text: /**
   * \file drm_fops.c
   * File operations for DRM
   *
   * \author Rickard E. (Rik) Faith <faith@valinux.com>
   * \author Daryll Strauss <daryll@valinux.com>
   * \author Gareth Hughes <gareth@valinux.com>
   */
  
  /*
   * Created: Mon Jan  4 08:58:31 1999 by faith@valinux.com
   *
   * Copyright 1999 Precision Insight, Inc., Cedar Park, Texas.
   * Copyright 2000 VA Linux Systems, Inc., Sunnyvale, California.
   * All Rights Reserved.
   *
   * Permission is hereby granted, free of charge, to any person obtaining a
   * copy of this software and associated documentation files (the "Software"),
   * to deal in the Software without restriction, including without limitation
   * the rights to use, copy, modify, merge, publish, distribute, sublicense,
   * and/or sell copies of the Software, and to permit persons to whom the
   * Software is furnished to do so, subject to the following conditions:
   *
   * The above copyright notice and this permission notice (including the next
   * paragraph) shall be included in all copies or substantial portions of the
   * Software.
   *
   * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
   * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
   * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
   * VA LINUX SYSTEMS AND/OR ITS SUPPLIERS BE LIABLE FOR ANY CLAIM, DAMAGES OR
   * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
   * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
   * OTHER DEALINGS IN THE SOFTWARE.
   */
  
  #include "drmP.h"
  #include <linux/poll.h>
  #include <linux/slab.h>
  #include <linux/smp_lock.h>
  
  /* from BKL pushdown: note that nothing else serializes idr_find() */
  DEFINE_MUTEX(drm_global_mutex);
  EXPORT_SYMBOL(drm_global_mutex);
  
  static int drm_open_helper(struct inode *inode, struct file *filp,
  			   struct drm_device * dev);
  
  static int drm_setup(struct drm_device * dev)
  {
  	int i;
  	int ret;
  
  	if (dev->driver->firstopen) {
  		ret = dev->driver->firstopen(dev);
  		if (ret != 0)
  			return ret;
  	}
  
  	atomic_set(&dev->ioctl_count, 0);
  	atomic_set(&dev->vma_count, 0);
  
  	if (drm_core_check_feature(dev, DRIVER_HAVE_DMA) &&
  	    !drm_core_check_feature(dev, DRIVER_MODESET)) {
  		dev->buf_use = 0;
  		atomic_set(&dev->buf_alloc, 0);
  
  		i = drm_dma_setup(dev);
  		if (i < 0)
  			return i;
  	}
  
  	for (i = 0; i < ARRAY_SIZE(dev->counts); i++)
  		atomic_set(&dev->counts[i], 0);
  
  	dev->sigdata.lock = NULL;
  
  	dev->queue_count = 0;
  	dev->queue_reserved = 0;
  	dev->queue_slots = 0;
  	dev->queuelist = NULL;
  	dev->context_flag = 0;
  	dev->interrupt_flag = 0;
  	dev->dma_flag = 0;
  	dev->last_context = 0;
  	dev->last_switch = 0;
  	dev->last_checked = 0;
  	init_waitqueue_head(&dev->context_wait);
  	dev->if_version = 0;
  
  	dev->ctx_start = 0;
  	dev->lck_start = 0;
  
  	dev->buf_async = NULL;
  	init_waitqueue_head(&dev->buf_readers);
  	init_waitqueue_head(&dev->buf_writers);
  
  	DRM_DEBUG("\n");
  
  	/*
  	 * The kernel's context could be created here, but is now created
  	 * in drm_dma_enqueue.  This is more resource-efficient for
  	 * hardware that does not do DMA, but may mean that
  	 * drm_select_queue fails between the time the interrupt is
  	 * initialized and the time the queues are initialized.
  	 */
  
  	return 0;
  }
  
  /**
   * Open file.
   *
   * \param inode device inode
   * \param filp file pointer.
   * \return zero on success or a negative number on failure.
   *
   * Searches the DRM device with the same minor number, calls open_helper(), and
   * increments the device open count. If the open count was previous at zero,
   * i.e., it's the first that the device is open, then calls setup().
   */
  int drm_open(struct inode *inode, struct file *filp)
  {
  	struct drm_device *dev = NULL;
  	int minor_id = iminor(inode);
  	struct drm_minor *minor;
  	int retcode = 0;
  
  	minor = idr_find(&drm_minors_idr, minor_id);
  	if (!minor)
  		return -ENODEV;
  
  	if (!(dev = minor->dev))
  		return -ENODEV;
  
  	retcode = drm_open_helper(inode, filp, dev);
  	if (!retcode) {
  		atomic_inc(&dev->counts[_DRM_STAT_OPENS]);
  		if (!dev->open_count++)
  			retcode = drm_setup(dev);
  	}
  	if (!retcode) {
  		mutex_lock(&dev->struct_mutex);
  		if (minor->type == DRM_MINOR_LEGACY) {
  			if (dev->dev_mapping == NULL)
  				dev->dev_mapping = inode->i_mapping;
  			else if (dev->dev_mapping != inode->i_mapping)
  				retcode = -ENODEV;
  		}
  		mutex_unlock(&dev->struct_mutex);
  	}
  
  	return retcode;
  }
  EXPORT_SYMBOL(drm_open);
  
  /**
   * File \c open operation.
   *
   * \param inode device inode.
   * \param filp file pointer.
   *
   * Puts the dev->fops corresponding to the device minor number into
   * \p filp, call the \c open method, and restore the file operations.
   */
  int drm_stub_open(struct inode *inode, struct file *filp)
  {
  	struct drm_device *dev = NULL;
  	struct drm_minor *minor;
  	int minor_id = iminor(inode);
  	int err = -ENODEV;
  	const struct file_operations *old_fops;
  
  	DRM_DEBUG("\n");
  
  	mutex_lock(&drm_global_mutex);
  	minor = idr_find(&drm_minors_idr, minor_id);
  	if (!minor)
  		goto out;
  
  	if (!(dev = minor->dev))
  		goto out;
  
  	old_fops = filp->f_op;
  	filp->f_op = fops_get(&dev->driver->fops);
  	if (filp->f_op == NULL) {
  		filp->f_op = old_fops;
  		goto out;
  	}
  	if (filp->f_op->open && (err = filp->f_op->open(inode, filp))) {
  		fops_put(filp->f_op);
  		filp->f_op = fops_get(old_fops);
  	}
  	fops_put(old_fops);
  
  out:
  	mutex_unlock(&drm_global_mutex);
  	return err;
  }
  
  /**
   * Check whether DRI will run on this CPU.
   *
   * \return non-zero if the DRI will run on this CPU, or zero otherwise.
   */
  static int drm_cpu_valid(void)
  {
  #if defined(__i386__)
  	if (boot_cpu_data.x86 == 3)
  		return 0;	/* No cmpxchg on a 386 */
  #endif
  #if defined(__sparc__) && !defined(__sparc_v9__)
  	return 0;		/* No cmpxchg before v9 sparc. */
  #endif
  	return 1;
  }
  
  /**
   * Called whenever a process opens /dev/drm.
   *
   * \param inode device inode.
   * \param filp file pointer.
   * \param dev device.
   * \return zero on success or a negative number on failure.
   *
   * Creates and initializes a drm_file structure for the file private data in \p
   * filp and add it into the double linked list in \p dev.
   */
  static int drm_open_helper(struct inode *inode, struct file *filp,
  			   struct drm_device * dev)
  {
  	int minor_id = iminor(inode);
  	struct drm_file *priv;
  	int ret;
  
  	if (filp->f_flags & O_EXCL)
  		return -EBUSY;	/* No exclusive opens */
  	if (!drm_cpu_valid())
  		return -EINVAL;
  
  	DRM_DEBUG("pid = %d, minor = %d\n", task_pid_nr(current), minor_id);
  
  	priv = kzalloc(sizeof(*priv), GFP_KERNEL);
  	if (!priv)
  		return -ENOMEM;
  
  	filp->private_data = priv;
  	priv->filp = filp;
  	priv->uid = current_euid();
  	priv->pid = task_pid_nr(current);
  	priv->minor = idr_find(&drm_minors_idr, minor_id);
  	priv->ioctl_count = 0;
  	/* for compatibility root is always authenticated */
  	priv->authenticated = capable(CAP_SYS_ADMIN);
  	priv->lock_count = 0;
  
  	INIT_LIST_HEAD(&priv->lhead);
  	INIT_LIST_HEAD(&priv->fbs);
  	INIT_LIST_HEAD(&priv->event_list);
  	init_waitqueue_head(&priv->event_wait);
  	priv->event_space = 4096; /* set aside 4k for event buffer */
  
  	if (dev->driver->driver_features & DRIVER_GEM)
  		drm_gem_open(dev, priv);
  
  	if (dev->driver->open) {
  		ret = dev->driver->open(dev, priv);
  		if (ret < 0)
  			goto out_free;
  	}
  
  
  	/* if there is no current master make this fd it */
  	mutex_lock(&dev->struct_mutex);
  	if (!priv->minor->master) {
  		/* create a new master */
  		priv->minor->master = drm_master_create(priv->minor);
  		if (!priv->minor->master) {
  			mutex_unlock(&dev->struct_mutex);
  			ret = -ENOMEM;
  			goto out_free;
  		}
  
  		priv->is_master = 1;
  		/* take another reference for the copy in the local file priv */
  		priv->master = drm_master_get(priv->minor->master);
  
  		priv->authenticated = 1;
  
  		mutex_unlock(&dev->struct_mutex);
  		if (dev->driver->master_create) {
  			ret = dev->driver->master_create(dev, priv->master);
  			if (ret) {
  				mutex_lock(&dev->struct_mutex);
  				/* drop both references if this fails */
  				drm_master_put(&priv->minor->master);
  				drm_master_put(&priv->master);
  				mutex_unlock(&dev->struct_mutex);
  				goto out_free;
  			}
  		}
  		mutex_lock(&dev->struct_mutex);
  		if (dev->driver->master_set) {
  			ret = dev->driver->master_set(dev, priv, true);
  			if (ret) {
  				/* drop both references if this fails */
  				drm_master_put(&priv->minor->master);
  				drm_master_put(&priv->master);
  				mutex_unlock(&dev->struct_mutex);
  				goto out_free;
  			}
  		}
  		mutex_unlock(&dev->struct_mutex);
  	} else {
  		/* get a reference to the master */
  		priv->master = drm_master_get(priv->minor->master);
  		mutex_unlock(&dev->struct_mutex);
  	}
  
  	mutex_lock(&dev->struct_mutex);
  	list_add(&priv->lhead, &dev->filelist);
  	mutex_unlock(&dev->struct_mutex);
  
  #ifdef __alpha__
  	/*
  	 * Default the hose
  	 */
  	if (!dev->hose) {
  		struct pci_dev *pci_dev;
  		pci_dev = pci_get_class(PCI_CLASS_DISPLAY_VGA << 8, NULL);
  		if (pci_dev) {
  			dev->hose = pci_dev->sysdata;
  			pci_dev_put(pci_dev);
  		}
  		if (!dev->hose) {
  			struct pci_bus *b = pci_bus_b(pci_root_buses.next);
  			if (b)
  				dev->hose = b->sysdata;
  		}
  	}
  #endif
  
  	return 0;
        out_free:
  	kfree(priv);
  	filp->private_data = NULL;
  	return ret;
  }
  
  /** No-op. */
  int drm_fasync(int fd, struct file *filp, int on)
  {
  	struct drm_file *priv = filp->private_data;
  	struct drm_device *dev = priv->minor->dev;
  
  	DRM_DEBUG("fd = %d, device = 0x%lx\n", fd,
  		  (long)old_encode_dev(priv->minor->device));
  	return fasync_helper(fd, filp, on, &dev->buf_async);
  }
  EXPORT_SYMBOL(drm_fasync);
  
  /*
   * Reclaim locked buffers; note that this may be a bad idea if the current
   * context doesn't have the hw lock...
   */
  static void drm_reclaim_locked_buffers(struct drm_device *dev, struct file *f)
  {
  	struct drm_file *file_priv = f->private_data;
  
  	if (drm_i_have_hw_lock(dev, file_priv)) {
  		dev->driver->reclaim_buffers_locked(dev, file_priv);
  	} else {
  		unsigned long _end = jiffies + 3 * DRM_HZ;
  		int locked = 0;
  
  		drm_idlelock_take(&file_priv->master->lock);
  
  		/*
  		 * Wait for a while.
  		 */
  		do {
  			spin_lock_bh(&file_priv->master->lock.spinlock);
  			locked = file_priv->master->lock.idle_has_lock;
  			spin_unlock_bh(&file_priv->master->lock.spinlock);
  			if (locked)
  				break;
  			schedule();
  		} while (!time_after_eq(jiffies, _end));
  
  		if (!locked) {
  			DRM_ERROR("reclaim_buffers_locked() deadlock. Please rework this\n"
  				  "\tdriver to use reclaim_buffers_idlelocked() instead.\n"
  				  "\tI will go on reclaiming the buffers anyway.\n");
  		}
  
  		dev->driver->reclaim_buffers_locked(dev, file_priv);
  		drm_idlelock_release(&file_priv->master->lock);
  	}
  }
  
  static void drm_master_release(struct drm_device *dev, struct file *filp)
  {
  	struct drm_file *file_priv = filp->private_data;
  
  	if (dev->driver->reclaim_buffers_locked &&
  	    file_priv->master->lock.hw_lock)
  		drm_reclaim_locked_buffers(dev, filp);
  
  	if (dev->driver->reclaim_buffers_idlelocked &&
  	    file_priv->master->lock.hw_lock) {
  		drm_idlelock_take(&file_priv->master->lock);
  		dev->driver->reclaim_buffers_idlelocked(dev, file_priv);
  		drm_idlelock_release(&file_priv->master->lock);
  	}
  
  
  	if (drm_i_have_hw_lock(dev, file_priv)) {
  		DRM_DEBUG("File %p released, freeing lock for context %d\n",
  			  filp, _DRM_LOCKING_CONTEXT(file_priv->master->lock.hw_lock->lock));
  		drm_lock_free(&file_priv->master->lock,
  			      _DRM_LOCKING_CONTEXT(file_priv->master->lock.hw_lock->lock));
  	}
  
  	if (drm_core_check_feature(dev, DRIVER_HAVE_DMA) &&
  	    !dev->driver->reclaim_buffers_locked) {
  		dev->driver->reclaim_buffers(dev, file_priv);
  	}
  }
  
  static void drm_events_release(struct drm_file *file_priv)
  {
  	struct drm_device *dev = file_priv->minor->dev;
  	struct drm_pending_event *e, *et;
  	struct drm_pending_vblank_event *v, *vt;
  	unsigned long flags;
  
  	spin_lock_irqsave(&dev->event_lock, flags);
  
  	/* Remove pending flips */
  	list_for_each_entry_safe(v, vt, &dev->vblank_event_list, base.link)
  		if (v->base.file_priv == file_priv) {
  			list_del(&v->base.link);
  			drm_vblank_put(dev, v->pipe);
  			v->base.destroy(&v->base);
  		}
  
  	/* Remove unconsumed events */
  	list_for_each_entry_safe(e, et, &file_priv->event_list, link)
  		e->destroy(e);
  
  	spin_unlock_irqrestore(&dev->event_lock, flags);
  }
  
  /**
   * Release file.
   *
   * \param inode device inode
   * \param file_priv DRM file private.
   * \return zero on success or a negative number on failure.
   *
   * If the hardware lock is held then free it, and take it again for the kernel
   * context since it's necessary to reclaim buffers. Unlink the file private
   * data from its list and free it. Decreases the open count and if it reaches
   * zero calls drm_lastclose().
   */
  int drm_release(struct inode *inode, struct file *filp)
  {
  	struct drm_file *file_priv = filp->private_data;
  	struct drm_device *dev = file_priv->minor->dev;
  	int retcode = 0;
  
  	mutex_lock(&drm_global_mutex);
  
  	DRM_DEBUG("open_count = %d\n", dev->open_count);
  
  	if (dev->driver->preclose)
  		dev->driver->preclose(dev, file_priv);
  
  	/* ========================================================
  	 * Begin inline drm_release
  	 */
  
  	DRM_DEBUG("pid = %d, device = 0x%lx, open_count = %d\n",
  		  task_pid_nr(current),
  		  (long)old_encode_dev(file_priv->minor->device),
  		  dev->open_count);
  
  	/* if the master has gone away we can't do anything with the lock */
  	if (file_priv->minor->master)
  		drm_master_release(dev, filp);
  
  	drm_events_release(file_priv);
  
  	if (dev->driver->driver_features & DRIVER_GEM)
  		drm_gem_release(dev, file_priv);
  
  	if (dev->driver->driver_features & DRIVER_MODESET)
  		drm_fb_release(file_priv);
  
  	mutex_lock(&dev->ctxlist_mutex);
  	if (!list_empty(&dev->ctxlist)) {
  		struct drm_ctx_list *pos, *n;
  
  		list_for_each_entry_safe(pos, n, &dev->ctxlist, head) {
  			if (pos->tag == file_priv &&
  			    pos->handle != DRM_KERNEL_CONTEXT) {
  				if (dev->driver->context_dtor)
  					dev->driver->context_dtor(dev,
  								  pos->handle);
  
  				drm_ctxbitmap_free(dev, pos->handle);
  
  				list_del(&pos->head);
  				kfree(pos);
  				--dev->ctx_count;
  			}
  		}
  	}
  	mutex_unlock(&dev->ctxlist_mutex);
  
  	mutex_lock(&dev->struct_mutex);
  
  	if (file_priv->is_master) {
  		struct drm_master *master = file_priv->master;
  		struct drm_file *temp;
  		list_for_each_entry(temp, &dev->filelist, lhead) {
  			if ((temp->master == file_priv->master) &&
  			    (temp != file_priv))
  				temp->authenticated = 0;
  		}
  
  		/**
  		 * Since the master is disappearing, so is the
  		 * possibility to lock.
  		 */
  
  		if (master->lock.hw_lock) {
  			if (dev->sigdata.lock == master->lock.hw_lock)
  				dev->sigdata.lock = NULL;
  			master->lock.hw_lock = NULL;
  			master->lock.file_priv = NULL;
  			wake_up_interruptible_all(&master->lock.lock_queue);
  		}
  
  		if (file_priv->minor->master == file_priv->master) {
  			/* drop the reference held my the minor */
  			if (dev->driver->master_drop)
  				dev->driver->master_drop(dev, file_priv, true);
  			drm_master_put(&file_priv->minor->master);
  		}
  	}
  
  	/* drop the reference held my the file priv */
  	drm_master_put(&file_priv->master);
  	file_priv->is_master = 0;
  	list_del(&file_priv->lhead);
  	mutex_unlock(&dev->struct_mutex);
  
  	if (dev->driver->postclose)
  		dev->driver->postclose(dev, file_priv);
  	kfree(file_priv);
  
  	/* ========================================================
  	 * End inline drm_release
  	 */
  
  	atomic_inc(&dev->counts[_DRM_STAT_CLOSES]);
  	if (!--dev->open_count) {
  		if (atomic_read(&dev->ioctl_count)) {
  			DRM_ERROR("Device busy: %d\n",
  				  atomic_read(&dev->ioctl_count));
  			retcode = -EBUSY;
  		} else
  			retcode = drm_lastclose(dev);
  	}
  	mutex_unlock(&drm_global_mutex);
  
  	return retcode;
  }
  EXPORT_SYMBOL(drm_release);
  
  static bool
  drm_dequeue_event(struct drm_file *file_priv,
  		  size_t total, size_t max, struct drm_pending_event **out)
  {
  	struct drm_device *dev = file_priv->minor->dev;
  	struct drm_pending_event *e;
  	unsigned long flags;
  	bool ret = false;
  
  	spin_lock_irqsave(&dev->event_lock, flags);
  
  	*out = NULL;
  	if (list_empty(&file_priv->event_list))
  		goto out;
  	e = list_first_entry(&file_priv->event_list,
  			     struct drm_pending_event, link);
  	if (e->event->length + total > max)
  		goto out;
  
  	file_priv->event_space += e->event->length;
  	list_del(&e->link);
  	*out = e;
  	ret = true;
  
  out:
  	spin_unlock_irqrestore(&dev->event_lock, flags);
  	return ret;
  }
  
  ssize_t drm_read(struct file *filp, char __user *buffer,
  		 size_t count, loff_t *offset)
  {
  	struct drm_file *file_priv = filp->private_data;
  	struct drm_pending_event *e;
  	size_t total;
  	ssize_t ret;
  
  	ret = wait_event_interruptible(file_priv->event_wait,
  				       !list_empty(&file_priv->event_list));
  	if (ret < 0)
  		return ret;
  
  	total = 0;
  	while (drm_dequeue_event(file_priv, total, count, &e)) {
  		if (copy_to_user(buffer + total,
  				 e->event, e->event->length)) {
  			total = -EFAULT;
  			break;
  		}
  
  		total += e->event->length;
  		e->destroy(e);
  	}
  
  	return total;
  }
  EXPORT_SYMBOL(drm_read);
  
  unsigned int drm_poll(struct file *filp, struct poll_table_struct *wait)
  {
  	struct drm_file *file_priv = filp->private_data;
  	unsigned int mask = 0;
  
  	poll_wait(filp, &file_priv->event_wait, wait);
  
  	if (!list_empty(&file_priv->event_list))
  		mask |= POLLIN | POLLRDNORM;
  
  	return mask;
  }
  EXPORT_SYMBOL(drm_poll);
  