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1 | /* | |
2 | * fs/sysfs/file.c - sysfs regular (text) file implementation | |
3 | * | |
4 | * Copyright (c) 2001-3 Patrick Mochel | |
5 | * Copyright (c) 2007 SUSE Linux Products GmbH | |
6 | * Copyright (c) 2007 Tejun Heo <teheo@suse.de> | |
7 | * | |
8 | * This file is released under the GPLv2. | |
9 | * | |
10 | * Please see Documentation/filesystems/sysfs.txt for more information. | |
11 | */ | |
12 | ||
13 | #include <linux/module.h> | |
14 | #include <linux/kobject.h> | |
15 | #include <linux/kallsyms.h> | |
16 | #include <linux/slab.h> | |
17 | #include <linux/list.h> | |
18 | #include <linux/mutex.h> | |
19 | #include <linux/seq_file.h> | |
20 | ||
21 | #include "sysfs.h" | |
22 | #include "../kernfs/kernfs-internal.h" | |
23 | ||
24 | /* | |
25 | * Determine ktype->sysfs_ops for the given kernfs_node. This function | |
26 | * must be called while holding an active reference. | |
27 | */ | |
28 | static const struct sysfs_ops *sysfs_file_ops(struct kernfs_node *kn) | |
29 | { | |
30 | struct kobject *kobj = kn->parent->priv; | |
31 | ||
32 | if (kn->flags & SYSFS_FLAG_LOCKDEP) | |
33 | lockdep_assert_held(kn); | |
34 | return kobj->ktype ? kobj->ktype->sysfs_ops : NULL; | |
35 | } | |
36 | ||
37 | /* | |
38 | * Reads on sysfs are handled through seq_file, which takes care of hairy | |
39 | * details like buffering and seeking. The following function pipes | |
40 | * sysfs_ops->show() result through seq_file. | |
41 | */ | |
42 | static int sysfs_kf_seq_show(struct seq_file *sf, void *v) | |
43 | { | |
44 | struct sysfs_open_file *of = sf->private; | |
45 | struct kobject *kobj = of->kn->parent->priv; | |
46 | const struct sysfs_ops *ops = sysfs_file_ops(of->kn); | |
47 | ssize_t count; | |
48 | char *buf; | |
49 | ||
50 | /* acquire buffer and ensure that it's >= PAGE_SIZE */ | |
51 | count = seq_get_buf(sf, &buf); | |
52 | if (count < PAGE_SIZE) { | |
53 | seq_commit(sf, -1); | |
54 | return 0; | |
55 | } | |
56 | ||
57 | /* | |
58 | * Invoke show(). Control may reach here via seq file lseek even | |
59 | * if @ops->show() isn't implemented. | |
60 | */ | |
61 | if (ops->show) { | |
62 | count = ops->show(kobj, of->kn->priv, buf); | |
63 | if (count < 0) | |
64 | return count; | |
65 | } | |
66 | ||
67 | /* | |
68 | * The code works fine with PAGE_SIZE return but it's likely to | |
69 | * indicate truncated result or overflow in normal use cases. | |
70 | */ | |
71 | if (count >= (ssize_t)PAGE_SIZE) { | |
72 | print_symbol("fill_read_buffer: %s returned bad count\n", | |
73 | (unsigned long)ops->show); | |
74 | /* Try to struggle along */ | |
75 | count = PAGE_SIZE - 1; | |
76 | } | |
77 | seq_commit(sf, count); | |
78 | return 0; | |
79 | } | |
80 | ||
81 | static ssize_t sysfs_kf_bin_read(struct sysfs_open_file *of, char *buf, | |
82 | size_t count, loff_t pos) | |
83 | { | |
84 | struct bin_attribute *battr = of->kn->priv; | |
85 | struct kobject *kobj = of->kn->parent->priv; | |
86 | loff_t size = file_inode(of->file)->i_size; | |
87 | ||
88 | if (!count) | |
89 | return 0; | |
90 | ||
91 | if (size) { | |
92 | if (pos > size) | |
93 | return 0; | |
94 | if (pos + count > size) | |
95 | count = size - pos; | |
96 | } | |
97 | ||
98 | if (!battr->read) | |
99 | return -EIO; | |
100 | ||
101 | return battr->read(of->file, kobj, battr, buf, pos, count); | |
102 | } | |
103 | ||
104 | /* kernfs write callback for regular sysfs files */ | |
105 | static ssize_t sysfs_kf_write(struct sysfs_open_file *of, char *buf, | |
106 | size_t count, loff_t pos) | |
107 | { | |
108 | const struct sysfs_ops *ops = sysfs_file_ops(of->kn); | |
109 | struct kobject *kobj = of->kn->parent->priv; | |
110 | ||
111 | if (!count) | |
112 | return 0; | |
113 | ||
114 | return ops->store(kobj, of->kn->priv, buf, count); | |
115 | } | |
116 | ||
117 | /* kernfs write callback for bin sysfs files */ | |
118 | static ssize_t sysfs_kf_bin_write(struct sysfs_open_file *of, char *buf, | |
119 | size_t count, loff_t pos) | |
120 | { | |
121 | struct bin_attribute *battr = of->kn->priv; | |
122 | struct kobject *kobj = of->kn->parent->priv; | |
123 | loff_t size = file_inode(of->file)->i_size; | |
124 | ||
125 | if (size) { | |
126 | if (size <= pos) | |
127 | return 0; | |
128 | count = min_t(ssize_t, count, size - pos); | |
129 | } | |
130 | if (!count) | |
131 | return 0; | |
132 | ||
133 | if (!battr->write) | |
134 | return -EIO; | |
135 | ||
136 | return battr->write(of->file, kobj, battr, buf, pos, count); | |
137 | } | |
138 | ||
139 | static int sysfs_kf_bin_mmap(struct sysfs_open_file *of, | |
140 | struct vm_area_struct *vma) | |
141 | { | |
142 | struct bin_attribute *battr = of->kn->priv; | |
143 | struct kobject *kobj = of->kn->parent->priv; | |
144 | ||
145 | return battr->mmap(of->file, kobj, battr, vma); | |
146 | } | |
147 | ||
148 | void sysfs_notify(struct kobject *kobj, const char *dir, const char *attr) | |
149 | { | |
150 | struct kernfs_node *kn = kobj->sd, *tmp; | |
151 | ||
152 | if (kn && dir) | |
153 | kn = kernfs_find_and_get(kn, dir); | |
154 | else | |
155 | kernfs_get(kn); | |
156 | ||
157 | if (kn && attr) { | |
158 | tmp = kernfs_find_and_get(kn, attr); | |
159 | kernfs_put(kn); | |
160 | kn = tmp; | |
161 | } | |
162 | ||
163 | if (kn) { | |
164 | kernfs_notify(kn); | |
165 | kernfs_put(kn); | |
166 | } | |
167 | } | |
168 | EXPORT_SYMBOL_GPL(sysfs_notify); | |
169 | ||
170 | static const struct kernfs_ops sysfs_file_kfops_empty = { | |
171 | }; | |
172 | ||
173 | static const struct kernfs_ops sysfs_file_kfops_ro = { | |
174 | .seq_show = sysfs_kf_seq_show, | |
175 | }; | |
176 | ||
177 | static const struct kernfs_ops sysfs_file_kfops_wo = { | |
178 | .write = sysfs_kf_write, | |
179 | }; | |
180 | ||
181 | static const struct kernfs_ops sysfs_file_kfops_rw = { | |
182 | .seq_show = sysfs_kf_seq_show, | |
183 | .write = sysfs_kf_write, | |
184 | }; | |
185 | ||
186 | static const struct kernfs_ops sysfs_bin_kfops_ro = { | |
187 | .read = sysfs_kf_bin_read, | |
188 | }; | |
189 | ||
190 | static const struct kernfs_ops sysfs_bin_kfops_wo = { | |
191 | .write = sysfs_kf_bin_write, | |
192 | }; | |
193 | ||
194 | static const struct kernfs_ops sysfs_bin_kfops_rw = { | |
195 | .read = sysfs_kf_bin_read, | |
196 | .write = sysfs_kf_bin_write, | |
197 | }; | |
198 | ||
199 | static const struct kernfs_ops sysfs_bin_kfops_mmap = { | |
200 | .read = sysfs_kf_bin_read, | |
201 | .write = sysfs_kf_bin_write, | |
202 | .mmap = sysfs_kf_bin_mmap, | |
203 | }; | |
204 | ||
205 | int sysfs_add_file_mode_ns(struct kernfs_node *parent, | |
206 | const struct attribute *attr, bool is_bin, | |
207 | umode_t mode, const void *ns) | |
208 | { | |
209 | struct lock_class_key *key = NULL; | |
210 | const struct kernfs_ops *ops; | |
211 | struct kernfs_node *kn; | |
212 | loff_t size; | |
213 | ||
214 | if (!is_bin) { | |
215 | struct kobject *kobj = parent->priv; | |
216 | const struct sysfs_ops *sysfs_ops = kobj->ktype->sysfs_ops; | |
217 | ||
218 | /* every kobject with an attribute needs a ktype assigned */ | |
219 | if (WARN(!sysfs_ops, KERN_ERR | |
220 | "missing sysfs attribute operations for kobject: %s\n", | |
221 | kobject_name(kobj))) | |
222 | return -EINVAL; | |
223 | ||
224 | if (sysfs_ops->show && sysfs_ops->store) | |
225 | ops = &sysfs_file_kfops_rw; | |
226 | else if (sysfs_ops->show) | |
227 | ops = &sysfs_file_kfops_ro; | |
228 | else if (sysfs_ops->store) | |
229 | ops = &sysfs_file_kfops_wo; | |
230 | else | |
231 | ops = &sysfs_file_kfops_empty; | |
232 | ||
233 | size = PAGE_SIZE; | |
234 | } else { | |
235 | struct bin_attribute *battr = (void *)attr; | |
236 | ||
237 | if (battr->mmap) | |
238 | ops = &sysfs_bin_kfops_mmap; | |
239 | else if (battr->read && battr->write) | |
240 | ops = &sysfs_bin_kfops_rw; | |
241 | else if (battr->read) | |
242 | ops = &sysfs_bin_kfops_ro; | |
243 | else if (battr->write) | |
244 | ops = &sysfs_bin_kfops_wo; | |
245 | else | |
246 | ops = &sysfs_file_kfops_empty; | |
247 | ||
248 | size = battr->size; | |
249 | } | |
250 | ||
251 | #ifdef CONFIG_DEBUG_LOCK_ALLOC | |
252 | if (!attr->ignore_lockdep) | |
253 | key = attr->key ?: (struct lock_class_key *)&attr->skey; | |
254 | #endif | |
255 | kn = kernfs_create_file_ns_key(parent, attr->name, mode, size, | |
256 | ops, (void *)attr, ns, key); | |
257 | if (IS_ERR(kn)) { | |
258 | if (PTR_ERR(kn) == -EEXIST) | |
259 | sysfs_warn_dup(parent, attr->name); | |
260 | return PTR_ERR(kn); | |
261 | } | |
262 | return 0; | |
263 | } | |
264 | ||
265 | int sysfs_add_file(struct kernfs_node *parent, const struct attribute *attr, | |
266 | bool is_bin) | |
267 | { | |
268 | return sysfs_add_file_mode_ns(parent, attr, is_bin, attr->mode, NULL); | |
269 | } | |
270 | ||
271 | /** | |
272 | * sysfs_create_file_ns - create an attribute file for an object with custom ns | |
273 | * @kobj: object we're creating for | |
274 | * @attr: attribute descriptor | |
275 | * @ns: namespace the new file should belong to | |
276 | */ | |
277 | int sysfs_create_file_ns(struct kobject *kobj, const struct attribute *attr, | |
278 | const void *ns) | |
279 | { | |
280 | BUG_ON(!kobj || !kobj->sd || !attr); | |
281 | ||
282 | return sysfs_add_file_mode_ns(kobj->sd, attr, false, attr->mode, ns); | |
283 | ||
284 | } | |
285 | EXPORT_SYMBOL_GPL(sysfs_create_file_ns); | |
286 | ||
287 | int sysfs_create_files(struct kobject *kobj, const struct attribute **ptr) | |
288 | { | |
289 | int err = 0; | |
290 | int i; | |
291 | ||
292 | for (i = 0; ptr[i] && !err; i++) | |
293 | err = sysfs_create_file(kobj, ptr[i]); | |
294 | if (err) | |
295 | while (--i >= 0) | |
296 | sysfs_remove_file(kobj, ptr[i]); | |
297 | return err; | |
298 | } | |
299 | EXPORT_SYMBOL_GPL(sysfs_create_files); | |
300 | ||
301 | /** | |
302 | * sysfs_add_file_to_group - add an attribute file to a pre-existing group. | |
303 | * @kobj: object we're acting for. | |
304 | * @attr: attribute descriptor. | |
305 | * @group: group name. | |
306 | */ | |
307 | int sysfs_add_file_to_group(struct kobject *kobj, | |
308 | const struct attribute *attr, const char *group) | |
309 | { | |
310 | struct kernfs_node *parent; | |
311 | int error; | |
312 | ||
313 | if (group) { | |
314 | parent = kernfs_find_and_get(kobj->sd, group); | |
315 | } else { | |
316 | parent = kobj->sd; | |
317 | kernfs_get(parent); | |
318 | } | |
319 | ||
320 | if (!parent) | |
321 | return -ENOENT; | |
322 | ||
323 | error = sysfs_add_file(parent, attr, false); | |
324 | kernfs_put(parent); | |
325 | ||
326 | return error; | |
327 | } | |
328 | EXPORT_SYMBOL_GPL(sysfs_add_file_to_group); | |
329 | ||
330 | /** | |
331 | * sysfs_chmod_file - update the modified mode value on an object attribute. | |
332 | * @kobj: object we're acting for. | |
333 | * @attr: attribute descriptor. | |
334 | * @mode: file permissions. | |
335 | * | |
336 | */ | |
337 | int sysfs_chmod_file(struct kobject *kobj, const struct attribute *attr, | |
338 | umode_t mode) | |
339 | { | |
340 | struct kernfs_node *kn; | |
341 | struct iattr newattrs; | |
342 | int rc; | |
343 | ||
344 | kn = kernfs_find_and_get(kobj->sd, attr->name); | |
345 | if (!kn) | |
346 | return -ENOENT; | |
347 | ||
348 | newattrs.ia_mode = (mode & S_IALLUGO) | (kn->mode & ~S_IALLUGO); | |
349 | newattrs.ia_valid = ATTR_MODE; | |
350 | ||
351 | rc = kernfs_setattr(kn, &newattrs); | |
352 | ||
353 | kernfs_put(kn); | |
354 | return rc; | |
355 | } | |
356 | EXPORT_SYMBOL_GPL(sysfs_chmod_file); | |
357 | ||
358 | /** | |
359 | * sysfs_remove_file_ns - remove an object attribute with a custom ns tag | |
360 | * @kobj: object we're acting for | |
361 | * @attr: attribute descriptor | |
362 | * @ns: namespace tag of the file to remove | |
363 | * | |
364 | * Hash the attribute name and namespace tag and kill the victim. | |
365 | */ | |
366 | void sysfs_remove_file_ns(struct kobject *kobj, const struct attribute *attr, | |
367 | const void *ns) | |
368 | { | |
369 | struct kernfs_node *parent = kobj->sd; | |
370 | ||
371 | kernfs_remove_by_name_ns(parent, attr->name, ns); | |
372 | } | |
373 | EXPORT_SYMBOL_GPL(sysfs_remove_file_ns); | |
374 | ||
375 | void sysfs_remove_files(struct kobject *kobj, const struct attribute **ptr) | |
376 | { | |
377 | int i; | |
378 | for (i = 0; ptr[i]; i++) | |
379 | sysfs_remove_file(kobj, ptr[i]); | |
380 | } | |
381 | EXPORT_SYMBOL_GPL(sysfs_remove_files); | |
382 | ||
383 | /** | |
384 | * sysfs_remove_file_from_group - remove an attribute file from a group. | |
385 | * @kobj: object we're acting for. | |
386 | * @attr: attribute descriptor. | |
387 | * @group: group name. | |
388 | */ | |
389 | void sysfs_remove_file_from_group(struct kobject *kobj, | |
390 | const struct attribute *attr, const char *group) | |
391 | { | |
392 | struct kernfs_node *parent; | |
393 | ||
394 | if (group) { | |
395 | parent = kernfs_find_and_get(kobj->sd, group); | |
396 | } else { | |
397 | parent = kobj->sd; | |
398 | kernfs_get(parent); | |
399 | } | |
400 | ||
401 | if (parent) { | |
402 | kernfs_remove_by_name(parent, attr->name); | |
403 | kernfs_put(parent); | |
404 | } | |
405 | } | |
406 | EXPORT_SYMBOL_GPL(sysfs_remove_file_from_group); | |
407 | ||
408 | /** | |
409 | * sysfs_create_bin_file - create binary file for object. | |
410 | * @kobj: object. | |
411 | * @attr: attribute descriptor. | |
412 | */ | |
413 | int sysfs_create_bin_file(struct kobject *kobj, | |
414 | const struct bin_attribute *attr) | |
415 | { | |
416 | BUG_ON(!kobj || !kobj->sd || !attr); | |
417 | ||
418 | return sysfs_add_file(kobj->sd, &attr->attr, true); | |
419 | } | |
420 | EXPORT_SYMBOL_GPL(sysfs_create_bin_file); | |
421 | ||
422 | /** | |
423 | * sysfs_remove_bin_file - remove binary file for object. | |
424 | * @kobj: object. | |
425 | * @attr: attribute descriptor. | |
426 | */ | |
427 | void sysfs_remove_bin_file(struct kobject *kobj, | |
428 | const struct bin_attribute *attr) | |
429 | { | |
430 | kernfs_remove_by_name(kobj->sd, attr->attr.name); | |
431 | } | |
432 | EXPORT_SYMBOL_GPL(sysfs_remove_bin_file); | |
433 | ||
434 | struct sysfs_schedule_callback_struct { | |
435 | struct list_head workq_list; | |
436 | struct kobject *kobj; | |
437 | void (*func)(void *); | |
438 | void *data; | |
439 | struct module *owner; | |
440 | struct work_struct work; | |
441 | }; | |
442 | ||
443 | static struct workqueue_struct *sysfs_workqueue; | |
444 | static DEFINE_MUTEX(sysfs_workq_mutex); | |
445 | static LIST_HEAD(sysfs_workq); | |
446 | static void sysfs_schedule_callback_work(struct work_struct *work) | |
447 | { | |
448 | struct sysfs_schedule_callback_struct *ss = container_of(work, | |
449 | struct sysfs_schedule_callback_struct, work); | |
450 | ||
451 | (ss->func)(ss->data); | |
452 | kobject_put(ss->kobj); | |
453 | module_put(ss->owner); | |
454 | mutex_lock(&sysfs_workq_mutex); | |
455 | list_del(&ss->workq_list); | |
456 | mutex_unlock(&sysfs_workq_mutex); | |
457 | kfree(ss); | |
458 | } | |
459 | ||
460 | /** | |
461 | * sysfs_schedule_callback - helper to schedule a callback for a kobject | |
462 | * @kobj: object we're acting for. | |
463 | * @func: callback function to invoke later. | |
464 | * @data: argument to pass to @func. | |
465 | * @owner: module owning the callback code | |
466 | * | |
467 | * sysfs attribute methods must not unregister themselves or their parent | |
468 | * kobject (which would amount to the same thing). Attempts to do so will | |
469 | * deadlock, since unregistration is mutually exclusive with driver | |
470 | * callbacks. | |
471 | * | |
472 | * Instead methods can call this routine, which will attempt to allocate | |
473 | * and schedule a workqueue request to call back @func with @data as its | |
474 | * argument in the workqueue's process context. @kobj will be pinned | |
475 | * until @func returns. | |
476 | * | |
477 | * Returns 0 if the request was submitted, -ENOMEM if storage could not | |
478 | * be allocated, -ENODEV if a reference to @owner isn't available, | |
479 | * -EAGAIN if a callback has already been scheduled for @kobj. | |
480 | */ | |
481 | int sysfs_schedule_callback(struct kobject *kobj, void (*func)(void *), | |
482 | void *data, struct module *owner) | |
483 | { | |
484 | struct sysfs_schedule_callback_struct *ss, *tmp; | |
485 | ||
486 | if (!try_module_get(owner)) | |
487 | return -ENODEV; | |
488 | ||
489 | mutex_lock(&sysfs_workq_mutex); | |
490 | list_for_each_entry_safe(ss, tmp, &sysfs_workq, workq_list) | |
491 | if (ss->kobj == kobj) { | |
492 | module_put(owner); | |
493 | mutex_unlock(&sysfs_workq_mutex); | |
494 | return -EAGAIN; | |
495 | } | |
496 | mutex_unlock(&sysfs_workq_mutex); | |
497 | ||
498 | if (sysfs_workqueue == NULL) { | |
499 | sysfs_workqueue = create_singlethread_workqueue("sysfsd"); | |
500 | if (sysfs_workqueue == NULL) { | |
501 | module_put(owner); | |
502 | return -ENOMEM; | |
503 | } | |
504 | } | |
505 | ||
506 | ss = kmalloc(sizeof(*ss), GFP_KERNEL); | |
507 | if (!ss) { | |
508 | module_put(owner); | |
509 | return -ENOMEM; | |
510 | } | |
511 | kobject_get(kobj); | |
512 | ss->kobj = kobj; | |
513 | ss->func = func; | |
514 | ss->data = data; | |
515 | ss->owner = owner; | |
516 | INIT_WORK(&ss->work, sysfs_schedule_callback_work); | |
517 | INIT_LIST_HEAD(&ss->workq_list); | |
518 | mutex_lock(&sysfs_workq_mutex); | |
519 | list_add_tail(&ss->workq_list, &sysfs_workq); | |
520 | mutex_unlock(&sysfs_workq_mutex); | |
521 | queue_work(sysfs_workqueue, &ss->work); | |
522 | return 0; | |
523 | } | |
524 | EXPORT_SYMBOL_GPL(sysfs_schedule_callback); |