1/**************************************************************************
  2 *
  3 * Copyright (c) 2009 VMware, Inc., Palo Alto, CA., USA
  4 * All Rights Reserved.
  5 *
  6 * Permission is hereby granted, free of charge, to any person obtaining a
  7 * copy of this software and associated documentation files (the
  8 * "Software"), to deal in the Software without restriction, including
  9 * without limitation the rights to use, copy, modify, merge, publish,
 10 * distribute, sub license, and/or sell copies of the Software, and to
 11 * permit persons to whom the Software is furnished to do so, subject to
 12 * the following conditions:
 13 *
 14 * The above copyright notice and this permission notice (including the
 15 * next paragraph) shall be included in all copies or substantial portions
 16 * of the Software.
 17 *
 18 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 19 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 20 * FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT. IN NO EVENT SHALL
 21 * THE COPYRIGHT HOLDERS, AUTHORS AND/OR ITS SUPPLIERS BE LIABLE FOR ANY CLAIM,
 22 * DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
 23 * OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
 24 * USE OR OTHER DEALINGS IN THE SOFTWARE.
 25 *
 26 **************************************************************************/
 27/*
 28 * Authors: Thomas Hellstrom <thellstrom-at-vmware-dot-com>
 29 */
 30/** @file ttm_ref_object.c
 31 *
 32 * Base- and reference object implementation for the various
 33 * ttm objects. Implements reference counting, minimal security checks
 34 * and release on file close.
 35 */
 36
 37/**
 38 * struct ttm_object_file
 39 *
 40 * @tdev: Pointer to the ttm_object_device.
 41 *
 42 * @lock: Lock that protects the ref_list list and the
 43 * ref_hash hash tables.
 44 *
 45 * @ref_list: List of ttm_ref_objects to be destroyed at
 46 * file release.
 47 *
 48 * @ref_hash: Hash tables of ref objects, one per ttm_ref_type,
 49 * for fast lookup of ref objects given a base object.
 50 */
 51
 52#define pr_fmt(fmt) "[TTM] " fmt
 53
 54#include "ttm/ttm_object.h"
 55#include "ttm/ttm_module.h"
 56#include <linux/list.h>
 57#include <linux/spinlock.h>
 58#include <linux/slab.h>
 59#include <linux/module.h>
 60#include <linux/atomic.h>
 61
 62struct ttm_object_file {
 63	struct ttm_object_device *tdev;
 64	rwlock_t lock;
 65	struct list_head ref_list;
 66	struct drm_open_hash ref_hash[TTM_REF_NUM];
 67	struct kref refcount;
 68};
 69
 70/**
 71 * struct ttm_object_device
 72 *
 73 * @object_lock: lock that protects the object_hash hash table.
 74 *
 75 * @object_hash: hash table for fast lookup of object global names.
 76 *
 77 * @object_count: Per device object count.
 78 *
 79 * This is the per-device data structure needed for ttm object management.
 80 */
 81
 82struct ttm_object_device {
 83	rwlock_t object_lock;
 84	struct drm_open_hash object_hash;
 85	atomic_t object_count;
 86	struct ttm_mem_global *mem_glob;
 87};
 88
 89/**
 90 * struct ttm_ref_object
 91 *
 92 * @hash: Hash entry for the per-file object reference hash.
 93 *
 94 * @head: List entry for the per-file list of ref-objects.
 95 *
 96 * @kref: Ref count.
 97 *
 98 * @obj: Base object this ref object is referencing.
 99 *
100 * @ref_type: Type of ref object.
101 *
102 * This is similar to an idr object, but it also has a hash table entry
103 * that allows lookup with a pointer to the referenced object as a key. In
104 * that way, one can easily detect whether a base object is referenced by
105 * a particular ttm_object_file. It also carries a ref count to avoid creating
106 * multiple ref objects if a ttm_object_file references the same base
107 * object more than once.
108 */
109
110struct ttm_ref_object {
111	struct drm_hash_item hash;
112	struct list_head head;
113	struct kref kref;
114	enum ttm_ref_type ref_type;
115	struct ttm_base_object *obj;
116	struct ttm_object_file *tfile;
117};
118
119static inline struct ttm_object_file *
120ttm_object_file_ref(struct ttm_object_file *tfile)
121{
122	kref_get(&tfile->refcount);
123	return tfile;
124}
125
126static void ttm_object_file_destroy(struct kref *kref)
127{
128	struct ttm_object_file *tfile =
129		container_of(kref, struct ttm_object_file, refcount);
130
131	kfree(tfile);
132}
133
134
135static inline void ttm_object_file_unref(struct ttm_object_file **p_tfile)
136{
137	struct ttm_object_file *tfile = *p_tfile;
138
139	*p_tfile = NULL;
140	kref_put(&tfile->refcount, ttm_object_file_destroy);
141}
142
143
144int ttm_base_object_init(struct ttm_object_file *tfile,
145			 struct ttm_base_object *base,
146			 bool shareable,
147			 enum ttm_object_type object_type,
148			 void (*refcount_release) (struct ttm_base_object **),
149			 void (*ref_obj_release) (struct ttm_base_object *,
150						  enum ttm_ref_type ref_type))
151{
152	struct ttm_object_device *tdev = tfile->tdev;
153	int ret;
154
155	base->shareable = shareable;
156	base->tfile = ttm_object_file_ref(tfile);
157	base->refcount_release = refcount_release;
158	base->ref_obj_release = ref_obj_release;
159	base->object_type = object_type;
160	write_lock(&tdev->object_lock);
161	kref_init(&base->refcount);
162	ret = drm_ht_just_insert_please(&tdev->object_hash,
163					&base->hash,
164					(unsigned long)base, 31, 0, 0);
165	write_unlock(&tdev->object_lock);
166	if (unlikely(ret != 0))
167		goto out_err0;
168
169	ret = ttm_ref_object_add(tfile, base, TTM_REF_USAGE, NULL);
170	if (unlikely(ret != 0))
171		goto out_err1;
172
173	ttm_base_object_unref(&base);
174
175	return 0;
176out_err1:
177	(void)drm_ht_remove_item(&tdev->object_hash, &base->hash);
178out_err0:
179	return ret;
180}
181EXPORT_SYMBOL(ttm_base_object_init);
182
183static void ttm_release_base(struct kref *kref)
184{
185	struct ttm_base_object *base =
186	    container_of(kref, struct ttm_base_object, refcount);
187	struct ttm_object_device *tdev = base->tfile->tdev;
188
189	(void)drm_ht_remove_item(&tdev->object_hash, &base->hash);
190	write_unlock(&tdev->object_lock);
191	if (base->refcount_release) {
192		ttm_object_file_unref(&base->tfile);
193		base->refcount_release(&base);
194	}
195	write_lock(&tdev->object_lock);
196}
197
198void ttm_base_object_unref(struct ttm_base_object **p_base)
199{
200	struct ttm_base_object *base = *p_base;
201	struct ttm_object_device *tdev = base->tfile->tdev;
202
203	*p_base = NULL;
204
205	/*
206	 * Need to take the lock here to avoid racing with
207	 * users trying to look up the object.
208	 */
209
210	write_lock(&tdev->object_lock);
211	kref_put(&base->refcount, ttm_release_base);
212	write_unlock(&tdev->object_lock);
213}
214EXPORT_SYMBOL(ttm_base_object_unref);
215
216struct ttm_base_object *ttm_base_object_lookup(struct ttm_object_file *tfile,
217					       uint32_t key)
218{
219	struct ttm_object_device *tdev = tfile->tdev;
220	struct ttm_base_object *base;
221	struct drm_hash_item *hash;
222	int ret;
223
224	read_lock(&tdev->object_lock);
225	ret = drm_ht_find_item(&tdev->object_hash, key, &hash);
226
227	if (likely(ret == 0)) {
228		base = drm_hash_entry(hash, struct ttm_base_object, hash);
229		kref_get(&base->refcount);
230	}
231	read_unlock(&tdev->object_lock);
232
233	if (unlikely(ret != 0))
234		return NULL;
235
236	if (tfile != base->tfile && !base->shareable) {
237		pr_err("Attempted access of non-shareable object\n");
238		ttm_base_object_unref(&base);
239		return NULL;
240	}
241
242	return base;
243}
244EXPORT_SYMBOL(ttm_base_object_lookup);
245
246int ttm_ref_object_add(struct ttm_object_file *tfile,
247		       struct ttm_base_object *base,
248		       enum ttm_ref_type ref_type, bool *existed)
249{
250	struct drm_open_hash *ht = &tfile->ref_hash[ref_type];
251	struct ttm_ref_object *ref;
252	struct drm_hash_item *hash;
253	struct ttm_mem_global *mem_glob = tfile->tdev->mem_glob;
254	int ret = -EINVAL;
255
256	if (existed != NULL)
257		*existed = true;
258
259	while (ret == -EINVAL) {
260		read_lock(&tfile->lock);
261		ret = drm_ht_find_item(ht, base->hash.key, &hash);
262
263		if (ret == 0) {
264			ref = drm_hash_entry(hash, struct ttm_ref_object, hash);
265			kref_get(&ref->kref);
266			read_unlock(&tfile->lock);
267			break;
268		}
269
270		read_unlock(&tfile->lock);
271		ret = ttm_mem_global_alloc(mem_glob, sizeof(*ref),
272					   false, false);
273		if (unlikely(ret != 0))
274			return ret;
275		ref = kmalloc(sizeof(*ref), GFP_KERNEL);
276		if (unlikely(ref == NULL)) {
277			ttm_mem_global_free(mem_glob, sizeof(*ref));
278			return -ENOMEM;
279		}
280
281		ref->hash.key = base->hash.key;
282		ref->obj = base;
283		ref->tfile = tfile;
284		ref->ref_type = ref_type;
285		kref_init(&ref->kref);
286
287		write_lock(&tfile->lock);
288		ret = drm_ht_insert_item(ht, &ref->hash);
289
290		if (likely(ret == 0)) {
291			list_add_tail(&ref->head, &tfile->ref_list);
292			kref_get(&base->refcount);
293			write_unlock(&tfile->lock);
294			if (existed != NULL)
295				*existed = false;
296			break;
297		}
298
299		write_unlock(&tfile->lock);
300		BUG_ON(ret != -EINVAL);
301
302		ttm_mem_global_free(mem_glob, sizeof(*ref));
303		kfree(ref);
304	}
305
306	return ret;
307}
308EXPORT_SYMBOL(ttm_ref_object_add);
309
310static void ttm_ref_object_release(struct kref *kref)
311{
312	struct ttm_ref_object *ref =
313	    container_of(kref, struct ttm_ref_object, kref);
314	struct ttm_base_object *base = ref->obj;
315	struct ttm_object_file *tfile = ref->tfile;
316	struct drm_open_hash *ht;
317	struct ttm_mem_global *mem_glob = tfile->tdev->mem_glob;
318
319	ht = &tfile->ref_hash[ref->ref_type];
320	(void)drm_ht_remove_item(ht, &ref->hash);
321	list_del(&ref->head);
322	write_unlock(&tfile->lock);
323
324	if (ref->ref_type != TTM_REF_USAGE && base->ref_obj_release)
325		base->ref_obj_release(base, ref->ref_type);
326
327	ttm_base_object_unref(&ref->obj);
328	ttm_mem_global_free(mem_glob, sizeof(*ref));
329	kfree(ref);
330	write_lock(&tfile->lock);
331}
332
333int ttm_ref_object_base_unref(struct ttm_object_file *tfile,
334			      unsigned long key, enum ttm_ref_type ref_type)
335{
336	struct drm_open_hash *ht = &tfile->ref_hash[ref_type];
337	struct ttm_ref_object *ref;
338	struct drm_hash_item *hash;
339	int ret;
340
341	write_lock(&tfile->lock);
342	ret = drm_ht_find_item(ht, key, &hash);
343	if (unlikely(ret != 0)) {
344		write_unlock(&tfile->lock);
345		return -EINVAL;
346	}
347	ref = drm_hash_entry(hash, struct ttm_ref_object, hash);
348	kref_put(&ref->kref, ttm_ref_object_release);
349	write_unlock(&tfile->lock);
350	return 0;
351}
352EXPORT_SYMBOL(ttm_ref_object_base_unref);
353
354void ttm_object_file_release(struct ttm_object_file **p_tfile)
355{
356	struct ttm_ref_object *ref;
357	struct list_head *list;
358	unsigned int i;
359	struct ttm_object_file *tfile = *p_tfile;
360
361	*p_tfile = NULL;
362	write_lock(&tfile->lock);
363
364	/*
365	 * Since we release the lock within the loop, we have to
366	 * restart it from the beginning each time.
367	 */
368
369	while (!list_empty(&tfile->ref_list)) {
370		list = tfile->ref_list.next;
371		ref = list_entry(list, struct ttm_ref_object, head);
372		ttm_ref_object_release(&ref->kref);
373	}
374
375	for (i = 0; i < TTM_REF_NUM; ++i)
376		drm_ht_remove(&tfile->ref_hash[i]);
377
378	write_unlock(&tfile->lock);
379	ttm_object_file_unref(&tfile);
380}
381EXPORT_SYMBOL(ttm_object_file_release);
382
383struct ttm_object_file *ttm_object_file_init(struct ttm_object_device *tdev,
384					     unsigned int hash_order)
385{
386	struct ttm_object_file *tfile = kmalloc(sizeof(*tfile), GFP_KERNEL);
387	unsigned int i;
388	unsigned int j = 0;
389	int ret;
390
391	if (unlikely(tfile == NULL))
392		return NULL;
393
394	rwlock_init(&tfile->lock);
395	tfile->tdev = tdev;
396	kref_init(&tfile->refcount);
397	INIT_LIST_HEAD(&tfile->ref_list);
398
399	for (i = 0; i < TTM_REF_NUM; ++i) {
400		ret = drm_ht_create(&tfile->ref_hash[i], hash_order);
401		if (ret) {
402			j = i;
403			goto out_err;
404		}
405	}
406
407	return tfile;
408out_err:
409	for (i = 0; i < j; ++i)
410		drm_ht_remove(&tfile->ref_hash[i]);
411
412	kfree(tfile);
413
414	return NULL;
415}
416EXPORT_SYMBOL(ttm_object_file_init);
417
418struct ttm_object_device *ttm_object_device_init(struct ttm_mem_global
419						 *mem_glob,
420						 unsigned int hash_order)
421{
422	struct ttm_object_device *tdev = kmalloc(sizeof(*tdev), GFP_KERNEL);
423	int ret;
424
425	if (unlikely(tdev == NULL))
426		return NULL;
427
428	tdev->mem_glob = mem_glob;
429	rwlock_init(&tdev->object_lock);
430	atomic_set(&tdev->object_count, 0);
431	ret = drm_ht_create(&tdev->object_hash, hash_order);
432
433	if (likely(ret == 0))
434		return tdev;
435
436	kfree(tdev);
437	return NULL;
438}
439EXPORT_SYMBOL(ttm_object_device_init);
440
441void ttm_object_device_release(struct ttm_object_device **p_tdev)
442{
443	struct ttm_object_device *tdev = *p_tdev;
444
445	*p_tdev = NULL;
446
447	write_lock(&tdev->object_lock);
448	drm_ht_remove(&tdev->object_hash);
449	write_unlock(&tdev->object_lock);
450
451	kfree(tdev);
452}
453EXPORT_SYMBOL(ttm_object_device_release);