drivers/gpu/drm/drm_fops.c - kernel/msm-4.19 - Gitiles

 /**
  * \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 <drm/drmP.h>
 #include <linux/poll.h>
 #include <linux/slab.h>
 #include <linux/module.h>
 #include "drm_legacy.h"
 #include "drm_internal.h"

 /* from BKL pushdown */
 DEFINE_MUTEX(drm_global_mutex);

 static int drm_open_helper(struct file *filp, struct drm_minor *minor);

 static int drm_setup(struct drm_device * dev)
 {
 	int ret;

 	if (dev->driver->firstopen &&
 	    !drm_core_check_feature(dev, DRIVER_MODESET)) {
 		ret = dev->driver->firstopen(dev);
 		if (ret != 0)
 			return ret;
 	}

 	ret = drm_legacy_dma_setup(dev);
 	if (ret < 0)
 		return ret;


 	DRM_DEBUG("\n");
 	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;
 	struct drm_minor *minor;
 	int retcode;
 	int need_setup = 0;

 	minor = drm_minor_acquire(iminor(inode));
 	if (IS_ERR(minor))
 		return PTR_ERR(minor);

 	dev = minor->dev;
 	if (!dev->open_count++)
 		need_setup = 1;

 	/* share address_space across all char-devs of a single device */
 	filp->f_mapping = dev->anon_inode->i_mapping;

 	retcode = drm_open_helper(filp, minor);
 	if (retcode)
 		goto err_undo;
 	if (need_setup) {
 		retcode = drm_setup(dev);
 		if (retcode)
 			goto err_undo;
 	}
 	return 0;

 err_undo:
 	dev->open_count--;
 	drm_minor_release(minor);
 	return retcode;
 }
 EXPORT_SYMBOL(drm_open);

 /**
  * 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(__sparc__) && !defined(__sparc_v9__)
 	return 0;		/* No cmpxchg before v9 sparc. */
 #endif
 	return 1;
 }

 /**
  * drm_new_set_master - Allocate a new master object and become master for the
  * associated master realm.
  *
  * @dev: The associated device.
  * @fpriv: File private identifying the client.
  *
  * This function must be called with dev::struct_mutex held.
  * Returns negative error code on failure. Zero on success.
  */
 int drm_new_set_master(struct drm_device *dev, struct drm_file *fpriv)
 {
 	struct drm_master *old_master;
 	int ret;

 	lockdep_assert_held_once(&dev->master_mutex);

 	/* create a new master */
 	fpriv->minor->master = drm_master_create(fpriv->minor);
 	if (!fpriv->minor->master)
 		return -ENOMEM;

 	/* take another reference for the copy in the local file priv */
 	old_master = fpriv->master;
 	fpriv->master = drm_master_get(fpriv->minor->master);

 	if (dev->driver->master_create) {
 		ret = dev->driver->master_create(dev, fpriv->master);
 		if (ret)
 			goto out_err;
 	}
 	if (dev->driver->master_set) {
 		ret = dev->driver->master_set(dev, fpriv, true);
 		if (ret)
 			goto out_err;
 	}

 	fpriv->is_master = 1;
 	fpriv->allowed_master = 1;
 	fpriv->authenticated = 1;
 	if (old_master)
 		drm_master_put(&old_master);

 	return 0;

 out_err:
 	/* drop both references and restore old master on failure */
 	drm_master_put(&fpriv->minor->master);
 	drm_master_put(&fpriv->master);
 	fpriv->master = old_master;

 	return ret;
 }

 /**
  * Called whenever a process opens /dev/drm.
  *
  * \param filp file pointer.
  * \param minor acquired minor-object.
  * \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 file *filp, struct drm_minor *minor)
 {
 	struct drm_device *dev = minor->dev;
 	struct drm_file *priv;
 	int ret;

 	if (filp->f_flags & O_EXCL)
 		return -EBUSY;	/* No exclusive opens */
 	if (!drm_cpu_valid())
 		return -EINVAL;
 	if (dev->switch_power_state != DRM_SWITCH_POWER_ON && dev->switch_power_state != DRM_SWITCH_POWER_DYNAMIC_OFF)
 		return -EINVAL;

 	DRM_DEBUG("pid = %d, minor = %d\n", task_pid_nr(current), minor->index);

 	priv = kzalloc(sizeof(*priv), GFP_KERNEL);
 	if (!priv)
 		return -ENOMEM;

 	filp->private_data = priv;
 	priv->filp = filp;
 	priv->uid = current_euid();
 	priv->pid = get_pid(task_pid(current));
 	priv->minor = minor;

 	/* 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);
 	mutex_init(&priv->fbs_lock);
 	INIT_LIST_HEAD(&priv->blobs);
 	INIT_LIST_HEAD(&priv->event_list);
 	init_waitqueue_head(&priv->event_wait);
 	priv->event_space = 4096; /* set aside 4k for event buffer */

 	mutex_init(&priv->event_read_lock);

 	if (drm_core_check_feature(dev, DRIVER_GEM))
 		drm_gem_open(dev, priv);

 	if (drm_core_check_feature(dev, DRIVER_PRIME))
 		drm_prime_init_file_private(&priv->prime);

 	if (dev->driver->open) {
 		ret = dev->driver->open(dev, priv);
 		if (ret < 0)
 			goto out_prime_destroy;
 	}

 	/* if there is no current master make this fd it, but do not create
 	 * any master object for render clients */
 	mutex_lock(&dev->master_mutex);
 	if (drm_is_primary_client(priv) && !priv->minor->master) {
 		/* create a new master */
 		ret = drm_new_set_master(dev, priv);
 		if (ret)
 			goto out_close;
 	} else if (drm_is_primary_client(priv)) {
 		/* get a reference to the master */
 		priv->master = drm_master_get(priv->minor->master);
 	}
 	mutex_unlock(&dev->master_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 = list_entry(pci_root_buses.next,
 				struct pci_bus, node);
 			if (b)
 				dev->hose = b->sysdata;
 		}
 	}
 #endif

 	return 0;

 out_close:
 	mutex_unlock(&dev->master_mutex);
 	if (dev->driver->postclose)
 		dev->driver->postclose(dev, priv);
 out_prime_destroy:
 	if (drm_core_check_feature(dev, DRIVER_PRIME))
 		drm_prime_destroy_file_private(&priv->prime);
 	if (drm_core_check_feature(dev, DRIVER_GEM))
 		drm_gem_release(dev, priv);
 	put_pid(priv->pid);
 	kfree(priv);
 	filp->private_data = NULL;
 	return ret;
 }

 static void drm_master_release(struct drm_device *dev, struct file *filp)
 {
 	struct drm_file *file_priv = filp->private_data;

 	if (drm_legacy_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_legacy_lock_free(&file_priv->master->lock,
 				     _DRM_LOCKING_CONTEXT(file_priv->master->lock.hw_lock->lock));
 	}
 }

 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) {
 		list_del(&e->link);
 		e->destroy(e);
 	}

 	spin_unlock_irqrestore(&dev->event_lock, flags);
 }

 /**
  * drm_legacy_dev_reinit
  *
  * Reinitializes a legacy/ums drm device in it's lastclose function.
  */
 static void drm_legacy_dev_reinit(struct drm_device *dev)
 {
 	if (drm_core_check_feature(dev, DRIVER_MODESET))
 		return;

 	dev->sigdata.lock = NULL;

 	dev->context_flag = 0;
 	dev->last_context = 0;
 	dev->if_version = 0;
 }

 /**
  * Take down the DRM device.
  *
  * \param dev DRM device structure.
  *
  * Frees every resource in \p dev.
  *
  * \sa drm_device
  */
 int drm_lastclose(struct drm_device * dev)
 {
 	DRM_DEBUG("\n");

 	if (dev->driver->lastclose)
 		dev->driver->lastclose(dev);
 	DRM_DEBUG("driver lastclose completed\n");

 	if (dev->irq_enabled && !drm_core_check_feature(dev, DRIVER_MODESET))
 		drm_irq_uninstall(dev);

 	mutex_lock(&dev->struct_mutex);

 	drm_agp_clear(dev);

 	drm_legacy_sg_cleanup(dev);
 	drm_legacy_vma_flush(dev);
 	drm_legacy_dma_takedown(dev);

 	mutex_unlock(&dev->struct_mutex);

 	drm_legacy_dev_reinit(dev);

 	DRM_DEBUG("lastclose completed\n");
 	return 0;
 }

 /**
  * 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_minor *minor = file_priv->minor;
 	struct drm_device *dev = minor->dev;
 	int retcode = 0;

 	mutex_lock(&drm_global_mutex);

 	DRM_DEBUG("open_count = %d\n", dev->open_count);

 	mutex_lock(&dev->struct_mutex);
 	list_del(&file_priv->lhead);
 	if (file_priv->magic)
 		idr_remove(&file_priv->master->magic_map, file_priv->magic);
 	mutex_unlock(&dev->struct_mutex);

 	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->kdev->devt),
 		  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);

 	if (drm_core_check_feature(dev, DRIVER_HAVE_DMA))
 		drm_legacy_reclaim_buffers(dev, file_priv);

 	drm_events_release(file_priv);

 	if (drm_core_check_feature(dev, DRIVER_MODESET)) {
 		drm_fb_release(file_priv);
 		drm_property_destroy_user_blobs(dev, file_priv);
 	}

 	if (drm_core_check_feature(dev, DRIVER_GEM))
 		drm_gem_release(dev, file_priv);

 	drm_legacy_ctxbitmap_flush(dev, file_priv);

 	mutex_lock(&dev->master_mutex);

 	if (file_priv->is_master) {
 		struct drm_master *master = file_priv->master;

 		/**
 		 * Since the master is disappearing, so is the
 		 * possibility to lock.
 		 */
 		mutex_lock(&dev->struct_mutex);
 		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);
 		}
 		mutex_unlock(&dev->struct_mutex);

 		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 master reference held by the file priv */
 	if (file_priv->master)
 		drm_master_put(&file_priv->master);
 	file_priv->is_master = 0;
 	mutex_unlock(&dev->master_mutex);

 	if (dev->driver->postclose)
 		dev->driver->postclose(dev, file_priv);


 	if (drm_core_check_feature(dev, DRIVER_PRIME))
 		drm_prime_destroy_file_private(&file_priv->prime);

 	WARN_ON(!list_empty(&file_priv->event_list));

 	put_pid(file_priv->pid);
 	kfree(file_priv);

 	/* ========================================================
 	 * End inline drm_release
 	 */

 	if (!--dev->open_count) {
 		retcode = drm_lastclose(dev);
 		if (drm_device_is_unplugged(dev))
 			drm_put_dev(dev);
 	}
 	mutex_unlock(&drm_global_mutex);

 	drm_minor_release(minor);

 	return retcode;
 }
 EXPORT_SYMBOL(drm_release);

 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_device *dev = file_priv->minor->dev;
 	ssize_t ret;

 	if (!access_ok(VERIFY_WRITE, buffer, count))
 		return -EFAULT;

 	ret = mutex_lock_interruptible(&file_priv->event_read_lock);
 	if (ret)
 		return ret;

 	for (;;) {
 		struct drm_pending_event *e = NULL;

 		spin_lock_irq(&dev->event_lock);
 		if (!list_empty(&file_priv->event_list)) {
 			e = list_first_entry(&file_priv->event_list,
 					struct drm_pending_event, link);
 			file_priv->event_space += e->event->length;
 			list_del(&e->link);
 		}
 		spin_unlock_irq(&dev->event_lock);

 		if (e == NULL) {
 			if (ret)
 				break;

 			if (filp->f_flags & O_NONBLOCK) {
 				ret = -EAGAIN;
 				break;
 			}

 			mutex_unlock(&file_priv->event_read_lock);
 			ret = wait_event_interruptible(file_priv->event_wait,
 						       !list_empty(&file_priv->event_list));
 			if (ret >= 0)
 				ret = mutex_lock_interruptible(&file_priv->event_read_lock);
 			if (ret)
 				return ret;
 		} else {
 			unsigned length = e->event->length;

 			if (length > count - ret) {
 put_back_event:
 				spin_lock_irq(&dev->event_lock);
 				file_priv->event_space -= length;
 				list_add(&e->link, &file_priv->event_list);
 				spin_unlock_irq(&dev->event_lock);
 				break;
 			}

 			if (copy_to_user(buffer + ret, e->event, length)) {
 				if (ret == 0)
 					ret = -EFAULT;
 				goto put_back_event;
 			}

 			ret += length;
 			e->destroy(e);
 		}
 	}
 	mutex_unlock(&file_priv->event_read_lock);

 	return ret;
 }
 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);
	/**
	* \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 <drm/drmP.h>
	#include <linux/poll.h>
	#include <linux/slab.h>
	#include <linux/module.h>
	#include "drm_legacy.h"
	#include "drm_internal.h"

	/* from BKL pushdown */
	DEFINE_MUTEX(drm_global_mutex);

	static int drm_open_helper(struct file filp, struct drm_minor minor);

	static int drm_setup(struct drm_device * dev)
	{
	int ret;

	if (dev->driver->firstopen &&
	!drm_core_check_feature(dev, DRIVER_MODESET)) {
	ret = dev->driver->firstopen(dev);
	if (ret != 0)
	return ret;
	}

	ret = drm_legacy_dma_setup(dev);
	if (ret < 0)
	return ret;


	DRM_DEBUG("\n");
	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;
	struct drm_minor *minor;
	int retcode;
	int need_setup = 0;

	minor = drm_minor_acquire(iminor(inode));
	if (IS_ERR(minor))
	return PTR_ERR(minor);

	dev = minor->dev;
	if (!dev->open_count++)
	need_setup = 1;

	/* share address_space across all char-devs of a single device */
	filp->f_mapping = dev->anon_inode->i_mapping;

	retcode = drm_open_helper(filp, minor);
	if (retcode)
	goto err_undo;
	if (need_setup) {
	retcode = drm_setup(dev);
	if (retcode)
	goto err_undo;
	}
	return 0;

	err_undo:
	dev->open_count--;
	drm_minor_release(minor);
	return retcode;
	}
	EXPORT_SYMBOL(drm_open);

	/**
	* 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(__sparc__) && !defined(__sparc_v9__)
	return 0; /* No cmpxchg before v9 sparc. */
	#endif
	return 1;
	}

	/**
	* drm_new_set_master - Allocate a new master object and become master for the
	* associated master realm.
	*
	* @dev: The associated device.
	* @fpriv: File private identifying the client.
	*
	* This function must be called with dev::struct_mutex held.
	* Returns negative error code on failure. Zero on success.
	*/
	int drm_new_set_master(struct drm_device dev, struct drm_file fpriv)
	{
	struct drm_master *old_master;
	int ret;

	lockdep_assert_held_once(&dev->master_mutex);

	/* create a new master */
	fpriv->minor->master = drm_master_create(fpriv->minor);
	if (!fpriv->minor->master)
	return -ENOMEM;

	/* take another reference for the copy in the local file priv */
	old_master = fpriv->master;
	fpriv->master = drm_master_get(fpriv->minor->master);

	if (dev->driver->master_create) {
	ret = dev->driver->master_create(dev, fpriv->master);
	if (ret)
	goto out_err;
	}
	if (dev->driver->master_set) {
	ret = dev->driver->master_set(dev, fpriv, true);
	if (ret)
	goto out_err;
	}

	fpriv->is_master = 1;
	fpriv->allowed_master = 1;
	fpriv->authenticated = 1;
	if (old_master)
	drm_master_put(&old_master);

	return 0;

	out_err:
	/* drop both references and restore old master on failure */
	drm_master_put(&fpriv->minor->master);
	drm_master_put(&fpriv->master);
	fpriv->master = old_master;

	return ret;
	}

	/**
	* Called whenever a process opens /dev/drm.
	*
	* \param filp file pointer.
	* \param minor acquired minor-object.
	* \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 file filp, struct drm_minor minor)
	{
	struct drm_device *dev = minor->dev;
	struct drm_file *priv;
	int ret;

	if (filp->f_flags & O_EXCL)
	return -EBUSY; /* No exclusive opens */
	if (!drm_cpu_valid())
	return -EINVAL;
	if (dev->switch_power_state != DRM_SWITCH_POWER_ON && dev->switch_power_state != DRM_SWITCH_POWER_DYNAMIC_OFF)
	return -EINVAL;

	DRM_DEBUG("pid = %d, minor = %d\n", task_pid_nr(current), minor->index);

	priv = kzalloc(sizeof(*priv), GFP_KERNEL);
	if (!priv)
	return -ENOMEM;

	filp->private_data = priv;
	priv->filp = filp;
	priv->uid = current_euid();
	priv->pid = get_pid(task_pid(current));
	priv->minor = minor;

	/* 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);
	mutex_init(&priv->fbs_lock);
	INIT_LIST_HEAD(&priv->blobs);
	INIT_LIST_HEAD(&priv->event_list);
	init_waitqueue_head(&priv->event_wait);
	priv->event_space = 4096; /* set aside 4k for event buffer */

	mutex_init(&priv->event_read_lock);

	if (drm_core_check_feature(dev, DRIVER_GEM))
	drm_gem_open(dev, priv);

	if (drm_core_check_feature(dev, DRIVER_PRIME))
	drm_prime_init_file_private(&priv->prime);

	if (dev->driver->open) {
	ret = dev->driver->open(dev, priv);
	if (ret < 0)
	goto out_prime_destroy;
	}

	/* if there is no current master make this fd it, but do not create
	* any master object for render clients */
	mutex_lock(&dev->master_mutex);
	if (drm_is_primary_client(priv) && !priv->minor->master) {
	/* create a new master */
	ret = drm_new_set_master(dev, priv);
	if (ret)
	goto out_close;
	} else if (drm_is_primary_client(priv)) {
	/* get a reference to the master */
	priv->master = drm_master_get(priv->minor->master);
	}
	mutex_unlock(&dev->master_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 = list_entry(pci_root_buses.next,
	struct pci_bus, node);
	if (b)
	dev->hose = b->sysdata;
	}
	}
	#endif

	return 0;

	out_close:
	mutex_unlock(&dev->master_mutex);
	if (dev->driver->postclose)
	dev->driver->postclose(dev, priv);
	out_prime_destroy:
	if (drm_core_check_feature(dev, DRIVER_PRIME))
	drm_prime_destroy_file_private(&priv->prime);
	if (drm_core_check_feature(dev, DRIVER_GEM))
	drm_gem_release(dev, priv);
	put_pid(priv->pid);
	kfree(priv);
	filp->private_data = NULL;
	return ret;
	}

	static void drm_master_release(struct drm_device dev, struct file filp)
	{
	struct drm_file *file_priv = filp->private_data;

	if (drm_legacy_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_legacy_lock_free(&file_priv->master->lock,
	_DRM_LOCKING_CONTEXT(file_priv->master->lock.hw_lock->lock));
	}
	}

	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) {
	list_del(&e->link);
	e->destroy(e);
	}

	spin_unlock_irqrestore(&dev->event_lock, flags);
	}

	/**
	* drm_legacy_dev_reinit
	*
	* Reinitializes a legacy/ums drm device in it's lastclose function.
	*/
	static void drm_legacy_dev_reinit(struct drm_device *dev)
	{
	if (drm_core_check_feature(dev, DRIVER_MODESET))
	return;

	dev->sigdata.lock = NULL;

	dev->context_flag = 0;
	dev->last_context = 0;
	dev->if_version = 0;
	}

	/**
	* Take down the DRM device.
	*
	* \param dev DRM device structure.
	*
	* Frees every resource in \p dev.
	*
	* \sa drm_device
	*/
	int drm_lastclose(struct drm_device * dev)
	{
	DRM_DEBUG("\n");

	if (dev->driver->lastclose)
	dev->driver->lastclose(dev);
	DRM_DEBUG("driver lastclose completed\n");

	if (dev->irq_enabled && !drm_core_check_feature(dev, DRIVER_MODESET))
	drm_irq_uninstall(dev);

	mutex_lock(&dev->struct_mutex);

	drm_agp_clear(dev);

	drm_legacy_sg_cleanup(dev);
	drm_legacy_vma_flush(dev);
	drm_legacy_dma_takedown(dev);

	mutex_unlock(&dev->struct_mutex);

	drm_legacy_dev_reinit(dev);

	DRM_DEBUG("lastclose completed\n");
	return 0;
	}

	/**
	* 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_minor *minor = file_priv->minor;
	struct drm_device *dev = minor->dev;
	int retcode = 0;

	mutex_lock(&drm_global_mutex);

	DRM_DEBUG("open_count = %d\n", dev->open_count);

	mutex_lock(&dev->struct_mutex);
	list_del(&file_priv->lhead);
	if (file_priv->magic)
	idr_remove(&file_priv->master->magic_map, file_priv->magic);
	mutex_unlock(&dev->struct_mutex);

	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->kdev->devt),
	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);

	if (drm_core_check_feature(dev, DRIVER_HAVE_DMA))
	drm_legacy_reclaim_buffers(dev, file_priv);

	drm_events_release(file_priv);

	if (drm_core_check_feature(dev, DRIVER_MODESET)) {
	drm_fb_release(file_priv);
	drm_property_destroy_user_blobs(dev, file_priv);
	}

	if (drm_core_check_feature(dev, DRIVER_GEM))
	drm_gem_release(dev, file_priv);

	drm_legacy_ctxbitmap_flush(dev, file_priv);

	mutex_lock(&dev->master_mutex);

	if (file_priv->is_master) {
	struct drm_master *master = file_priv->master;

	/**
	* Since the master is disappearing, so is the
	* possibility to lock.
	*/
	mutex_lock(&dev->struct_mutex);
	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);
	}
	mutex_unlock(&dev->struct_mutex);

	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 master reference held by the file priv */
	if (file_priv->master)
	drm_master_put(&file_priv->master);
	file_priv->is_master = 0;
	mutex_unlock(&dev->master_mutex);

	if (dev->driver->postclose)
	dev->driver->postclose(dev, file_priv);


	if (drm_core_check_feature(dev, DRIVER_PRIME))
	drm_prime_destroy_file_private(&file_priv->prime);

	WARN_ON(!list_empty(&file_priv->event_list));

	put_pid(file_priv->pid);
	kfree(file_priv);

	/* ========================================================
	* End inline drm_release
	*/

	if (!--dev->open_count) {
	retcode = drm_lastclose(dev);
	if (drm_device_is_unplugged(dev))
	drm_put_dev(dev);
	}
	mutex_unlock(&drm_global_mutex);

	drm_minor_release(minor);

	return retcode;
	}
	EXPORT_SYMBOL(drm_release);

	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_device *dev = file_priv->minor->dev;
	ssize_t ret;

	if (!access_ok(VERIFY_WRITE, buffer, count))
	return -EFAULT;

	ret = mutex_lock_interruptible(&file_priv->event_read_lock);
	if (ret)
	return ret;

	for (;;) {
	struct drm_pending_event *e = NULL;

	spin_lock_irq(&dev->event_lock);
	if (!list_empty(&file_priv->event_list)) {
	e = list_first_entry(&file_priv->event_list,
	struct drm_pending_event, link);
	file_priv->event_space += e->event->length;
	list_del(&e->link);
	}
	spin_unlock_irq(&dev->event_lock);

	if (e == NULL) {
	if (ret)
	break;

	if (filp->f_flags & O_NONBLOCK) {
	ret = -EAGAIN;
	break;
	}

	mutex_unlock(&file_priv->event_read_lock);
	ret = wait_event_interruptible(file_priv->event_wait,
	!list_empty(&file_priv->event_list));
	if (ret >= 0)
	ret = mutex_lock_interruptible(&file_priv->event_read_lock);
	if (ret)
	return ret;
	} else {
	unsigned length = e->event->length;

	if (length > count - ret) {
	put_back_event:
	spin_lock_irq(&dev->event_lock);
	file_priv->event_space -= length;
	list_add(&e->link, &file_priv->event_list);
	spin_unlock_irq(&dev->event_lock);
	break;
	}

	if (copy_to_user(buffer + ret, e->event, length)) {
	if (ret == 0)
	ret = -EFAULT;
	goto put_back_event;
	}

	ret += length;
	e->destroy(e);
	}
	}
	mutex_unlock(&file_priv->event_read_lock);

	return ret;
	}
	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);