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/**************************************************************************

 *

 * Copyright (c) 2009-2013 VMware, Inc., Palo Alto, CA., USA

 * 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, sub license, 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 NON-INFRINGEMENT. IN NO EVENT SHALL

 * THE COPYRIGHT HOLDERS, AUTHORS 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.

 *

 **************************************************************************/

/*

 * Authors: Thomas Hellstrom 

 *

 * While no substantial code is shared, the prime code is inspired by

 * drm_prime.c, with

 * Authors:

 *      Dave Airlie 

 *      Rob Clark 

 */

/** @file ttm_ref_object.c

 *

 * Base- and reference object implementation for the various

 * ttm objects. Implements reference counting, minimal security checks

 * and release on file close.

 */

/**

 * struct ttm_object_file

 *

 * @tdev: Pointer to the ttm_object_device.

 *

 * @lock: Lock that protects the ref_list list and the

 * ref_hash hash tables.

 *

 * @ref_list: List of ttm_ref_objects to be destroyed at

 * file release.

 *

 * @ref_hash: Hash tables of ref objects, one per ttm_ref_type,

 * for fast lookup of ref objects given a base object.

 */

#define pr_fmt(fmt) "[TTM] " fmt

#include 

#include 

#include 

#include 

#include 

#include 

#include 

struct ttm_object_file {

	struct ttm_object_device *tdev;

	spinlock_t lock;

	struct list_head ref_list;

	struct drm_open_hash ref_hash[TTM_REF_NUM];

	struct kref refcount;

};

/**

 * struct ttm_object_device

 *

 * @object_lock: lock that protects the object_hash hash table.

 *

 * @object_hash: hash table for fast lookup of object global names.

 *

 * @object_count: Per device object count.

 *

 * This is the per-device data structure needed for ttm object management.

 */

struct ttm_object_device {

	spinlock_t object_lock;

	struct drm_open_hash object_hash;

	atomic_t object_count;

	struct ttm_mem_global *mem_glob;

	struct dma_buf_ops ops;

	void (*dmabuf_release)(struct dma_buf *dma_buf);

	size_t dma_buf_size;

};

/**

 * struct ttm_ref_object

 *

 * @hash: Hash entry for the per-file object reference hash.

 *

 * @head: List entry for the per-file list of ref-objects.

 *

 * @kref: Ref count.

 *

 * @obj: Base object this ref object is referencing.

 *

 * @ref_type: Type of ref object.

 *

 * This is similar to an idr object, but it also has a hash table entry

 * that allows lookup with a pointer to the referenced object as a key. In

 * that way, one can easily detect whether a base object is referenced by

 * a particular ttm_object_file. It also carries a ref count to avoid creating

 * multiple ref objects if a ttm_object_file references the same base

 * object more than once.

 */

struct ttm_ref_object {

	struct rcu_head rcu_head;

	struct drm_hash_item hash;

	struct list_head head;

	struct kref kref;

	enum ttm_ref_type ref_type;

	struct ttm_base_object *obj;

	struct ttm_object_file *tfile;

};

static void ttm_prime_dmabuf_release(struct dma_buf *dma_buf);

static inline struct ttm_object_file *

ttm_object_file_ref(struct ttm_object_file *tfile)

{

	kref_get(&tfile->refcount);

	return tfile;

}

static void ttm_object_file_destroy(struct kref *kref)

{

	struct ttm_object_file *tfile =

		container_of(kref, struct ttm_object_file, refcount);

	kfree(tfile);

}

static inline void ttm_object_file_unref(struct ttm_object_file **p_tfile)

{

	struct ttm_object_file *tfile = *p_tfile;

	*p_tfile = NULL;

	kref_put(&tfile->refcount, ttm_object_file_destroy);

}

int ttm_base_object_init(struct ttm_object_file *tfile,

			 struct ttm_base_object *base,

			 bool shareable,

			 enum ttm_object_type object_type,

			 void (*refcount_release) (struct ttm_base_object **),

			 void (*ref_obj_release) (struct ttm_base_object *,

						  enum ttm_ref_type ref_type))

{

	struct ttm_object_device *tdev = tfile->tdev;

	int ret;

	base->shareable = shareable;

	base->tfile = ttm_object_file_ref(tfile);

	base->refcount_release = refcount_release;

	base->ref_obj_release = ref_obj_release;

	base->object_type = object_type;

	kref_init(&base->refcount);

	spin_lock(&tdev->object_lock);

	ret = drm_ht_just_insert_please_rcu(&tdev->object_hash,

					    &base->hash,

					    (unsigned long)base, 31, 0, 0);

	spin_unlock(&tdev->object_lock);

	if (unlikely(ret != 0))

		goto out_err0;

	ret = ttm_ref_object_add(tfile, base, TTM_REF_USAGE, NULL);

	if (unlikely(ret != 0))

		goto out_err1;

	ttm_base_object_unref(&base);

	return 0;

out_err1:

	spin_lock(&tdev->object_lock);

	(void)drm_ht_remove_item_rcu(&tdev->object_hash, &base->hash);

	spin_unlock(&tdev->object_lock);

out_err0:

	return ret;

}

EXPORT_SYMBOL(ttm_base_object_init);

static void ttm_release_base(struct kref *kref)

{

	struct ttm_base_object *base =

	    container_of(kref, struct ttm_base_object, refcount);

	struct ttm_object_device *tdev = base->tfile->tdev;

	spin_lock(&tdev->object_lock);

	(void)drm_ht_remove_item_rcu(&tdev->object_hash, &base->hash);

	spin_unlock(&tdev->object_lock);

	/*

	 * Note: We don't use synchronize_rcu() here because it's far

	 * too slow. It's up to the user to free the object using

	 * call_rcu() or ttm_base_object_kfree().

	 */

	ttm_object_file_unref(&base->tfile);

	if (base->refcount_release)

		base->refcount_release(&base);

}

void ttm_base_object_unref(struct ttm_base_object **p_base)

{

	struct ttm_base_object *base = *p_base;

	*p_base = NULL;

	kref_put(&base->refcount, ttm_release_base);

}

EXPORT_SYMBOL(ttm_base_object_unref);

struct ttm_base_object *ttm_base_object_lookup(struct ttm_object_file *tfile,

					       uint32_t key)

{

	struct ttm_base_object *base = NULL;

	struct drm_hash_item *hash;

	struct drm_open_hash *ht = &tfile->ref_hash[TTM_REF_USAGE];

	int ret;

	rcu_read_lock();

	ret = drm_ht_find_item_rcu(ht, key, &hash);

	if (likely(ret == 0)) {

		base = drm_hash_entry(hash, struct ttm_ref_object, hash)->obj;

		if (!kref_get_unless_zero(&base->refcount))

			base = NULL;

	}

	rcu_read_unlock();

	return base;

}

EXPORT_SYMBOL(ttm_base_object_lookup);

struct ttm_base_object *

ttm_base_object_lookup_for_ref(struct ttm_object_device *tdev, uint32_t key)

{

	struct ttm_base_object *base = NULL;

	struct drm_hash_item *hash;

	struct drm_open_hash *ht = &tdev->object_hash;

	int ret;

	rcu_read_lock();

	ret = drm_ht_find_item_rcu(ht, key, &hash);

	if (likely(ret == 0)) {

		base = drm_hash_entry(hash, struct ttm_base_object, hash);

		if (!kref_get_unless_zero(&base->refcount))

			base = NULL;

	}

	rcu_read_unlock();

	return base;

}

EXPORT_SYMBOL(ttm_base_object_lookup_for_ref);

int ttm_ref_object_add(struct ttm_object_file *tfile,

		       struct ttm_base_object *base,

		       enum ttm_ref_type ref_type, bool *existed)

{

	struct drm_open_hash *ht = &tfile->ref_hash[ref_type];

	struct ttm_ref_object *ref;

	struct drm_hash_item *hash;

	struct ttm_mem_global *mem_glob = tfile->tdev->mem_glob;

	int ret = -EINVAL;

	if (existed != NULL)

		*existed = true;

	while (ret == -EINVAL) {

		rcu_read_lock();

		ret = drm_ht_find_item_rcu(ht, base->hash.key, &hash);

		if (ret == 0) {

			ref = drm_hash_entry(hash, struct ttm_ref_object, hash);

			if (kref_get_unless_zero(&ref->kref)) {

				rcu_read_unlock();

				break;

			}

		}

		rcu_read_unlock();

		ret = ttm_mem_global_alloc(mem_glob, sizeof(*ref),

					   false, false);

		if (unlikely(ret != 0))

			return ret;

		ref = kmalloc(sizeof(*ref), GFP_KERNEL);

		if (unlikely(ref == NULL)) {

			ttm_mem_global_free(mem_glob, sizeof(*ref));

			return -ENOMEM;

		}

		ref->hash.key = base->hash.key;

		ref->obj = base;

		ref->tfile = tfile;

		ref->ref_type = ref_type;

		kref_init(&ref->kref);

		spin_lock(&tfile->lock);

		ret = drm_ht_insert_item_rcu(ht, &ref->hash);

		if (likely(ret == 0)) {

			list_add_tail(&ref->head, &tfile->ref_list);

			kref_get(&base->refcount);

			spin_unlock(&tfile->lock);

			if (existed != NULL)

				*existed = false;

			break;

		}

		spin_unlock(&tfile->lock);

		BUG_ON(ret != -EINVAL);

		ttm_mem_global_free(mem_glob, sizeof(*ref));

		kfree(ref);

	}

	return ret;

}

EXPORT_SYMBOL(ttm_ref_object_add);

static void ttm_ref_object_release(struct kref *kref)

{

	struct ttm_ref_object *ref =

	    container_of(kref, struct ttm_ref_object, kref);

	struct ttm_base_object *base = ref->obj;

	struct ttm_object_file *tfile = ref->tfile;

	struct drm_open_hash *ht;

	struct ttm_mem_global *mem_glob = tfile->tdev->mem_glob;

	ht = &tfile->ref_hash[ref->ref_type];

	(void)drm_ht_remove_item_rcu(ht, &ref->hash);

	list_del(&ref->head);

	spin_unlock(&tfile->lock);

	if (ref->ref_type != TTM_REF_USAGE && base->ref_obj_release)

		base->ref_obj_release(base, ref->ref_type);

	ttm_base_object_unref(&ref->obj);

	ttm_mem_global_free(mem_glob, sizeof(*ref));

	kfree_rcu(ref, rcu_head);

	spin_lock(&tfile->lock);

}

int ttm_ref_object_base_unref(struct ttm_object_file *tfile,

			      unsigned long key, enum ttm_ref_type ref_type)

{

	struct drm_open_hash *ht = &tfile->ref_hash[ref_type];

	struct ttm_ref_object *ref;

	struct drm_hash_item *hash;

	int ret;

	spin_lock(&tfile->lock);

	ret = drm_ht_find_item(ht, key, &hash);

	if (unlikely(ret != 0)) {

		spin_unlock(&tfile->lock);

		return -EINVAL;

	}

	ref = drm_hash_entry(hash, struct ttm_ref_object, hash);

	kref_put(&ref->kref, ttm_ref_object_release);

	spin_unlock(&tfile->lock);

	return 0;

}

EXPORT_SYMBOL(ttm_ref_object_base_unref);

void ttm_object_file_release(struct ttm_object_file **p_tfile)

{

	struct ttm_ref_object *ref;

	struct list_head *list;

	unsigned int i;

	struct ttm_object_file *tfile = *p_tfile;

	*p_tfile = NULL;

	spin_lock(&tfile->lock);

	/*

	 * Since we release the lock within the loop, we have to

	 * restart it from the beginning each time.

	 */

	while (!list_empty(&tfile->ref_list)) {

		list = tfile->ref_list.next;

		ref = list_entry(list, struct ttm_ref_object, head);

		ttm_ref_object_release(&ref->kref);

	}

	for (i = 0; i < TTM_REF_NUM; ++i)

		drm_ht_remove(&tfile->ref_hash[i]);

	spin_unlock(&tfile->lock);

	ttm_object_file_unref(&tfile);

}

EXPORT_SYMBOL(ttm_object_file_release);

struct ttm_object_file *ttm_object_file_init(struct ttm_object_device *tdev,

					     unsigned int hash_order)

{

	struct ttm_object_file *tfile = kmalloc(sizeof(*tfile), GFP_KERNEL);

	unsigned int i;

	unsigned int j = 0;

	int ret;

	if (unlikely(tfile == NULL))

		return NULL;

	spin_lock_init(&tfile->lock);

	tfile->tdev = tdev;

	kref_init(&tfile->refcount);

	INIT_LIST_HEAD(&tfile->ref_list);

	for (i = 0; i < TTM_REF_NUM; ++i) {

		ret = drm_ht_create(&tfile->ref_hash[i], hash_order);

		if (ret) {

			j = i;

			goto out_err;

		}

	}

	return tfile;

out_err:

	for (i = 0; i < j; ++i)

		drm_ht_remove(&tfile->ref_hash[i]);

	kfree(tfile);

	return NULL;

}

EXPORT_SYMBOL(ttm_object_file_init);

struct ttm_object_device *

ttm_object_device_init(struct ttm_mem_global *mem_glob,

		       unsigned int hash_order,

		       const struct dma_buf_ops *ops)

{

	struct ttm_object_device *tdev = kmalloc(sizeof(*tdev), GFP_KERNEL);

	int ret;

	if (unlikely(tdev == NULL))

		return NULL;

	tdev->mem_glob = mem_glob;

	spin_lock_init(&tdev->object_lock);

	atomic_set(&tdev->object_count, 0);

	ret = drm_ht_create(&tdev->object_hash, hash_order);

	if (ret != 0)

		goto out_no_object_hash;

	tdev->ops = *ops;

	tdev->dmabuf_release = tdev->ops.release;

	tdev->ops.release = ttm_prime_dmabuf_release;

	tdev->dma_buf_size = ttm_round_pot(sizeof(struct dma_buf)) +

		ttm_round_pot(sizeof(struct file));

	return tdev;

out_no_object_hash:

	kfree(tdev);

	return NULL;

}

EXPORT_SYMBOL(ttm_object_device_init);

void ttm_object_device_release(struct ttm_object_device **p_tdev)

{

	struct ttm_object_device *tdev = *p_tdev;

	*p_tdev = NULL;

	spin_lock(&tdev->object_lock);

	drm_ht_remove(&tdev->object_hash);

	spin_unlock(&tdev->object_lock);

	kfree(tdev);

}

EXPORT_SYMBOL(ttm_object_device_release);

/**

 * get_dma_buf_unless_doomed - get a dma_buf reference if possible.

 *

 * @dma_buf: Non-refcounted pointer to a struct dma-buf.

 *

 * Obtain a file reference from a lookup structure that doesn't refcount

 * the file, but synchronizes with its release method to make sure it has

 * not been freed yet. See for example kref_get_unless_zero documentation.

 * Returns true if refcounting succeeds, false otherwise.

 *

 * Nobody really wants this as a public API yet, so let it mature here

 * for some time...

 */

static bool __must_check get_dma_buf_unless_doomed(struct dma_buf *dmabuf)

{

	return atomic_long_inc_not_zero(&dmabuf->file->f_count) != 0L;

}

/**

 * ttm_prime_refcount_release - refcount release method for a prime object.

 *

 * @p_base: Pointer to ttm_base_object pointer.

 *

 * This is a wrapper that calls the refcount_release founction of the

 * underlying object. At the same time it cleans up the prime object.

 * This function is called when all references to the base object we

 * derive from are gone.

 */

static void ttm_prime_refcount_release(struct ttm_base_object **p_base)

{

	struct ttm_base_object *base = *p_base;

	struct ttm_prime_object *prime;

	*p_base = NULL;

	prime = container_of(base, struct ttm_prime_object, base);

	BUG_ON(prime->dma_buf != NULL);

	mutex_destroy(&prime->mutex);

	if (prime->refcount_release)

		prime->refcount_release(&base);

}

/**

 * ttm_prime_dmabuf_release - Release method for the dma-bufs we export

 *

 * @dma_buf:

 *

 * This function first calls the dma_buf release method the driver

 * provides. Then it cleans up our dma_buf pointer used for lookup,

 * and finally releases the reference the dma_buf has on our base

 * object.

 */

static void ttm_prime_dmabuf_release(struct dma_buf *dma_buf)

{

	struct ttm_prime_object *prime =

		(struct ttm_prime_object *) dma_buf->priv;

	struct ttm_base_object *base = &prime->base;

	struct ttm_object_device *tdev = base->tfile->tdev;

	if (tdev->dmabuf_release)

		tdev->dmabuf_release(dma_buf);

	mutex_lock(&prime->mutex);

	if (prime->dma_buf == dma_buf)

		prime->dma_buf = NULL;

	mutex_unlock(&prime->mutex);

	ttm_mem_global_free(tdev->mem_glob, tdev->dma_buf_size);

	ttm_base_object_unref(&base);

}

/**

 * ttm_prime_fd_to_handle - Get a base object handle from a prime fd

 *

 * @tfile: A struct ttm_object_file identifying the caller.

 * @fd: The prime / dmabuf fd.

 * @handle: The returned handle.

 *

 * This function returns a handle to an object that previously exported

 * a dma-buf. Note that we don't handle imports yet, because we simply

 * have no consumers of that implementation.

 */

int ttm_prime_fd_to_handle(struct ttm_object_file *tfile,

			   int fd, u32 *handle)

{

	struct ttm_object_device *tdev = tfile->tdev;

	struct dma_buf *dma_buf;

	struct ttm_prime_object *prime;

	struct ttm_base_object *base;

	int ret;

	dma_buf = dma_buf_get(fd);

	if (IS_ERR(dma_buf))

		return PTR_ERR(dma_buf);

	if (dma_buf->ops != &tdev->ops)

		return -ENOSYS;

	prime = (struct ttm_prime_object *) dma_buf->priv;

	base = &prime->base;

	*handle = base->hash.key;

	ret = ttm_ref_object_add(tfile, base, TTM_REF_USAGE, NULL);

	dma_buf_put(dma_buf);

	return ret;

}

EXPORT_SYMBOL_GPL(ttm_prime_fd_to_handle);

/**

 * ttm_prime_handle_to_fd - Return a dma_buf fd from a ttm prime object

 *

 * @tfile: Struct ttm_object_file identifying the caller.

 * @handle: Handle to the object we're exporting from.

 * @flags: flags for dma-buf creation. We just pass them on.

 * @prime_fd: The returned file descriptor.

 *

 */

int ttm_prime_handle_to_fd(struct ttm_object_file *tfile,

			   uint32_t handle, uint32_t flags,

			   int *prime_fd)

{

	struct ttm_object_device *tdev = tfile->tdev;

	struct ttm_base_object *base;

	struct dma_buf *dma_buf;

	struct ttm_prime_object *prime;

	int ret;

	base = ttm_base_object_lookup(tfile, handle);

	if (unlikely(base == NULL ||

		     base->object_type != ttm_prime_type)) {

		ret = -ENOENT;

		goto out_unref;

	}

	prime = container_of(base, struct ttm_prime_object, base);

	if (unlikely(!base->shareable)) {

		ret = -EPERM;

		goto out_unref;

	}

	ret = mutex_lock_interruptible(&prime->mutex);

	if (unlikely(ret != 0)) {

		ret = -ERESTARTSYS;

		goto out_unref;

	}

	dma_buf = prime->dma_buf;

	if (!dma_buf || !get_dma_buf_unless_doomed(dma_buf)) {

		DEFINE_DMA_BUF_EXPORT_INFO(exp_info);

		exp_info.ops = &tdev->ops;

		exp_info.size = prime->size;

		exp_info.flags = flags;

		exp_info.priv = prime;

		/*

		 * Need to create a new dma_buf, with memory accounting.

		 */

		ret = ttm_mem_global_alloc(tdev->mem_glob, tdev->dma_buf_size,

					   false, true);

		if (unlikely(ret != 0)) {

			mutex_unlock(&prime->mutex);

			goto out_unref;

		}

		dma_buf = dma_buf_export(&exp_info);

		if (IS_ERR(dma_buf)) {

			ret = PTR_ERR(dma_buf);

			ttm_mem_global_free(tdev->mem_glob,

					    tdev->dma_buf_size);

			mutex_unlock(&prime->mutex);

			goto out_unref;

		}

		/*

		 * dma_buf has taken the base object reference

		 */

		base = NULL;

		prime->dma_buf = dma_buf;

	}

	mutex_unlock(&prime->mutex);

	ret = dma_buf_fd(dma_buf, flags);

	if (ret >= 0) {

		*prime_fd = ret;

		ret = 0;

	} else

		dma_buf_put(dma_buf);

out_unref:

	if (base)

		ttm_base_object_unref(&base);

	return ret;

}

EXPORT_SYMBOL_GPL(ttm_prime_handle_to_fd);

/**

 * ttm_prime_object_init - Initialize a ttm_prime_object

 *

 * @tfile: struct ttm_object_file identifying the caller

 * @size: The size of the dma_bufs we export.

 * @prime: The object to be initialized.

 * @shareable: See ttm_base_object_init

 * @type: See ttm_base_object_init

 * @refcount_release: See ttm_base_object_init

 * @ref_obj_release: See ttm_base_object_init

 *

 * Initializes an object which is compatible with the drm_prime model

 * for data sharing between processes and devices.

 */

int ttm_prime_object_init(struct ttm_object_file *tfile, size_t size,

			  struct ttm_prime_object *prime, bool shareable,

			  enum ttm_object_type type,

			  void (*refcount_release) (struct ttm_base_object **),

			  void (*ref_obj_release) (struct ttm_base_object *,

						   enum ttm_ref_type ref_type))

{

	mutex_init(&prime->mutex);

	prime->size = PAGE_ALIGN(size);

	prime->real_type = type;

	prime->dma_buf = NULL;

	prime->refcount_release = refcount_release;

	return ttm_base_object_init(tfile, &prime->base, shareable,

				    ttm_prime_type,

				    ttm_prime_refcount_release,

				    ref_obj_release);

}

EXPORT_SYMBOL(ttm_prime_object_init);