ia64/linux-2.6.18-xen.hg

view drivers/char/misc.c @ 893:f994bfe9b93b

linux/blktap2: reduce TLB flush scope

c/s 885 added very coarse TLB flushing. Since these flushes always
follow single page updates, single page flushes (when available) are
sufficient.

Signed-off-by: Jan Beulich <jbeulich@novell.com>
author Keir Fraser <keir.fraser@citrix.com>
date Thu Jun 04 10:32:57 2009 +0100 (2009-06-04)
parents 831230e53067
children
line source
1 /*
2 * linux/drivers/char/misc.c
3 *
4 * Generic misc open routine by Johan Myreen
5 *
6 * Based on code from Linus
7 *
8 * Teemu Rantanen's Microsoft Busmouse support and Derrick Cole's
9 * changes incorporated into 0.97pl4
10 * by Peter Cervasio (pete%q106fm.uucp@wupost.wustl.edu) (08SEP92)
11 * See busmouse.c for particulars.
12 *
13 * Made things a lot mode modular - easy to compile in just one or two
14 * of the misc drivers, as they are now completely independent. Linus.
15 *
16 * Support for loadable modules. 8-Sep-95 Philip Blundell <pjb27@cam.ac.uk>
17 *
18 * Fixed a failing symbol register to free the device registration
19 * Alan Cox <alan@lxorguk.ukuu.org.uk> 21-Jan-96
20 *
21 * Dynamic minors and /proc/mice by Alessandro Rubini. 26-Mar-96
22 *
23 * Renamed to misc and miscdevice to be more accurate. Alan Cox 26-Mar-96
24 *
25 * Handling of mouse minor numbers for kerneld:
26 * Idea by Jacques Gelinas <jack@solucorp.qc.ca>,
27 * adapted by Bjorn Ekwall <bj0rn@blox.se>
28 * corrected by Alan Cox <alan@lxorguk.ukuu.org.uk>
29 *
30 * Changes for kmod (from kerneld):
31 * Cyrus Durgin <cider@speakeasy.org>
32 *
33 * Added devfs support. Richard Gooch <rgooch@atnf.csiro.au> 10-Jan-1998
34 */
36 #include <linux/module.h>
38 #include <linux/fs.h>
39 #include <linux/errno.h>
40 #include <linux/miscdevice.h>
41 #include <linux/kernel.h>
42 #include <linux/major.h>
43 #include <linux/slab.h>
44 #include <linux/proc_fs.h>
45 #include <linux/seq_file.h>
46 #include <linux/stat.h>
47 #include <linux/init.h>
48 #include <linux/device.h>
49 #include <linux/tty.h>
50 #include <linux/kmod.h>
52 /*
53 * Head entry for the doubly linked miscdevice list
54 */
55 static LIST_HEAD(misc_list);
56 static DECLARE_MUTEX(misc_sem);
58 /*
59 * Assigned numbers, used for dynamic minors
60 */
61 #define DYNAMIC_MINORS 64 /* like dynamic majors */
62 static unsigned char misc_minors[DYNAMIC_MINORS / 8];
64 extern int pmu_device_init(void);
66 #ifdef CONFIG_PROC_FS
67 static void *misc_seq_start(struct seq_file *seq, loff_t *pos)
68 {
69 struct miscdevice *p;
70 loff_t off = 0;
72 down(&misc_sem);
73 list_for_each_entry(p, &misc_list, list) {
74 if (*pos == off++)
75 return p;
76 }
77 return NULL;
78 }
80 static void *misc_seq_next(struct seq_file *seq, void *v, loff_t *pos)
81 {
82 struct list_head *n = ((struct miscdevice *)v)->list.next;
84 ++*pos;
86 return (n != &misc_list) ? list_entry(n, struct miscdevice, list)
87 : NULL;
88 }
90 static void misc_seq_stop(struct seq_file *seq, void *v)
91 {
92 up(&misc_sem);
93 }
95 static int misc_seq_show(struct seq_file *seq, void *v)
96 {
97 const struct miscdevice *p = v;
99 seq_printf(seq, "%3i %s\n", p->minor, p->name ? p->name : "");
100 return 0;
101 }
104 static struct seq_operations misc_seq_ops = {
105 .start = misc_seq_start,
106 .next = misc_seq_next,
107 .stop = misc_seq_stop,
108 .show = misc_seq_show,
109 };
111 static int misc_seq_open(struct inode *inode, struct file *file)
112 {
113 return seq_open(file, &misc_seq_ops);
114 }
116 static const struct file_operations misc_proc_fops = {
117 .owner = THIS_MODULE,
118 .open = misc_seq_open,
119 .read = seq_read,
120 .llseek = seq_lseek,
121 .release = seq_release,
122 };
123 #endif
125 static int misc_open(struct inode * inode, struct file * file)
126 {
127 int minor = iminor(inode);
128 struct miscdevice *c;
129 int err = -ENODEV;
130 const struct file_operations *old_fops, *new_fops = NULL;
132 down(&misc_sem);
134 list_for_each_entry(c, &misc_list, list) {
135 if (c->minor == minor) {
136 new_fops = fops_get(c->fops);
137 break;
138 }
139 }
141 if (!new_fops) {
142 up(&misc_sem);
143 request_module("char-major-%d-%d", MISC_MAJOR, minor);
144 down(&misc_sem);
146 list_for_each_entry(c, &misc_list, list) {
147 if (c->minor == minor) {
148 new_fops = fops_get(c->fops);
149 break;
150 }
151 }
152 if (!new_fops)
153 goto fail;
154 }
156 err = 0;
157 old_fops = file->f_op;
158 file->f_op = new_fops;
159 if (file->f_op->open) {
160 err=file->f_op->open(inode,file);
161 if (err) {
162 fops_put(file->f_op);
163 file->f_op = fops_get(old_fops);
164 }
165 }
166 fops_put(old_fops);
167 fail:
168 up(&misc_sem);
169 return err;
170 }
172 /*
173 * TODO for 2.7:
174 * - add a struct kref to struct miscdevice and make all usages of
175 * them dynamic.
176 */
177 static struct class *misc_class;
179 static const struct file_operations misc_fops = {
180 .owner = THIS_MODULE,
181 .open = misc_open,
182 };
185 /**
186 * misc_register - register a miscellaneous device
187 * @misc: device structure
188 *
189 * Register a miscellaneous device with the kernel. If the minor
190 * number is set to %MISC_DYNAMIC_MINOR a minor number is assigned
191 * and placed in the minor field of the structure. For other cases
192 * the minor number requested is used.
193 *
194 * The structure passed is linked into the kernel and may not be
195 * destroyed until it has been unregistered.
196 *
197 * A zero is returned on success and a negative errno code for
198 * failure.
199 */
201 int misc_register(struct miscdevice * misc)
202 {
203 struct miscdevice *c;
204 dev_t dev;
205 int err = 0;
207 down(&misc_sem);
208 list_for_each_entry(c, &misc_list, list) {
209 if (c->minor == misc->minor) {
210 up(&misc_sem);
211 return -EBUSY;
212 }
213 }
215 if (misc->minor == MISC_DYNAMIC_MINOR) {
216 int i = DYNAMIC_MINORS;
217 while (--i >= 0)
218 if ( (misc_minors[i>>3] & (1 << (i&7))) == 0)
219 break;
220 if (i<0) {
221 up(&misc_sem);
222 return -EBUSY;
223 }
224 misc->minor = i;
225 }
227 if (misc->minor < DYNAMIC_MINORS)
228 misc_minors[misc->minor >> 3] |= 1 << (misc->minor & 7);
229 dev = MKDEV(MISC_MAJOR, misc->minor);
231 misc->class = class_device_create(misc_class, NULL, dev, misc->dev,
232 "%s", misc->name);
233 if (IS_ERR(misc->class)) {
234 err = PTR_ERR(misc->class);
235 goto out;
236 }
238 /*
239 * Add it to the front, so that later devices can "override"
240 * earlier defaults
241 */
242 list_add(&misc->list, &misc_list);
243 out:
244 up(&misc_sem);
245 return err;
246 }
248 /**
249 * misc_deregister - unregister a miscellaneous device
250 * @misc: device to unregister
251 *
252 * Unregister a miscellaneous device that was previously
253 * successfully registered with misc_register(). Success
254 * is indicated by a zero return, a negative errno code
255 * indicates an error.
256 */
258 int misc_deregister(struct miscdevice * misc)
259 {
260 int i = misc->minor;
262 if (list_empty(&misc->list))
263 return -EINVAL;
265 down(&misc_sem);
266 list_del(&misc->list);
267 class_device_destroy(misc_class, MKDEV(MISC_MAJOR, misc->minor));
268 if (i < DYNAMIC_MINORS && i>0) {
269 misc_minors[i>>3] &= ~(1 << (misc->minor & 7));
270 }
271 up(&misc_sem);
272 return 0;
273 }
275 EXPORT_SYMBOL(misc_register);
276 EXPORT_SYMBOL(misc_deregister);
278 static int __init misc_init(void)
279 {
280 #ifdef CONFIG_PROC_FS
281 struct proc_dir_entry *ent;
283 ent = create_proc_entry("misc", 0, NULL);
284 if (ent)
285 ent->proc_fops = &misc_proc_fops;
286 #endif
287 misc_class = class_create(THIS_MODULE, "misc");
288 if (IS_ERR(misc_class))
289 return PTR_ERR(misc_class);
291 if (register_chrdev(MISC_MAJOR,"misc",&misc_fops)) {
292 printk("unable to get major %d for misc devices\n",
293 MISC_MAJOR);
294 class_destroy(misc_class);
295 return -EIO;
296 }
297 return 0;
298 }
299 subsys_initcall(misc_init);