5 * \author Rickard E. (Rik) Faith <faith@valinux.com>
6 * \author Gareth Hughes <gareth@valinux.com>
10 * Created: Tue Feb 2 08:37:54 1999 by faith@valinux.com
12 * Copyright 1999 Precision Insight, Inc., Cedar Park, Texas.
13 * Copyright 2000 VA Linux Systems, Inc., Sunnyvale, California.
14 * All Rights Reserved.
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:
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
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.
36 #include <linux/export.h>
37 #include <linux/sched/signal.h>
40 #include "drm_legacy.h"
41 #include "drm_internal.h"
44 static int drm_lock_take(struct drm_lock_data
*lock_data
, unsigned int context
);
47 * Take the heavyweight lock.
49 * \param lock lock pointer.
50 * \param context locking context.
51 * \return one if the lock is held, or zero otherwise.
53 * Attempt to mark the lock as held by the given context, via the \p cmpxchg instruction.
56 int drm_lock_take(struct drm_lock_data
*lock_data
,
59 unsigned int old
, new, prev
;
60 volatile unsigned int *lock
= &lock_data
->hw_lock
->lock
;
62 spin_lock_bh(&lock_data
->spinlock
);
65 if (old
& _DRM_LOCK_HELD
)
66 new = old
| _DRM_LOCK_CONT
;
68 new = context
| _DRM_LOCK_HELD
|
69 ((lock_data
->user_waiters
+ lock_data
->kernel_waiters
> 1) ?
72 prev
= cmpxchg(lock
, old
, new);
73 } while (prev
!= old
);
74 spin_unlock_bh(&lock_data
->spinlock
);
76 if (_DRM_LOCKING_CONTEXT(old
) == context
) {
77 if (old
& _DRM_LOCK_HELD
) {
78 if (context
!= DRM_KERNEL_CONTEXT
) {
79 DRM_ERROR("%d holds heavyweight lock\n",
86 if ((_DRM_LOCKING_CONTEXT(new)) == context
&& (new & _DRM_LOCK_HELD
)) {
94 * This takes a lock forcibly and hands it to context. Should ONLY be used
95 * inside *_unlock to give lock to kernel before calling *_dma_schedule.
97 * \param dev DRM device.
98 * \param lock lock pointer.
99 * \param context locking context.
100 * \return always one.
102 * Resets the lock file pointer.
103 * Marks the lock as held by the given context, via the \p cmpxchg instruction.
105 static int drm_lock_transfer(struct drm_lock_data
*lock_data
,
106 unsigned int context
)
108 unsigned int old
, new, prev
;
109 volatile unsigned int *lock
= &lock_data
->hw_lock
->lock
;
111 lock_data
->file_priv
= NULL
;
114 new = context
| _DRM_LOCK_HELD
;
115 prev
= cmpxchg(lock
, old
, new);
116 } while (prev
!= old
);
120 static int drm_legacy_lock_free(struct drm_lock_data
*lock_data
,
121 unsigned int context
)
123 unsigned int old
, new, prev
;
124 volatile unsigned int *lock
= &lock_data
->hw_lock
->lock
;
126 spin_lock_bh(&lock_data
->spinlock
);
127 if (lock_data
->kernel_waiters
!= 0) {
128 drm_lock_transfer(lock_data
, 0);
129 lock_data
->idle_has_lock
= 1;
130 spin_unlock_bh(&lock_data
->spinlock
);
133 spin_unlock_bh(&lock_data
->spinlock
);
137 new = _DRM_LOCKING_CONTEXT(old
);
138 prev
= cmpxchg(lock
, old
, new);
139 } while (prev
!= old
);
141 if (_DRM_LOCK_IS_HELD(old
) && _DRM_LOCKING_CONTEXT(old
) != context
) {
142 DRM_ERROR("%d freed heavyweight lock held by %d\n",
143 context
, _DRM_LOCKING_CONTEXT(old
));
146 wake_up_interruptible(&lock_data
->lock_queue
);
154 * \param inode device inode.
155 * \param file_priv DRM file private.
156 * \param cmd command.
157 * \param arg user argument, pointing to a drm_lock structure.
158 * \return zero on success or negative number on failure.
160 * Add the current task to the lock wait queue, and attempt to take to lock.
162 int drm_legacy_lock(struct drm_device
*dev
, void *data
,
163 struct drm_file
*file_priv
)
166 DECLARE_WAITQUEUE(entry
, current
);
167 struct drm_lock
*lock
= data
;
168 struct drm_master
*master
= file_priv
->master
;
171 if (!drm_core_check_feature(dev
, DRIVER_LEGACY
))
174 ++file_priv
->lock_count
;
176 if (lock
->context
== DRM_KERNEL_CONTEXT
) {
177 DRM_ERROR("Process %d using kernel context %d\n",
178 task_pid_nr(current
), lock
->context
);
182 DRM_DEBUG("%d (pid %d) requests lock (0x%08x), flags = 0x%08x\n",
183 lock
->context
, task_pid_nr(current
),
184 master
->lock
.hw_lock
? master
->lock
.hw_lock
->lock
: -1,
187 add_wait_queue(&master
->lock
.lock_queue
, &entry
);
188 spin_lock_bh(&master
->lock
.spinlock
);
189 master
->lock
.user_waiters
++;
190 spin_unlock_bh(&master
->lock
.spinlock
);
193 __set_current_state(TASK_INTERRUPTIBLE
);
194 if (!master
->lock
.hw_lock
) {
195 /* Device has been unregistered */
196 send_sig(SIGTERM
, current
, 0);
200 if (drm_lock_take(&master
->lock
, lock
->context
)) {
201 master
->lock
.file_priv
= file_priv
;
202 master
->lock
.lock_time
= jiffies
;
203 break; /* Got lock */
207 mutex_unlock(&drm_global_mutex
);
209 mutex_lock(&drm_global_mutex
);
210 if (signal_pending(current
)) {
215 spin_lock_bh(&master
->lock
.spinlock
);
216 master
->lock
.user_waiters
--;
217 spin_unlock_bh(&master
->lock
.spinlock
);
218 __set_current_state(TASK_RUNNING
);
219 remove_wait_queue(&master
->lock
.lock_queue
, &entry
);
221 DRM_DEBUG("%d %s\n", lock
->context
,
222 ret
? "interrupted" : "has lock");
225 /* don't set the block all signals on the master process for now
226 * really probably not the correct answer but lets us debug xkb
228 if (!drm_is_current_master(file_priv
)) {
229 dev
->sigdata
.context
= lock
->context
;
230 dev
->sigdata
.lock
= master
->lock
.hw_lock
;
233 if (dev
->driver
->dma_quiescent
&& (lock
->flags
& _DRM_LOCK_QUIESCENT
))
235 if (dev
->driver
->dma_quiescent(dev
)) {
236 DRM_DEBUG("%d waiting for DMA quiescent\n",
249 * \param inode device inode.
250 * \param file_priv DRM file private.
251 * \param cmd command.
252 * \param arg user argument, pointing to a drm_lock structure.
253 * \return zero on success or negative number on failure.
255 * Transfer and free the lock.
257 int drm_legacy_unlock(struct drm_device
*dev
, void *data
, struct drm_file
*file_priv
)
260 struct drm_lock
*lock
= data
;
261 struct drm_master
*master
= file_priv
->master
;
263 if (!drm_core_check_feature(dev
, DRIVER_LEGACY
))
266 if (lock
->context
== DRM_KERNEL_CONTEXT
) {
267 DRM_ERROR("Process %d using kernel context %d\n",
268 task_pid_nr(current
), lock
->context
);
272 if (drm_legacy_lock_free(&master
->lock
, lock
->context
)) {
273 /* FIXME: Should really bail out here. */
282 * This function returns immediately and takes the hw lock
283 * with the kernel context if it is free, otherwise it gets the highest priority when and if
284 * it is eventually released.
286 * This guarantees that the kernel will _eventually_ have the lock _unless_ it is held
287 * by a blocked process. (In the latter case an explicit wait for the hardware lock would cause
288 * a deadlock, which is why the "idlelock" was invented).
290 * This should be sufficient to wait for GPU idle without
291 * having to worry about starvation.
294 void drm_legacy_idlelock_take(struct drm_lock_data
*lock_data
)
298 spin_lock_bh(&lock_data
->spinlock
);
299 lock_data
->kernel_waiters
++;
300 if (!lock_data
->idle_has_lock
) {
302 spin_unlock_bh(&lock_data
->spinlock
);
303 ret
= drm_lock_take(lock_data
, DRM_KERNEL_CONTEXT
);
304 spin_lock_bh(&lock_data
->spinlock
);
307 lock_data
->idle_has_lock
= 1;
309 spin_unlock_bh(&lock_data
->spinlock
);
311 EXPORT_SYMBOL(drm_legacy_idlelock_take
);
313 void drm_legacy_idlelock_release(struct drm_lock_data
*lock_data
)
315 unsigned int old
, prev
;
316 volatile unsigned int *lock
= &lock_data
->hw_lock
->lock
;
318 spin_lock_bh(&lock_data
->spinlock
);
319 if (--lock_data
->kernel_waiters
== 0) {
320 if (lock_data
->idle_has_lock
) {
323 prev
= cmpxchg(lock
, old
, DRM_KERNEL_CONTEXT
);
324 } while (prev
!= old
);
325 wake_up_interruptible(&lock_data
->lock_queue
);
326 lock_data
->idle_has_lock
= 0;
329 spin_unlock_bh(&lock_data
->spinlock
);
331 EXPORT_SYMBOL(drm_legacy_idlelock_release
);
333 static int drm_legacy_i_have_hw_lock(struct drm_device
*dev
,
334 struct drm_file
*file_priv
)
336 struct drm_master
*master
= file_priv
->master
;
337 return (file_priv
->lock_count
&& master
->lock
.hw_lock
&&
338 _DRM_LOCK_IS_HELD(master
->lock
.hw_lock
->lock
) &&
339 master
->lock
.file_priv
== file_priv
);
343 void drm_legacy_lock_release(struct drm_device
*dev
, struct file
*filp
)
346 struct drm_file
*file_priv
= filp
->private_data
;
348 /* if the master has gone away we can't do anything with the lock */
352 if (drm_legacy_i_have_hw_lock(dev
, file_priv
)) {
353 DRM_DEBUG("File %p released, freeing lock for context %d\n",
354 filp
, _DRM_LOCKING_CONTEXT(file_priv
->master
->lock
.hw_lock
->lock
));
355 drm_legacy_lock_free(&file_priv
->master
->lock
,
356 _DRM_LOCKING_CONTEXT(file_priv
->master
->lock
.hw_lock
->lock
));