drm_lock.c revision 152909 
1/* lock.c -- IOCTLs for locking -*- linux-c -*-
2 * Created: Tue Feb  2 08:37:54 1999 by faith@valinux.com
3 */
4/*-
5 * Copyright 1999 Precision Insight, Inc., Cedar Park, Texas.
6 * Copyright 2000 VA Linux Systems, Inc., Sunnyvale, California.
7 * All Rights Reserved.
8 *
9 * Permission is hereby granted, free of charge, to any person obtaining a
10 * copy of this software and associated documentation files (the "Software"),
11 * to deal in the Software without restriction, including without limitation
12 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
13 * and/or sell copies of the Software, and to permit persons to whom the
14 * Software is furnished to do so, subject to the following conditions:
15 *
16 * The above copyright notice and this permission notice (including the next
17 * paragraph) shall be included in all copies or substantial portions of the
18 * Software.
19 *
20 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
21 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
22 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
23 * VA LINUX SYSTEMS AND/OR ITS SUPPLIERS BE LIABLE FOR ANY CLAIM, DAMAGES OR
24 * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
25 * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
26 * OTHER DEALINGS IN THE SOFTWARE.
27 *
28 * Authors:
29 *    Rickard E. (Rik) Faith <faith@valinux.com>
30 *    Gareth Hughes <gareth@valinux.com>
31 *
32 */
33
34#include <sys/cdefs.h>
35__FBSDID("$FreeBSD: head/sys/dev/drm/drm_lock.c 152909 2005-11-28 23:13:57Z anholt $");
36
37#include "dev/drm/drmP.h"
38
39int drm_lock_take(__volatile__ unsigned int *lock, unsigned int context)
40{
41	unsigned int old, new;
42
43	do {
44		old = *lock;
45		if (old & _DRM_LOCK_HELD) new = old | _DRM_LOCK_CONT;
46		else			  new = context | _DRM_LOCK_HELD;
47	} while (!atomic_cmpset_int(lock, old, new));
48
49	if (_DRM_LOCKING_CONTEXT(old) == context) {
50		if (old & _DRM_LOCK_HELD) {
51			if (context != DRM_KERNEL_CONTEXT) {
52				DRM_ERROR("%d holds heavyweight lock\n",
53					  context);
54			}
55			return 0;
56		}
57	}
58	if (new == (context | _DRM_LOCK_HELD)) {
59				/* Have lock */
60		return 1;
61	}
62	return 0;
63}
64
65/* This takes a lock forcibly and hands it to context.	Should ONLY be used
66   inside *_unlock to give lock to kernel before calling *_dma_schedule. */
67int drm_lock_transfer(drm_device_t *dev,
68		       __volatile__ unsigned int *lock, unsigned int context)
69{
70	unsigned int old, new;
71
72	dev->lock.filp = NULL;
73	do {
74		old  = *lock;
75		new  = context | _DRM_LOCK_HELD;
76	} while (!atomic_cmpset_int(lock, old, new));
77
78	return 1;
79}
80
81int drm_lock_free(drm_device_t *dev,
82		   __volatile__ unsigned int *lock, unsigned int context)
83{
84	unsigned int old, new;
85
86	dev->lock.filp = NULL;
87	do {
88		old  = *lock;
89		new  = 0;
90	} while (!atomic_cmpset_int(lock, old, new));
91
92	if (_DRM_LOCK_IS_HELD(old) && _DRM_LOCKING_CONTEXT(old) != context) {
93		DRM_ERROR("%d freed heavyweight lock held by %d\n",
94			  context, _DRM_LOCKING_CONTEXT(old));
95		return 1;
96	}
97	DRM_WAKEUP_INT((void *)&dev->lock.lock_queue);
98	return 0;
99}
100
101int drm_lock(DRM_IOCTL_ARGS)
102{
103	DRM_DEVICE;
104        drm_lock_t lock;
105        int ret = 0;
106
107	DRM_COPY_FROM_USER_IOCTL(lock, (drm_lock_t *)data, sizeof(lock));
108
109        if (lock.context == DRM_KERNEL_CONTEXT) {
110                DRM_ERROR("Process %d using kernel context %d\n",
111		    DRM_CURRENTPID, lock.context);
112                return EINVAL;
113        }
114
115        DRM_DEBUG("%d (pid %d) requests lock (0x%08x), flags = 0x%08x\n",
116	    lock.context, DRM_CURRENTPID, dev->lock.hw_lock->lock, lock.flags);
117
118        if (dev->driver.use_dma_queue && lock.context < 0)
119                return EINVAL;
120
121	DRM_LOCK();
122	for (;;) {
123		if (drm_lock_take(&dev->lock.hw_lock->lock, lock.context)) {
124			dev->lock.filp = (void *)(uintptr_t)DRM_CURRENTPID;
125			dev->lock.lock_time = jiffies;
126			atomic_inc(&dev->counts[_DRM_STAT_LOCKS]);
127			break;  /* Got lock */
128		}
129
130		/* Contention */
131#if defined(__FreeBSD__) && __FreeBSD_version > 500000
132		ret = msleep((void *)&dev->lock.lock_queue, &dev->dev_lock,
133		    PZERO | PCATCH, "drmlk2", 0);
134#else
135		ret = tsleep((void *)&dev->lock.lock_queue, PZERO | PCATCH,
136		    "drmlk2", 0);
137#endif
138		if (ret != 0)
139			break;
140	}
141	DRM_UNLOCK();
142	DRM_DEBUG("%d %s\n", lock.context, ret ? "interrupted" : "has lock");
143
144	if (ret != 0)
145		return ret;
146
147	/* XXX: Add signal blocking here */
148
149	if (dev->driver.dma_quiescent != NULL &&
150	    (lock.flags & _DRM_LOCK_QUIESCENT))
151		dev->driver.dma_quiescent(dev);
152
153	return 0;
154}
155
156int drm_unlock(DRM_IOCTL_ARGS)
157{
158	DRM_DEVICE;
159	drm_lock_t lock;
160
161	DRM_COPY_FROM_USER_IOCTL(lock, (drm_lock_t *)data, sizeof(lock));
162
163	if (lock.context == DRM_KERNEL_CONTEXT) {
164		DRM_ERROR("Process %d using kernel context %d\n",
165		    DRM_CURRENTPID, lock.context);
166		return EINVAL;
167	}
168
169	atomic_inc(&dev->counts[_DRM_STAT_UNLOCKS]);
170
171	DRM_LOCK();
172	drm_lock_transfer(dev, &dev->lock.hw_lock->lock, DRM_KERNEL_CONTEXT);
173
174	if (drm_lock_free(dev, &dev->lock.hw_lock->lock, DRM_KERNEL_CONTEXT)) {
175		DRM_ERROR("\n");
176	}
177	DRM_UNLOCK();
178
179	return 0;
180}
181