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 38static 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 */ 51int 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 mutex_unlock(&drm_global_mutex); 96 schedule(); 97 mutex_lock(&drm_global_mutex); 98 if (signal_pending(current)) { 99 ret = -EINTR; 100 break; 101 } 102 } 103 spin_lock_bh(&master->lock.spinlock); 104 master->lock.user_waiters--; 105 spin_unlock_bh(&master->lock.spinlock); 106 __set_current_state(TASK_RUNNING); 107 remove_wait_queue(&master->lock.lock_queue, &entry); 108 109 DRM_DEBUG("%d %s\n", lock->context, 110 ret ? "interrupted" : "has lock"); 111 if (ret) return ret; 112 113 /* don't set the block all signals on the master process for now 114 * really probably not the correct answer but lets us debug xkb 115 * xserver for now */ 116 if (!file_priv->is_master) { 117 sigemptyset(&dev->sigmask); 118 sigaddset(&dev->sigmask, SIGSTOP); 119 sigaddset(&dev->sigmask, SIGTSTP); 120 sigaddset(&dev->sigmask, SIGTTIN); 121 sigaddset(&dev->sigmask, SIGTTOU); 122 dev->sigdata.context = lock->context; 123 dev->sigdata.lock = master->lock.hw_lock; 124 block_all_signals(drm_notifier, &dev->sigdata, &dev->sigmask); 125 } 126 127 if (dev->driver->dma_ready && (lock->flags & _DRM_LOCK_READY)) 128 dev->driver->dma_ready(dev); 129 130 if (dev->driver->dma_quiescent && (lock->flags & _DRM_LOCK_QUIESCENT)) 131 { 132 if (dev->driver->dma_quiescent(dev)) { 133 DRM_DEBUG("%d waiting for DMA quiescent\n", 134 lock->context); 135 return -EBUSY; 136 } 137 } 138 139 if (dev->driver->kernel_context_switch && 140 dev->last_context != lock->context) { 141 dev->driver->kernel_context_switch(dev, dev->last_context, 142 lock->context); 143 } 144 145 return 0; 146} 147 148/** 149 * Unlock ioctl. 150 * 151 * \param inode device inode. 152 * \param file_priv DRM file private. 153 * \param cmd command. 154 * \param arg user argument, pointing to a drm_lock structure. 155 * \return zero on success or negative number on failure. 156 * 157 * Transfer and free the lock. 158 */ 159int drm_unlock(struct drm_device *dev, void *data, struct drm_file *file_priv) 160{ 161 struct drm_lock *lock = data; 162 struct drm_master *master = file_priv->master; 163 164 if (lock->context == DRM_KERNEL_CONTEXT) { 165 DRM_ERROR("Process %d using kernel context %d\n", 166 task_pid_nr(current), lock->context); 167 return -EINVAL; 168 } 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(&master->lock, lock->context)) { 179 } 180 } 181 182 unblock_all_signals(); 183 return 0; 184} 185 186/** 187 * Take the heavyweight lock. 188 * 189 * \param lock lock pointer. 190 * \param context locking context. 191 * \return one if the lock is held, or zero otherwise. 192 * 193 * Attempt to mark the lock as held by the given context, via the \p cmpxchg instruction. 194 */ 195int drm_lock_take(struct drm_lock_data *lock_data, 196 unsigned int context) 197{ 198 unsigned int old, new, prev; 199 volatile unsigned int *lock = &lock_data->hw_lock->lock; 200 201 spin_lock_bh(&lock_data->spinlock); 202 do { 203 old = *lock; 204 if (old & _DRM_LOCK_HELD) 205 new = old | _DRM_LOCK_CONT; 206 else { 207 new = context | _DRM_LOCK_HELD | 208 ((lock_data->user_waiters + lock_data->kernel_waiters > 1) ? 209 _DRM_LOCK_CONT : 0); 210 } 211 prev = cmpxchg(lock, old, new); 212 } while (prev != old); 213 spin_unlock_bh(&lock_data->spinlock); 214 215 if (_DRM_LOCKING_CONTEXT(old) == context) { 216 if (old & _DRM_LOCK_HELD) { 217 if (context != DRM_KERNEL_CONTEXT) { 218 DRM_ERROR("%d holds heavyweight lock\n", 219 context); 220 } 221 return 0; 222 } 223 } 224 225 if ((_DRM_LOCKING_CONTEXT(new)) == context && (new & _DRM_LOCK_HELD)) { 226 /* Have lock */ 227 return 1; 228 } 229 return 0; 230} 231EXPORT_SYMBOL(drm_lock_take); 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 */ 245static 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 */ 271int 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} 299EXPORT_SYMBOL(drm_lock_free); 300 301/** 302 * If we get here, it means that the process has called DRM_IOCTL_LOCK 303 * without calling DRM_IOCTL_UNLOCK. 304 * 305 * If the lock is not held, then let the signal proceed as usual. If the lock 306 * is held, then set the contended flag and keep the signal blocked. 307 * 308 * \param priv pointer to a drm_sigdata structure. 309 * \return one if the signal should be delivered normally, or zero if the 310 * signal should be blocked. 311 */ 312static int drm_notifier(void *priv) 313{ 314 struct drm_sigdata *s = (struct drm_sigdata *) priv; 315 unsigned int old, new, prev; 316 317 /* Allow signal delivery if lock isn't held */ 318 if (!s->lock || !_DRM_LOCK_IS_HELD(s->lock->lock) 319 || _DRM_LOCKING_CONTEXT(s->lock->lock) != s->context) 320 return 1; 321 322 /* Otherwise, set flag to force call to 323 drmUnlock */ 324 do { 325 old = s->lock->lock; 326 new = old | _DRM_LOCK_CONT; 327 prev = cmpxchg(&s->lock->lock, old, new); 328 } while (prev != old); 329 return 0; 330} 331 332/** 333 * This function returns immediately and takes the hw lock 334 * with the kernel context if it is free, otherwise it gets the highest priority when and if 335 * it is eventually released. 336 * 337 * This guarantees that the kernel will _eventually_ have the lock _unless_ it is held 338 * by a blocked process. (In the latter case an explicit wait for the hardware lock would cause 339 * a deadlock, which is why the "idlelock" was invented). 340 * 341 * This should be sufficient to wait for GPU idle without 342 * having to worry about starvation. 343 */ 344 345void drm_idlelock_take(struct drm_lock_data *lock_data) 346{ 347 int ret = 0; 348 349 spin_lock_bh(&lock_data->spinlock); 350 lock_data->kernel_waiters++; 351 if (!lock_data->idle_has_lock) { 352 353 spin_unlock_bh(&lock_data->spinlock); 354 ret = drm_lock_take(lock_data, DRM_KERNEL_CONTEXT); 355 spin_lock_bh(&lock_data->spinlock); 356 357 if (ret == 1) 358 lock_data->idle_has_lock = 1; 359 } 360 spin_unlock_bh(&lock_data->spinlock); 361} 362EXPORT_SYMBOL(drm_idlelock_take); 363 364void drm_idlelock_release(struct drm_lock_data *lock_data) 365{ 366 unsigned int old, prev; 367 volatile unsigned int *lock = &lock_data->hw_lock->lock; 368 369 spin_lock_bh(&lock_data->spinlock); 370 if (--lock_data->kernel_waiters == 0) { 371 if (lock_data->idle_has_lock) { 372 do { 373 old = *lock; 374 prev = cmpxchg(lock, old, DRM_KERNEL_CONTEXT); 375 } while (prev != old); 376 wake_up_interruptible(&lock_data->lock_queue); 377 lock_data->idle_has_lock = 0; 378 } 379 } 380 spin_unlock_bh(&lock_data->spinlock); 381} 382EXPORT_SYMBOL(drm_idlelock_release); 383 384 385int drm_i_have_hw_lock(struct drm_device *dev, struct drm_file *file_priv) 386{ 387 struct drm_master *master = file_priv->master; 388 return (file_priv->lock_count && master->lock.hw_lock && 389 _DRM_LOCK_IS_HELD(master->lock.hw_lock->lock) && 390 master->lock.file_priv == file_priv); 391} 392 393EXPORT_SYMBOL(drm_i_have_hw_lock); 394