drivers/gpu/drm/drm_gem.c - kernel/msm-4.9 - Gitiles

 /*
  * Copyright © 2008 Intel Corporation
  *
  * 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
  * THE AUTHORS OR COPYRIGHT HOLDERS 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.
  *
  * Authors:
  *    Eric Anholt <eric@anholt.net>
  *
  */

 #include <linux/types.h>
 #include <linux/slab.h>
 #include <linux/mm.h>
 #include <linux/uaccess.h>
 #include <linux/fs.h>
 #include <linux/file.h>
 #include <linux/module.h>
 #include <linux/mman.h>
 #include <linux/pagemap.h>
 #include "drmP.h"

 /** @file drm_gem.c
  *
  * This file provides some of the base ioctls and library routines for
  * the graphics memory manager implemented by each device driver.
  *
  * Because various devices have different requirements in terms of
  * synchronization and migration strategies, implementing that is left up to
  * the driver, and all that the general API provides should be generic --
  * allocating objects, reading/writing data with the cpu, freeing objects.
  * Even there, platform-dependent optimizations for reading/writing data with
  * the CPU mean we'll likely hook those out to driver-specific calls.  However,
  * the DRI2 implementation wants to have at least allocate/mmap be generic.
  *
  * The goal was to have swap-backed object allocation managed through
  * struct file.  However, file descriptors as handles to a struct file have
  * two major failings:
  * - Process limits prevent more than 1024 or so being used at a time by
  *   default.
  * - Inability to allocate high fds will aggravate the X Server's select()
  *   handling, and likely that of many GL client applications as well.
  *
  * This led to a plan of using our own integer IDs (called handles, following
  * DRM terminology) to mimic fds, and implement the fd syscalls we need as
  * ioctls.  The objects themselves will still include the struct file so
  * that we can transition to fds if the required kernel infrastructure shows
  * up at a later date, and as our interface with shmfs for memory allocation.
  */

 /*
  * We make up offsets for buffer objects so we can recognize them at
  * mmap time.
  */
 #define DRM_FILE_PAGE_OFFSET_START ((0xFFFFFFFFUL >> PAGE_SHIFT) + 1)
 #define DRM_FILE_PAGE_OFFSET_SIZE ((0xFFFFFFFFUL >> PAGE_SHIFT) * 16)

 /**
  * Initialize the GEM device fields
  */

 int
 drm_gem_init(struct drm_device *dev)
 {
 	struct drm_gem_mm *mm;

 	spin_lock_init(&dev->object_name_lock);
 	idr_init(&dev->object_name_idr);
 	atomic_set(&dev->object_count, 0);
 	atomic_set(&dev->object_memory, 0);
 	atomic_set(&dev->pin_count, 0);
 	atomic_set(&dev->pin_memory, 0);
 	atomic_set(&dev->gtt_count, 0);
 	atomic_set(&dev->gtt_memory, 0);

 	mm = drm_calloc(1, sizeof(struct drm_gem_mm), DRM_MEM_MM);
 	if (!mm) {
 		DRM_ERROR("out of memory\n");
 		return -ENOMEM;
 	}

 	dev->mm_private = mm;

 	if (drm_ht_create(&mm->offset_hash, 19)) {
 		drm_free(mm, sizeof(struct drm_gem_mm), DRM_MEM_MM);
 		return -ENOMEM;
 	}

 	if (drm_mm_init(&mm->offset_manager, DRM_FILE_PAGE_OFFSET_START,
 			DRM_FILE_PAGE_OFFSET_SIZE)) {
 		drm_free(mm, sizeof(struct drm_gem_mm), DRM_MEM_MM);
 		drm_ht_remove(&mm->offset_hash);
 		return -ENOMEM;
 	}

 	return 0;
 }

 void
 drm_gem_destroy(struct drm_device *dev)
 {
 	struct drm_gem_mm *mm = dev->mm_private;

 	drm_mm_takedown(&mm->offset_manager);
 	drm_ht_remove(&mm->offset_hash);
 	drm_free(mm, sizeof(struct drm_gem_mm), DRM_MEM_MM);
 	dev->mm_private = NULL;
 }

 /**
  * Allocate a GEM object of the specified size with shmfs backing store
  */
 struct drm_gem_object *
 drm_gem_object_alloc(struct drm_device *dev, size_t size)
 {
 	struct drm_gem_object *obj;

 	BUG_ON((size & (PAGE_SIZE - 1)) != 0);

 	obj = kcalloc(1, sizeof(*obj), GFP_KERNEL);

 	obj->dev = dev;
 	obj->filp = shmem_file_setup("drm mm object", size, VM_NORESERVE);
 	if (IS_ERR(obj->filp)) {
 		kfree(obj);
 		return NULL;
 	}

 	kref_init(&obj->refcount);
 	kref_init(&obj->handlecount);
 	obj->size = size;
 	if (dev->driver->gem_init_object != NULL &&
 	    dev->driver->gem_init_object(obj) != 0) {
 		fput(obj->filp);
 		kfree(obj);
 		return NULL;
 	}
 	atomic_inc(&dev->object_count);
 	atomic_add(obj->size, &dev->object_memory);
 	return obj;
 }
 EXPORT_SYMBOL(drm_gem_object_alloc);

 /**
  * Removes the mapping from handle to filp for this object.
  */
 static int
 drm_gem_handle_delete(struct drm_file *filp, int handle)
 {
 	struct drm_device *dev;
 	struct drm_gem_object *obj;

 	/* This is gross. The idr system doesn't let us try a delete and
 	 * return an error code.  It just spews if you fail at deleting.
 	 * So, we have to grab a lock around finding the object and then
 	 * doing the delete on it and dropping the refcount, or the user
 	 * could race us to double-decrement the refcount and cause a
 	 * use-after-free later.  Given the frequency of our handle lookups,
 	 * we may want to use ida for number allocation and a hash table
 	 * for the pointers, anyway.
 	 */
 	spin_lock(&filp->table_lock);

 	/* Check if we currently have a reference on the object */
 	obj = idr_find(&filp->object_idr, handle);
 	if (obj == NULL) {
 		spin_unlock(&filp->table_lock);
 		return -EINVAL;
 	}
 	dev = obj->dev;

 	/* Release reference and decrement refcount. */
 	idr_remove(&filp->object_idr, handle);
 	spin_unlock(&filp->table_lock);

 	mutex_lock(&dev->struct_mutex);
 	drm_gem_object_handle_unreference(obj);
 	mutex_unlock(&dev->struct_mutex);

 	return 0;
 }

 /**
  * Create a handle for this object. This adds a handle reference
  * to the object, which includes a regular reference count. Callers
  * will likely want to dereference the object afterwards.
  */
 int
 drm_gem_handle_create(struct drm_file *file_priv,
 		       struct drm_gem_object *obj,
 		       int *handlep)
 {
 	int	ret;

 	/*
 	 * Get the user-visible handle using idr.
 	 */
 again:
 	/* ensure there is space available to allocate a handle */
 	if (idr_pre_get(&file_priv->object_idr, GFP_KERNEL) == 0)
 		return -ENOMEM;

 	/* do the allocation under our spinlock */
 	spin_lock(&file_priv->table_lock);
 	ret = idr_get_new_above(&file_priv->object_idr, obj, 1, handlep);
 	spin_unlock(&file_priv->table_lock);
 	if (ret == -EAGAIN)
 		goto again;

 	if (ret != 0)
 		return ret;

 	drm_gem_object_handle_reference(obj);
 	return 0;
 }
 EXPORT_SYMBOL(drm_gem_handle_create);

 /** Returns a reference to the object named by the handle. */
 struct drm_gem_object *
 drm_gem_object_lookup(struct drm_device *dev, struct drm_file *filp,
 		      int handle)
 {
 	struct drm_gem_object *obj;

 	spin_lock(&filp->table_lock);

 	/* Check if we currently have a reference on the object */
 	obj = idr_find(&filp->object_idr, handle);
 	if (obj == NULL) {
 		spin_unlock(&filp->table_lock);
 		return NULL;
 	}

 	drm_gem_object_reference(obj);

 	spin_unlock(&filp->table_lock);

 	return obj;
 }
 EXPORT_SYMBOL(drm_gem_object_lookup);

 /**
  * Releases the handle to an mm object.
  */
 int
 drm_gem_close_ioctl(struct drm_device *dev, void *data,
 		    struct drm_file *file_priv)
 {
 	struct drm_gem_close *args = data;
 	int ret;

 	if (!(dev->driver->driver_features & DRIVER_GEM))
 		return -ENODEV;

 	ret = drm_gem_handle_delete(file_priv, args->handle);

 	return ret;
 }

 /**
  * Create a global name for an object, returning the name.
  *
  * Note that the name does not hold a reference; when the object
  * is freed, the name goes away.
  */
 int
 drm_gem_flink_ioctl(struct drm_device *dev, void *data,
 		    struct drm_file *file_priv)
 {
 	struct drm_gem_flink *args = data;
 	struct drm_gem_object *obj;
 	int ret;

 	if (!(dev->driver->driver_features & DRIVER_GEM))
 		return -ENODEV;

 	obj = drm_gem_object_lookup(dev, file_priv, args->handle);
 	if (obj == NULL)
 		return -EBADF;

 again:
 	if (idr_pre_get(&dev->object_name_idr, GFP_KERNEL) == 0)
 		return -ENOMEM;

 	spin_lock(&dev->object_name_lock);
 	if (obj->name) {
 		args->name = obj->name;
 		spin_unlock(&dev->object_name_lock);
 		return 0;
 	}
 	ret = idr_get_new_above(&dev->object_name_idr, obj, 1,
 				 &obj->name);
 	spin_unlock(&dev->object_name_lock);
 	if (ret == -EAGAIN)
 		goto again;

 	if (ret != 0) {
 		mutex_lock(&dev->struct_mutex);
 		drm_gem_object_unreference(obj);
 		mutex_unlock(&dev->struct_mutex);
 		return ret;
 	}

 	/*
 	 * Leave the reference from the lookup around as the
 	 * name table now holds one
 	 */
 	args->name = (uint64_t) obj->name;

 	return 0;
 }

 /**
  * Open an object using the global name, returning a handle and the size.
  *
  * This handle (of course) holds a reference to the object, so the object
  * will not go away until the handle is deleted.
  */
 int
 drm_gem_open_ioctl(struct drm_device *dev, void *data,
 		   struct drm_file *file_priv)
 {
 	struct drm_gem_open *args = data;
 	struct drm_gem_object *obj;
 	int ret;
 	int handle;

 	if (!(dev->driver->driver_features & DRIVER_GEM))
 		return -ENODEV;

 	spin_lock(&dev->object_name_lock);
 	obj = idr_find(&dev->object_name_idr, (int) args->name);
 	if (obj)
 		drm_gem_object_reference(obj);
 	spin_unlock(&dev->object_name_lock);
 	if (!obj)
 		return -ENOENT;

 	ret = drm_gem_handle_create(file_priv, obj, &handle);
 	mutex_lock(&dev->struct_mutex);
 	drm_gem_object_unreference(obj);
 	mutex_unlock(&dev->struct_mutex);
 	if (ret)
 		return ret;

 	args->handle = handle;
 	args->size = obj->size;

 	return 0;
 }

 /**
  * Called at device open time, sets up the structure for handling refcounting
  * of mm objects.
  */
 void
 drm_gem_open(struct drm_device *dev, struct drm_file *file_private)
 {
 	idr_init(&file_private->object_idr);
 	spin_lock_init(&file_private->table_lock);
 }

 /**
  * Called at device close to release the file's
  * handle references on objects.
  */
 static int
 drm_gem_object_release_handle(int id, void *ptr, void *data)
 {
 	struct drm_gem_object *obj = ptr;

 	drm_gem_object_handle_unreference(obj);

 	return 0;
 }

 /**
  * Called at close time when the filp is going away.
  *
  * Releases any remaining references on objects by this filp.
  */
 void
 drm_gem_release(struct drm_device *dev, struct drm_file *file_private)
 {
 	mutex_lock(&dev->struct_mutex);
 	idr_for_each(&file_private->object_idr,
 		     &drm_gem_object_release_handle, NULL);

 	idr_destroy(&file_private->object_idr);
 	mutex_unlock(&dev->struct_mutex);
 }

 /**
  * Called after the last reference to the object has been lost.
  *
  * Frees the object
  */
 void
 drm_gem_object_free(struct kref *kref)
 {
 	struct drm_gem_object *obj = (struct drm_gem_object *) kref;
 	struct drm_device *dev = obj->dev;

 	BUG_ON(!mutex_is_locked(&dev->struct_mutex));

 	if (dev->driver->gem_free_object != NULL)
 		dev->driver->gem_free_object(obj);

 	fput(obj->filp);
 	atomic_dec(&dev->object_count);
 	atomic_sub(obj->size, &dev->object_memory);
 	kfree(obj);
 }
 EXPORT_SYMBOL(drm_gem_object_free);

 /**
  * Called after the last handle to the object has been closed
  *
  * Removes any name for the object. Note that this must be
  * called before drm_gem_object_free or we'll be touching
  * freed memory
  */
 void
 drm_gem_object_handle_free(struct kref *kref)
 {
 	struct drm_gem_object *obj = container_of(kref,
 						  struct drm_gem_object,
 						  handlecount);
 	struct drm_device *dev = obj->dev;

 	/* Remove any name for this object */
 	spin_lock(&dev->object_name_lock);
 	if (obj->name) {
 		idr_remove(&dev->object_name_idr, obj->name);
 		spin_unlock(&dev->object_name_lock);
 		/*
 		 * The object name held a reference to this object, drop
 		 * that now.
 		 */
 		drm_gem_object_unreference(obj);
 	} else
 		spin_unlock(&dev->object_name_lock);

 }
 EXPORT_SYMBOL(drm_gem_object_handle_free);

 /**
  * drm_gem_mmap - memory map routine for GEM objects
  * @filp: DRM file pointer
  * @vma: VMA for the area to be mapped
  *
  * If a driver supports GEM object mapping, mmap calls on the DRM file
  * descriptor will end up here.
  *
  * If we find the object based on the offset passed in (vma->vm_pgoff will
  * contain the fake offset we created when the GTT map ioctl was called on
  * the object), we set up the driver fault handler so that any accesses
  * to the object can be trapped, to perform migration, GTT binding, surface
  * register allocation, or performance monitoring.
  */
 int drm_gem_mmap(struct file *filp, struct vm_area_struct *vma)
 {
 	struct drm_file *priv = filp->private_data;
 	struct drm_device *dev = priv->minor->dev;
 	struct drm_gem_mm *mm = dev->mm_private;
 	struct drm_map *map = NULL;
 	struct drm_gem_object *obj;
 	struct drm_hash_item *hash;
 	unsigned long prot;
 	int ret = 0;

 	mutex_lock(&dev->struct_mutex);

 	if (drm_ht_find_item(&mm->offset_hash, vma->vm_pgoff, &hash)) {
 		mutex_unlock(&dev->struct_mutex);
 		return drm_mmap(filp, vma);
 	}

 	map = drm_hash_entry(hash, struct drm_map_list, hash)->map;
 	if (!map ||
 	    ((map->flags & _DRM_RESTRICTED) && !capable(CAP_SYS_ADMIN))) {
 		ret =  -EPERM;
 		goto out_unlock;
 	}

 	/* Check for valid size. */
 	if (map->size < vma->vm_end - vma->vm_start) {
 		ret = -EINVAL;
 		goto out_unlock;
 	}

 	obj = map->handle;
 	if (!obj->dev->driver->gem_vm_ops) {
 		ret = -EINVAL;
 		goto out_unlock;
 	}

 	vma->vm_flags |= VM_RESERVED | VM_IO | VM_PFNMAP | VM_DONTEXPAND;
 	vma->vm_ops = obj->dev->driver->gem_vm_ops;
 	vma->vm_private_data = map->handle;
 	/* FIXME: use pgprot_writecombine when available */
 	prot = pgprot_val(vma->vm_page_prot);
 #ifdef CONFIG_X86
 	prot |= _PAGE_CACHE_WC;
 #endif
 	vma->vm_page_prot = __pgprot(prot);

 	vma->vm_file = filp;	/* Needed for drm_vm_open() */
 	drm_vm_open_locked(vma);

 out_unlock:
 	mutex_unlock(&dev->struct_mutex);

 	return ret;
 }
 EXPORT_SYMBOL(drm_gem_mmap);
	/*
	* Copyright © 2008 Intel Corporation
	*
	* 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
	* THE AUTHORS OR COPYRIGHT HOLDERS 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.
	*
	* Authors:
	* Eric Anholt <eric@anholt.net>
	*
	*/

	#include <linux/types.h>
	#include <linux/slab.h>
	#include <linux/mm.h>
	#include <linux/uaccess.h>
	#include <linux/fs.h>
	#include <linux/file.h>
	#include <linux/module.h>
	#include <linux/mman.h>
	#include <linux/pagemap.h>
	#include "drmP.h"

	/** @file drm_gem.c
	*
	* This file provides some of the base ioctls and library routines for
	* the graphics memory manager implemented by each device driver.
	*
	* Because various devices have different requirements in terms of
	* synchronization and migration strategies, implementing that is left up to
	* the driver, and all that the general API provides should be generic --
	* allocating objects, reading/writing data with the cpu, freeing objects.
	* Even there, platform-dependent optimizations for reading/writing data with
	* the CPU mean we'll likely hook those out to driver-specific calls. However,
	* the DRI2 implementation wants to have at least allocate/mmap be generic.
	*
	* The goal was to have swap-backed object allocation managed through
	* struct file. However, file descriptors as handles to a struct file have
	* two major failings:
	* - Process limits prevent more than 1024 or so being used at a time by
	* default.
	* - Inability to allocate high fds will aggravate the X Server's select()
	* handling, and likely that of many GL client applications as well.
	*
	* This led to a plan of using our own integer IDs (called handles, following
	* DRM terminology) to mimic fds, and implement the fd syscalls we need as
	* ioctls. The objects themselves will still include the struct file so
	* that we can transition to fds if the required kernel infrastructure shows
	* up at a later date, and as our interface with shmfs for memory allocation.
	*/

	/*
	* We make up offsets for buffer objects so we can recognize them at
	* mmap time.
	*/
	#define DRM_FILE_PAGE_OFFSET_START ((0xFFFFFFFFUL >> PAGE_SHIFT) + 1)
	#define DRM_FILE_PAGE_OFFSET_SIZE ((0xFFFFFFFFUL >> PAGE_SHIFT) * 16)

	/**
	* Initialize the GEM device fields
	*/

	int
	drm_gem_init(struct drm_device *dev)
	{
	struct drm_gem_mm *mm;

	spin_lock_init(&dev->object_name_lock);
	idr_init(&dev->object_name_idr);
	atomic_set(&dev->object_count, 0);
	atomic_set(&dev->object_memory, 0);
	atomic_set(&dev->pin_count, 0);
	atomic_set(&dev->pin_memory, 0);
	atomic_set(&dev->gtt_count, 0);
	atomic_set(&dev->gtt_memory, 0);

	mm = drm_calloc(1, sizeof(struct drm_gem_mm), DRM_MEM_MM);
	if (!mm) {
	DRM_ERROR("out of memory\n");
	return -ENOMEM;
	}

	dev->mm_private = mm;

	if (drm_ht_create(&mm->offset_hash, 19)) {
	drm_free(mm, sizeof(struct drm_gem_mm), DRM_MEM_MM);
	return -ENOMEM;
	}

	if (drm_mm_init(&mm->offset_manager, DRM_FILE_PAGE_OFFSET_START,
	DRM_FILE_PAGE_OFFSET_SIZE)) {
	drm_free(mm, sizeof(struct drm_gem_mm), DRM_MEM_MM);
	drm_ht_remove(&mm->offset_hash);
	return -ENOMEM;
	}

	return 0;
	}

	void
	drm_gem_destroy(struct drm_device *dev)
	{
	struct drm_gem_mm *mm = dev->mm_private;

	drm_mm_takedown(&mm->offset_manager);
	drm_ht_remove(&mm->offset_hash);
	drm_free(mm, sizeof(struct drm_gem_mm), DRM_MEM_MM);
	dev->mm_private = NULL;
	}

	/**
	* Allocate a GEM object of the specified size with shmfs backing store
	*/
	struct drm_gem_object *
	drm_gem_object_alloc(struct drm_device *dev, size_t size)
	{
	struct drm_gem_object *obj;

	BUG_ON((size & (PAGE_SIZE - 1)) != 0);

	obj = kcalloc(1, sizeof(*obj), GFP_KERNEL);

	obj->dev = dev;
	obj->filp = shmem_file_setup("drm mm object", size, VM_NORESERVE);
	if (IS_ERR(obj->filp)) {
	kfree(obj);
	return NULL;
	}

	kref_init(&obj->refcount);
	kref_init(&obj->handlecount);
	obj->size = size;
	if (dev->driver->gem_init_object != NULL &&
	dev->driver->gem_init_object(obj) != 0) {
	fput(obj->filp);
	kfree(obj);
	return NULL;
	}
	atomic_inc(&dev->object_count);
	atomic_add(obj->size, &dev->object_memory);
	return obj;
	}
	EXPORT_SYMBOL(drm_gem_object_alloc);

	/**
	* Removes the mapping from handle to filp for this object.
	*/
	static int
	drm_gem_handle_delete(struct drm_file *filp, int handle)
	{
	struct drm_device *dev;
	struct drm_gem_object *obj;

	/* This is gross. The idr system doesn't let us try a delete and
	* return an error code. It just spews if you fail at deleting.
	* So, we have to grab a lock around finding the object and then
	* doing the delete on it and dropping the refcount, or the user
	* could race us to double-decrement the refcount and cause a
	* use-after-free later. Given the frequency of our handle lookups,
	* we may want to use ida for number allocation and a hash table
	* for the pointers, anyway.
	*/
	spin_lock(&filp->table_lock);

	/* Check if we currently have a reference on the object */
	obj = idr_find(&filp->object_idr, handle);
	if (obj == NULL) {
	spin_unlock(&filp->table_lock);
	return -EINVAL;
	}
	dev = obj->dev;

	/* Release reference and decrement refcount. */
	idr_remove(&filp->object_idr, handle);
	spin_unlock(&filp->table_lock);

	mutex_lock(&dev->struct_mutex);
	drm_gem_object_handle_unreference(obj);
	mutex_unlock(&dev->struct_mutex);

	return 0;
	}

	/**
	* Create a handle for this object. This adds a handle reference
	* to the object, which includes a regular reference count. Callers
	* will likely want to dereference the object afterwards.
	*/
	int
	drm_gem_handle_create(struct drm_file *file_priv,
	struct drm_gem_object *obj,
	int *handlep)
	{
	int ret;

	/*
	* Get the user-visible handle using idr.
	*/
	again:
	/* ensure there is space available to allocate a handle */
	if (idr_pre_get(&file_priv->object_idr, GFP_KERNEL) == 0)
	return -ENOMEM;

	/* do the allocation under our spinlock */
	spin_lock(&file_priv->table_lock);
	ret = idr_get_new_above(&file_priv->object_idr, obj, 1, handlep);
	spin_unlock(&file_priv->table_lock);
	if (ret == -EAGAIN)
	goto again;

	if (ret != 0)
	return ret;

	drm_gem_object_handle_reference(obj);
	return 0;
	}
	EXPORT_SYMBOL(drm_gem_handle_create);

	/** Returns a reference to the object named by the handle. */
	struct drm_gem_object *
	drm_gem_object_lookup(struct drm_device dev, struct drm_file filp,
	int handle)
	{
	struct drm_gem_object *obj;

	spin_lock(&filp->table_lock);

	/* Check if we currently have a reference on the object */
	obj = idr_find(&filp->object_idr, handle);
	if (obj == NULL) {
	spin_unlock(&filp->table_lock);
	return NULL;
	}

	drm_gem_object_reference(obj);

	spin_unlock(&filp->table_lock);

	return obj;
	}
	EXPORT_SYMBOL(drm_gem_object_lookup);

	/**
	* Releases the handle to an mm object.
	*/
	int
	drm_gem_close_ioctl(struct drm_device dev, void data,
	struct drm_file *file_priv)
	{
	struct drm_gem_close *args = data;
	int ret;

	if (!(dev->driver->driver_features & DRIVER_GEM))
	return -ENODEV;

	ret = drm_gem_handle_delete(file_priv, args->handle);

	return ret;
	}

	/**
	* Create a global name for an object, returning the name.
	*
	* Note that the name does not hold a reference; when the object
	* is freed, the name goes away.
	*/
	int
	drm_gem_flink_ioctl(struct drm_device dev, void data,
	struct drm_file *file_priv)
	{
	struct drm_gem_flink *args = data;
	struct drm_gem_object *obj;
	int ret;

	if (!(dev->driver->driver_features & DRIVER_GEM))
	return -ENODEV;

	obj = drm_gem_object_lookup(dev, file_priv, args->handle);
	if (obj == NULL)
	return -EBADF;

	again:
	if (idr_pre_get(&dev->object_name_idr, GFP_KERNEL) == 0)
	return -ENOMEM;

	spin_lock(&dev->object_name_lock);
	if (obj->name) {
	args->name = obj->name;
	spin_unlock(&dev->object_name_lock);
	return 0;
	}
	ret = idr_get_new_above(&dev->object_name_idr, obj, 1,
	&obj->name);
	spin_unlock(&dev->object_name_lock);
	if (ret == -EAGAIN)
	goto again;

	if (ret != 0) {
	mutex_lock(&dev->struct_mutex);
	drm_gem_object_unreference(obj);
	mutex_unlock(&dev->struct_mutex);
	return ret;
	}

	/*
	* Leave the reference from the lookup around as the
	* name table now holds one
	*/
	args->name = (uint64_t) obj->name;

	return 0;
	}

	/**
	* Open an object using the global name, returning a handle and the size.
	*
	* This handle (of course) holds a reference to the object, so the object
	* will not go away until the handle is deleted.
	*/
	int
	drm_gem_open_ioctl(struct drm_device dev, void data,
	struct drm_file *file_priv)
	{
	struct drm_gem_open *args = data;
	struct drm_gem_object *obj;
	int ret;
	int handle;

	if (!(dev->driver->driver_features & DRIVER_GEM))
	return -ENODEV;

	spin_lock(&dev->object_name_lock);
	obj = idr_find(&dev->object_name_idr, (int) args->name);
	if (obj)
	drm_gem_object_reference(obj);
	spin_unlock(&dev->object_name_lock);
	if (!obj)
	return -ENOENT;

	ret = drm_gem_handle_create(file_priv, obj, &handle);
	mutex_lock(&dev->struct_mutex);
	drm_gem_object_unreference(obj);
	mutex_unlock(&dev->struct_mutex);
	if (ret)
	return ret;

	args->handle = handle;
	args->size = obj->size;

	return 0;
	}

	/**
	* Called at device open time, sets up the structure for handling refcounting
	* of mm objects.
	*/
	void
	drm_gem_open(struct drm_device dev, struct drm_file file_private)
	{
	idr_init(&file_private->object_idr);
	spin_lock_init(&file_private->table_lock);
	}

	/**
	* Called at device close to release the file's
	* handle references on objects.
	*/
	static int
	drm_gem_object_release_handle(int id, void ptr, void data)
	{
	struct drm_gem_object *obj = ptr;

	drm_gem_object_handle_unreference(obj);

	return 0;
	}

	/**
	* Called at close time when the filp is going away.
	*
	* Releases any remaining references on objects by this filp.
	*/
	void
	drm_gem_release(struct drm_device dev, struct drm_file file_private)
	{
	mutex_lock(&dev->struct_mutex);
	idr_for_each(&file_private->object_idr,
	&drm_gem_object_release_handle, NULL);

	idr_destroy(&file_private->object_idr);
	mutex_unlock(&dev->struct_mutex);
	}

	/**
	* Called after the last reference to the object has been lost.
	*
	* Frees the object
	*/
	void
	drm_gem_object_free(struct kref *kref)
	{
	struct drm_gem_object obj = (struct drm_gem_object ) kref;
	struct drm_device *dev = obj->dev;

	BUG_ON(!mutex_is_locked(&dev->struct_mutex));

	if (dev->driver->gem_free_object != NULL)
	dev->driver->gem_free_object(obj);

	fput(obj->filp);
	atomic_dec(&dev->object_count);
	atomic_sub(obj->size, &dev->object_memory);
	kfree(obj);
	}
	EXPORT_SYMBOL(drm_gem_object_free);

	/**
	* Called after the last handle to the object has been closed
	*
	* Removes any name for the object. Note that this must be
	* called before drm_gem_object_free or we'll be touching
	* freed memory
	*/
	void
	drm_gem_object_handle_free(struct kref *kref)
	{
	struct drm_gem_object *obj = container_of(kref,
	struct drm_gem_object,
	handlecount);
	struct drm_device *dev = obj->dev;

	/* Remove any name for this object */
	spin_lock(&dev->object_name_lock);
	if (obj->name) {
	idr_remove(&dev->object_name_idr, obj->name);
	spin_unlock(&dev->object_name_lock);
	/*
	* The object name held a reference to this object, drop
	* that now.
	*/
	drm_gem_object_unreference(obj);
	} else
	spin_unlock(&dev->object_name_lock);

	}
	EXPORT_SYMBOL(drm_gem_object_handle_free);

	/**
	* drm_gem_mmap - memory map routine for GEM objects
	* @filp: DRM file pointer
	* @vma: VMA for the area to be mapped
	*
	* If a driver supports GEM object mapping, mmap calls on the DRM file
	* descriptor will end up here.
	*
	* If we find the object based on the offset passed in (vma->vm_pgoff will
	* contain the fake offset we created when the GTT map ioctl was called on
	* the object), we set up the driver fault handler so that any accesses
	* to the object can be trapped, to perform migration, GTT binding, surface
	* register allocation, or performance monitoring.
	*/
	int drm_gem_mmap(struct file filp, struct vm_area_struct vma)
	{
	struct drm_file *priv = filp->private_data;
	struct drm_device *dev = priv->minor->dev;
	struct drm_gem_mm *mm = dev->mm_private;
	struct drm_map *map = NULL;
	struct drm_gem_object *obj;
	struct drm_hash_item *hash;
	unsigned long prot;
	int ret = 0;

	mutex_lock(&dev->struct_mutex);

	if (drm_ht_find_item(&mm->offset_hash, vma->vm_pgoff, &hash)) {
	mutex_unlock(&dev->struct_mutex);
	return drm_mmap(filp, vma);
	}

	map = drm_hash_entry(hash, struct drm_map_list, hash)->map;
	if (!map \|\|
	((map->flags & _DRM_RESTRICTED) && !capable(CAP_SYS_ADMIN))) {
	ret = -EPERM;
	goto out_unlock;
	}

	/* Check for valid size. */
	if (map->size < vma->vm_end - vma->vm_start) {
	ret = -EINVAL;
	goto out_unlock;
	}

	obj = map->handle;
	if (!obj->dev->driver->gem_vm_ops) {
	ret = -EINVAL;
	goto out_unlock;
	}

	vma->vm_flags \|= VM_RESERVED \| VM_IO \| VM_PFNMAP \| VM_DONTEXPAND;
	vma->vm_ops = obj->dev->driver->gem_vm_ops;
	vma->vm_private_data = map->handle;
	/* FIXME: use pgprot_writecombine when available */
	prot = pgprot_val(vma->vm_page_prot);
	#ifdef CONFIG_X86
	prot \|= _PAGE_CACHE_WC;
	#endif
	vma->vm_page_prot = __pgprot(prot);

	vma->vm_file = filp; /* Needed for drm_vm_open() */
	drm_vm_open_locked(vma);

	out_unlock:
	mutex_unlock(&dev->struct_mutex);

	return ret;
	}
	EXPORT_SYMBOL(drm_gem_mmap);