sys/dev/drm/drm_lock.c

   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_notifier(void *priv);
  43
  44 static int drm_lock_take(struct drm_lock_data *lock_data, unsigned int context);
  45 #endif
  46
  47 /**
  48  * Lock ioctl.
  49  *
  50  * \param inode device inode.
  51  * \param file_priv DRM file private.
  52  * \param cmd command.
  53  * \param arg user argument, pointing to a drm_lock structure.
  54  * \return zero on success or negative number on failure.
  55  *
  56  * Add the current task to the lock wait queue, and attempt to take to lock.
  57  */
  58 int drm_legacy_lock(struct drm_device *dev, void *data,
  59                     struct drm_file *file_priv)
  60 {
  61 #if 0
  62         DECLARE_WAITQUEUE(entry, current);
  63         struct drm_lock *lock = data;
  64         struct drm_master *master = file_priv->master;
  65         int ret = 0;
  66
  67         if (drm_core_check_feature(dev, DRIVER_MODESET))
  68                 return -EINVAL;
  69
  70         ++file_priv->lock_count;
  71
  72         if (lock->context == DRM_KERNEL_CONTEXT) {
  73                 DRM_ERROR("Process %d using kernel context %d\n",
  74                           task_pid_nr(current), lock->context);
  75                 return -EINVAL;
  76         }
  77
  78         DRM_DEBUG("%d (pid %d) requests lock (0x%08x), flags = 0x%08x\n",
  79                   lock->context, task_pid_nr(current),
  80                   master->lock.hw_lock->lock, lock->flags);
  81
  82         add_wait_queue(&master->lock.lock_queue, &entry);
  83         spin_lock_bh(&master->lock.spinlock);
  84         master->lock.user_waiters++;
  85         spin_unlock_bh(&master->lock.spinlock);
  86
  87         for (;;) {
  88                 __set_current_state(TASK_INTERRUPTIBLE);
  89                 if (!master->lock.hw_lock) {
  90                         /* Device has been unregistered */
  91                         send_sig(SIGTERM, current, 0);
  92                         ret = -EINTR;
  93                         break;
  94                 }
  95                 if (drm_lock_take(&master->lock, lock->context)) {
  96                         master->lock.file_priv = file_priv;
  97                         master->lock.lock_time = jiffies;
  98                         break;  /* Got lock */
  99                 }
 100
 101                 /* Contention */
 102                 mutex_unlock(&drm_global_mutex);
 103                 schedule();
 104                 mutex_lock(&drm_global_mutex);
 105                 if (signal_pending(current)) {
 106                         ret = -EINTR;
 107                         break;
 108                 }
 109         }
 110         spin_lock_bh(&master->lock.spinlock);
 111         master->lock.user_waiters--;
 112         spin_unlock_bh(&master->lock.spinlock);
 113         __set_current_state(TASK_RUNNING);
 114         remove_wait_queue(&master->lock.lock_queue, &entry);
 115
 116         DRM_DEBUG("%d %s\n", lock->context,
 117                   ret ? "interrupted" : "has lock");
 118         if (ret) return ret;
 119
 120         /* don't set the block all signals on the master process for now
 121          * really probably not the correct answer but lets us debug xkb
 122          * xserver for now */
 123         if (!file_priv->is_master) {
 124                 dev->sigdata.context = lock->context;
 125                 dev->sigdata.lock = master->lock.hw_lock;
 126         }
 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 #endif
 137
 138         return 0;
 139 }
 140
 141 /**
 142  * Unlock ioctl.
 143  *
 144  * \param inode device inode.
 145  * \param file_priv DRM file private.
 146  * \param cmd command.
 147  * \param arg user argument, pointing to a drm_lock structure.
 148  * \return zero on success or negative number on failure.
 149  *
 150  * Transfer and free the lock.
 151  */
 152 int drm_legacy_unlock(struct drm_device *dev, void *data, struct drm_file *file_priv)
 153 {
 154 #if 0
 155         struct drm_lock *lock = data;
 156         struct drm_master *master = file_priv->master;
 157
 158         if (drm_core_check_feature(dev, DRIVER_MODESET))
 159                 return -EINVAL;
 160
 161         if (lock->context == DRM_KERNEL_CONTEXT) {
 162                 DRM_ERROR("Process %d using kernel context %d\n",
 163                           task_pid_nr(current), lock->context);
 164                 return -EINVAL;
 165         }
 166
 167         if (drm_legacy_lock_free(&master->lock, lock->context)) {
 168                 /* FIXME: Should really bail out here. */
 169         }
 170
 171         unblock_all_signals();
 172 #endif
 173         return 0;
 174 }
 175
 176 #if 0
 177 /**
 178  * Take the heavyweight lock.
 179  *
 180  * \param lock lock pointer.
 181  * \param context locking context.
 182  * \return one if the lock is held, or zero otherwise.
 183  *
 184  * Attempt to mark the lock as held by the given context, via the \p cmpxchg instruction.
 185  */
 186 static
 187 int drm_lock_take(struct drm_lock_data *lock_data,
 188                   unsigned int context)
 189 {
 190         unsigned int old, new, prev;
 191         volatile unsigned int *lock = &lock_data->hw_lock->lock;
 192
 193         spin_lock_bh(&lock_data->spinlock);
 194         do {
 195                 old = *lock;
 196                 if (old & _DRM_LOCK_HELD)
 197                         new = old | _DRM_LOCK_CONT;
 198                 else {
 199                         new = context | _DRM_LOCK_HELD |
 200                                 ((lock_data->user_waiters + lock_data->kernel_waiters > 1) ?
 201                                  _DRM_LOCK_CONT : 0);
 202                 }
 203                 prev = cmpxchg(lock, old, new);
 204         } while (prev != old);
 205         spin_unlock_bh(&lock_data->spinlock);
 206
 207         if (_DRM_LOCKING_CONTEXT(old) == context) {
 208                 if (old & _DRM_LOCK_HELD) {
 209                         if (context != DRM_KERNEL_CONTEXT) {
 210                                 DRM_ERROR("%d holds heavyweight lock\n",
 211                                           context);
 212                         }
 213                         return 0;
 214                 }
 215         }
 216
 217         if ((_DRM_LOCKING_CONTEXT(new)) == context && (new & _DRM_LOCK_HELD)) {
 218                 /* Have lock */
 219                 return 1;
 220         }
 221         return 0;
 222 }
 223
 224 /**
 225  * This takes a lock forcibly and hands it to context.  Should ONLY be used
 226  * inside *_unlock to give lock to kernel before calling *_dma_schedule.
 227  *
 228  * \param dev DRM device.
 229  * \param lock lock pointer.
 230  * \param context locking context.
 231  * \return always one.
 232  *
 233  * Resets the lock file pointer.
 234  * Marks the lock as held by the given context, via the \p cmpxchg instruction.
 235  */
 236 static int drm_lock_transfer(struct drm_lock_data *lock_data,
 237                              unsigned int context)
 238 {
 239         unsigned int old, new, prev;
 240         volatile unsigned int *lock = &lock_data->hw_lock->lock;
 241
 242         lock_data->file_priv = NULL;
 243         do {
 244                 old = *lock;
 245                 new = context | _DRM_LOCK_HELD;
 246                 prev = cmpxchg(lock, old, new);
 247         } while (prev != old);
 248         return 1;
 249 }
 250 #endif
 251
 252 /**
 253  * Free lock.
 254  *
 255  * \param dev DRM device.
 256  * \param lock lock.
 257  * \param context context.
 258  *
 259  * Resets the lock file pointer.
 260  * Marks the lock as not held, via the \p cmpxchg instruction. Wakes any task
 261  * waiting on the lock queue.
 262  */
 263 int drm_legacy_lock_free(struct drm_lock_data *lock_data, unsigned int context)
 264 {
 265 #if 0
 266         unsigned int old, new, prev;
 267         volatile unsigned int *lock = &lock_data->hw_lock->lock;
 268
 269         spin_lock_bh(&lock_data->spinlock);
 270         if (lock_data->kernel_waiters != 0) {
 271                 drm_lock_transfer(lock_data, 0);
 272                 lock_data->idle_has_lock = 1;
 273                 spin_unlock_bh(&lock_data->spinlock);
 274                 return 1;
 275         }
 276         spin_unlock_bh(&lock_data->spinlock);
 277
 278         do {
 279                 old = *lock;
 280                 new = _DRM_LOCKING_CONTEXT(old);
 281                 prev = cmpxchg(lock, old, new);
 282         } while (prev != old);
 283
 284         if (_DRM_LOCK_IS_HELD(old) && _DRM_LOCKING_CONTEXT(old) != context) {
 285                 DRM_ERROR("%d freed heavyweight lock held by %d\n",
 286                           context, _DRM_LOCKING_CONTEXT(old));
 287                 return 1;
 288         }
 289         wake_up_interruptible(&lock_data->lock_queue);
 290 #endif
 291         return 0;
 292 }
 293
 294 #if 0
 295 /**
 296  * If we get here, it means that the process has called DRM_IOCTL_LOCK
 297  * without calling DRM_IOCTL_UNLOCK.
 298  *
 299  * If the lock is not held, then let the signal proceed as usual.  If the lock
 300  * is held, then set the contended flag and keep the signal blocked.
 301  *
 302  * \param priv pointer to a drm_device structure.
 303  * \return one if the signal should be delivered normally, or zero if the
 304  * signal should be blocked.
 305  */
 306 static int drm_notifier(void *priv)
 307 {
 308         struct drm_device *dev = priv;
 309         struct drm_hw_lock *lock = dev->sigdata.lock;
 310         unsigned int old, new, prev;
 311
 312         /* Allow signal delivery if lock isn't held */
 313         if (!lock || !_DRM_LOCK_IS_HELD(lock->lock)
 314             || _DRM_LOCKING_CONTEXT(lock->lock) != dev->sigdata.context)
 315                 return 1;
 316
 317         /* Otherwise, set flag to force call to
 318            drmUnlock */
 319         do {
 320                 old = lock->lock;
 321                 new = old | _DRM_LOCK_CONT;
 322                 prev = cmpxchg(&lock->lock, old, new);
 323         } while (prev != old);
 324         return 0;
 325 }
 326 #endif
 327
 328 /**
 329  * This function returns immediately and takes the hw lock
 330  * with the kernel context if it is free, otherwise it gets the highest priority when and if
 331  * it is eventually released.
 332  *
 333  * This guarantees that the kernel will _eventually_ have the lock _unless_ it is held
 334  * by a blocked process. (In the latter case an explicit wait for the hardware lock would cause
 335  * a deadlock, which is why the "idlelock" was invented).
 336  *
 337  * This should be sufficient to wait for GPU idle without
 338  * having to worry about starvation.
 339  */
 340
 341 void drm_legacy_idlelock_take(struct drm_lock_data *lock_data)
 342 {
 343 #if 0
 344         int ret;
 345
 346         spin_lock_bh(&lock_data->spinlock);
 347         lock_data->kernel_waiters++;
 348         if (!lock_data->idle_has_lock) {
 349
 350                 spin_unlock_bh(&lock_data->spinlock);
 351                 ret = drm_lock_take(lock_data, DRM_KERNEL_CONTEXT);
 352                 spin_lock_bh(&lock_data->spinlock);
 353
 354                 if (ret == 1)
 355                         lock_data->idle_has_lock = 1;
 356         }
 357         spin_unlock_bh(&lock_data->spinlock);
 358 #endif
 359 }
 360 EXPORT_SYMBOL(drm_legacy_idlelock_take);
 361
 362 void drm_legacy_idlelock_release(struct drm_lock_data *lock_data)
 363 {
 364 #if 0
 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 #endif
 381 }
 382 EXPORT_SYMBOL(drm_legacy_idlelock_release);
 383
 384 int drm_legacy_i_have_hw_lock(struct drm_device *dev,
 385                               struct drm_file *file_priv)
 386 {
 387 #if 0
 388         struct drm_master *master = file_priv->master;
 389         return (file_priv->lock_count && master->lock.hw_lock &&
 390                 _DRM_LOCK_IS_HELD(master->lock.hw_lock->lock) &&
 391                 master->lock.file_priv == file_priv);
 392 #endif
 393         return 0;
 394 }