drivers/gpu/drm/drm_fops.c

   1 /**
   2  * \file drm_fops.c
   3  * File operations for DRM
   4  *
   5  * \author Rickard E. (Rik) Faith <faith@valinux.com>
   6  * \author Daryll Strauss <daryll@valinux.com>
   7  * \author Gareth Hughes <gareth@valinux.com>
   8  */
   9
  10 /*
  11  * Created: Mon Jan  4 08:58:31 1999 by faith@valinux.com
  12  *
  13  * Copyright 1999 Precision Insight, Inc., Cedar Park, Texas.
  14  * Copyright 2000 VA Linux Systems, Inc., Sunnyvale, California.
  15  * All Rights Reserved.
  16  *
  17  * Permission is hereby granted, free of charge, to any person obtaining a
  18  * copy of this software and associated documentation files (the "Software"),
  19  * to deal in the Software without restriction, including without limitation
  20  * the rights to use, copy, modify, merge, publish, distribute, sublicense,
  21  * and/or sell copies of the Software, and to permit persons to whom the
  22  * Software is furnished to do so, subject to the following conditions:
  23  *
  24  * The above copyright notice and this permission notice (including the next
  25  * paragraph) shall be included in all copies or substantial portions of the
  26  * Software.
  27  *
  28  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  29  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  30  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
  31  * VA LINUX SYSTEMS AND/OR ITS SUPPLIERS BE LIABLE FOR ANY CLAIM, DAMAGES OR
  32  * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
  33  * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
  34  * OTHER DEALINGS IN THE SOFTWARE.
  35  */
  36
  37 #include <drm/drmP.h>
  38 #include <linux/poll.h>
  39 #include <linux/slab.h>
  40 #include <linux/module.h>
  41
  42 /* from BKL pushdown: note that nothing else serializes idr_find() */
  43 DEFINE_MUTEX(drm_global_mutex);
  44 EXPORT_SYMBOL(drm_global_mutex);
  45
  46 static int drm_open_helper(struct inode *inode, struct file *filp,
  47                            struct drm_device * dev);
  48
  49 static int drm_setup(struct drm_device * dev)
  50 {
  51         int ret;
  52
  53         if (dev->driver->firstopen &&
  54             !drm_core_check_feature(dev, DRIVER_MODESET)) {
  55                 ret = dev->driver->firstopen(dev);
  56                 if (ret != 0)
  57                         return ret;
  58         }
  59
  60         ret = drm_legacy_dma_setup(dev);
  61         if (ret < 0)
  62                 return ret;
  63
  64
  65         DRM_DEBUG("\n");
  66         return 0;
  67 }
  68
  69 /**
  70  * Open file.
  71  *
  72  * \param inode device inode
  73  * \param filp file pointer.
  74  * \return zero on success or a negative number on failure.
  75  *
  76  * Searches the DRM device with the same minor number, calls open_helper(), and
  77  * increments the device open count. If the open count was previous at zero,
  78  * i.e., it's the first that the device is open, then calls setup().
  79  */
  80 int drm_open(struct inode *inode, struct file *filp)
  81 {
  82         struct drm_device *dev = NULL;
  83         int minor_id = iminor(inode);
  84         struct drm_minor *minor;
  85         int retcode = 0;
  86         int need_setup = 0;
  87         struct address_space *old_mapping;
  88         struct address_space *old_imapping;
  89
  90         minor = idr_find(&drm_minors_idr, minor_id);
  91         if (!minor)
  92                 return -ENODEV;
  93
  94         if (!(dev = minor->dev))
  95                 return -ENODEV;
  96
  97         if (drm_device_is_unplugged(dev))
  98                 return -ENODEV;
  99
 100         if (!dev->open_count++)
 101                 need_setup = 1;
 102         mutex_lock(&dev->struct_mutex);
 103         old_imapping = inode->i_mapping;
 104         old_mapping = dev->dev_mapping;
 105         if (old_mapping == NULL)
 106                 dev->dev_mapping = &inode->i_data;
 107         /* ihold ensures nobody can remove inode with our i_data */
 108         ihold(container_of(dev->dev_mapping, struct inode, i_data));
 109         inode->i_mapping = dev->dev_mapping;
 110         filp->f_mapping = dev->dev_mapping;
 111         mutex_unlock(&dev->struct_mutex);
 112
 113         retcode = drm_open_helper(inode, filp, dev);
 114         if (retcode)
 115                 goto err_undo;
 116         atomic_inc(&dev->counts[_DRM_STAT_OPENS]);
 117         if (need_setup) {
 118                 retcode = drm_setup(dev);
 119                 if (retcode)
 120                         goto err_undo;
 121         }
 122         return 0;
 123
 124 err_undo:
 125         mutex_lock(&dev->struct_mutex);
 126         filp->f_mapping = old_imapping;
 127         inode->i_mapping = old_imapping;
 128         iput(container_of(dev->dev_mapping, struct inode, i_data));
 129         dev->dev_mapping = old_mapping;
 130         mutex_unlock(&dev->struct_mutex);
 131         dev->open_count--;
 132         return retcode;
 133 }
 134 EXPORT_SYMBOL(drm_open);
 135
 136 /**
 137  * File \c open operation.
 138  *
 139  * \param inode device inode.
 140  * \param filp file pointer.
 141  *
 142  * Puts the dev->fops corresponding to the device minor number into
 143  * \p filp, call the \c open method, and restore the file operations.
 144  */
 145 int drm_stub_open(struct inode *inode, struct file *filp)
 146 {
 147         struct drm_device *dev = NULL;
 148         struct drm_minor *minor;
 149         int minor_id = iminor(inode);
 150         int err = -ENODEV;
 151         const struct file_operations *old_fops;
 152
 153         DRM_DEBUG("\n");
 154
 155         mutex_lock(&drm_global_mutex);
 156         minor = idr_find(&drm_minors_idr, minor_id);
 157         if (!minor)
 158                 goto out;
 159
 160         if (!(dev = minor->dev))
 161                 goto out;
 162
 163         if (drm_device_is_unplugged(dev))
 164                 goto out;
 165
 166         old_fops = filp->f_op;
 167         filp->f_op = fops_get(dev->driver->fops);
 168         if (filp->f_op == NULL) {
 169                 filp->f_op = old_fops;
 170                 goto out;
 171         }
 172         if (filp->f_op->open && (err = filp->f_op->open(inode, filp))) {
 173                 fops_put(filp->f_op);
 174                 filp->f_op = fops_get(old_fops);
 175         }
 176         fops_put(old_fops);
 177
 178 out:
 179         mutex_unlock(&drm_global_mutex);
 180         return err;
 181 }
 182
 183 /**
 184  * Check whether DRI will run on this CPU.
 185  *
 186  * \return non-zero if the DRI will run on this CPU, or zero otherwise.
 187  */
 188 static int drm_cpu_valid(void)
 189 {
 190 #if defined(__i386__)
 191         if (boot_cpu_data.x86 == 3)
 192                 return 0;       /* No cmpxchg on a 386 */
 193 #endif
 194 #if defined(__sparc__) && !defined(__sparc_v9__)
 195         return 0;               /* No cmpxchg before v9 sparc. */
 196 #endif
 197         return 1;
 198 }
 199
 200 /**
 201  * Called whenever a process opens /dev/drm.
 202  *
 203  * \param inode device inode.
 204  * \param filp file pointer.
 205  * \param dev device.
 206  * \return zero on success or a negative number on failure.
 207  *
 208  * Creates and initializes a drm_file structure for the file private data in \p
 209  * filp and add it into the double linked list in \p dev.
 210  */
 211 static int drm_open_helper(struct inode *inode, struct file *filp,
 212                            struct drm_device * dev)
 213 {
 214         int minor_id = iminor(inode);
 215         struct drm_file *priv;
 216         int ret;
 217
 218         if (filp->f_flags & O_EXCL)
 219                 return -EBUSY;  /* No exclusive opens */
 220         if (!drm_cpu_valid())
 221                 return -EINVAL;
 222         if (dev->switch_power_state != DRM_SWITCH_POWER_ON && dev->switch_power_state != DRM_SWITCH_POWER_DYNAMIC_OFF)
 223                 return -EINVAL;
 224
 225         DRM_DEBUG("pid = %d, minor = %d\n", task_pid_nr(current), minor_id);
 226
 227         priv = kzalloc(sizeof(*priv), GFP_KERNEL);
 228         if (!priv)
 229                 return -ENOMEM;
 230
 231         filp->private_data = priv;
 232         priv->filp = filp;
 233         priv->uid = current_euid();
 234         priv->pid = get_pid(task_pid(current));
 235         priv->minor = idr_find(&drm_minors_idr, minor_id);
 236         if (!priv->minor) {
 237                 ret = -ENODEV;
 238                 goto out_put_pid;
 239         }
 240
 241         priv->ioctl_count = 0;
 242         /* for compatibility root is always authenticated */
 243         priv->authenticated = capable(CAP_SYS_ADMIN);
 244         priv->lock_count = 0;
 245
 246         INIT_LIST_HEAD(&priv->lhead);
 247         INIT_LIST_HEAD(&priv->fbs);
 248         mutex_init(&priv->fbs_lock);
 249         INIT_LIST_HEAD(&priv->event_list);
 250         init_waitqueue_head(&priv->event_wait);
 251         priv->event_space = 4096; /* set aside 4k for event buffer */
 252
 253         if (dev->driver->driver_features & DRIVER_GEM)
 254                 drm_gem_open(dev, priv);
 255
 256         if (drm_core_check_feature(dev, DRIVER_PRIME))
 257                 drm_prime_init_file_private(&priv->prime);
 258
 259         if (dev->driver->open) {
 260                 ret = dev->driver->open(dev, priv);
 261                 if (ret < 0)
 262                         goto out_prime_destroy;
 263         }
 264
 265         /* if there is no current master make this fd it, but do not create
 266          * any master object for render clients */
 267         mutex_lock(&dev->struct_mutex);
 268         if (!priv->minor->master && !drm_is_render_client(priv)) {
 269                 /* create a new master */
 270                 priv->minor->master = drm_master_create(priv->minor);
 271                 if (!priv->minor->master) {
 272                         mutex_unlock(&dev->struct_mutex);
 273                         ret = -ENOMEM;
 274                         goto out_close;
 275                 }
 276
 277                 priv->is_master = 1;
 278                 /* take another reference for the copy in the local file priv */
 279                 priv->master = drm_master_get(priv->minor->master);
 280
 281                 priv->authenticated = 1;
 282
 283                 mutex_unlock(&dev->struct_mutex);
 284                 if (dev->driver->master_create) {
 285                         ret = dev->driver->master_create(dev, priv->master);
 286                         if (ret) {
 287                                 mutex_lock(&dev->struct_mutex);
 288                                 /* drop both references if this fails */
 289                                 drm_master_put(&priv->minor->master);
 290                                 drm_master_put(&priv->master);
 291                                 mutex_unlock(&dev->struct_mutex);
 292                                 goto out_close;
 293                         }
 294                 }
 295                 mutex_lock(&dev->struct_mutex);
 296                 if (dev->driver->master_set) {
 297                         ret = dev->driver->master_set(dev, priv, true);
 298                         if (ret) {
 299                                 /* drop both references if this fails */
 300                                 drm_master_put(&priv->minor->master);
 301                                 drm_master_put(&priv->master);
 302                                 mutex_unlock(&dev->struct_mutex);
 303                                 goto out_close;
 304                         }
 305                 }
 306         } else if (!drm_is_render_client(priv)) {
 307                 /* get a reference to the master */
 308                 priv->master = drm_master_get(priv->minor->master);
 309         }
 310         mutex_unlock(&dev->struct_mutex);
 311
 312         mutex_lock(&dev->struct_mutex);
 313         list_add(&priv->lhead, &dev->filelist);
 314         mutex_unlock(&dev->struct_mutex);
 315
 316 #ifdef __alpha__
 317         /*
 318          * Default the hose
 319          */
 320         if (!dev->hose) {
 321                 struct pci_dev *pci_dev;
 322                 pci_dev = pci_get_class(PCI_CLASS_DISPLAY_VGA << 8, NULL);
 323                 if (pci_dev) {
 324                         dev->hose = pci_dev->sysdata;
 325                         pci_dev_put(pci_dev);
 326                 }
 327                 if (!dev->hose) {
 328                         struct pci_bus *b = pci_bus_b(pci_root_buses.next);
 329                         if (b)
 330                                 dev->hose = b->sysdata;
 331                 }
 332         }
 333 #endif
 334
 335         return 0;
 336
 337 out_close:
 338         if (dev->driver->postclose)
 339                 dev->driver->postclose(dev, priv);
 340 out_prime_destroy:
 341         if (drm_core_check_feature(dev, DRIVER_PRIME))
 342                 drm_prime_destroy_file_private(&priv->prime);
 343         if (dev->driver->driver_features & DRIVER_GEM)
 344                 drm_gem_release(dev, priv);
 345 out_put_pid:
 346         put_pid(priv->pid);
 347         kfree(priv);
 348         filp->private_data = NULL;
 349         return ret;
 350 }
 351
 352 static void drm_master_release(struct drm_device *dev, struct file *filp)
 353 {
 354         struct drm_file *file_priv = filp->private_data;
 355
 356         if (drm_i_have_hw_lock(dev, file_priv)) {
 357                 DRM_DEBUG("File %p released, freeing lock for context %d\n",
 358                           filp, _DRM_LOCKING_CONTEXT(file_priv->master->lock.hw_lock->lock));
 359                 drm_lock_free(&file_priv->master->lock,
 360                               _DRM_LOCKING_CONTEXT(file_priv->master->lock.hw_lock->lock));
 361         }
 362 }
 363
 364 static void drm_events_release(struct drm_file *file_priv)
 365 {
 366         struct drm_device *dev = file_priv->minor->dev;
 367         struct drm_pending_event *e, *et;
 368         struct drm_pending_vblank_event *v, *vt;
 369         unsigned long flags;
 370
 371         spin_lock_irqsave(&dev->event_lock, flags);
 372
 373         /* Remove pending flips */
 374         list_for_each_entry_safe(v, vt, &dev->vblank_event_list, base.link)
 375                 if (v->base.file_priv == file_priv) {
 376                         list_del(&v->base.link);
 377                         drm_vblank_put(dev, v->pipe);
 378                         v->base.destroy(&v->base);
 379                 }
 380
 381         /* Remove unconsumed events */
 382         list_for_each_entry_safe(e, et, &file_priv->event_list, link)
 383                 e->destroy(e);
 384
 385         spin_unlock_irqrestore(&dev->event_lock, flags);
 386 }
 387
 388 /**
 389  * drm_legacy_dev_reinit
 390  *
 391  * Reinitializes a legacy/ums drm device in it's lastclose function.
 392  */
 393 static void drm_legacy_dev_reinit(struct drm_device *dev)
 394 {
 395         int i;
 396
 397         if (drm_core_check_feature(dev, DRIVER_MODESET))
 398                 return;
 399
 400         atomic_set(&dev->ioctl_count, 0);
 401         atomic_set(&dev->vma_count, 0);
 402
 403         for (i = 0; i < ARRAY_SIZE(dev->counts); i++)
 404                 atomic_set(&dev->counts[i], 0);
 405
 406         dev->sigdata.lock = NULL;
 407
 408         dev->context_flag = 0;
 409         dev->last_context = 0;
 410         dev->if_version = 0;
 411 }
 412
 413 /**
 414  * Take down the DRM device.
 415  *
 416  * \param dev DRM device structure.
 417  *
 418  * Frees every resource in \p dev.
 419  *
 420  * \sa drm_device
 421  */
 422 int drm_lastclose(struct drm_device * dev)
 423 {
 424         struct drm_vma_entry *vma, *vma_temp;
 425
 426         DRM_DEBUG("\n");
 427
 428         if (dev->driver->lastclose)
 429                 dev->driver->lastclose(dev);
 430         DRM_DEBUG("driver lastclose completed\n");
 431
 432         if (dev->irq_enabled && !drm_core_check_feature(dev, DRIVER_MODESET))
 433                 drm_irq_uninstall(dev);
 434
 435         mutex_lock(&dev->struct_mutex);
 436
 437         drm_agp_clear(dev);
 438
 439         drm_legacy_sg_cleanup(dev);
 440
 441         /* Clear vma list (only built for debugging) */
 442         list_for_each_entry_safe(vma, vma_temp, &dev->vmalist, head) {
 443                 list_del(&vma->head);
 444                 kfree(vma);
 445         }
 446
 447         drm_legacy_dma_takedown(dev);
 448
 449         dev->dev_mapping = NULL;
 450         mutex_unlock(&dev->struct_mutex);
 451
 452         drm_legacy_dev_reinit(dev);
 453
 454         DRM_DEBUG("lastclose completed\n");
 455         return 0;
 456 }
 457
 458 /**
 459  * Release file.
 460  *
 461  * \param inode device inode
 462  * \param file_priv DRM file private.
 463  * \return zero on success or a negative number on failure.
 464  *
 465  * If the hardware lock is held then free it, and take it again for the kernel
 466  * context since it's necessary to reclaim buffers. Unlink the file private
 467  * data from its list and free it. Decreases the open count and if it reaches
 468  * zero calls drm_lastclose().
 469  */
 470 int drm_release(struct inode *inode, struct file *filp)
 471 {
 472         struct drm_file *file_priv = filp->private_data;
 473         struct drm_device *dev = file_priv->minor->dev;
 474         int retcode = 0;
 475
 476         mutex_lock(&drm_global_mutex);
 477
 478         DRM_DEBUG("open_count = %d\n", dev->open_count);
 479
 480         if (dev->driver->preclose)
 481                 dev->driver->preclose(dev, file_priv);
 482
 483         /* ========================================================
 484          * Begin inline drm_release
 485          */
 486
 487         DRM_DEBUG("pid = %d, device = 0x%lx, open_count = %d\n",
 488                   task_pid_nr(current),
 489                   (long)old_encode_dev(file_priv->minor->device),
 490                   dev->open_count);
 491
 492         /* Release any auth tokens that might point to this file_priv,
 493            (do that under the drm_global_mutex) */
 494         if (file_priv->magic)
 495                 (void) drm_remove_magic(file_priv->master, file_priv->magic);
 496
 497         /* if the master has gone away we can't do anything with the lock */
 498         if (file_priv->minor->master)
 499                 drm_master_release(dev, filp);
 500
 501         if (drm_core_check_feature(dev, DRIVER_HAVE_DMA))
 502                 drm_core_reclaim_buffers(dev, file_priv);
 503
 504         drm_events_release(file_priv);
 505
 506         if (dev->driver->driver_features & DRIVER_MODESET)
 507                 drm_fb_release(file_priv);
 508
 509         if (dev->driver->driver_features & DRIVER_GEM)
 510                 drm_gem_release(dev, file_priv);
 511
 512         mutex_lock(&dev->ctxlist_mutex);
 513         if (!list_empty(&dev->ctxlist)) {
 514                 struct drm_ctx_list *pos, *n;
 515
 516                 list_for_each_entry_safe(pos, n, &dev->ctxlist, head) {
 517                         if (pos->tag == file_priv &&
 518                             pos->handle != DRM_KERNEL_CONTEXT) {
 519                                 if (dev->driver->context_dtor)
 520                                         dev->driver->context_dtor(dev,
 521                                                                   pos->handle);
 522
 523                                 drm_ctxbitmap_free(dev, pos->handle);
 524
 525                                 list_del(&pos->head);
 526                                 kfree(pos);
 527                         }
 528                 }
 529         }
 530         mutex_unlock(&dev->ctxlist_mutex);
 531
 532         mutex_lock(&dev->struct_mutex);
 533
 534         if (file_priv->is_master) {
 535                 struct drm_master *master = file_priv->master;
 536                 struct drm_file *temp;
 537                 list_for_each_entry(temp, &dev->filelist, lhead) {
 538                         if ((temp->master == file_priv->master) &&
 539                             (temp != file_priv))
 540                                 temp->authenticated = 0;
 541                 }
 542
 543                 /**
 544                  * Since the master is disappearing, so is the
 545                  * possibility to lock.
 546                  */
 547
 548                 if (master->lock.hw_lock) {
 549                         if (dev->sigdata.lock == master->lock.hw_lock)
 550                                 dev->sigdata.lock = NULL;
 551                         master->lock.hw_lock = NULL;
 552                         master->lock.file_priv = NULL;
 553                         wake_up_interruptible_all(&master->lock.lock_queue);
 554                 }
 555
 556                 if (file_priv->minor->master == file_priv->master) {
 557                         /* drop the reference held my the minor */
 558                         if (dev->driver->master_drop)
 559                                 dev->driver->master_drop(dev, file_priv, true);
 560                         drm_master_put(&file_priv->minor->master);
 561                 }
 562         }
 563
 564         BUG_ON(dev->dev_mapping == NULL);
 565         iput(container_of(dev->dev_mapping, struct inode, i_data));
 566
 567         /* drop the reference held my the file priv */
 568         if (file_priv->master)
 569                 drm_master_put(&file_priv->master);
 570         file_priv->is_master = 0;
 571         list_del(&file_priv->lhead);
 572         mutex_unlock(&dev->struct_mutex);
 573
 574         if (dev->driver->postclose)
 575                 dev->driver->postclose(dev, file_priv);
 576
 577
 578         if (drm_core_check_feature(dev, DRIVER_PRIME))
 579                 drm_prime_destroy_file_private(&file_priv->prime);
 580
 581         put_pid(file_priv->pid);
 582         kfree(file_priv);
 583
 584         /* ========================================================
 585          * End inline drm_release
 586          */
 587
 588         atomic_inc(&dev->counts[_DRM_STAT_CLOSES]);
 589         if (!--dev->open_count) {
 590                 if (atomic_read(&dev->ioctl_count)) {
 591                         DRM_ERROR("Device busy: %d\n",
 592                                   atomic_read(&dev->ioctl_count));
 593                         retcode = -EBUSY;
 594                 } else
 595                         retcode = drm_lastclose(dev);
 596                 if (drm_device_is_unplugged(dev))
 597                         drm_put_dev(dev);
 598         }
 599         mutex_unlock(&drm_global_mutex);
 600
 601         return retcode;
 602 }
 603 EXPORT_SYMBOL(drm_release);
 604
 605 static bool
 606 drm_dequeue_event(struct drm_file *file_priv,
 607                   size_t total, size_t max, struct drm_pending_event **out)
 608 {
 609         struct drm_device *dev = file_priv->minor->dev;
 610         struct drm_pending_event *e;
 611         unsigned long flags;
 612         bool ret = false;
 613
 614         spin_lock_irqsave(&dev->event_lock, flags);
 615
 616         *out = NULL;
 617         if (list_empty(&file_priv->event_list))
 618                 goto out;
 619         e = list_first_entry(&file_priv->event_list,
 620                              struct drm_pending_event, link);
 621         if (e->event->length + total > max)
 622                 goto out;
 623
 624         file_priv->event_space += e->event->length;
 625         list_del(&e->link);
 626         *out = e;
 627         ret = true;
 628
 629 out:
 630         spin_unlock_irqrestore(&dev->event_lock, flags);
 631         return ret;
 632 }
 633
 634 ssize_t drm_read(struct file *filp, char __user *buffer,
 635                  size_t count, loff_t *offset)
 636 {
 637         struct drm_file *file_priv = filp->private_data;
 638         struct drm_pending_event *e;
 639         size_t total;
 640         ssize_t ret;
 641
 642         ret = wait_event_interruptible(file_priv->event_wait,
 643                                        !list_empty(&file_priv->event_list));
 644         if (ret < 0)
 645                 return ret;
 646
 647         total = 0;
 648         while (drm_dequeue_event(file_priv, total, count, &e)) {
 649                 if (copy_to_user(buffer + total,
 650                                  e->event, e->event->length)) {
 651                         total = -EFAULT;
 652                         break;
 653                 }
 654
 655                 total += e->event->length;
 656                 e->destroy(e);
 657         }
 658
 659         return total;
 660 }
 661 EXPORT_SYMBOL(drm_read);
 662
 663 unsigned int drm_poll(struct file *filp, struct poll_table_struct *wait)
 664 {
 665         struct drm_file *file_priv = filp->private_data;
 666         unsigned int mask = 0;
 667
 668         poll_wait(filp, &file_priv->event_wait, wait);
 669
 670         if (!list_empty(&file_priv->event_list))
 671                 mask |= POLLIN | POLLRDNORM;
 672
 673         return mask;
 674 }
 675 EXPORT_SYMBOL(drm_poll);