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 struct drm_master *master = file_priv->master; 56 int ret = 0; 57 58 ++file_priv->lock_count; 59 60 if (lock->context == DRM_KERNEL_CONTEXT) { 61 DRM_ERROR("Process %d using kernel context %d\n", 62 task_pid_nr(current), lock->context); 63 return -EINVAL; 64 } 65 66 DRM_DEBUG("%d (pid %d) requests lock (0x%08x), flags = 0x%08x\n", 67 lock->context, task_pid_nr(current), 68 master->lock.hw_lock->lock, lock->flags); 69 70 if (drm_core_check_feature(dev, DRIVER_DMA_QUEUE)) 71 if (lock->context < 0) 72 return -EINVAL; 73 74 add_wait_queue(&master->lock.lock_queue, &entry); 75 spin_lock_bh(&master->lock.spinlock); 76 master->lock.user_waiters++; 77 spin_unlock_bh(&master->lock.spinlock); 78 79 for (;;) { 80 __set_current_state(TASK_INTERRUPTIBLE); 81 if (!master->lock.hw_lock) { 82 /* Device has been unregistered */ 83 send_sig(SIGTERM, current, 0); 84 ret = -EINTR; 85 break; 86 } 87 if (drm_lock_take(&master->lock, lock->context)) { 88 master->lock.file_priv = file_priv; 89 master->lock.lock_time = jiffies; 90 atomic_inc(&dev->counts[_DRM_STAT_LOCKS]); 91 break; /* Got lock */ 92 } 93 94 /* Contention */ 95 schedule(); 96 if (signal_pending(current)) { 97 ret = -EINTR; 98 break; 99 } 100 } 101 spin_lock_bh(&master->lock.spinlock); 102 master->lock.user_waiters--; 103 spin_unlock_bh(&master->lock.spinlock); 104 __set_current_state(TASK_RUNNING); 105 remove_wait_queue(&master->lock.lock_queue, &entry); 106 107 DRM_DEBUG("%d %s\n", lock->context, 108 ret ? "interrupted" : "has lock"); 109 if (ret) return ret; 110 111 /* don't set the block all signals on the master process for now 112 * really probably not the correct answer but lets us debug xkb 113 * xserver for now */ 114 if (!file_priv->is_master) { 115 sigemptyset(&dev->sigmask); 116 sigaddset(&dev->sigmask, SIGSTOP); 117 sigaddset(&dev->sigmask, SIGTSTP); 118 sigaddset(&dev->sigmask, SIGTTIN); 119 sigaddset(&dev->sigmask, SIGTTOU); 120 dev->sigdata.context = lock->context; 121 dev->sigdata.lock = master->lock.hw_lock; 122 block_all_signals(drm_notifier, &dev->sigdata, &dev->sigmask); 123 } 124 125 if (dev->driver->dma_ready && (lock->flags & _DRM_LOCK_READY)) 126 dev->driver->dma_ready(dev); 127 128 if (dev->driver->dma_quiescent && (lock->flags & _DRM_LOCK_QUIESCENT)) 129 { 130 if (dev->driver->dma_quiescent(dev)) { 131 DRM_DEBUG("%d waiting for DMA quiescent\n", 132 lock->context); 133 return -EBUSY; 134 } 135 } 136 137 if (dev->driver->kernel_context_switch && 138 dev->last_context != lock->context) { 139 dev->driver->kernel_context_switch(dev, dev->last_context, 140 lock->context); 141 } 142 143 return 0; 144 } 145 146 /** 147 * Unlock ioctl. 148 * 149 * \param inode device inode. 150 * \param file_priv DRM file private. 151 * \param cmd command. 152 * \param arg user argument, pointing to a drm_lock structure. 153 * \return zero on success or negative number on failure. 154 * 155 * Transfer and free the lock. 156 */ 157 int drm_unlock(struct drm_device *dev, void *data, struct drm_file *file_priv) 158 { 159 struct drm_lock *lock = data; 160 struct drm_master *master = file_priv->master; 161 162 if (lock->context == DRM_KERNEL_CONTEXT) { 163 DRM_ERROR("Process %d using kernel context %d\n", 164 task_pid_nr(current), lock->context); 165 return -EINVAL; 166 } 167 168 atomic_inc(&dev->counts[_DRM_STAT_UNLOCKS]); 169 170 /* kernel_context_switch isn't used by any of the x86 drm 171 * modules but is required by the Sparc driver. 172 */ 173 if (dev->driver->kernel_context_switch_unlock) 174 dev->driver->kernel_context_switch_unlock(dev); 175 else { 176 if (drm_lock_free(&master->lock, lock->context)) { 177 /* FIXME: Should really bail out here. */ 178 } 179 } 180 181 unblock_all_signals(); 182 return 0; 183 } 184 185 /** 186 * Take the heavyweight lock. 187 * 188 * \param lock lock pointer. 189 * \param context locking context. 190 * \return one if the lock is held, or zero otherwise. 191 * 192 * Attempt to mark the lock as held by the given context, via the \p cmpxchg instruction. 193 */ 194 int drm_lock_take(struct drm_lock_data *lock_data, 195 unsigned int context) 196 { 197 unsigned int old, new, prev; 198 volatile unsigned int *lock = &lock_data->hw_lock->lock; 199 200 spin_lock_bh(&lock_data->spinlock); 201 do { 202 old = *lock; 203 if (old & _DRM_LOCK_HELD) 204 new = old | _DRM_LOCK_CONT; 205 else { 206 new = context | _DRM_LOCK_HELD | 207 ((lock_data->user_waiters + lock_data->kernel_waiters > 1) ? 208 _DRM_LOCK_CONT : 0); 209 } 210 prev = cmpxchg(lock, old, new); 211 } while (prev != old); 212 spin_unlock_bh(&lock_data->spinlock); 213 214 if (_DRM_LOCKING_CONTEXT(old) == context) { 215 if (old & _DRM_LOCK_HELD) { 216 if (context != DRM_KERNEL_CONTEXT) { 217 DRM_ERROR("%d holds heavyweight lock\n", 218 context); 219 } 220 return 0; 221 } 222 } 223 224 if ((_DRM_LOCKING_CONTEXT(new)) == context && (new & _DRM_LOCK_HELD)) { 225 /* Have lock */ 226 return 1; 227 } 228 return 0; 229 } 230 EXPORT_SYMBOL(drm_lock_take); 231 232 /** 233 * This takes a lock forcibly and hands it to context. Should ONLY be used 234 * inside *_unlock to give lock to kernel before calling *_dma_schedule. 235 * 236 * \param dev DRM device. 237 * \param lock lock pointer. 238 * \param context locking context. 239 * \return always one. 240 * 241 * Resets the lock file pointer. 242 * Marks the lock as held by the given context, via the \p cmpxchg instruction. 243 */ 244 static int drm_lock_transfer(struct drm_lock_data *lock_data, 245 unsigned int context) 246 { 247 unsigned int old, new, prev; 248 volatile unsigned int *lock = &lock_data->hw_lock->lock; 249 250 lock_data->file_priv = NULL; 251 do { 252 old = *lock; 253 new = context | _DRM_LOCK_HELD; 254 prev = cmpxchg(lock, old, new); 255 } while (prev != old); 256 return 1; 257 } 258 259 /** 260 * Free lock. 261 * 262 * \param dev DRM device. 263 * \param lock lock. 264 * \param context context. 265 * 266 * Resets the lock file pointer. 267 * Marks the lock as not held, via the \p cmpxchg instruction. Wakes any task 268 * waiting on the lock queue. 269 */ 270 int drm_lock_free(struct drm_lock_data *lock_data, unsigned int context) 271 { 272 unsigned int old, new, prev; 273 volatile unsigned int *lock = &lock_data->hw_lock->lock; 274 275 spin_lock_bh(&lock_data->spinlock); 276 if (lock_data->kernel_waiters != 0) { 277 drm_lock_transfer(lock_data, 0); 278 lock_data->idle_has_lock = 1; 279 spin_unlock_bh(&lock_data->spinlock); 280 return 1; 281 } 282 spin_unlock_bh(&lock_data->spinlock); 283 284 do { 285 old = *lock; 286 new = _DRM_LOCKING_CONTEXT(old); 287 prev = cmpxchg(lock, old, new); 288 } while (prev != old); 289 290 if (_DRM_LOCK_IS_HELD(old) && _DRM_LOCKING_CONTEXT(old) != context) { 291 DRM_ERROR("%d freed heavyweight lock held by %d\n", 292 context, _DRM_LOCKING_CONTEXT(old)); 293 return 1; 294 } 295 wake_up_interruptible(&lock_data->lock_queue); 296 return 0; 297 } 298 EXPORT_SYMBOL(drm_lock_free); 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 struct drm_master *master = file_priv->master; 387 return (file_priv->lock_count && master->lock.hw_lock && 388 _DRM_LOCK_IS_HELD(master->lock.hw_lock->lock) && 389 master->lock.file_priv == file_priv); 390 } 391 392 EXPORT_SYMBOL(drm_i_have_hw_lock); 393