1/**************************************************************************
2 *
3 * Copyright (c) 2007-2009 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
31#include <drm/ttm/ttm_lock.h>
32#include <drm/ttm/ttm_module.h>
33#include <linux/atomic.h>
34#include <linux/errno.h>
35#include <linux/wait.h>
36#include <linux/sched.h>
37#include <linux/module.h>
38
39#define TTM_WRITE_LOCK_PENDING    (1 << 0)
40#define TTM_VT_LOCK_PENDING       (1 << 1)
41#define TTM_SUSPEND_LOCK_PENDING  (1 << 2)
42#define TTM_VT_LOCK               (1 << 3)
43#define TTM_SUSPEND_LOCK          (1 << 4)
44
45void ttm_lock_init(struct ttm_lock *lock)
46{
47	spin_lock_init(&lock->lock);
48	init_waitqueue_head(&lock->queue);
49	lock->rw = 0;
50	lock->flags = 0;
51	lock->kill_takers = false;
52	lock->signal = SIGKILL;
53}
54EXPORT_SYMBOL(ttm_lock_init);
55
56void ttm_read_unlock(struct ttm_lock *lock)
57{
58	spin_lock(&lock->lock);
59	if (--lock->rw == 0)
60		wake_up_all(&lock->queue);
61	spin_unlock(&lock->lock);
62}
63EXPORT_SYMBOL(ttm_read_unlock);
64
65static bool __ttm_read_lock(struct ttm_lock *lock)
66{
67	bool locked = false;
68
69	spin_lock(&lock->lock);
70	if (unlikely(lock->kill_takers)) {
71		send_sig(lock->signal, current, 0);
72		spin_unlock(&lock->lock);
73		return false;
74	}
75	if (lock->rw >= 0 && lock->flags == 0) {
76		++lock->rw;
77		locked = true;
78	}
79	spin_unlock(&lock->lock);
80	return locked;
81}
82
83int ttm_read_lock(struct ttm_lock *lock, bool interruptible)
84{
85	int ret = 0;
86
87	if (interruptible)
88		ret = wait_event_interruptible(lock->queue,
89					       __ttm_read_lock(lock));
90	else
91		wait_event(lock->queue, __ttm_read_lock(lock));
92	return ret;
93}
94EXPORT_SYMBOL(ttm_read_lock);
95
96static bool __ttm_read_trylock(struct ttm_lock *lock, bool *locked)
97{
98	bool block = true;
99
100	*locked = false;
101
102	spin_lock(&lock->lock);
103	if (unlikely(lock->kill_takers)) {
104		send_sig(lock->signal, current, 0);
105		spin_unlock(&lock->lock);
106		return false;
107	}
108	if (lock->rw >= 0 && lock->flags == 0) {
109		++lock->rw;
110		block = false;
111		*locked = true;
112	} else if (lock->flags == 0) {
113		block = false;
114	}
115	spin_unlock(&lock->lock);
116
117	return !block;
118}
119
120int ttm_read_trylock(struct ttm_lock *lock, bool interruptible)
121{
122	int ret = 0;
123	bool locked;
124
125	if (interruptible)
126		ret = wait_event_interruptible
127			(lock->queue, __ttm_read_trylock(lock, &locked));
128	else
129		wait_event(lock->queue, __ttm_read_trylock(lock, &locked));
130
131	if (unlikely(ret != 0)) {
132		BUG_ON(locked);
133		return ret;
134	}
135
136	return (locked) ? 0 : -EBUSY;
137}
138
139void ttm_write_unlock(struct ttm_lock *lock)
140{
141	spin_lock(&lock->lock);
142	lock->rw = 0;
143	wake_up_all(&lock->queue);
144	spin_unlock(&lock->lock);
145}
146EXPORT_SYMBOL(ttm_write_unlock);
147
148static bool __ttm_write_lock(struct ttm_lock *lock)
149{
150	bool locked = false;
151
152	spin_lock(&lock->lock);
153	if (unlikely(lock->kill_takers)) {
154		send_sig(lock->signal, current, 0);
155		spin_unlock(&lock->lock);
156		return false;
157	}
158	if (lock->rw == 0 && ((lock->flags & ~TTM_WRITE_LOCK_PENDING) == 0)) {
159		lock->rw = -1;
160		lock->flags &= ~TTM_WRITE_LOCK_PENDING;
161		locked = true;
162	} else {
163		lock->flags |= TTM_WRITE_LOCK_PENDING;
164	}
165	spin_unlock(&lock->lock);
166	return locked;
167}
168
169int ttm_write_lock(struct ttm_lock *lock, bool interruptible)
170{
171	int ret = 0;
172
173	if (interruptible) {
174		ret = wait_event_interruptible(lock->queue,
175					       __ttm_write_lock(lock));
176		if (unlikely(ret != 0)) {
177			spin_lock(&lock->lock);
178			lock->flags &= ~TTM_WRITE_LOCK_PENDING;
179			wake_up_all(&lock->queue);
180			spin_unlock(&lock->lock);
181		}
182	} else
183		wait_event(lock->queue, __ttm_read_lock(lock));
184
185	return ret;
186}
187EXPORT_SYMBOL(ttm_write_lock);
188
189static int __ttm_vt_unlock(struct ttm_lock *lock)
190{
191	int ret = 0;
192
193	spin_lock(&lock->lock);
194	if (unlikely(!(lock->flags & TTM_VT_LOCK)))
195		ret = -EINVAL;
196	lock->flags &= ~TTM_VT_LOCK;
197	wake_up_all(&lock->queue);
198	spin_unlock(&lock->lock);
199
200	return ret;
201}
202
203static void ttm_vt_lock_remove(struct ttm_base_object **p_base)
204{
205	struct ttm_base_object *base = *p_base;
206	struct ttm_lock *lock = container_of(base, struct ttm_lock, base);
207	int ret;
208
209	*p_base = NULL;
210	ret = __ttm_vt_unlock(lock);
211	BUG_ON(ret != 0);
212}
213
214static bool __ttm_vt_lock(struct ttm_lock *lock)
215{
216	bool locked = false;
217
218	spin_lock(&lock->lock);
219	if (lock->rw == 0) {
220		lock->flags &= ~TTM_VT_LOCK_PENDING;
221		lock->flags |= TTM_VT_LOCK;
222		locked = true;
223	} else {
224		lock->flags |= TTM_VT_LOCK_PENDING;
225	}
226	spin_unlock(&lock->lock);
227	return locked;
228}
229
230int ttm_vt_lock(struct ttm_lock *lock,
231		bool interruptible,
232		struct ttm_object_file *tfile)
233{
234	int ret = 0;
235
236	if (interruptible) {
237		ret = wait_event_interruptible(lock->queue,
238					       __ttm_vt_lock(lock));
239		if (unlikely(ret != 0)) {
240			spin_lock(&lock->lock);
241			lock->flags &= ~TTM_VT_LOCK_PENDING;
242			wake_up_all(&lock->queue);
243			spin_unlock(&lock->lock);
244			return ret;
245		}
246	} else
247		wait_event(lock->queue, __ttm_vt_lock(lock));
248
249	/*
250	 * Add a base-object, the destructor of which will
251	 * make sure the lock is released if the client dies
252	 * while holding it.
253	 */
254
255	ret = ttm_base_object_init(tfile, &lock->base, false,
256				   ttm_lock_type, &ttm_vt_lock_remove, NULL);
257	if (ret)
258		(void)__ttm_vt_unlock(lock);
259	else
260		lock->vt_holder = tfile;
261
262	return ret;
263}
264EXPORT_SYMBOL(ttm_vt_lock);
265
266int ttm_vt_unlock(struct ttm_lock *lock)
267{
268	return ttm_ref_object_base_unref(lock->vt_holder,
269					 lock->base.hash.key, TTM_REF_USAGE);
270}
271EXPORT_SYMBOL(ttm_vt_unlock);
272
273void ttm_suspend_unlock(struct ttm_lock *lock)
274{
275	spin_lock(&lock->lock);
276	lock->flags &= ~TTM_SUSPEND_LOCK;
277	wake_up_all(&lock->queue);
278	spin_unlock(&lock->lock);
279}
280EXPORT_SYMBOL(ttm_suspend_unlock);
281
282static bool __ttm_suspend_lock(struct ttm_lock *lock)
283{
284	bool locked = false;
285
286	spin_lock(&lock->lock);
287	if (lock->rw == 0) {
288		lock->flags &= ~TTM_SUSPEND_LOCK_PENDING;
289		lock->flags |= TTM_SUSPEND_LOCK;
290		locked = true;
291	} else {
292		lock->flags |= TTM_SUSPEND_LOCK_PENDING;
293	}
294	spin_unlock(&lock->lock);
295	return locked;
296}
297
298void ttm_suspend_lock(struct ttm_lock *lock)
299{
300	wait_event(lock->queue, __ttm_suspend_lock(lock));
301}
302EXPORT_SYMBOL(ttm_suspend_lock);
303