File: /usr/src/linux/drivers/char/drm/drm_lock.h
1 /* lock.c -- IOCTLs for locking -*- linux-c -*-
2 * Created: Tue Feb 2 08:37:54 1999 by faith@valinux.com
3 *
4 * Copyright 1999 Precision Insight, Inc., Cedar Park, Texas.
5 * Copyright 2000 VA Linux Systems, Inc., Sunnyvale, California.
6 * All Rights Reserved.
7 *
8 * Permission is hereby granted, free of charge, to any person obtaining a
9 * copy of this software and associated documentation files (the "Software"),
10 * to deal in the Software without restriction, including without limitation
11 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
12 * and/or sell copies of the Software, and to permit persons to whom the
13 * Software is furnished to do so, subject to the following conditions:
14 *
15 * The above copyright notice and this permission notice (including the next
16 * paragraph) shall be included in all copies or substantial portions of the
17 * Software.
18 *
19 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
20 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
21 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
22 * VA LINUX SYSTEMS AND/OR ITS SUPPLIERS BE LIABLE FOR ANY CLAIM, DAMAGES OR
23 * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
24 * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
25 * OTHER DEALINGS IN THE SOFTWARE.
26 *
27 * Authors:
28 * Rickard E. (Rik) Faith <faith@valinux.com>
29 * Gareth Hughes <gareth@valinux.com>
30 */
31
32 #define __NO_VERSION__
33 #include "drmP.h"
34
35 int DRM(block)(struct inode *inode, struct file *filp, unsigned int cmd,
36 unsigned long arg)
37 {
38 DRM_DEBUG("\n");
39 return 0;
40 }
41
42 int DRM(unblock)(struct inode *inode, struct file *filp, unsigned int cmd,
43 unsigned long arg)
44 {
45 DRM_DEBUG("\n");
46 return 0;
47 }
48
49 int DRM(lock_take)(__volatile__ unsigned int *lock, unsigned int context)
50 {
51 unsigned int old, new, prev;
52
53 do {
54 old = *lock;
55 if (old & _DRM_LOCK_HELD) new = old | _DRM_LOCK_CONT;
56 else new = context | _DRM_LOCK_HELD;
57 prev = cmpxchg(lock, old, new);
58 } while (prev != old);
59 if (_DRM_LOCKING_CONTEXT(old) == context) {
60 if (old & _DRM_LOCK_HELD) {
61 if (context != DRM_KERNEL_CONTEXT) {
62 DRM_ERROR("%d holds heavyweight lock\n",
63 context);
64 }
65 return 0;
66 }
67 }
68 if (new == (context | _DRM_LOCK_HELD)) {
69 /* Have lock */
70 return 1;
71 }
72 return 0;
73 }
74
75 /* This takes a lock forcibly and hands it to context. Should ONLY be used
76 inside *_unlock to give lock to kernel before calling *_dma_schedule. */
77 int DRM(lock_transfer)(drm_device_t *dev,
78 __volatile__ unsigned int *lock, unsigned int context)
79 {
80 unsigned int old, new, prev;
81
82 dev->lock.pid = 0;
83 do {
84 old = *lock;
85 new = context | _DRM_LOCK_HELD;
86 prev = cmpxchg(lock, old, new);
87 } while (prev != old);
88 return 1;
89 }
90
91 int DRM(lock_free)(drm_device_t *dev,
92 __volatile__ unsigned int *lock, unsigned int context)
93 {
94 unsigned int old, new, prev;
95 pid_t pid = dev->lock.pid;
96
97 dev->lock.pid = 0;
98 do {
99 old = *lock;
100 new = 0;
101 prev = cmpxchg(lock, old, new);
102 } while (prev != old);
103 if (_DRM_LOCK_IS_HELD(old) && _DRM_LOCKING_CONTEXT(old) != context) {
104 DRM_ERROR("%d freed heavyweight lock held by %d (pid %d)\n",
105 context,
106 _DRM_LOCKING_CONTEXT(old),
107 pid);
108 return 1;
109 }
110 wake_up_interruptible(&dev->lock.lock_queue);
111 return 0;
112 }
113
114 static int DRM(flush_queue)(drm_device_t *dev, int context)
115 {
116 DECLARE_WAITQUEUE(entry, current);
117 int ret = 0;
118 drm_queue_t *q = dev->queuelist[context];
119
120 DRM_DEBUG("\n");
121
122 atomic_inc(&q->use_count);
123 if (atomic_read(&q->use_count) > 1) {
124 atomic_inc(&q->block_write);
125 add_wait_queue(&q->flush_queue, &entry);
126 atomic_inc(&q->block_count);
127 for (;;) {
128 current->state = TASK_INTERRUPTIBLE;
129 if (!DRM_BUFCOUNT(&q->waitlist)) break;
130 schedule();
131 if (signal_pending(current)) {
132 ret = -EINTR; /* Can't restart */
133 break;
134 }
135 }
136 atomic_dec(&q->block_count);
137 current->state = TASK_RUNNING;
138 remove_wait_queue(&q->flush_queue, &entry);
139 }
140 atomic_dec(&q->use_count);
141
142 /* NOTE: block_write is still incremented!
143 Use drm_flush_unlock_queue to decrement. */
144 return ret;
145 }
146
147 static int DRM(flush_unblock_queue)(drm_device_t *dev, int context)
148 {
149 drm_queue_t *q = dev->queuelist[context];
150
151 DRM_DEBUG("\n");
152
153 atomic_inc(&q->use_count);
154 if (atomic_read(&q->use_count) > 1) {
155 if (atomic_read(&q->block_write)) {
156 atomic_dec(&q->block_write);
157 wake_up_interruptible(&q->write_queue);
158 }
159 }
160 atomic_dec(&q->use_count);
161 return 0;
162 }
163
164 int DRM(flush_block_and_flush)(drm_device_t *dev, int context,
165 drm_lock_flags_t flags)
166 {
167 int ret = 0;
168 int i;
169
170 DRM_DEBUG("\n");
171
172 if (flags & _DRM_LOCK_FLUSH) {
173 ret = DRM(flush_queue)(dev, DRM_KERNEL_CONTEXT);
174 if (!ret) ret = DRM(flush_queue)(dev, context);
175 }
176 if (flags & _DRM_LOCK_FLUSH_ALL) {
177 for (i = 0; !ret && i < dev->queue_count; i++) {
178 ret = DRM(flush_queue)(dev, i);
179 }
180 }
181 return ret;
182 }
183
184 int DRM(flush_unblock)(drm_device_t *dev, int context, drm_lock_flags_t flags)
185 {
186 int ret = 0;
187 int i;
188
189 DRM_DEBUG("\n");
190
191 if (flags & _DRM_LOCK_FLUSH) {
192 ret = DRM(flush_unblock_queue)(dev, DRM_KERNEL_CONTEXT);
193 if (!ret) ret = DRM(flush_unblock_queue)(dev, context);
194 }
195 if (flags & _DRM_LOCK_FLUSH_ALL) {
196 for (i = 0; !ret && i < dev->queue_count; i++) {
197 ret = DRM(flush_unblock_queue)(dev, i);
198 }
199 }
200
201 return ret;
202 }
203
204 int DRM(finish)(struct inode *inode, struct file *filp, unsigned int cmd,
205 unsigned long arg)
206 {
207 drm_file_t *priv = filp->private_data;
208 drm_device_t *dev = priv->dev;
209 int ret = 0;
210 drm_lock_t lock;
211
212 DRM_DEBUG("\n");
213
214 if (copy_from_user(&lock, (drm_lock_t *)arg, sizeof(lock)))
215 return -EFAULT;
216 ret = DRM(flush_block_and_flush)(dev, lock.context, lock.flags);
217 DRM(flush_unblock)(dev, lock.context, lock.flags);
218 return ret;
219 }
220
221 /* If we get here, it means that the process has called DRM_IOCTL_LOCK
222 without calling DRM_IOCTL_UNLOCK.
223
224 If the lock is not held, then let the signal proceed as usual.
225
226 If the lock is held, then set the contended flag and keep the signal
227 blocked.
228
229
230 Return 1 if the signal should be delivered normally.
231 Return 0 if the signal should be blocked. */
232
233 int DRM(notifier)(void *priv)
234 {
235 drm_sigdata_t *s = (drm_sigdata_t *)priv;
236 unsigned int old, new, prev;
237
238
239 /* Allow signal delivery if lock isn't held */
240 if (!_DRM_LOCK_IS_HELD(s->lock->lock)
241 || _DRM_LOCKING_CONTEXT(s->lock->lock) != s->context) return 1;
242
243 /* Otherwise, set flag to force call to
244 drmUnlock */
245 do {
246 old = s->lock->lock;
247 new = old | _DRM_LOCK_CONT;
248 prev = cmpxchg(&s->lock->lock, old, new);
249 } while (prev != old);
250 return 0;
251 }
252