172 /* kernel_context_switch isn't used by any of the x86 drm 173 * modules but is required by the Sparc driver. 174 */ 175 if (dev->driver->kernel_context_switch_unlock) 176 dev->driver->kernel_context_switch_unlock(dev); 177 else { 178 if (drm_lock_free(&dev->lock,lock->context)) { 179 /* FIXME: Should really bail out here. */ 180 } 181 } 182 183 unblock_all_signals(); 184 return 0; 185 } 186 187 /** 188 * Take the heavyweight lock. 189 * 190 * \param lock lock pointer. 191 * \param context locking context. 192 * \return one if the lock is held, or zero otherwise. 193 * 194 * Attempt to mark the lock as held by the given context, via the \p cmpxchg instruction. 195 */ 196 int drm_lock_take(struct drm_lock_data *lock_data, 197 unsigned int context) 198 { 199 unsigned int old, new, prev; 200 volatile unsigned int *lock = &lock_data->hw_lock->lock; 201 202 spin_lock_bh(&lock_data->spinlock); 203 do { 204 old = *lock; 205 if (old & _DRM_LOCK_HELD) 206 new = old | _DRM_LOCK_CONT; 207 else { 208 new = context | _DRM_LOCK_HELD | 209 ((lock_data->user_waiters + lock_data->kernel_waiters > 1) ? 210 _DRM_LOCK_CONT : 0); 211 } 212 prev = cmpxchg(lock, old, new); 213 } while (prev != old); 214 spin_unlock_bh(&lock_data->spinlock); 215 216 if (_DRM_LOCKING_CONTEXT(old) == context) { 217 if (old & _DRM_LOCK_HELD) { 218 if (context != DRM_KERNEL_CONTEXT) { 219 DRM_ERROR("%d holds heavyweight lock\n", 220 context); 221 } 222 return 0; 223 } 224 } 225 226 if ((_DRM_LOCKING_CONTEXT(new)) == context && (new & _DRM_LOCK_HELD)) { 227 /* Have lock */ 228 return 1; 229 } 230 return 0; 231 } 232 233 /** 234 * This takes a lock forcibly and hands it to context. Should ONLY be used 235 * inside *_unlock to give lock to kernel before calling *_dma_schedule. 236 * 237 * \param dev DRM device. 238 * \param lock lock pointer. 239 * \param context locking context. 240 * \return always one. 241 * 242 * Resets the lock file pointer. 243 * Marks the lock as held by the given context, via the \p cmpxchg instruction. 244 */ 245 static int drm_lock_transfer(struct drm_lock_data *lock_data, 246 unsigned int context) 247 { 248 unsigned int old, new, prev; 249 volatile unsigned int *lock = &lock_data->hw_lock->lock; 250 251 lock_data->file_priv = NULL; 252 do { 253 old = *lock; 254 new = context | _DRM_LOCK_HELD; 255 prev = cmpxchg(lock, old, new); 256 } while (prev != old); 257 return 1; 258 } 259 260 /** 261 * Free lock. 262 * 263 * \param dev DRM device. 264 * \param lock lock. 265 * \param context context. 266 * 267 * Resets the lock file pointer. 268 * Marks the lock as not held, via the \p cmpxchg instruction. Wakes any task 269 * waiting on the lock queue. 270 */ 271 int drm_lock_free(struct drm_lock_data *lock_data, unsigned int context) 272 { 273 unsigned int old, new, prev; 274 volatile unsigned int *lock = &lock_data->hw_lock->lock; 275 276 spin_lock_bh(&lock_data->spinlock); 277 if (lock_data->kernel_waiters != 0) { 278 drm_lock_transfer(lock_data, 0); 279 lock_data->idle_has_lock = 1; 280 spin_unlock_bh(&lock_data->spinlock); 281 return 1; 282 } 283 spin_unlock_bh(&lock_data->spinlock); 284 285 do { 286 old = *lock; 287 new = _DRM_LOCKING_CONTEXT(old); 288 prev = cmpxchg(lock, old, new); 289 } while (prev != old); 290 291 if (_DRM_LOCK_IS_HELD(old) && _DRM_LOCKING_CONTEXT(old) != context) { 292 DRM_ERROR("%d freed heavyweight lock held by %d\n", 293 context, _DRM_LOCKING_CONTEXT(old)); 294 return 1; 295 } 296 wake_up_interruptible(&lock_data->lock_queue); 297 return 0; 298 } 299 300 /** 301 * If we get here, it means that the process has called DRM_IOCTL_LOCK 302 * without calling DRM_IOCTL_UNLOCK. 303 * 304 * If the lock is not held, then let the signal proceed as usual. If the lock 305 * is held, then set the contended flag and keep the signal blocked. 306 * 307 * \param priv pointer to a drm_sigdata structure. 308 * \return one if the signal should be delivered normally, or zero if the 309 * signal should be blocked. 310 */ 311 static int drm_notifier(void *priv) 312 { 313 struct drm_sigdata *s = (struct drm_sigdata *) priv; 314 unsigned int old, new, prev; 315 316 /* Allow signal delivery if lock isn't held */ 317 if (!s->lock || !_DRM_LOCK_IS_HELD(s->lock->lock) 318 || _DRM_LOCKING_CONTEXT(s->lock->lock) != s->context) 319 return 1; 320 321 /* Otherwise, set flag to force call to 322 drmUnlock */ 323 do { 324 old = s->lock->lock; 325 new = old | _DRM_LOCK_CONT; 326 prev = cmpxchg(&s->lock->lock, old, new); 327 } while (prev != old); 328 return 0; 329 } 330 331 /** 332 * This function returns immediately and takes the hw lock 333 * with the kernel context if it is free, otherwise it gets the highest priority when and if 334 * it is eventually released. 335 * 336 * This guarantees that the kernel will _eventually_ have the lock _unless_ it is held 337 * by a blocked process. (In the latter case an explicit wait for the hardware lock would cause 338 * a deadlock, which is why the "idlelock" was invented). 339 * 340 * This should be sufficient to wait for GPU idle without 341 * having to worry about starvation. 342 */ 343 344 void drm_idlelock_take(struct drm_lock_data *lock_data) 345 { 346 int ret = 0; 347 348 spin_lock_bh(&lock_data->spinlock); 349 lock_data->kernel_waiters++; 350 if (!lock_data->idle_has_lock) { 351 352 spin_unlock_bh(&lock_data->spinlock); 353 ret = drm_lock_take(lock_data, DRM_KERNEL_CONTEXT); 354 spin_lock_bh(&lock_data->spinlock); 355 356 if (ret == 1) 357 lock_data->idle_has_lock = 1; 358 } 359 spin_unlock_bh(&lock_data->spinlock); 360 } 361 EXPORT_SYMBOL(drm_idlelock_take); 362 363 void drm_idlelock_release(struct drm_lock_data *lock_data) 364 { 365 unsigned int old, prev; 366 volatile unsigned int *lock = &lock_data->hw_lock->lock; 367 368 spin_lock_bh(&lock_data->spinlock); 369 if (--lock_data->kernel_waiters == 0) { 370 if (lock_data->idle_has_lock) { 371 do { 372 old = *lock; 373 prev = cmpxchg(lock, old, DRM_KERNEL_CONTEXT); 374 } while (prev != old); 375 wake_up_interruptible(&lock_data->lock_queue); 376 lock_data->idle_has_lock = 0; 377 } 378 } 379 spin_unlock_bh(&lock_data->spinlock); 380 } 381 EXPORT_SYMBOL(drm_idlelock_release); 382 383 384 int drm_i_have_hw_lock(struct drm_device *dev, struct drm_file *file_priv) 385 { 386 return (file_priv->lock_count && dev->lock.hw_lock && 387 _DRM_LOCK_IS_HELD(dev->lock.hw_lock->lock) && 388 dev->lock.file_priv == file_priv); 389 } 390 391 EXPORT_SYMBOL(drm_i_have_hw_lock); 392