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

 *

 * Copyright (c) 2009 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 

 */

/** @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 

static inline int __must_check kref_get_unless_zero(struct kref *kref)

{

    return atomic_add_unless(&kref->refcount, 1, 0);

}

#define pr_err(fmt, ...) \

        printk(KERN_ERR pr_fmt(fmt), ##__VA_ARGS__)

struct ttm_object_file {

	struct ttm_object_device *tdev;

	rwlock_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 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 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 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().

	 */

	if (base->refcount_release) {

		ttm_object_file_unref(&base->tfile);

		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_object_device *tdev = tfile->tdev;

	struct ttm_base_object *base;

	struct drm_hash_item *hash;

	int ret;

//   rcu_read_lock();

	ret = drm_ht_find_item_rcu(&tdev->object_hash, key, &hash);

	if (likely(ret == 0)) {

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

		ret = kref_get_unless_zero(&base->refcount) ? 0 : -EINVAL;

	}

//   rcu_read_unlock();

	if (unlikely(ret != 0))

		return NULL;

	if (tfile != base->tfile && !base->shareable) {

		pr_err("Attempted access of non-shareable object\n");

		ttm_base_object_unref(&base);

		return NULL;

	}

	return base;

}

EXPORT_SYMBOL(ttm_base_object_lookup);

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) {

		read_lock(&tfile->lock);

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

		if (ret == 0) {

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

			kref_get(&ref->kref);

			read_unlock(&tfile->lock);

			break;

		}

		read_unlock(&tfile->lock);

		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);

		write_lock(&tfile->lock);

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

		if (likely(ret == 0)) {

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

			kref_get(&base->refcount);

			write_unlock(&tfile->lock);

			if (existed != NULL)

				*existed = false;

			break;

		}

		write_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(ht, &ref->hash);

	list_del(&ref->head);

	write_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(ref);

	write_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;

	write_lock(&tfile->lock);

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

	if (unlikely(ret != 0)) {

		write_unlock(&tfile->lock);

		return -EINVAL;

	}

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

	kref_put(&ref->kref, ttm_ref_object_release);

	write_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;

	write_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]);

	write_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;

	rwlock_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)

{

	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 (likely(ret == 0))

		return tdev;

	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);