Merge branch 'x86-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git...
[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         int ret = 0;
56
57         ++file_priv->lock_count;
58
59         if (lock->context == DRM_KERNEL_CONTEXT) {
60                 DRM_ERROR("Process %d using kernel context %d\n",
61                           task_pid_nr(current), lock->context);
62                 return -EINVAL;
63         }
64
65         DRM_DEBUG("%d (pid %d) requests lock (0x%08x), flags = 0x%08x\n",
66                   lock->context, task_pid_nr(current),
67                   dev->lock.hw_lock->lock, lock->flags);
68
69         if (drm_core_check_feature(dev, DRIVER_DMA_QUEUE))
70                 if (lock->context < 0)
71                         return -EINVAL;
72
73         add_wait_queue(&dev->lock.lock_queue, &entry);
74         spin_lock_bh(&dev->lock.spinlock);
75         dev->lock.user_waiters++;
76         spin_unlock_bh(&dev->lock.spinlock);
77         for (;;) {
78                 __set_current_state(TASK_INTERRUPTIBLE);
79                 if (!dev->lock.hw_lock) {
80                         /* Device has been unregistered */
81                         ret = -EINTR;
82                         break;
83                 }
84                 if (drm_lock_take(&dev->lock, lock->context)) {
85                         dev->lock.file_priv = file_priv;
86                         dev->lock.lock_time = jiffies;
87                         atomic_inc(&dev->counts[_DRM_STAT_LOCKS]);
88                         break;  /* Got lock */
89                 }
90
91                 /* Contention */
92                 schedule();
93                 if (signal_pending(current)) {
94                         ret = -ERESTARTSYS;
95                         break;
96                 }
97         }
98         spin_lock_bh(&dev->lock.spinlock);
99         dev->lock.user_waiters--;
100         spin_unlock_bh(&dev->lock.spinlock);
101         __set_current_state(TASK_RUNNING);
102         remove_wait_queue(&dev->lock.lock_queue, &entry);
103
104         DRM_DEBUG("%d %s\n", lock->context,
105                   ret ? "interrupted" : "has lock");
106         if (ret) return ret;
107
108         /* don't set the block all signals on the master process for now 
109          * really probably not the correct answer but lets us debug xkb
110          * xserver for now */
111         if (!file_priv->master) {
112                 sigemptyset(&dev->sigmask);
113                 sigaddset(&dev->sigmask, SIGSTOP);
114                 sigaddset(&dev->sigmask, SIGTSTP);
115                 sigaddset(&dev->sigmask, SIGTTIN);
116                 sigaddset(&dev->sigmask, SIGTTOU);
117                 dev->sigdata.context = lock->context;
118                 dev->sigdata.lock = dev->lock.hw_lock;
119                 block_all_signals(drm_notifier, &dev->sigdata, &dev->sigmask);
120         }
121
122         if (dev->driver->dma_ready && (lock->flags & _DRM_LOCK_READY))
123                 dev->driver->dma_ready(dev);
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         if (dev->driver->kernel_context_switch &&
135             dev->last_context != lock->context) {
136                 dev->driver->kernel_context_switch(dev, dev->last_context,
137                                                    lock->context);
138         }
139
140         return 0;
141 }
142
143 /**
144  * Unlock ioctl.
145  *
146  * \param inode device inode.
147  * \param file_priv DRM file private.
148  * \param cmd command.
149  * \param arg user argument, pointing to a drm_lock structure.
150  * \return zero on success or negative number on failure.
151  *
152  * Transfer and free the lock.
153  */
154 int drm_unlock(struct drm_device *dev, void *data, struct drm_file *file_priv)
155 {
156         struct drm_lock *lock = data;
157
158         if (lock->context == DRM_KERNEL_CONTEXT) {
159                 DRM_ERROR("Process %d using kernel context %d\n",
160                           task_pid_nr(current), lock->context);
161                 return -EINVAL;
162         }
163
164         atomic_inc(&dev->counts[_DRM_STAT_UNLOCKS]);
165
166         /* kernel_context_switch isn't used by any of the x86 drm
167          * modules but is required by the Sparc driver.
168          */
169         if (dev->driver->kernel_context_switch_unlock)
170                 dev->driver->kernel_context_switch_unlock(dev);
171         else {
172                 if (drm_lock_free(&dev->lock,lock->context)) {
173                         /* FIXME: Should really bail out here. */
174                 }
175         }
176
177         unblock_all_signals();
178         return 0;
179 }
180
181 /**
182  * Take the heavyweight lock.
183  *
184  * \param lock lock pointer.
185  * \param context locking context.
186  * \return one if the lock is held, or zero otherwise.
187  *
188  * Attempt to mark the lock as held by the given context, via the \p cmpxchg instruction.
189  */
190 int drm_lock_take(struct drm_lock_data *lock_data,
191                   unsigned int context)
192 {
193         unsigned int old, new, prev;
194         volatile unsigned int *lock = &lock_data->hw_lock->lock;
195
196         spin_lock_bh(&lock_data->spinlock);
197         do {
198                 old = *lock;
199                 if (old & _DRM_LOCK_HELD)
200                         new = old | _DRM_LOCK_CONT;
201                 else {
202                         new = context | _DRM_LOCK_HELD |
203                                 ((lock_data->user_waiters + lock_data->kernel_waiters > 1) ?
204                                  _DRM_LOCK_CONT : 0);
205                 }
206                 prev = cmpxchg(lock, old, new);
207         } while (prev != old);
208         spin_unlock_bh(&lock_data->spinlock);
209
210         if (_DRM_LOCKING_CONTEXT(old) == context) {
211                 if (old & _DRM_LOCK_HELD) {
212                         if (context != DRM_KERNEL_CONTEXT) {
213                                 DRM_ERROR("%d holds heavyweight lock\n",
214                                           context);
215                         }
216                         return 0;
217                 }
218         }
219
220         if ((_DRM_LOCKING_CONTEXT(new)) == context && (new & _DRM_LOCK_HELD)) {
221                 /* Have lock */
222                 return 1;
223         }
224         return 0;
225 }
226 EXPORT_SYMBOL(drm_lock_take);
227
228 /**
229  * This takes a lock forcibly and hands it to context.  Should ONLY be used
230  * inside *_unlock to give lock to kernel before calling *_dma_schedule.
231  *
232  * \param dev DRM device.
233  * \param lock lock pointer.
234  * \param context locking context.
235  * \return always one.
236  *
237  * Resets the lock file pointer.
238  * Marks the lock as held by the given context, via the \p cmpxchg instruction.
239  */
240 static int drm_lock_transfer(struct drm_lock_data *lock_data,
241                              unsigned int context)
242 {
243         unsigned int old, new, prev;
244         volatile unsigned int *lock = &lock_data->hw_lock->lock;
245
246         lock_data->file_priv = NULL;
247         do {
248                 old = *lock;
249                 new = context | _DRM_LOCK_HELD;
250                 prev = cmpxchg(lock, old, new);
251         } while (prev != old);
252         return 1;
253 }
254
255 /**
256  * Free lock.
257  *
258  * \param dev DRM device.
259  * \param lock lock.
260  * \param context context.
261  *
262  * Resets the lock file pointer.
263  * Marks the lock as not held, via the \p cmpxchg instruction. Wakes any task
264  * waiting on the lock queue.
265  */
266 int drm_lock_free(struct drm_lock_data *lock_data, unsigned int context)
267 {
268         unsigned int old, new, prev;
269         volatile unsigned int *lock = &lock_data->hw_lock->lock;
270
271         spin_lock_bh(&lock_data->spinlock);
272         if (lock_data->kernel_waiters != 0) {
273                 drm_lock_transfer(lock_data, 0);
274                 lock_data->idle_has_lock = 1;
275                 spin_unlock_bh(&lock_data->spinlock);
276                 return 1;
277         }
278         spin_unlock_bh(&lock_data->spinlock);
279
280         do {
281                 old = *lock;
282                 new = _DRM_LOCKING_CONTEXT(old);
283                 prev = cmpxchg(lock, old, new);
284         } while (prev != old);
285
286         if (_DRM_LOCK_IS_HELD(old) && _DRM_LOCKING_CONTEXT(old) != context) {
287                 DRM_ERROR("%d freed heavyweight lock held by %d\n",
288                           context, _DRM_LOCKING_CONTEXT(old));
289                 return 1;
290         }
291         wake_up_interruptible(&lock_data->lock_queue);
292         return 0;
293 }
294 EXPORT_SYMBOL(drm_lock_free);
295
296 /**
297  * If we get here, it means that the process has called DRM_IOCTL_LOCK
298  * without calling DRM_IOCTL_UNLOCK.
299  *
300  * If the lock is not held, then let the signal proceed as usual.  If the lock
301  * is held, then set the contended flag and keep the signal blocked.
302  *
303  * \param priv pointer to a drm_sigdata structure.
304  * \return one if the signal should be delivered normally, or zero if the
305  * signal should be blocked.
306  */
307 static int drm_notifier(void *priv)
308 {
309         struct drm_sigdata *s = (struct drm_sigdata *) priv;
310         unsigned int old, new, prev;
311
312         /* Allow signal delivery if lock isn't held */
313         if (!s->lock || !_DRM_LOCK_IS_HELD(s->lock->lock)
314             || _DRM_LOCKING_CONTEXT(s->lock->lock) != s->context)
315                 return 1;
316
317         /* Otherwise, set flag to force call to
318            drmUnlock */
319         do {
320                 old = s->lock->lock;
321                 new = old | _DRM_LOCK_CONT;
322                 prev = cmpxchg(&s->lock->lock, old, new);
323         } while (prev != old);
324         return 0;
325 }
326
327 /**
328  * This function returns immediately and takes the hw lock
329  * with the kernel context if it is free, otherwise it gets the highest priority when and if
330  * it is eventually released.
331  *
332  * This guarantees that the kernel will _eventually_ have the lock _unless_ it is held
333  * by a blocked process. (In the latter case an explicit wait for the hardware lock would cause
334  * a deadlock, which is why the "idlelock" was invented).
335  *
336  * This should be sufficient to wait for GPU idle without
337  * having to worry about starvation.
338  */
339
340 void drm_idlelock_take(struct drm_lock_data *lock_data)
341 {
342         int ret = 0;
343
344         spin_lock_bh(&lock_data->spinlock);
345         lock_data->kernel_waiters++;
346         if (!lock_data->idle_has_lock) {
347
348                 spin_unlock_bh(&lock_data->spinlock);
349                 ret = drm_lock_take(lock_data, DRM_KERNEL_CONTEXT);
350                 spin_lock_bh(&lock_data->spinlock);
351
352                 if (ret == 1)
353                         lock_data->idle_has_lock = 1;
354         }
355         spin_unlock_bh(&lock_data->spinlock);
356 }
357 EXPORT_SYMBOL(drm_idlelock_take);
358
359 void drm_idlelock_release(struct drm_lock_data *lock_data)
360 {
361         unsigned int old, prev;
362         volatile unsigned int *lock = &lock_data->hw_lock->lock;
363
364         spin_lock_bh(&lock_data->spinlock);
365         if (--lock_data->kernel_waiters == 0) {
366                 if (lock_data->idle_has_lock) {
367                         do {
368                                 old = *lock;
369                                 prev = cmpxchg(lock, old, DRM_KERNEL_CONTEXT);
370                         } while (prev != old);
371                         wake_up_interruptible(&lock_data->lock_queue);
372                         lock_data->idle_has_lock = 0;
373                 }
374         }
375         spin_unlock_bh(&lock_data->spinlock);
376 }
377 EXPORT_SYMBOL(drm_idlelock_release);
378
379
380 int drm_i_have_hw_lock(struct drm_device *dev, struct drm_file *file_priv)
381 {
382         return (file_priv->lock_count && dev->lock.hw_lock &&
383                 _DRM_LOCK_IS_HELD(dev->lock.hw_lock->lock) &&
384                 dev->lock.file_priv == file_priv);
385 }
386
387 EXPORT_SYMBOL(drm_i_have_hw_lock);