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
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
|
/*
* usema.c: software semaphore driver (see IRIX's usema(7M))
* written 1997 Mike Shaver (shaver@neon.ingenia.ca)
* 1997 Miguel de Icaza (miguel@kernel.org)
*
* This file contains the implementation of /dev/usemaclone,
* the devices used by IRIX's us* semaphore routines.
*
* /dev/usemaclone is used to create a new semaphore device, and then
* the semaphore is manipulated via ioctls.
*
* At least for the zero-contention case, lock set and unset as well
* as semaphore P and V are done in userland, which makes things a
* little bit better. I suspect that the ioctls are used to register
* the process as blocking, etc.
*
* Much inspiration and structure stolen from Miguel's shmiq work.
*
* For more information:
* usema(7m), usinit(3p), usnewsema(3p)
* /usr/include/sys/usioctl.h
*
*/
#include <linux/fs.h>
#include <linux/miscdevice.h>
#include <linux/sched.h>
#include <linux/file.h>
#include <linux/major.h>
#include <linux/poll.h>
#include <linux/string.h>
#include <linux/dcache.h>
#include <linux/mm.h>
#include <linux/slab.h>
#include <linux/smp_lock.h>
#include "usema.h"
#include <asm/usioctl.h>
#include <asm/mman.h>
#include <asm/uaccess.h>
struct irix_usema {
struct file *filp;
wait_queue_head_t proc_list;
};
static int
sgi_usema_attach (usattach_t * attach, struct irix_usema *usema)
{
int newfd;
newfd = get_unused_fd();
if (newfd < 0)
return newfd;
get_file(usema->filp);
fd_install(newfd, usema->filp);
/* Is that it? */
printk("UIOCATTACHSEMA: new usema fd is %d", newfd);
return newfd;
}
static int
sgi_usemaclone_ioctl(struct inode *inode, struct file *file, unsigned int cmd,
unsigned long arg)
{
struct irix_usema *usema = file->private_data;
int retval;
printk("[%s:%d] wants ioctl 0x%xd (arg 0x%lx)",
current->comm, current->pid, cmd, arg);
switch(cmd) {
case UIOCATTACHSEMA: {
/* They pass us information about the semaphore to
which they wish to be attached, and we create&return
a new fd corresponding to the appropriate semaphore.
*/
usattach_t *attach = (usattach_t *)arg;
retval = verify_area(VERIFY_READ, attach, sizeof(usattach_t));
if (retval) {
printk("[%s:%d] sgi_usema_ioctl(UIOCATTACHSEMA): "
"verify_area failure",
current->comm, current->pid);
return retval;
}
if (usema == 0)
return -EINVAL;
printk("UIOCATTACHSEMA: attaching usema %p to process %d\n",
usema, current->pid);
/* XXX what is attach->us_handle for? */
return sgi_usema_attach(attach, usema);
break;
}
case UIOCABLOCK: /* XXX make `async' */
case UIOCNOIBLOCK: /* XXX maybe? */
case UIOCBLOCK: {
/* Block this process on the semaphore */
usattach_t *attach = (usattach_t *)arg;
retval = verify_area(VERIFY_READ, attach, sizeof(usattach_t));
if (retval) {
printk("[%s:%d] sgi_usema_ioctl(UIOC*BLOCK): "
"verify_area failure",
current->comm, current->pid);
return retval;
}
printk("UIOC*BLOCK: putting process %d to sleep on usema %p",
current->pid, usema);
if (cmd == UIOCNOIBLOCK)
interruptible_sleep_on(&usema->proc_list);
else
sleep_on(&usema->proc_list);
return 0;
}
case UIOCAUNBLOCK: /* XXX make `async' */
case UIOCUNBLOCK: {
/* Wake up all process waiting on this semaphore */
usattach_t *attach = (usattach_t *)arg;
retval = verify_area(VERIFY_READ, attach, sizeof(usattach_t));
if (retval) {
printk("[%s:%d] sgi_usema_ioctl(UIOC*BLOCK): "
"verify_area failure",
current->comm, current->pid);
return retval;
}
printk("[%s:%d] releasing usema %p",
current->comm, current->pid, usema);
wake_up(&usema->proc_list);
return 0;
}
}
return -ENOSYS;
}
static unsigned int
sgi_usemaclone_poll(struct file *filp, poll_table *wait)
{
struct irix_usema *usema = filp->private_data;
printk("[%s:%d] wants to poll usema %p",
current->comm, current->pid, usema);
return 0;
}
static int
sgi_usemaclone_open(struct inode *inode, struct file *filp)
{
struct irix_usema *usema;
usema = kmalloc (sizeof (struct irix_usema), GFP_KERNEL);
if (!usema)
return -ENOMEM;
usema->filp = filp;
init_waitqueue_head(&usema->proc_list);
filp->private_data = usema;
return 0;
}
static int
sgi_usemaclone_release(struct inode *inode, struct file *filp)
{
return 0;
}
struct file_operations sgi_usemaclone_fops = {
poll: sgi_usemaclone_poll,
ioctl: sgi_usemaclone_ioctl,
open: sgi_usemaclone_open,
release: sgi_usemaclone_release,
};
static struct miscdevice dev_usemaclone = {
SGI_USEMACLONE, "usemaclone", &sgi_usemaclone_fops
};
void
usema_init(void)
{
printk("usemaclone misc device registered (minor: %d)\n",
SGI_USEMACLONE);
misc_register(&dev_usemaclone);
}
|
