Merge git://git.kernel.org/pub/scm/linux/kernel/git/hirofumi/fatfs-2.6
[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                         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                         atomic_inc(&dev->counts[_DRM_STAT_LOCKS]);
90                         break;  /* Got lock */
91                 }
92
93                 /* Contention */
94                 schedule();
95                 if (signal_pending(current)) {
96                         ret = -ERESTARTSYS;
97                         break;
98                 }
99         }
100         spin_lock_bh(&master->lock.spinlock);
101         master->lock.user_waiters--;
102         spin_unlock_bh(&master->lock.spinlock);
103         __set_current_state(TASK_RUNNING);
104         remove_wait_queue(&master->lock.lock_queue, &entry);
105
106         DRM_DEBUG("%d %s\n", lock->context,
107                   ret ? "interrupted" : "has lock");
108         if (ret) return ret;
109
110         /* don't set the block all signals on the master process for now 
111          * really probably not the correct answer but lets us debug xkb
112          * xserver for now */
113         if (!file_priv->is_master) {
114                 sigemptyset(&dev->sigmask);
115                 sigaddset(&dev->sigmask, SIGSTOP);
116                 sigaddset(&dev->sigmask, SIGTSTP);
117                 sigaddset(&dev->sigmask, SIGTTIN);
118                 sigaddset(&dev->sigmask, SIGTTOU);
119                 dev->sigdata.context = lock->context;
120                 dev->sigdata.lock = master->lock.hw_lock;
121                 block_all_signals(drm_notifier, &dev->sigdata, &dev->sigmask);
122         }
123
124         if (dev->driver->dma_ready && (lock->flags & _DRM_LOCK_READY))
125                 dev->driver->dma_ready(dev);
126
127         if (dev->driver->dma_quiescent && (lock->flags & _DRM_LOCK_QUIESCENT))
128         {
129                 if (dev->driver->dma_quiescent(dev)) {
130                         DRM_DEBUG("%d waiting for DMA quiescent\n",
131                                   lock->context);
132                         return -EBUSY;
133                 }
134         }
135
136         if (dev->driver->kernel_context_switch &&
137             dev->last_context != lock->context) {
138                 dev->driver->kernel_context_switch(dev, dev->last_context,
139                                                    lock->context);
140         }
141
142         return 0;
143 }
144
145 /**
146  * Unlock ioctl.
147  *
148  * \param inode device inode.
149  * \param file_priv DRM file private.
150  * \param cmd command.
151  * \param arg user argument, pointing to a drm_lock structure.
152  * \return zero on success or negative number on failure.
153  *
154  * Transfer and free the lock.
155  */
156 int drm_unlock(struct drm_device *dev, void *data, struct drm_file *file_priv)
157 {
158         struct drm_lock *lock = data;
159         struct drm_master *master = file_priv->master;
160
161         if (lock->context == DRM_KERNEL_CONTEXT) {
162                 DRM_ERROR("Process %d using kernel context %d\n",
163                           task_pid_nr(current), lock->context);
164                 return -EINVAL;
165         }
166
167         atomic_inc(&dev->counts[_DRM_STAT_UNLOCKS]);
168
169         /* kernel_context_switch isn't used by any of the x86 drm
170          * modules but is required by the Sparc driver.
171          */
172         if (dev->driver->kernel_context_switch_unlock)
173                 dev->driver->kernel_context_switch_unlock(dev);
174         else {
175                 if (drm_lock_free(&master->lock, lock->context)) {
176                         /* FIXME: Should really bail out here. */
177                 }
178         }
179
180         unblock_all_signals();
181         return 0;
182 }
183
184 /**
185  * Take the heavyweight lock.
186  *
187  * \param lock lock pointer.
188  * \param context locking context.
189  * \return one if the lock is held, or zero otherwise.
190  *
191  * Attempt to mark the lock as held by the given context, via the \p cmpxchg instruction.
192  */
193 int drm_lock_take(struct drm_lock_data *lock_data,
194                   unsigned int context)
195 {
196         unsigned int old, new, prev;
197         volatile unsigned int *lock = &lock_data->hw_lock->lock;
198
199         spin_lock_bh(&lock_data->spinlock);
200         do {
201                 old = *lock;
202                 if (old & _DRM_LOCK_HELD)
203                         new = old | _DRM_LOCK_CONT;
204                 else {
205                         new = context | _DRM_LOCK_HELD |
206                                 ((lock_data->user_waiters + lock_data->kernel_waiters > 1) ?
207                                  _DRM_LOCK_CONT : 0);
208                 }
209                 prev = cmpxchg(lock, old, new);
210         } while (prev != old);
211         spin_unlock_bh(&lock_data->spinlock);
212
213         if (_DRM_LOCKING_CONTEXT(old) == context) {
214                 if (old & _DRM_LOCK_HELD) {
215                         if (context != DRM_KERNEL_CONTEXT) {
216                                 DRM_ERROR("%d holds heavyweight lock\n",
217                                           context);
218                         }
219                         return 0;
220                 }
221         }
222
223         if ((_DRM_LOCKING_CONTEXT(new)) == context && (new & _DRM_LOCK_HELD)) {
224                 /* Have lock */
225                 return 1;
226         }
227         return 0;
228 }
229 EXPORT_SYMBOL(drm_lock_take);
230
231 /**
232  * This takes a lock forcibly and hands it to context.  Should ONLY be used
233  * inside *_unlock to give lock to kernel before calling *_dma_schedule.
234  *
235  * \param dev DRM device.
236  * \param lock lock pointer.
237  * \param context locking context.
238  * \return always one.
239  *
240  * Resets the lock file pointer.
241  * Marks the lock as held by the given context, via the \p cmpxchg instruction.
242  */
243 static int drm_lock_transfer(struct drm_lock_data *lock_data,
244                              unsigned int context)
245 {
246         unsigned int old, new, prev;
247         volatile unsigned int *lock = &lock_data->hw_lock->lock;
248
249         lock_data->file_priv = NULL;
250         do {
251                 old = *lock;
252                 new = context | _DRM_LOCK_HELD;
253                 prev = cmpxchg(lock, old, new);
254         } while (prev != old);
255         return 1;
256 }
257
258 /**
259  * Free lock.
260  *
261  * \param dev DRM device.
262  * \param lock lock.
263  * \param context context.
264  *
265  * Resets the lock file pointer.
266  * Marks the lock as not held, via the \p cmpxchg instruction. Wakes any task
267  * waiting on the lock queue.
268  */
269 int drm_lock_free(struct drm_lock_data *lock_data, unsigned int context)
270 {
271         unsigned int old, new, prev;
272         volatile unsigned int *lock = &lock_data->hw_lock->lock;
273
274         spin_lock_bh(&lock_data->spinlock);
275         if (lock_data->kernel_waiters != 0) {
276                 drm_lock_transfer(lock_data, 0);
277                 lock_data->idle_has_lock = 1;
278                 spin_unlock_bh(&lock_data->spinlock);
279                 return 1;
280         }
281         spin_unlock_bh(&lock_data->spinlock);
282
283         do {
284                 old = *lock;
285                 new = _DRM_LOCKING_CONTEXT(old);
286                 prev = cmpxchg(lock, old, new);
287         } while (prev != old);
288
289         if (_DRM_LOCK_IS_HELD(old) && _DRM_LOCKING_CONTEXT(old) != context) {
290                 DRM_ERROR("%d freed heavyweight lock held by %d\n",
291                           context, _DRM_LOCKING_CONTEXT(old));
292                 return 1;
293         }
294         wake_up_interruptible(&lock_data->lock_queue);
295         return 0;
296 }
297 EXPORT_SYMBOL(drm_lock_free);
298
299 /**
300  * If we get here, it means that the process has called DRM_IOCTL_LOCK
301  * without calling DRM_IOCTL_UNLOCK.
302  *
303  * If the lock is not held, then let the signal proceed as usual.  If the lock
304  * is held, then set the contended flag and keep the signal blocked.
305  *
306  * \param priv pointer to a drm_sigdata structure.
307  * \return one if the signal should be delivered normally, or zero if the
308  * signal should be blocked.
309  */
310 static int drm_notifier(void *priv)
311 {
312         struct drm_sigdata *s = (struct drm_sigdata *) priv;
313         unsigned int old, new, prev;
314
315         /* Allow signal delivery if lock isn't held */
316         if (!s->lock || !_DRM_LOCK_IS_HELD(s->lock->lock)
317             || _DRM_LOCKING_CONTEXT(s->lock->lock) != s->context)
318                 return 1;
319
320         /* Otherwise, set flag to force call to
321            drmUnlock */
322         do {
323                 old = s->lock->lock;
324                 new = old | _DRM_LOCK_CONT;
325                 prev = cmpxchg(&s->lock->lock, old, new);
326         } while (prev != old);
327         return 0;
328 }
329
330 /**
331  * This function returns immediately and takes the hw lock
332  * with the kernel context if it is free, otherwise it gets the highest priority when and if
333  * it is eventually released.
334  *
335  * This guarantees that the kernel will _eventually_ have the lock _unless_ it is held
336  * by a blocked process. (In the latter case an explicit wait for the hardware lock would cause
337  * a deadlock, which is why the "idlelock" was invented).
338  *
339  * This should be sufficient to wait for GPU idle without
340  * having to worry about starvation.
341  */
342
343 void drm_idlelock_take(struct drm_lock_data *lock_data)
344 {
345         int ret = 0;
346
347         spin_lock_bh(&lock_data->spinlock);
348         lock_data->kernel_waiters++;
349         if (!lock_data->idle_has_lock) {
350
351                 spin_unlock_bh(&lock_data->spinlock);
352                 ret = drm_lock_take(lock_data, DRM_KERNEL_CONTEXT);
353                 spin_lock_bh(&lock_data->spinlock);
354
355                 if (ret == 1)
356                         lock_data->idle_has_lock = 1;
357         }
358         spin_unlock_bh(&lock_data->spinlock);
359 }
360 EXPORT_SYMBOL(drm_idlelock_take);
361
362 void drm_idlelock_release(struct drm_lock_data *lock_data)
363 {
364         unsigned int old, prev;
365         volatile unsigned int *lock = &lock_data->hw_lock->lock;
366
367         spin_lock_bh(&lock_data->spinlock);
368         if (--lock_data->kernel_waiters == 0) {
369                 if (lock_data->idle_has_lock) {
370                         do {
371                                 old = *lock;
372                                 prev = cmpxchg(lock, old, DRM_KERNEL_CONTEXT);
373                         } while (prev != old);
374                         wake_up_interruptible(&lock_data->lock_queue);
375                         lock_data->idle_has_lock = 0;
376                 }
377         }
378         spin_unlock_bh(&lock_data->spinlock);
379 }
380 EXPORT_SYMBOL(drm_idlelock_release);
381
382
383 int drm_i_have_hw_lock(struct drm_device *dev, struct drm_file *file_priv)
384 {
385         struct drm_master *master = file_priv->master;
386         return (file_priv->lock_count && master->lock.hw_lock &&
387                 _DRM_LOCK_IS_HELD(master->lock.hw_lock->lock) &&
388                 master->lock.file_priv == file_priv);
389 }
390
391 EXPORT_SYMBOL(drm_i_have_hw_lock);