1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
|
/*-
* Copyright 1999 Precision Insight, Inc., Cedar Park, Texas.
* Copyright 2000 VA Linux Systems, Inc., Sunnyvale, California.
* All Rights Reserved.
*
* Permission is hereby granted, free of charge, to any person obtaining a
* copy of this software and associated documentation files (the "Software"),
* to deal in the Software without restriction, including without limitation
* the rights to use, copy, modify, merge, publish, distribute, sublicense,
* and/or sell copies of the Software, and to permit persons to whom the
* Software is furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice (including the next
* paragraph) shall be included in all copies or substantial portions of the
* Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
* VA LINUX SYSTEMS AND/OR ITS SUPPLIERS BE LIABLE FOR ANY CLAIM, DAMAGES OR
* OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
* ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
* OTHER DEALINGS IN THE SOFTWARE.
*
* Authors:
* Rickard E. (Rik) Faith <faith@valinux.com>
* Gareth Hughes <gareth@valinux.com>
*
*/
/** @file drm_lock.c
* Implementation of the ioctls and other support code for dealing with the
* hardware lock.
*
* The DRM hardware lock is a shared structure between the kernel and userland.
*
* On uncontended access where the new context was the last context, the
* client may take the lock without dropping down into the kernel, using atomic
* compare-and-set.
*
* If the client finds during compare-and-set that it was not the last owner
* of the lock, it calls the DRM lock ioctl, which may sleep waiting for the
* lock, and may have side-effects of kernel-managed context switching.
*
* When the client releases the lock, if the lock is marked as being contended
* by another client, then the DRM unlock ioctl is called so that the
* contending client may be woken up.
*/
#include "drmP.h"
int
drm_lock_take(struct drm_lock_data *lock_data, unsigned int context)
{
volatile unsigned int *lock = &lock_data->hw_lock->lock;
unsigned int old, new;
do {
old = *lock;
if (old & _DRM_LOCK_HELD)
new = old | _DRM_LOCK_CONT;
else
new = context | _DRM_LOCK_HELD;
} while (!atomic_cmpset_int(lock, old, new));
if (_DRM_LOCKING_CONTEXT(old) == context) {
if (old & _DRM_LOCK_HELD) {
if (context != DRM_KERNEL_CONTEXT) {
DRM_ERROR("%d holds heavyweight lock\n",
context);
}
return 0;
}
}
if (new == (context | _DRM_LOCK_HELD)) {
/* Have lock */
return 1;
}
return 0;
}
int
drm_lock_free(struct drm_lock_data *lock_data, unsigned int context)
{
volatile unsigned int *lock = &lock_data->hw_lock->lock;
unsigned int old, new;
mtx_enter(&lock_data->spinlock);
lock_data->file_priv = NULL;
do {
old = *lock;
new = 0;
} while (!atomic_cmpset_int(lock, old, new));
mtx_leave(&lock_data->spinlock);
if (_DRM_LOCK_IS_HELD(old) && _DRM_LOCKING_CONTEXT(old) != context) {
DRM_ERROR("%d freed heavyweight lock held by %d\n",
context, _DRM_LOCKING_CONTEXT(old));
return 1;
}
wakeup(lock_data);
return 0;
}
int
drm_lock(struct drm_device *dev, void *data, struct drm_file *file_priv)
{
struct drm_lock *lock = data;
int ret = 0;
if (lock->context == DRM_KERNEL_CONTEXT) {
DRM_ERROR("Process %d using kernel context %d\n",
DRM_CURRENTPID, lock->context);
return EINVAL;
}
DRM_DEBUG("%d (pid %d) requests lock (0x%08x), flags = 0x%08x\n",
lock->context, DRM_CURRENTPID, dev->lock.hw_lock->lock,
lock->flags);
mtx_enter(&dev->lock.spinlock);
for (;;) {
if (drm_lock_take(&dev->lock, lock->context)) {
dev->lock.file_priv = file_priv;
dev->lock.lock_time = jiffies;
break; /* Got lock */
}
/* Contention */
ret = msleep(&dev->lock, &dev->lock.spinlock,
PZERO | PCATCH, "drmlkq", 0);
if (ret != 0)
break;
}
mtx_leave(&dev->lock.spinlock);
DRM_DEBUG("%d %s\n", lock->context, ret ? "interrupted" : "has lock");
if (ret != 0)
return ret;
/* XXX: Add signal blocking here */
if (dev->driver->dma_quiescent != NULL &&
(lock->flags & _DRM_LOCK_QUIESCENT))
dev->driver->dma_quiescent(dev);
return 0;
}
int
drm_unlock(struct drm_device *dev, void *data, struct drm_file *file_priv)
{
struct drm_lock *lock = data;
if (lock->context == DRM_KERNEL_CONTEXT) {
DRM_ERROR("Process %d using kernel context %d\n",
DRM_CURRENTPID, lock->context);
return EINVAL;
}
/* Check that the context unlock being requested actually matches
* who currently holds the lock.
*/
if (!_DRM_LOCK_IS_HELD(dev->lock.hw_lock->lock) ||
_DRM_LOCKING_CONTEXT(dev->lock.hw_lock->lock) != lock->context)
return EINVAL;
if (drm_lock_free(&dev->lock, lock->context)) {
DRM_ERROR("\n");
}
return 0;
}
|
