1 // SPDX-License-Identifier: GPL-2.0 1 // SPDX-License-Identifier: GPL-2.0
2 /* 2 /*
3 * linux/fs/char_dev.c 3 * linux/fs/char_dev.c
4 * 4 *
5 * Copyright (C) 1991, 1992 Linus Torvalds 5 * Copyright (C) 1991, 1992 Linus Torvalds
6 */ 6 */
7 7
8 #include <linux/init.h> 8 #include <linux/init.h>
9 #include <linux/fs.h> 9 #include <linux/fs.h>
10 #include <linux/kdev_t.h> 10 #include <linux/kdev_t.h>
11 #include <linux/slab.h> 11 #include <linux/slab.h>
12 #include <linux/string.h> 12 #include <linux/string.h>
13 13
14 #include <linux/major.h> 14 #include <linux/major.h>
15 #include <linux/errno.h> 15 #include <linux/errno.h>
16 #include <linux/module.h> 16 #include <linux/module.h>
17 #include <linux/seq_file.h> 17 #include <linux/seq_file.h>
18 18
19 #include <linux/kobject.h> 19 #include <linux/kobject.h>
20 #include <linux/kobj_map.h> 20 #include <linux/kobj_map.h>
21 #include <linux/cdev.h> 21 #include <linux/cdev.h>
22 #include <linux/mutex.h> 22 #include <linux/mutex.h>
23 #include <linux/backing-dev.h> 23 #include <linux/backing-dev.h>
24 #include <linux/tty.h> 24 #include <linux/tty.h>
25 25
26 #include "internal.h" 26 #include "internal.h"
27 27
28 static struct kobj_map *cdev_map __ro_after_in !! 28 static struct kobj_map *cdev_map;
29 29
30 static DEFINE_MUTEX(chrdevs_lock); 30 static DEFINE_MUTEX(chrdevs_lock);
31 31
32 #define CHRDEV_MAJOR_HASH_SIZE 255 32 #define CHRDEV_MAJOR_HASH_SIZE 255
33 33
34 static struct char_device_struct { 34 static struct char_device_struct {
35 struct char_device_struct *next; 35 struct char_device_struct *next;
36 unsigned int major; 36 unsigned int major;
37 unsigned int baseminor; 37 unsigned int baseminor;
38 int minorct; 38 int minorct;
39 char name[64]; 39 char name[64];
40 struct cdev *cdev; /* wil 40 struct cdev *cdev; /* will die */
41 } *chrdevs[CHRDEV_MAJOR_HASH_SIZE]; 41 } *chrdevs[CHRDEV_MAJOR_HASH_SIZE];
42 42
43 /* index in the above */ 43 /* index in the above */
44 static inline int major_to_index(unsigned majo 44 static inline int major_to_index(unsigned major)
45 { 45 {
46 return major % CHRDEV_MAJOR_HASH_SIZE; 46 return major % CHRDEV_MAJOR_HASH_SIZE;
47 } 47 }
48 48
49 #ifdef CONFIG_PROC_FS 49 #ifdef CONFIG_PROC_FS
50 50
51 void chrdev_show(struct seq_file *f, off_t off 51 void chrdev_show(struct seq_file *f, off_t offset)
52 { 52 {
53 struct char_device_struct *cd; 53 struct char_device_struct *cd;
54 54
55 mutex_lock(&chrdevs_lock); 55 mutex_lock(&chrdevs_lock);
56 for (cd = chrdevs[major_to_index(offse 56 for (cd = chrdevs[major_to_index(offset)]; cd; cd = cd->next) {
57 if (cd->major == offset) 57 if (cd->major == offset)
58 seq_printf(f, "%3d %s\ 58 seq_printf(f, "%3d %s\n", cd->major, cd->name);
59 } 59 }
60 mutex_unlock(&chrdevs_lock); 60 mutex_unlock(&chrdevs_lock);
61 } 61 }
62 62
63 #endif /* CONFIG_PROC_FS */ 63 #endif /* CONFIG_PROC_FS */
64 64
65 static int find_dynamic_major(void) 65 static int find_dynamic_major(void)
66 { 66 {
67 int i; 67 int i;
68 struct char_device_struct *cd; 68 struct char_device_struct *cd;
69 69
70 for (i = ARRAY_SIZE(chrdevs)-1; i >= C 70 for (i = ARRAY_SIZE(chrdevs)-1; i >= CHRDEV_MAJOR_DYN_END; i--) {
71 if (chrdevs[i] == NULL) 71 if (chrdevs[i] == NULL)
72 return i; 72 return i;
73 } 73 }
74 74
75 for (i = CHRDEV_MAJOR_DYN_EXT_START; 75 for (i = CHRDEV_MAJOR_DYN_EXT_START;
76 i >= CHRDEV_MAJOR_DYN_EXT_END; i- 76 i >= CHRDEV_MAJOR_DYN_EXT_END; i--) {
77 for (cd = chrdevs[major_to_ind 77 for (cd = chrdevs[major_to_index(i)]; cd; cd = cd->next)
78 if (cd->major == i) 78 if (cd->major == i)
79 break; 79 break;
80 80
81 if (cd == NULL) 81 if (cd == NULL)
82 return i; 82 return i;
83 } 83 }
84 84
85 return -EBUSY; 85 return -EBUSY;
86 } 86 }
87 87
88 /* 88 /*
89 * Register a single major with a specified mi 89 * Register a single major with a specified minor range.
90 * 90 *
91 * If major == 0 this function will dynamicall 91 * If major == 0 this function will dynamically allocate an unused major.
92 * If major > 0 this function will attempt to 92 * If major > 0 this function will attempt to reserve the range of minors
93 * with given major. 93 * with given major.
94 * 94 *
95 */ 95 */
96 static struct char_device_struct * 96 static struct char_device_struct *
97 __register_chrdev_region(unsigned int major, u 97 __register_chrdev_region(unsigned int major, unsigned int baseminor,
98 int minorct, const 98 int minorct, const char *name)
99 { 99 {
100 struct char_device_struct *cd, *curr, 100 struct char_device_struct *cd, *curr, *prev = NULL;
101 int ret; 101 int ret;
102 int i; 102 int i;
103 103
104 if (major >= CHRDEV_MAJOR_MAX) { 104 if (major >= CHRDEV_MAJOR_MAX) {
105 pr_err("CHRDEV \"%s\" major re 105 pr_err("CHRDEV \"%s\" major requested (%u) is greater than the maximum (%u)\n",
106 name, major, CHRDEV_MAJ 106 name, major, CHRDEV_MAJOR_MAX-1);
107 return ERR_PTR(-EINVAL); 107 return ERR_PTR(-EINVAL);
108 } 108 }
109 109
110 if (minorct > MINORMASK + 1 - basemino 110 if (minorct > MINORMASK + 1 - baseminor) {
111 pr_err("CHRDEV \"%s\" minor ra 111 pr_err("CHRDEV \"%s\" minor range requested (%u-%u) is out of range of maximum range (%u-%u) for a single major\n",
112 name, baseminor, basem 112 name, baseminor, baseminor + minorct - 1, 0, MINORMASK);
113 return ERR_PTR(-EINVAL); 113 return ERR_PTR(-EINVAL);
114 } 114 }
115 115
116 cd = kzalloc(sizeof(struct char_device 116 cd = kzalloc(sizeof(struct char_device_struct), GFP_KERNEL);
117 if (cd == NULL) 117 if (cd == NULL)
118 return ERR_PTR(-ENOMEM); 118 return ERR_PTR(-ENOMEM);
119 119
120 mutex_lock(&chrdevs_lock); 120 mutex_lock(&chrdevs_lock);
121 121
122 if (major == 0) { 122 if (major == 0) {
123 ret = find_dynamic_major(); 123 ret = find_dynamic_major();
124 if (ret < 0) { 124 if (ret < 0) {
125 pr_err("CHRDEV \"%s\" 125 pr_err("CHRDEV \"%s\" dynamic allocation region is full\n",
126 name); 126 name);
127 goto out; 127 goto out;
128 } 128 }
129 major = ret; 129 major = ret;
130 } 130 }
131 131
132 ret = -EBUSY; 132 ret = -EBUSY;
133 i = major_to_index(major); 133 i = major_to_index(major);
134 for (curr = chrdevs[i]; curr; prev = c 134 for (curr = chrdevs[i]; curr; prev = curr, curr = curr->next) {
135 if (curr->major < major) 135 if (curr->major < major)
136 continue; 136 continue;
137 137
138 if (curr->major > major) 138 if (curr->major > major)
139 break; 139 break;
140 140
141 if (curr->baseminor + curr->mi 141 if (curr->baseminor + curr->minorct <= baseminor)
142 continue; 142 continue;
143 143
144 if (curr->baseminor >= basemin 144 if (curr->baseminor >= baseminor + minorct)
145 break; 145 break;
146 146
147 goto out; 147 goto out;
148 } 148 }
149 149
150 cd->major = major; 150 cd->major = major;
151 cd->baseminor = baseminor; 151 cd->baseminor = baseminor;
152 cd->minorct = minorct; 152 cd->minorct = minorct;
153 strscpy(cd->name, name, sizeof(cd->nam !! 153 strlcpy(cd->name, name, sizeof(cd->name));
154 154
155 if (!prev) { 155 if (!prev) {
156 cd->next = curr; 156 cd->next = curr;
157 chrdevs[i] = cd; 157 chrdevs[i] = cd;
158 } else { 158 } else {
159 cd->next = prev->next; 159 cd->next = prev->next;
160 prev->next = cd; 160 prev->next = cd;
161 } 161 }
162 162
163 mutex_unlock(&chrdevs_lock); 163 mutex_unlock(&chrdevs_lock);
164 return cd; 164 return cd;
165 out: 165 out:
166 mutex_unlock(&chrdevs_lock); 166 mutex_unlock(&chrdevs_lock);
167 kfree(cd); 167 kfree(cd);
168 return ERR_PTR(ret); 168 return ERR_PTR(ret);
169 } 169 }
170 170
171 static struct char_device_struct * 171 static struct char_device_struct *
172 __unregister_chrdev_region(unsigned major, uns 172 __unregister_chrdev_region(unsigned major, unsigned baseminor, int minorct)
173 { 173 {
174 struct char_device_struct *cd = NULL, 174 struct char_device_struct *cd = NULL, **cp;
175 int i = major_to_index(major); 175 int i = major_to_index(major);
176 176
177 mutex_lock(&chrdevs_lock); 177 mutex_lock(&chrdevs_lock);
178 for (cp = &chrdevs[i]; *cp; cp = &(*cp 178 for (cp = &chrdevs[i]; *cp; cp = &(*cp)->next)
179 if ((*cp)->major == major && 179 if ((*cp)->major == major &&
180 (*cp)->baseminor == basemi 180 (*cp)->baseminor == baseminor &&
181 (*cp)->minorct == minorct) 181 (*cp)->minorct == minorct)
182 break; 182 break;
183 if (*cp) { 183 if (*cp) {
184 cd = *cp; 184 cd = *cp;
185 *cp = cd->next; 185 *cp = cd->next;
186 } 186 }
187 mutex_unlock(&chrdevs_lock); 187 mutex_unlock(&chrdevs_lock);
188 return cd; 188 return cd;
189 } 189 }
190 190
191 /** 191 /**
192 * register_chrdev_region() - register a range 192 * register_chrdev_region() - register a range of device numbers
193 * @from: the first in the desired range of de 193 * @from: the first in the desired range of device numbers; must include
194 * the major number. 194 * the major number.
195 * @count: the number of consecutive device nu 195 * @count: the number of consecutive device numbers required
196 * @name: the name of the device or driver. 196 * @name: the name of the device or driver.
197 * 197 *
198 * Return value is zero on success, a negative 198 * Return value is zero on success, a negative error code on failure.
199 */ 199 */
200 int register_chrdev_region(dev_t from, unsigne 200 int register_chrdev_region(dev_t from, unsigned count, const char *name)
201 { 201 {
202 struct char_device_struct *cd; 202 struct char_device_struct *cd;
203 dev_t to = from + count; 203 dev_t to = from + count;
204 dev_t n, next; 204 dev_t n, next;
205 205
206 for (n = from; n < to; n = next) { 206 for (n = from; n < to; n = next) {
207 next = MKDEV(MAJOR(n)+1, 0); 207 next = MKDEV(MAJOR(n)+1, 0);
208 if (next > to) 208 if (next > to)
209 next = to; 209 next = to;
210 cd = __register_chrdev_region( 210 cd = __register_chrdev_region(MAJOR(n), MINOR(n),
211 next - n, name) 211 next - n, name);
212 if (IS_ERR(cd)) 212 if (IS_ERR(cd))
213 goto fail; 213 goto fail;
214 } 214 }
215 return 0; 215 return 0;
216 fail: 216 fail:
217 to = n; 217 to = n;
218 for (n = from; n < to; n = next) { 218 for (n = from; n < to; n = next) {
219 next = MKDEV(MAJOR(n)+1, 0); 219 next = MKDEV(MAJOR(n)+1, 0);
220 kfree(__unregister_chrdev_regi 220 kfree(__unregister_chrdev_region(MAJOR(n), MINOR(n), next - n));
221 } 221 }
222 return PTR_ERR(cd); 222 return PTR_ERR(cd);
223 } 223 }
224 224
225 /** 225 /**
226 * alloc_chrdev_region() - register a range of 226 * alloc_chrdev_region() - register a range of char device numbers
227 * @dev: output parameter for first assigned n 227 * @dev: output parameter for first assigned number
228 * @baseminor: first of the requested range of 228 * @baseminor: first of the requested range of minor numbers
229 * @count: the number of minor numbers require 229 * @count: the number of minor numbers required
230 * @name: the name of the associated device or 230 * @name: the name of the associated device or driver
231 * 231 *
232 * Allocates a range of char device numbers. 232 * Allocates a range of char device numbers. The major number will be
233 * chosen dynamically, and returned (along wit 233 * chosen dynamically, and returned (along with the first minor number)
234 * in @dev. Returns zero or a negative error 234 * in @dev. Returns zero or a negative error code.
235 */ 235 */
236 int alloc_chrdev_region(dev_t *dev, unsigned b 236 int alloc_chrdev_region(dev_t *dev, unsigned baseminor, unsigned count,
237 const char *name) 237 const char *name)
238 { 238 {
239 struct char_device_struct *cd; 239 struct char_device_struct *cd;
240 cd = __register_chrdev_region(0, basem 240 cd = __register_chrdev_region(0, baseminor, count, name);
241 if (IS_ERR(cd)) 241 if (IS_ERR(cd))
242 return PTR_ERR(cd); 242 return PTR_ERR(cd);
243 *dev = MKDEV(cd->major, cd->baseminor) 243 *dev = MKDEV(cd->major, cd->baseminor);
244 return 0; 244 return 0;
245 } 245 }
246 246
247 /** 247 /**
248 * __register_chrdev() - create and register a 248 * __register_chrdev() - create and register a cdev occupying a range of minors
249 * @major: major device number or 0 for dynami 249 * @major: major device number or 0 for dynamic allocation
250 * @baseminor: first of the requested range of 250 * @baseminor: first of the requested range of minor numbers
251 * @count: the number of minor numbers require 251 * @count: the number of minor numbers required
252 * @name: name of this range of devices 252 * @name: name of this range of devices
253 * @fops: file operations associated with this 253 * @fops: file operations associated with this devices
254 * 254 *
255 * If @major == 0 this functions will dynamica 255 * If @major == 0 this functions will dynamically allocate a major and return
256 * its number. 256 * its number.
257 * 257 *
258 * If @major > 0 this function will attempt to 258 * If @major > 0 this function will attempt to reserve a device with the given
259 * major number and will return zero on succes 259 * major number and will return zero on success.
260 * 260 *
261 * Returns a -ve errno on failure. 261 * Returns a -ve errno on failure.
262 * 262 *
263 * The name of this device has nothing to do w 263 * The name of this device has nothing to do with the name of the device in
264 * /dev. It only helps to keep track of the di 264 * /dev. It only helps to keep track of the different owners of devices. If
265 * your module name has only one type of devic 265 * your module name has only one type of devices it's ok to use e.g. the name
266 * of the module here. 266 * of the module here.
267 */ 267 */
268 int __register_chrdev(unsigned int major, unsi 268 int __register_chrdev(unsigned int major, unsigned int baseminor,
269 unsigned int count, cons 269 unsigned int count, const char *name,
270 const struct file_operat 270 const struct file_operations *fops)
271 { 271 {
272 struct char_device_struct *cd; 272 struct char_device_struct *cd;
273 struct cdev *cdev; 273 struct cdev *cdev;
274 int err = -ENOMEM; 274 int err = -ENOMEM;
275 275
276 cd = __register_chrdev_region(major, b 276 cd = __register_chrdev_region(major, baseminor, count, name);
277 if (IS_ERR(cd)) 277 if (IS_ERR(cd))
278 return PTR_ERR(cd); 278 return PTR_ERR(cd);
279 279
280 cdev = cdev_alloc(); 280 cdev = cdev_alloc();
281 if (!cdev) 281 if (!cdev)
282 goto out2; 282 goto out2;
283 283
284 cdev->owner = fops->owner; 284 cdev->owner = fops->owner;
285 cdev->ops = fops; 285 cdev->ops = fops;
286 kobject_set_name(&cdev->kobj, "%s", na 286 kobject_set_name(&cdev->kobj, "%s", name);
287 287
288 err = cdev_add(cdev, MKDEV(cd->major, 288 err = cdev_add(cdev, MKDEV(cd->major, baseminor), count);
289 if (err) 289 if (err)
290 goto out; 290 goto out;
291 291
292 cd->cdev = cdev; 292 cd->cdev = cdev;
293 293
294 return major ? 0 : cd->major; 294 return major ? 0 : cd->major;
295 out: 295 out:
296 kobject_put(&cdev->kobj); 296 kobject_put(&cdev->kobj);
297 out2: 297 out2:
298 kfree(__unregister_chrdev_region(cd->m 298 kfree(__unregister_chrdev_region(cd->major, baseminor, count));
299 return err; 299 return err;
300 } 300 }
301 301
302 /** 302 /**
303 * unregister_chrdev_region() - unregister a r 303 * unregister_chrdev_region() - unregister a range of device numbers
304 * @from: the first in the range of numbers to 304 * @from: the first in the range of numbers to unregister
305 * @count: the number of device numbers to unr 305 * @count: the number of device numbers to unregister
306 * 306 *
307 * This function will unregister a range of @c 307 * This function will unregister a range of @count device numbers,
308 * starting with @from. The caller should nor 308 * starting with @from. The caller should normally be the one who
309 * allocated those numbers in the first place. 309 * allocated those numbers in the first place...
310 */ 310 */
311 void unregister_chrdev_region(dev_t from, unsi 311 void unregister_chrdev_region(dev_t from, unsigned count)
312 { 312 {
313 dev_t to = from + count; 313 dev_t to = from + count;
314 dev_t n, next; 314 dev_t n, next;
315 315
316 for (n = from; n < to; n = next) { 316 for (n = from; n < to; n = next) {
317 next = MKDEV(MAJOR(n)+1, 0); 317 next = MKDEV(MAJOR(n)+1, 0);
318 if (next > to) 318 if (next > to)
319 next = to; 319 next = to;
320 kfree(__unregister_chrdev_regi 320 kfree(__unregister_chrdev_region(MAJOR(n), MINOR(n), next - n));
321 } 321 }
322 } 322 }
323 323
324 /** 324 /**
325 * __unregister_chrdev - unregister and destro 325 * __unregister_chrdev - unregister and destroy a cdev
326 * @major: major device number 326 * @major: major device number
327 * @baseminor: first of the range of minor num 327 * @baseminor: first of the range of minor numbers
328 * @count: the number of minor numbers this cd 328 * @count: the number of minor numbers this cdev is occupying
329 * @name: name of this range of devices 329 * @name: name of this range of devices
330 * 330 *
331 * Unregister and destroy the cdev occupying t 331 * Unregister and destroy the cdev occupying the region described by
332 * @major, @baseminor and @count. This functi 332 * @major, @baseminor and @count. This function undoes what
333 * __register_chrdev() did. 333 * __register_chrdev() did.
334 */ 334 */
335 void __unregister_chrdev(unsigned int major, u 335 void __unregister_chrdev(unsigned int major, unsigned int baseminor,
336 unsigned int count, c 336 unsigned int count, const char *name)
337 { 337 {
338 struct char_device_struct *cd; 338 struct char_device_struct *cd;
339 339
340 cd = __unregister_chrdev_region(major, 340 cd = __unregister_chrdev_region(major, baseminor, count);
341 if (cd && cd->cdev) 341 if (cd && cd->cdev)
342 cdev_del(cd->cdev); 342 cdev_del(cd->cdev);
343 kfree(cd); 343 kfree(cd);
344 } 344 }
345 345
346 static DEFINE_SPINLOCK(cdev_lock); 346 static DEFINE_SPINLOCK(cdev_lock);
347 347
348 static struct kobject *cdev_get(struct cdev *p 348 static struct kobject *cdev_get(struct cdev *p)
349 { 349 {
350 struct module *owner = p->owner; 350 struct module *owner = p->owner;
351 struct kobject *kobj; 351 struct kobject *kobj;
352 352
353 if (!try_module_get(owner)) !! 353 if (owner && !try_module_get(owner))
354 return NULL; 354 return NULL;
355 kobj = kobject_get_unless_zero(&p->kob 355 kobj = kobject_get_unless_zero(&p->kobj);
356 if (!kobj) 356 if (!kobj)
357 module_put(owner); 357 module_put(owner);
358 return kobj; 358 return kobj;
359 } 359 }
360 360
361 void cdev_put(struct cdev *p) 361 void cdev_put(struct cdev *p)
362 { 362 {
363 if (p) { 363 if (p) {
364 struct module *owner = p->owne 364 struct module *owner = p->owner;
365 kobject_put(&p->kobj); 365 kobject_put(&p->kobj);
366 module_put(owner); 366 module_put(owner);
367 } 367 }
368 } 368 }
369 369
370 /* 370 /*
371 * Called every time a character special file 371 * Called every time a character special file is opened
372 */ 372 */
373 static int chrdev_open(struct inode *inode, st 373 static int chrdev_open(struct inode *inode, struct file *filp)
374 { 374 {
375 const struct file_operations *fops; 375 const struct file_operations *fops;
376 struct cdev *p; 376 struct cdev *p;
377 struct cdev *new = NULL; 377 struct cdev *new = NULL;
378 int ret = 0; 378 int ret = 0;
379 379
380 spin_lock(&cdev_lock); 380 spin_lock(&cdev_lock);
381 p = inode->i_cdev; 381 p = inode->i_cdev;
382 if (!p) { 382 if (!p) {
383 struct kobject *kobj; 383 struct kobject *kobj;
384 int idx; 384 int idx;
385 spin_unlock(&cdev_lock); 385 spin_unlock(&cdev_lock);
386 kobj = kobj_lookup(cdev_map, i 386 kobj = kobj_lookup(cdev_map, inode->i_rdev, &idx);
387 if (!kobj) 387 if (!kobj)
388 return -ENXIO; 388 return -ENXIO;
389 new = container_of(kobj, struc 389 new = container_of(kobj, struct cdev, kobj);
390 spin_lock(&cdev_lock); 390 spin_lock(&cdev_lock);
391 /* Check i_cdev again in case 391 /* Check i_cdev again in case somebody beat us to it while
392 we dropped the lock. */ 392 we dropped the lock. */
393 p = inode->i_cdev; 393 p = inode->i_cdev;
394 if (!p) { 394 if (!p) {
395 inode->i_cdev = p = ne 395 inode->i_cdev = p = new;
396 list_add(&inode->i_dev 396 list_add(&inode->i_devices, &p->list);
397 new = NULL; 397 new = NULL;
398 } else if (!cdev_get(p)) 398 } else if (!cdev_get(p))
399 ret = -ENXIO; 399 ret = -ENXIO;
400 } else if (!cdev_get(p)) 400 } else if (!cdev_get(p))
401 ret = -ENXIO; 401 ret = -ENXIO;
402 spin_unlock(&cdev_lock); 402 spin_unlock(&cdev_lock);
403 cdev_put(new); 403 cdev_put(new);
404 if (ret) 404 if (ret)
405 return ret; 405 return ret;
406 406
407 ret = -ENXIO; 407 ret = -ENXIO;
408 fops = fops_get(p->ops); 408 fops = fops_get(p->ops);
409 if (!fops) 409 if (!fops)
410 goto out_cdev_put; 410 goto out_cdev_put;
411 411
412 replace_fops(filp, fops); 412 replace_fops(filp, fops);
413 if (filp->f_op->open) { 413 if (filp->f_op->open) {
414 ret = filp->f_op->open(inode, 414 ret = filp->f_op->open(inode, filp);
415 if (ret) 415 if (ret)
416 goto out_cdev_put; 416 goto out_cdev_put;
417 } 417 }
418 418
419 return 0; 419 return 0;
420 420
421 out_cdev_put: 421 out_cdev_put:
422 cdev_put(p); 422 cdev_put(p);
423 return ret; 423 return ret;
424 } 424 }
425 425
426 void cd_forget(struct inode *inode) 426 void cd_forget(struct inode *inode)
427 { 427 {
428 spin_lock(&cdev_lock); 428 spin_lock(&cdev_lock);
429 list_del_init(&inode->i_devices); 429 list_del_init(&inode->i_devices);
430 inode->i_cdev = NULL; 430 inode->i_cdev = NULL;
431 inode->i_mapping = &inode->i_data; 431 inode->i_mapping = &inode->i_data;
432 spin_unlock(&cdev_lock); 432 spin_unlock(&cdev_lock);
433 } 433 }
434 434
435 static void cdev_purge(struct cdev *cdev) 435 static void cdev_purge(struct cdev *cdev)
436 { 436 {
437 spin_lock(&cdev_lock); 437 spin_lock(&cdev_lock);
438 while (!list_empty(&cdev->list)) { 438 while (!list_empty(&cdev->list)) {
439 struct inode *inode; 439 struct inode *inode;
440 inode = container_of(cdev->lis 440 inode = container_of(cdev->list.next, struct inode, i_devices);
441 list_del_init(&inode->i_device 441 list_del_init(&inode->i_devices);
442 inode->i_cdev = NULL; 442 inode->i_cdev = NULL;
443 } 443 }
444 spin_unlock(&cdev_lock); 444 spin_unlock(&cdev_lock);
445 } 445 }
446 446
447 /* 447 /*
448 * Dummy default file-operations: the only thi 448 * Dummy default file-operations: the only thing this does
449 * is contain the open that then fills in the 449 * is contain the open that then fills in the correct operations
450 * depending on the special file... 450 * depending on the special file...
451 */ 451 */
452 const struct file_operations def_chr_fops = { 452 const struct file_operations def_chr_fops = {
453 .open = chrdev_open, 453 .open = chrdev_open,
454 .llseek = noop_llseek, 454 .llseek = noop_llseek,
455 }; 455 };
456 456
457 static struct kobject *exact_match(dev_t dev, 457 static struct kobject *exact_match(dev_t dev, int *part, void *data)
458 { 458 {
459 struct cdev *p = data; 459 struct cdev *p = data;
460 return &p->kobj; 460 return &p->kobj;
461 } 461 }
462 462
463 static int exact_lock(dev_t dev, void *data) 463 static int exact_lock(dev_t dev, void *data)
464 { 464 {
465 struct cdev *p = data; 465 struct cdev *p = data;
466 return cdev_get(p) ? 0 : -1; 466 return cdev_get(p) ? 0 : -1;
467 } 467 }
468 468
469 /** 469 /**
470 * cdev_add() - add a char device to the syste 470 * cdev_add() - add a char device to the system
471 * @p: the cdev structure for the device 471 * @p: the cdev structure for the device
472 * @dev: the first device number for which thi 472 * @dev: the first device number for which this device is responsible
473 * @count: the number of consecutive minor num 473 * @count: the number of consecutive minor numbers corresponding to this
474 * device 474 * device
475 * 475 *
476 * cdev_add() adds the device represented by @ 476 * cdev_add() adds the device represented by @p to the system, making it
477 * live immediately. A negative error code is 477 * live immediately. A negative error code is returned on failure.
478 */ 478 */
479 int cdev_add(struct cdev *p, dev_t dev, unsign 479 int cdev_add(struct cdev *p, dev_t dev, unsigned count)
480 { 480 {
481 int error; 481 int error;
482 482
483 p->dev = dev; 483 p->dev = dev;
484 p->count = count; 484 p->count = count;
485 485
486 if (WARN_ON(dev == WHITEOUT_DEV)) { !! 486 if (WARN_ON(dev == WHITEOUT_DEV))
487 error = -EBUSY; !! 487 return -EBUSY;
488 goto err; <<
489 } <<
490 488
491 error = kobj_map(cdev_map, dev, count, 489 error = kobj_map(cdev_map, dev, count, NULL,
492 exact_match, exact_lo 490 exact_match, exact_lock, p);
493 if (error) 491 if (error)
494 goto err; !! 492 return error;
495 493
496 kobject_get(p->kobj.parent); 494 kobject_get(p->kobj.parent);
497 495
498 return 0; 496 return 0;
499 <<
500 err: <<
501 kfree_const(p->kobj.name); <<
502 p->kobj.name = NULL; <<
503 return error; <<
504 } 497 }
505 498
506 /** 499 /**
507 * cdev_set_parent() - set the parent kobject 500 * cdev_set_parent() - set the parent kobject for a char device
508 * @p: the cdev structure 501 * @p: the cdev structure
509 * @kobj: the kobject to take a reference to 502 * @kobj: the kobject to take a reference to
510 * 503 *
511 * cdev_set_parent() sets a parent kobject whi 504 * cdev_set_parent() sets a parent kobject which will be referenced
512 * appropriately so the parent is not freed be 505 * appropriately so the parent is not freed before the cdev. This
513 * should be called before cdev_add. 506 * should be called before cdev_add.
514 */ 507 */
515 void cdev_set_parent(struct cdev *p, struct ko 508 void cdev_set_parent(struct cdev *p, struct kobject *kobj)
516 { 509 {
517 WARN_ON(!kobj->state_initialized); 510 WARN_ON(!kobj->state_initialized);
518 p->kobj.parent = kobj; 511 p->kobj.parent = kobj;
519 } 512 }
520 513
521 /** 514 /**
522 * cdev_device_add() - add a char device and i 515 * cdev_device_add() - add a char device and it's corresponding
523 * struct device, linkink 516 * struct device, linkink
524 * @dev: the device structure 517 * @dev: the device structure
525 * @cdev: the cdev structure 518 * @cdev: the cdev structure
526 * 519 *
527 * cdev_device_add() adds the char device repr 520 * cdev_device_add() adds the char device represented by @cdev to the system,
528 * just as cdev_add does. It then adds @dev to 521 * just as cdev_add does. It then adds @dev to the system using device_add
529 * The dev_t for the char device will be taken 522 * The dev_t for the char device will be taken from the struct device which
530 * needs to be initialized first. This helper 523 * needs to be initialized first. This helper function correctly takes a
531 * reference to the parent device so the paren 524 * reference to the parent device so the parent will not get released until
532 * all references to the cdev are released. 525 * all references to the cdev are released.
533 * 526 *
534 * This helper uses dev->devt for the device n 527 * This helper uses dev->devt for the device number. If it is not set
535 * it will not add the cdev and it will be equ 528 * it will not add the cdev and it will be equivalent to device_add.
536 * 529 *
537 * This function should be used whenever the s 530 * This function should be used whenever the struct cdev and the
538 * struct device are members of the same struc 531 * struct device are members of the same structure whose lifetime is
539 * managed by the struct device. 532 * managed by the struct device.
540 * 533 *
541 * NOTE: Callers must assume that userspace wa 534 * NOTE: Callers must assume that userspace was able to open the cdev and
542 * can call cdev fops callbacks at any time, e 535 * can call cdev fops callbacks at any time, even if this function fails.
543 */ 536 */
544 int cdev_device_add(struct cdev *cdev, struct 537 int cdev_device_add(struct cdev *cdev, struct device *dev)
545 { 538 {
546 int rc = 0; 539 int rc = 0;
547 540
548 if (dev->devt) { 541 if (dev->devt) {
549 cdev_set_parent(cdev, &dev->ko 542 cdev_set_parent(cdev, &dev->kobj);
550 543
551 rc = cdev_add(cdev, dev->devt, 544 rc = cdev_add(cdev, dev->devt, 1);
552 if (rc) 545 if (rc)
553 return rc; 546 return rc;
554 } 547 }
555 548
556 rc = device_add(dev); 549 rc = device_add(dev);
557 if (rc && dev->devt) !! 550 if (rc)
558 cdev_del(cdev); 551 cdev_del(cdev);
559 552
560 return rc; 553 return rc;
561 } 554 }
562 555
563 /** 556 /**
564 * cdev_device_del() - inverse of cdev_device_ 557 * cdev_device_del() - inverse of cdev_device_add
565 * @dev: the device structure 558 * @dev: the device structure
566 * @cdev: the cdev structure 559 * @cdev: the cdev structure
567 * 560 *
568 * cdev_device_del() is a helper function to c 561 * cdev_device_del() is a helper function to call cdev_del and device_del.
569 * It should be used whenever cdev_device_add 562 * It should be used whenever cdev_device_add is used.
570 * 563 *
571 * If dev->devt is not set it will not remove 564 * If dev->devt is not set it will not remove the cdev and will be equivalent
572 * to device_del. 565 * to device_del.
573 * 566 *
574 * NOTE: This guarantees that associated sysfs 567 * NOTE: This guarantees that associated sysfs callbacks are not running
575 * or runnable, however any cdevs already open 568 * or runnable, however any cdevs already open will remain and their fops
576 * will still be callable even after this func 569 * will still be callable even after this function returns.
577 */ 570 */
578 void cdev_device_del(struct cdev *cdev, struct 571 void cdev_device_del(struct cdev *cdev, struct device *dev)
579 { 572 {
580 device_del(dev); 573 device_del(dev);
581 if (dev->devt) 574 if (dev->devt)
582 cdev_del(cdev); 575 cdev_del(cdev);
583 } 576 }
584 577
585 static void cdev_unmap(dev_t dev, unsigned cou 578 static void cdev_unmap(dev_t dev, unsigned count)
586 { 579 {
587 kobj_unmap(cdev_map, dev, count); 580 kobj_unmap(cdev_map, dev, count);
588 } 581 }
589 582
590 /** 583 /**
591 * cdev_del() - remove a cdev from the system 584 * cdev_del() - remove a cdev from the system
592 * @p: the cdev structure to be removed 585 * @p: the cdev structure to be removed
593 * 586 *
594 * cdev_del() removes @p from the system, poss 587 * cdev_del() removes @p from the system, possibly freeing the structure
595 * itself. 588 * itself.
596 * 589 *
597 * NOTE: This guarantees that cdev device will 590 * NOTE: This guarantees that cdev device will no longer be able to be
598 * opened, however any cdevs already open will 591 * opened, however any cdevs already open will remain and their fops will
599 * still be callable even after cdev_del retur 592 * still be callable even after cdev_del returns.
600 */ 593 */
601 void cdev_del(struct cdev *p) 594 void cdev_del(struct cdev *p)
602 { 595 {
603 cdev_unmap(p->dev, p->count); 596 cdev_unmap(p->dev, p->count);
604 kobject_put(&p->kobj); 597 kobject_put(&p->kobj);
605 } 598 }
606 599
607 600
608 static void cdev_default_release(struct kobjec 601 static void cdev_default_release(struct kobject *kobj)
609 { 602 {
610 struct cdev *p = container_of(kobj, st 603 struct cdev *p = container_of(kobj, struct cdev, kobj);
611 struct kobject *parent = kobj->parent; 604 struct kobject *parent = kobj->parent;
612 605
613 cdev_purge(p); 606 cdev_purge(p);
614 kobject_put(parent); 607 kobject_put(parent);
615 } 608 }
616 609
617 static void cdev_dynamic_release(struct kobjec 610 static void cdev_dynamic_release(struct kobject *kobj)
618 { 611 {
619 struct cdev *p = container_of(kobj, st 612 struct cdev *p = container_of(kobj, struct cdev, kobj);
620 struct kobject *parent = kobj->parent; 613 struct kobject *parent = kobj->parent;
621 614
622 cdev_purge(p); 615 cdev_purge(p);
623 kfree(p); 616 kfree(p);
624 kobject_put(parent); 617 kobject_put(parent);
625 } 618 }
626 619
627 static struct kobj_type ktype_cdev_default = { 620 static struct kobj_type ktype_cdev_default = {
628 .release = cdev_default_release 621 .release = cdev_default_release,
629 }; 622 };
630 623
631 static struct kobj_type ktype_cdev_dynamic = { 624 static struct kobj_type ktype_cdev_dynamic = {
632 .release = cdev_dynamic_release 625 .release = cdev_dynamic_release,
633 }; 626 };
634 627
635 /** 628 /**
636 * cdev_alloc() - allocate a cdev structure 629 * cdev_alloc() - allocate a cdev structure
637 * 630 *
638 * Allocates and returns a cdev structure, or 631 * Allocates and returns a cdev structure, or NULL on failure.
639 */ 632 */
640 struct cdev *cdev_alloc(void) 633 struct cdev *cdev_alloc(void)
641 { 634 {
642 struct cdev *p = kzalloc(sizeof(struct 635 struct cdev *p = kzalloc(sizeof(struct cdev), GFP_KERNEL);
643 if (p) { 636 if (p) {
644 INIT_LIST_HEAD(&p->list); 637 INIT_LIST_HEAD(&p->list);
645 kobject_init(&p->kobj, &ktype_ 638 kobject_init(&p->kobj, &ktype_cdev_dynamic);
646 } 639 }
647 return p; 640 return p;
648 } 641 }
649 642
650 /** 643 /**
651 * cdev_init() - initialize a cdev structure 644 * cdev_init() - initialize a cdev structure
652 * @cdev: the structure to initialize 645 * @cdev: the structure to initialize
653 * @fops: the file_operations for this device 646 * @fops: the file_operations for this device
654 * 647 *
655 * Initializes @cdev, remembering @fops, makin 648 * Initializes @cdev, remembering @fops, making it ready to add to the
656 * system with cdev_add(). 649 * system with cdev_add().
657 */ 650 */
658 void cdev_init(struct cdev *cdev, const struct 651 void cdev_init(struct cdev *cdev, const struct file_operations *fops)
659 { 652 {
660 memset(cdev, 0, sizeof *cdev); 653 memset(cdev, 0, sizeof *cdev);
661 INIT_LIST_HEAD(&cdev->list); 654 INIT_LIST_HEAD(&cdev->list);
662 kobject_init(&cdev->kobj, &ktype_cdev_ 655 kobject_init(&cdev->kobj, &ktype_cdev_default);
663 cdev->ops = fops; 656 cdev->ops = fops;
664 } 657 }
665 658
666 static struct kobject *base_probe(dev_t dev, i 659 static struct kobject *base_probe(dev_t dev, int *part, void *data)
667 { 660 {
668 if (request_module("char-major-%d-%d", 661 if (request_module("char-major-%d-%d", MAJOR(dev), MINOR(dev)) > 0)
669 /* Make old-style 2.4 aliases 662 /* Make old-style 2.4 aliases work */
670 request_module("char-major-%d" 663 request_module("char-major-%d", MAJOR(dev));
671 return NULL; 664 return NULL;
672 } 665 }
673 666
674 void __init chrdev_init(void) 667 void __init chrdev_init(void)
675 { 668 {
676 cdev_map = kobj_map_init(base_probe, & 669 cdev_map = kobj_map_init(base_probe, &chrdevs_lock);
677 } 670 }
678 671
679 672
680 /* Let modules do char dev stuff */ 673 /* Let modules do char dev stuff */
681 EXPORT_SYMBOL(register_chrdev_region); 674 EXPORT_SYMBOL(register_chrdev_region);
682 EXPORT_SYMBOL(unregister_chrdev_region); 675 EXPORT_SYMBOL(unregister_chrdev_region);
683 EXPORT_SYMBOL(alloc_chrdev_region); 676 EXPORT_SYMBOL(alloc_chrdev_region);
684 EXPORT_SYMBOL(cdev_init); 677 EXPORT_SYMBOL(cdev_init);
685 EXPORT_SYMBOL(cdev_alloc); 678 EXPORT_SYMBOL(cdev_alloc);
686 EXPORT_SYMBOL(cdev_del); 679 EXPORT_SYMBOL(cdev_del);
687 EXPORT_SYMBOL(cdev_add); 680 EXPORT_SYMBOL(cdev_add);
688 EXPORT_SYMBOL(cdev_set_parent); 681 EXPORT_SYMBOL(cdev_set_parent);
689 EXPORT_SYMBOL(cdev_device_add); 682 EXPORT_SYMBOL(cdev_device_add);
690 EXPORT_SYMBOL(cdev_device_del); 683 EXPORT_SYMBOL(cdev_device_del);
691 EXPORT_SYMBOL(__register_chrdev); 684 EXPORT_SYMBOL(__register_chrdev);
692 EXPORT_SYMBOL(__unregister_chrdev); 685 EXPORT_SYMBOL(__unregister_chrdev);
693 686
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