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1/**
2 * \file drm_lock.c
3 * IOCTLs for locking
4 *
5 * \author Rickard E. (Rik) Faith <faith@valinux.com>
6 * \author Gareth Hughes <gareth@valinux.com>
7 */
8
9/*
10 * Created: Tue Feb 2 08:37:54 1999 by faith@valinux.com
11 *
12 * Copyright 1999 Precision Insight, Inc., Cedar Park, Texas.
13 * Copyright 2000 VA Linux Systems, Inc., Sunnyvale, California.
14 * All Rights Reserved.
15 *
16 * Permission is hereby granted, free of charge, to any person obtaining a
17 * copy of this software and associated documentation files (the "Software"),
18 * to deal in the Software without restriction, including without limitation
19 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
20 * and/or sell copies of the Software, and to permit persons to whom the
21 * Software is furnished to do so, subject to the following conditions:
22 *
23 * The above copyright notice and this permission notice (including the next
24 * paragraph) shall be included in all copies or substantial portions of the
25 * Software.
26 *
27 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
28 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
29 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
30 * VA LINUX SYSTEMS AND/OR ITS SUPPLIERS BE LIABLE FOR ANY CLAIM, DAMAGES OR
31 * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
32 * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
33 * OTHER DEALINGS IN THE SOFTWARE.
34 */
35
36#include "drmP.h"
37
38static int drm_notifier(void *priv);
39
40static int drm_lock_take(struct drm_lock_data *lock_data, unsigned int context);
41
42/**
43 * Lock ioctl.
44 *
45 * \param inode device inode.
46 * \param file_priv DRM file private.
47 * \param cmd command.
48 * \param arg user argument, pointing to a drm_lock structure.
49 * \return zero on success or negative number on failure.
50 *
51 * Add the current task to the lock wait queue, and attempt to take to lock.
52 */
53int drm_lock(struct drm_device *dev, void *data, struct drm_file *file_priv)
54{
55 DECLARE_WAITQUEUE(entry, current);
56 struct drm_lock *lock = data;
57 struct drm_master *master = file_priv->master;
58 int ret = 0;
59
60 ++file_priv->lock_count;
61
62 if (lock->context == DRM_KERNEL_CONTEXT) {
63 DRM_ERROR("Process %d using kernel context %d\n",
64 task_pid_nr(current), lock->context);
65 return -EINVAL;
66 }
67
68 DRM_DEBUG("%d (pid %d) requests lock (0x%08x), flags = 0x%08x\n",
69 lock->context, task_pid_nr(current),
70 master->lock.hw_lock->lock, lock->flags);
71
72 if (drm_core_check_feature(dev, DRIVER_DMA_QUEUE))
73 if (lock->context < 0)
74 return -EINVAL;
75
76 add_wait_queue(&master->lock.lock_queue, &entry);
77 spin_lock_bh(&master->lock.spinlock);
78 master->lock.user_waiters++;
79 spin_unlock_bh(&master->lock.spinlock);
80
81 for (;;) {
82 __set_current_state(TASK_INTERRUPTIBLE);
83 if (!master->lock.hw_lock) {
84 /* Device has been unregistered */
85 send_sig(SIGTERM, current, 0);
86 ret = -EINTR;
87 break;
88 }
89 if (drm_lock_take(&master->lock, lock->context)) {
90 master->lock.file_priv = file_priv;
91 master->lock.lock_time = jiffies;
92 atomic_inc(&dev->counts[_DRM_STAT_LOCKS]);
93 break; /* Got lock */
94 }
95
96 /* Contention */
97 mutex_unlock(&drm_global_mutex);
98 schedule();
99 mutex_lock(&drm_global_mutex);
100 if (signal_pending(current)) {
101 ret = -EINTR;
102 break;
103 }
104 }
105 spin_lock_bh(&master->lock.spinlock);
106 master->lock.user_waiters--;
107 spin_unlock_bh(&master->lock.spinlock);
108 __set_current_state(TASK_RUNNING);
109 remove_wait_queue(&master->lock.lock_queue, &entry);
110
111 DRM_DEBUG("%d %s\n", lock->context,
112 ret ? "interrupted" : "has lock");
113 if (ret) return ret;
114
115 /* don't set the block all signals on the master process for now
116 * really probably not the correct answer but lets us debug xkb
117 * xserver for now */
118 if (!file_priv->is_master) {
119 sigemptyset(&dev->sigmask);
120 sigaddset(&dev->sigmask, SIGSTOP);
121 sigaddset(&dev->sigmask, SIGTSTP);
122 sigaddset(&dev->sigmask, SIGTTIN);
123 sigaddset(&dev->sigmask, SIGTTOU);
124 dev->sigdata.context = lock->context;
125 dev->sigdata.lock = master->lock.hw_lock;
126 block_all_signals(drm_notifier, &dev->sigdata, &dev->sigmask);
127 }
128
129 if (dev->driver->dma_quiescent && (lock->flags & _DRM_LOCK_QUIESCENT))
130 {
131 if (dev->driver->dma_quiescent(dev)) {
132 DRM_DEBUG("%d waiting for DMA quiescent\n",
133 lock->context);
134 return -EBUSY;
135 }
136 }
137
138 return 0;
139}
140
141/**
142 * Unlock ioctl.
143 *
144 * \param inode device inode.
145 * \param file_priv DRM file private.
146 * \param cmd command.
147 * \param arg user argument, pointing to a drm_lock structure.
148 * \return zero on success or negative number on failure.
149 *
150 * Transfer and free the lock.
151 */
152int drm_unlock(struct drm_device *dev, void *data, struct drm_file *file_priv)
153{
154 struct drm_lock *lock = data;
155 struct drm_master *master = file_priv->master;
156
157 if (lock->context == DRM_KERNEL_CONTEXT) {
158 DRM_ERROR("Process %d using kernel context %d\n",
159 task_pid_nr(current), lock->context);
160 return -EINVAL;
161 }
162
163 atomic_inc(&dev->counts[_DRM_STAT_UNLOCKS]);
164
165 if (drm_lock_free(&master->lock, lock->context)) {
166 /* FIXME: Should really bail out here. */
167 }
168
169 unblock_all_signals();
170 return 0;
171}
172
173/**
174 * Take the heavyweight lock.
175 *
176 * \param lock lock pointer.
177 * \param context locking context.
178 * \return one if the lock is held, or zero otherwise.
179 *
180 * Attempt to mark the lock as held by the given context, via the \p cmpxchg instruction.
181 */
182static
183int drm_lock_take(struct drm_lock_data *lock_data,
184 unsigned int context)
185{
186 unsigned int old, new, prev;
187 volatile unsigned int *lock = &lock_data->hw_lock->lock;
188
189 spin_lock_bh(&lock_data->spinlock);
190 do {
191 old = *lock;
192 if (old & _DRM_LOCK_HELD)
193 new = old | _DRM_LOCK_CONT;
194 else {
195 new = context | _DRM_LOCK_HELD |
196 ((lock_data->user_waiters + lock_data->kernel_waiters > 1) ?
197 _DRM_LOCK_CONT : 0);
198 }
199 prev = cmpxchg(lock, old, new);
200 } while (prev != old);
201 spin_unlock_bh(&lock_data->spinlock);
202
203 if (_DRM_LOCKING_CONTEXT(old) == context) {
204 if (old & _DRM_LOCK_HELD) {
205 if (context != DRM_KERNEL_CONTEXT) {
206 DRM_ERROR("%d holds heavyweight lock\n",
207 context);
208 }
209 return 0;
210 }
211 }
212
213 if ((_DRM_LOCKING_CONTEXT(new)) == context && (new & _DRM_LOCK_HELD)) {
214 /* Have lock */
215 return 1;
216 }
217 return 0;
218}
219
220/**
221 * This takes a lock forcibly and hands it to context. Should ONLY be used
222 * inside *_unlock to give lock to kernel before calling *_dma_schedule.
223 *
224 * \param dev DRM device.
225 * \param lock lock pointer.
226 * \param context locking context.
227 * \return always one.
228 *
229 * Resets the lock file pointer.
230 * Marks the lock as held by the given context, via the \p cmpxchg instruction.
231 */
232static int drm_lock_transfer(struct drm_lock_data *lock_data,
233 unsigned int context)
234{
235 unsigned int old, new, prev;
236 volatile unsigned int *lock = &lock_data->hw_lock->lock;
237
238 lock_data->file_priv = NULL;
239 do {
240 old = *lock;
241 new = context | _DRM_LOCK_HELD;
242 prev = cmpxchg(lock, old, new);
243 } while (prev != old);
244 return 1;
245}
246
247/**
248 * Free lock.
249 *
250 * \param dev DRM device.
251 * \param lock lock.
252 * \param context context.
253 *
254 * Resets the lock file pointer.
255 * Marks the lock as not held, via the \p cmpxchg instruction. Wakes any task
256 * waiting on the lock queue.
257 */
258int drm_lock_free(struct drm_lock_data *lock_data, unsigned int context)
259{
260 unsigned int old, new, prev;
261 volatile unsigned int *lock = &lock_data->hw_lock->lock;
262
263 spin_lock_bh(&lock_data->spinlock);
264 if (lock_data->kernel_waiters != 0) {
265 drm_lock_transfer(lock_data, 0);
266 lock_data->idle_has_lock = 1;
267 spin_unlock_bh(&lock_data->spinlock);
268 return 1;
269 }
270 spin_unlock_bh(&lock_data->spinlock);
271
272 do {
273 old = *lock;
274 new = _DRM_LOCKING_CONTEXT(old);
275 prev = cmpxchg(lock, old, new);
276 } while (prev != old);
277
278 if (_DRM_LOCK_IS_HELD(old) && _DRM_LOCKING_CONTEXT(old) != context) {
279 DRM_ERROR("%d freed heavyweight lock held by %d\n",
280 context, _DRM_LOCKING_CONTEXT(old));
281 return 1;
282 }
283 wake_up_interruptible(&lock_data->lock_queue);
284 return 0;
285}
286
287/**
288 * If we get here, it means that the process has called DRM_IOCTL_LOCK
289 * without calling DRM_IOCTL_UNLOCK.
290 *
291 * If the lock is not held, then let the signal proceed as usual. If the lock
292 * is held, then set the contended flag and keep the signal blocked.
293 *
294 * \param priv pointer to a drm_sigdata structure.
295 * \return one if the signal should be delivered normally, or zero if the
296 * signal should be blocked.
297 */
298static int drm_notifier(void *priv)
299{
300 struct drm_sigdata *s = (struct drm_sigdata *) priv;
301 unsigned int old, new, prev;
302
303 /* Allow signal delivery if lock isn't held */
304 if (!s->lock || !_DRM_LOCK_IS_HELD(s->lock->lock)
305 || _DRM_LOCKING_CONTEXT(s->lock->lock) != s->context)
306 return 1;
307
308 /* Otherwise, set flag to force call to
309 drmUnlock */
310 do {
311 old = s->lock->lock;
312 new = old | _DRM_LOCK_CONT;
313 prev = cmpxchg(&s->lock->lock, old, new);
314 } while (prev != old);
315 return 0;
316}
317
318/**
319 * This function returns immediately and takes the hw lock
320 * with the kernel context if it is free, otherwise it gets the highest priority when and if
321 * it is eventually released.
322 *
323 * This guarantees that the kernel will _eventually_ have the lock _unless_ it is held
324 * by a blocked process. (In the latter case an explicit wait for the hardware lock would cause
325 * a deadlock, which is why the "idlelock" was invented).
326 *
327 * This should be sufficient to wait for GPU idle without
328 * having to worry about starvation.
329 */
330
331void drm_idlelock_take(struct drm_lock_data *lock_data)
332{
333 int ret = 0;
334
335 spin_lock_bh(&lock_data->spinlock);
336 lock_data->kernel_waiters++;
337 if (!lock_data->idle_has_lock) {
338
339 spin_unlock_bh(&lock_data->spinlock);
340 ret = drm_lock_take(lock_data, DRM_KERNEL_CONTEXT);
341 spin_lock_bh(&lock_data->spinlock);
342
343 if (ret == 1)
344 lock_data->idle_has_lock = 1;
345 }
346 spin_unlock_bh(&lock_data->spinlock);
347}
348
349void drm_idlelock_release(struct drm_lock_data *lock_data)
350{
351 unsigned int old, prev;
352 volatile unsigned int *lock = &lock_data->hw_lock->lock;
353
354 spin_lock_bh(&lock_data->spinlock);
355 if (--lock_data->kernel_waiters == 0) {
356 if (lock_data->idle_has_lock) {
357 do {
358 old = *lock;
359 prev = cmpxchg(lock, old, DRM_KERNEL_CONTEXT);
360 } while (prev != old);
361 wake_up_interruptible(&lock_data->lock_queue);
362 lock_data->idle_has_lock = 0;
363 }
364 }
365 spin_unlock_bh(&lock_data->spinlock);
366}
367
368int drm_i_have_hw_lock(struct drm_device *dev, struct drm_file *file_priv)
369{
370 struct drm_master *master = file_priv->master;
371 return (file_priv->lock_count && master->lock.hw_lock &&
372 _DRM_LOCK_IS_HELD(master->lock.hw_lock->lock) &&
373 master->lock.file_priv == file_priv);
374}
1/**
2 * \file drm_lock.c
3 * IOCTLs for locking
4 *
5 * \author Rickard E. (Rik) Faith <faith@valinux.com>
6 * \author Gareth Hughes <gareth@valinux.com>
7 */
8
9/*
10 * Created: Tue Feb 2 08:37:54 1999 by faith@valinux.com
11 *
12 * Copyright 1999 Precision Insight, Inc., Cedar Park, Texas.
13 * Copyright 2000 VA Linux Systems, Inc., Sunnyvale, California.
14 * All Rights Reserved.
15 *
16 * Permission is hereby granted, free of charge, to any person obtaining a
17 * copy of this software and associated documentation files (the "Software"),
18 * to deal in the Software without restriction, including without limitation
19 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
20 * and/or sell copies of the Software, and to permit persons to whom the
21 * Software is furnished to do so, subject to the following conditions:
22 *
23 * The above copyright notice and this permission notice (including the next
24 * paragraph) shall be included in all copies or substantial portions of the
25 * Software.
26 *
27 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
28 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
29 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
30 * VA LINUX SYSTEMS AND/OR ITS SUPPLIERS BE LIABLE FOR ANY CLAIM, DAMAGES OR
31 * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
32 * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
33 * OTHER DEALINGS IN THE SOFTWARE.
34 */
35
36#include <linux/export.h>
37#include <drm/drmP.h>
38
39static int drm_notifier(void *priv);
40
41static int drm_lock_take(struct drm_lock_data *lock_data, unsigned int context);
42
43/**
44 * Lock ioctl.
45 *
46 * \param inode device inode.
47 * \param file_priv DRM file private.
48 * \param cmd command.
49 * \param arg user argument, pointing to a drm_lock structure.
50 * \return zero on success or negative number on failure.
51 *
52 * Add the current task to the lock wait queue, and attempt to take to lock.
53 */
54int drm_lock(struct drm_device *dev, void *data, struct drm_file *file_priv)
55{
56 DECLARE_WAITQUEUE(entry, current);
57 struct drm_lock *lock = data;
58 struct drm_master *master = file_priv->master;
59 int ret = 0;
60
61 ++file_priv->lock_count;
62
63 if (lock->context == DRM_KERNEL_CONTEXT) {
64 DRM_ERROR("Process %d using kernel context %d\n",
65 task_pid_nr(current), lock->context);
66 return -EINVAL;
67 }
68
69 DRM_DEBUG("%d (pid %d) requests lock (0x%08x), flags = 0x%08x\n",
70 lock->context, task_pid_nr(current),
71 master->lock.hw_lock->lock, lock->flags);
72
73 add_wait_queue(&master->lock.lock_queue, &entry);
74 spin_lock_bh(&master->lock.spinlock);
75 master->lock.user_waiters++;
76 spin_unlock_bh(&master->lock.spinlock);
77
78 for (;;) {
79 __set_current_state(TASK_INTERRUPTIBLE);
80 if (!master->lock.hw_lock) {
81 /* Device has been unregistered */
82 send_sig(SIGTERM, current, 0);
83 ret = -EINTR;
84 break;
85 }
86 if (drm_lock_take(&master->lock, lock->context)) {
87 master->lock.file_priv = file_priv;
88 master->lock.lock_time = jiffies;
89 break; /* Got lock */
90 }
91
92 /* Contention */
93 mutex_unlock(&drm_global_mutex);
94 schedule();
95 mutex_lock(&drm_global_mutex);
96 if (signal_pending(current)) {
97 ret = -EINTR;
98 break;
99 }
100 }
101 spin_lock_bh(&master->lock.spinlock);
102 master->lock.user_waiters--;
103 spin_unlock_bh(&master->lock.spinlock);
104 __set_current_state(TASK_RUNNING);
105 remove_wait_queue(&master->lock.lock_queue, &entry);
106
107 DRM_DEBUG("%d %s\n", lock->context,
108 ret ? "interrupted" : "has lock");
109 if (ret) return ret;
110
111 /* don't set the block all signals on the master process for now
112 * really probably not the correct answer but lets us debug xkb
113 * xserver for now */
114 if (!file_priv->is_master) {
115 sigemptyset(&dev->sigmask);
116 sigaddset(&dev->sigmask, SIGSTOP);
117 sigaddset(&dev->sigmask, SIGTSTP);
118 sigaddset(&dev->sigmask, SIGTTIN);
119 sigaddset(&dev->sigmask, SIGTTOU);
120 dev->sigdata.context = lock->context;
121 dev->sigdata.lock = master->lock.hw_lock;
122 block_all_signals(drm_notifier, &dev->sigdata, &dev->sigmask);
123 }
124
125 if (dev->driver->dma_quiescent && (lock->flags & _DRM_LOCK_QUIESCENT))
126 {
127 if (dev->driver->dma_quiescent(dev)) {
128 DRM_DEBUG("%d waiting for DMA quiescent\n",
129 lock->context);
130 return -EBUSY;
131 }
132 }
133
134 return 0;
135}
136
137/**
138 * Unlock ioctl.
139 *
140 * \param inode device inode.
141 * \param file_priv DRM file private.
142 * \param cmd command.
143 * \param arg user argument, pointing to a drm_lock structure.
144 * \return zero on success or negative number on failure.
145 *
146 * Transfer and free the lock.
147 */
148int drm_unlock(struct drm_device *dev, void *data, struct drm_file *file_priv)
149{
150 struct drm_lock *lock = data;
151 struct drm_master *master = file_priv->master;
152
153 if (lock->context == DRM_KERNEL_CONTEXT) {
154 DRM_ERROR("Process %d using kernel context %d\n",
155 task_pid_nr(current), lock->context);
156 return -EINVAL;
157 }
158
159 if (drm_lock_free(&master->lock, lock->context)) {
160 /* FIXME: Should really bail out here. */
161 }
162
163 unblock_all_signals();
164 return 0;
165}
166
167/**
168 * Take the heavyweight lock.
169 *
170 * \param lock lock pointer.
171 * \param context locking context.
172 * \return one if the lock is held, or zero otherwise.
173 *
174 * Attempt to mark the lock as held by the given context, via the \p cmpxchg instruction.
175 */
176static
177int drm_lock_take(struct drm_lock_data *lock_data,
178 unsigned int context)
179{
180 unsigned int old, new, prev;
181 volatile unsigned int *lock = &lock_data->hw_lock->lock;
182
183 spin_lock_bh(&lock_data->spinlock);
184 do {
185 old = *lock;
186 if (old & _DRM_LOCK_HELD)
187 new = old | _DRM_LOCK_CONT;
188 else {
189 new = context | _DRM_LOCK_HELD |
190 ((lock_data->user_waiters + lock_data->kernel_waiters > 1) ?
191 _DRM_LOCK_CONT : 0);
192 }
193 prev = cmpxchg(lock, old, new);
194 } while (prev != old);
195 spin_unlock_bh(&lock_data->spinlock);
196
197 if (_DRM_LOCKING_CONTEXT(old) == context) {
198 if (old & _DRM_LOCK_HELD) {
199 if (context != DRM_KERNEL_CONTEXT) {
200 DRM_ERROR("%d holds heavyweight lock\n",
201 context);
202 }
203 return 0;
204 }
205 }
206
207 if ((_DRM_LOCKING_CONTEXT(new)) == context && (new & _DRM_LOCK_HELD)) {
208 /* Have lock */
209 return 1;
210 }
211 return 0;
212}
213
214/**
215 * This takes a lock forcibly and hands it to context. Should ONLY be used
216 * inside *_unlock to give lock to kernel before calling *_dma_schedule.
217 *
218 * \param dev DRM device.
219 * \param lock lock pointer.
220 * \param context locking context.
221 * \return always one.
222 *
223 * Resets the lock file pointer.
224 * Marks the lock as held by the given context, via the \p cmpxchg instruction.
225 */
226static int drm_lock_transfer(struct drm_lock_data *lock_data,
227 unsigned int context)
228{
229 unsigned int old, new, prev;
230 volatile unsigned int *lock = &lock_data->hw_lock->lock;
231
232 lock_data->file_priv = NULL;
233 do {
234 old = *lock;
235 new = context | _DRM_LOCK_HELD;
236 prev = cmpxchg(lock, old, new);
237 } while (prev != old);
238 return 1;
239}
240
241/**
242 * Free lock.
243 *
244 * \param dev DRM device.
245 * \param lock lock.
246 * \param context context.
247 *
248 * Resets the lock file pointer.
249 * Marks the lock as not held, via the \p cmpxchg instruction. Wakes any task
250 * waiting on the lock queue.
251 */
252int drm_lock_free(struct drm_lock_data *lock_data, unsigned int context)
253{
254 unsigned int old, new, prev;
255 volatile unsigned int *lock = &lock_data->hw_lock->lock;
256
257 spin_lock_bh(&lock_data->spinlock);
258 if (lock_data->kernel_waiters != 0) {
259 drm_lock_transfer(lock_data, 0);
260 lock_data->idle_has_lock = 1;
261 spin_unlock_bh(&lock_data->spinlock);
262 return 1;
263 }
264 spin_unlock_bh(&lock_data->spinlock);
265
266 do {
267 old = *lock;
268 new = _DRM_LOCKING_CONTEXT(old);
269 prev = cmpxchg(lock, old, new);
270 } while (prev != old);
271
272 if (_DRM_LOCK_IS_HELD(old) && _DRM_LOCKING_CONTEXT(old) != context) {
273 DRM_ERROR("%d freed heavyweight lock held by %d\n",
274 context, _DRM_LOCKING_CONTEXT(old));
275 return 1;
276 }
277 wake_up_interruptible(&lock_data->lock_queue);
278 return 0;
279}
280
281/**
282 * If we get here, it means that the process has called DRM_IOCTL_LOCK
283 * without calling DRM_IOCTL_UNLOCK.
284 *
285 * If the lock is not held, then let the signal proceed as usual. If the lock
286 * is held, then set the contended flag and keep the signal blocked.
287 *
288 * \param priv pointer to a drm_sigdata structure.
289 * \return one if the signal should be delivered normally, or zero if the
290 * signal should be blocked.
291 */
292static int drm_notifier(void *priv)
293{
294 struct drm_sigdata *s = (struct drm_sigdata *) priv;
295 unsigned int old, new, prev;
296
297 /* Allow signal delivery if lock isn't held */
298 if (!s->lock || !_DRM_LOCK_IS_HELD(s->lock->lock)
299 || _DRM_LOCKING_CONTEXT(s->lock->lock) != s->context)
300 return 1;
301
302 /* Otherwise, set flag to force call to
303 drmUnlock */
304 do {
305 old = s->lock->lock;
306 new = old | _DRM_LOCK_CONT;
307 prev = cmpxchg(&s->lock->lock, old, new);
308 } while (prev != old);
309 return 0;
310}
311
312/**
313 * This function returns immediately and takes the hw lock
314 * with the kernel context if it is free, otherwise it gets the highest priority when and if
315 * it is eventually released.
316 *
317 * This guarantees that the kernel will _eventually_ have the lock _unless_ it is held
318 * by a blocked process. (In the latter case an explicit wait for the hardware lock would cause
319 * a deadlock, which is why the "idlelock" was invented).
320 *
321 * This should be sufficient to wait for GPU idle without
322 * having to worry about starvation.
323 */
324
325void drm_idlelock_take(struct drm_lock_data *lock_data)
326{
327 int ret;
328
329 spin_lock_bh(&lock_data->spinlock);
330 lock_data->kernel_waiters++;
331 if (!lock_data->idle_has_lock) {
332
333 spin_unlock_bh(&lock_data->spinlock);
334 ret = drm_lock_take(lock_data, DRM_KERNEL_CONTEXT);
335 spin_lock_bh(&lock_data->spinlock);
336
337 if (ret == 1)
338 lock_data->idle_has_lock = 1;
339 }
340 spin_unlock_bh(&lock_data->spinlock);
341}
342EXPORT_SYMBOL(drm_idlelock_take);
343
344void drm_idlelock_release(struct drm_lock_data *lock_data)
345{
346 unsigned int old, prev;
347 volatile unsigned int *lock = &lock_data->hw_lock->lock;
348
349 spin_lock_bh(&lock_data->spinlock);
350 if (--lock_data->kernel_waiters == 0) {
351 if (lock_data->idle_has_lock) {
352 do {
353 old = *lock;
354 prev = cmpxchg(lock, old, DRM_KERNEL_CONTEXT);
355 } while (prev != old);
356 wake_up_interruptible(&lock_data->lock_queue);
357 lock_data->idle_has_lock = 0;
358 }
359 }
360 spin_unlock_bh(&lock_data->spinlock);
361}
362EXPORT_SYMBOL(drm_idlelock_release);
363
364int drm_i_have_hw_lock(struct drm_device *dev, struct drm_file *file_priv)
365{
366 struct drm_master *master = file_priv->master;
367 return (file_priv->lock_count && master->lock.hw_lock &&
368 _DRM_LOCK_IS_HELD(master->lock.hw_lock->lock) &&
369 master->lock.file_priv == file_priv);
370}