Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/drzeus/mmc
[linux-2.6] / drivers / gpu / drm / drm_lock.c
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
38 static int drm_notifier(void *priv);
39
40 /**
41  * Lock ioctl.
42  *
43  * \param inode device inode.
44  * \param file_priv DRM file private.
45  * \param cmd command.
46  * \param arg user argument, pointing to a drm_lock structure.
47  * \return zero on success or negative number on failure.
48  *
49  * Add the current task to the lock wait queue, and attempt to take to lock.
50  */
51 int drm_lock(struct drm_device *dev, void *data, struct drm_file *file_priv)
52 {
53         DECLARE_WAITQUEUE(entry, current);
54         struct drm_lock *lock = data;
55         struct drm_master *master = file_priv->master;
56         int ret = 0;
57
58         ++file_priv->lock_count;
59
60         if (lock->context == DRM_KERNEL_CONTEXT) {
61                 DRM_ERROR("Process %d using kernel context %d\n",
62                           task_pid_nr(current), lock->context);
63                 return -EINVAL;
64         }
65
66         DRM_DEBUG("%d (pid %d) requests lock (0x%08x), flags = 0x%08x\n",
67                   lock->context, task_pid_nr(current),
68                   master->lock.hw_lock->lock, lock->flags);
69
70         if (drm_core_check_feature(dev, DRIVER_DMA_QUEUE))
71                 if (lock->context < 0)
72                         return -EINVAL;
73
74         add_wait_queue(&master->lock.lock_queue, &entry);
75         spin_lock_bh(&master->lock.spinlock);
76         master->lock.user_waiters++;
77         spin_unlock_bh(&master->lock.spinlock);
78
79         for (;;) {
80                 __set_current_state(TASK_INTERRUPTIBLE);
81                 if (!master->lock.hw_lock) {
82                         /* Device has been unregistered */
83                         send_sig(SIGTERM, current, 0);
84                         ret = -EINTR;
85                         break;
86                 }
87                 if (drm_lock_take(&master->lock, lock->context)) {
88                         master->lock.file_priv = file_priv;
89                         master->lock.lock_time = jiffies;
90                         atomic_inc(&dev->counts[_DRM_STAT_LOCKS]);
91                         break;  /* Got lock */
92                 }
93
94                 /* Contention */
95                 schedule();
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_ready && (lock->flags & _DRM_LOCK_READY))
126                 dev->driver->dma_ready(dev);
127
128         if (dev->driver->dma_quiescent && (lock->flags & _DRM_LOCK_QUIESCENT))
129         {
130                 if (dev->driver->dma_quiescent(dev)) {
131                         DRM_DEBUG("%d waiting for DMA quiescent\n",
132                                   lock->context);
133                         return -EBUSY;
134                 }
135         }
136
137         if (dev->driver->kernel_context_switch &&
138             dev->last_context != lock->context) {
139                 dev->driver->kernel_context_switch(dev, dev->last_context,
140                                                    lock->context);
141         }
142
143         return 0;
144 }
145
146 /**
147  * Unlock ioctl.
148  *
149  * \param inode device inode.
150  * \param file_priv DRM file private.
151  * \param cmd command.
152  * \param arg user argument, pointing to a drm_lock structure.
153  * \return zero on success or negative number on failure.
154  *
155  * Transfer and free the lock.
156  */
157 int drm_unlock(struct drm_device *dev, void *data, struct drm_file *file_priv)
158 {
159         struct drm_lock *lock = data;
160         struct drm_master *master = file_priv->master;
161
162         if (lock->context == DRM_KERNEL_CONTEXT) {
163                 DRM_ERROR("Process %d using kernel context %d\n",
164                           task_pid_nr(current), lock->context);
165                 return -EINVAL;
166         }
167
168         atomic_inc(&dev->counts[_DRM_STAT_UNLOCKS]);
169
170         /* kernel_context_switch isn't used by any of the x86 drm
171          * modules but is required by the Sparc driver.
172          */
173         if (dev->driver->kernel_context_switch_unlock)
174                 dev->driver->kernel_context_switch_unlock(dev);
175         else {
176                 if (drm_lock_free(&master->lock, lock->context)) {
177                         /* FIXME: Should really bail out here. */
178                 }
179         }
180
181         unblock_all_signals();
182         return 0;
183 }
184
185 /**
186  * Take the heavyweight lock.
187  *
188  * \param lock lock pointer.
189  * \param context locking context.
190  * \return one if the lock is held, or zero otherwise.
191  *
192  * Attempt to mark the lock as held by the given context, via the \p cmpxchg instruction.
193  */
194 int drm_lock_take(struct drm_lock_data *lock_data,
195                   unsigned int context)
196 {
197         unsigned int old, new, prev;
198         volatile unsigned int *lock = &lock_data->hw_lock->lock;
199
200         spin_lock_bh(&lock_data->spinlock);
201         do {
202                 old = *lock;
203                 if (old & _DRM_LOCK_HELD)
204                         new = old | _DRM_LOCK_CONT;
205                 else {
206                         new = context | _DRM_LOCK_HELD |
207                                 ((lock_data->user_waiters + lock_data->kernel_waiters > 1) ?
208                                  _DRM_LOCK_CONT : 0);
209                 }
210                 prev = cmpxchg(lock, old, new);
211         } while (prev != old);
212         spin_unlock_bh(&lock_data->spinlock);
213
214         if (_DRM_LOCKING_CONTEXT(old) == context) {
215                 if (old & _DRM_LOCK_HELD) {
216                         if (context != DRM_KERNEL_CONTEXT) {
217                                 DRM_ERROR("%d holds heavyweight lock\n",
218                                           context);
219                         }
220                         return 0;
221                 }
222         }
223
224         if ((_DRM_LOCKING_CONTEXT(new)) == context && (new & _DRM_LOCK_HELD)) {
225                 /* Have lock */
226                 return 1;
227         }
228         return 0;
229 }
230 EXPORT_SYMBOL(drm_lock_take);
231
232 /**
233  * This takes a lock forcibly and hands it to context.  Should ONLY be used
234  * inside *_unlock to give lock to kernel before calling *_dma_schedule.
235  *
236  * \param dev DRM device.
237  * \param lock lock pointer.
238  * \param context locking context.
239  * \return always one.
240  *
241  * Resets the lock file pointer.
242  * Marks the lock as held by the given context, via the \p cmpxchg instruction.
243  */
244 static int drm_lock_transfer(struct drm_lock_data *lock_data,
245                              unsigned int context)
246 {
247         unsigned int old, new, prev;
248         volatile unsigned int *lock = &lock_data->hw_lock->lock;
249
250         lock_data->file_priv = NULL;
251         do {
252                 old = *lock;
253                 new = context | _DRM_LOCK_HELD;
254                 prev = cmpxchg(lock, old, new);
255         } while (prev != old);
256         return 1;
257 }
258
259 /**
260  * Free lock.
261  *
262  * \param dev DRM device.
263  * \param lock lock.
264  * \param context context.
265  *
266  * Resets the lock file pointer.
267  * Marks the lock as not held, via the \p cmpxchg instruction. Wakes any task
268  * waiting on the lock queue.
269  */
270 int drm_lock_free(struct drm_lock_data *lock_data, unsigned int context)
271 {
272         unsigned int old, new, prev;
273         volatile unsigned int *lock = &lock_data->hw_lock->lock;
274
275         spin_lock_bh(&lock_data->spinlock);
276         if (lock_data->kernel_waiters != 0) {
277                 drm_lock_transfer(lock_data, 0);
278                 lock_data->idle_has_lock = 1;
279                 spin_unlock_bh(&lock_data->spinlock);
280                 return 1;
281         }
282         spin_unlock_bh(&lock_data->spinlock);
283
284         do {
285                 old = *lock;
286                 new = _DRM_LOCKING_CONTEXT(old);
287                 prev = cmpxchg(lock, old, new);
288         } while (prev != old);
289
290         if (_DRM_LOCK_IS_HELD(old) && _DRM_LOCKING_CONTEXT(old) != context) {
291                 DRM_ERROR("%d freed heavyweight lock held by %d\n",
292                           context, _DRM_LOCKING_CONTEXT(old));
293                 return 1;
294         }
295         wake_up_interruptible(&lock_data->lock_queue);
296         return 0;
297 }
298 EXPORT_SYMBOL(drm_lock_free);
299
300 /**
301  * If we get here, it means that the process has called DRM_IOCTL_LOCK
302  * without calling DRM_IOCTL_UNLOCK.
303  *
304  * If the lock is not held, then let the signal proceed as usual.  If the lock
305  * is held, then set the contended flag and keep the signal blocked.
306  *
307  * \param priv pointer to a drm_sigdata structure.
308  * \return one if the signal should be delivered normally, or zero if the
309  * signal should be blocked.
310  */
311 static int drm_notifier(void *priv)
312 {
313         struct drm_sigdata *s = (struct drm_sigdata *) priv;
314         unsigned int old, new, prev;
315
316         /* Allow signal delivery if lock isn't held */
317         if (!s->lock || !_DRM_LOCK_IS_HELD(s->lock->lock)
318             || _DRM_LOCKING_CONTEXT(s->lock->lock) != s->context)
319                 return 1;
320
321         /* Otherwise, set flag to force call to
322            drmUnlock */
323         do {
324                 old = s->lock->lock;
325                 new = old | _DRM_LOCK_CONT;
326                 prev = cmpxchg(&s->lock->lock, old, new);
327         } while (prev != old);
328         return 0;
329 }
330
331 /**
332  * This function returns immediately and takes the hw lock
333  * with the kernel context if it is free, otherwise it gets the highest priority when and if
334  * it is eventually released.
335  *
336  * This guarantees that the kernel will _eventually_ have the lock _unless_ it is held
337  * by a blocked process. (In the latter case an explicit wait for the hardware lock would cause
338  * a deadlock, which is why the "idlelock" was invented).
339  *
340  * This should be sufficient to wait for GPU idle without
341  * having to worry about starvation.
342  */
343
344 void drm_idlelock_take(struct drm_lock_data *lock_data)
345 {
346         int ret = 0;
347
348         spin_lock_bh(&lock_data->spinlock);
349         lock_data->kernel_waiters++;
350         if (!lock_data->idle_has_lock) {
351
352                 spin_unlock_bh(&lock_data->spinlock);
353                 ret = drm_lock_take(lock_data, DRM_KERNEL_CONTEXT);
354                 spin_lock_bh(&lock_data->spinlock);
355
356                 if (ret == 1)
357                         lock_data->idle_has_lock = 1;
358         }
359         spin_unlock_bh(&lock_data->spinlock);
360 }
361 EXPORT_SYMBOL(drm_idlelock_take);
362
363 void drm_idlelock_release(struct drm_lock_data *lock_data)
364 {
365         unsigned int old, prev;
366         volatile unsigned int *lock = &lock_data->hw_lock->lock;
367
368         spin_lock_bh(&lock_data->spinlock);
369         if (--lock_data->kernel_waiters == 0) {
370                 if (lock_data->idle_has_lock) {
371                         do {
372                                 old = *lock;
373                                 prev = cmpxchg(lock, old, DRM_KERNEL_CONTEXT);
374                         } while (prev != old);
375                         wake_up_interruptible(&lock_data->lock_queue);
376                         lock_data->idle_has_lock = 0;
377                 }
378         }
379         spin_unlock_bh(&lock_data->spinlock);
380 }
381 EXPORT_SYMBOL(drm_idlelock_release);
382
383
384 int drm_i_have_hw_lock(struct drm_device *dev, struct drm_file *file_priv)
385 {
386         struct drm_master *master = file_priv->master;
387         return (file_priv->lock_count && master->lock.hw_lock &&
388                 _DRM_LOCK_IS_HELD(master->lock.hw_lock->lock) &&
389                 master->lock.file_priv == file_priv);
390 }
391
392 EXPORT_SYMBOL(drm_i_have_hw_lock);