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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/fsnotify.h> | |
18 | #include <linux/namei.h> | |
19 | #include <linux/poll.h> | |
20 | #include <linux/list.h> | |
21 | #include <linux/mutex.h> | |
22 | #include <linux/limits.h> | |
23 | #include <asm/uaccess.h> | |
24 | ||
25 | #include "sysfs.h" | |
26 | ||
27 | /* used in crash dumps to help with debugging */ | |
28 | static char last_sysfs_file[PATH_MAX]; | |
29 | void sysfs_printk_last_file(void) | |
30 | { | |
31 | printk(KERN_EMERG "last sysfs file: %s\n", last_sysfs_file); | |
32 | } | |
33 | ||
34 | /* | |
35 | * There's one sysfs_buffer for each open file and one | |
36 | * sysfs_open_dirent for each sysfs_dirent with one or more open | |
37 | * files. | |
38 | * | |
39 | * filp->private_data points to sysfs_buffer and | |
40 | * sysfs_dirent->s_attr.open points to sysfs_open_dirent. s_attr.open | |
41 | * is protected by sysfs_open_dirent_lock. | |
42 | */ | |
43 | static DEFINE_SPINLOCK(sysfs_open_dirent_lock); | |
44 | ||
45 | struct sysfs_open_dirent { | |
46 | atomic_t refcnt; | |
47 | atomic_t event; | |
48 | wait_queue_head_t poll; | |
49 | struct list_head buffers; /* goes through sysfs_buffer.list */ | |
50 | }; | |
51 | ||
52 | struct sysfs_buffer { | |
53 | size_t count; | |
54 | loff_t pos; | |
55 | char * page; | |
56 | const struct sysfs_ops * ops; | |
57 | struct mutex mutex; | |
58 | int needs_read_fill; | |
59 | int event; | |
60 | struct list_head list; | |
61 | }; | |
62 | ||
63 | /** | |
64 | * fill_read_buffer - allocate and fill buffer from object. | |
65 | * @dentry: dentry pointer. | |
66 | * @buffer: data buffer for file. | |
67 | * | |
68 | * Allocate @buffer->page, if it hasn't been already, then call the | |
69 | * kobject's show() method to fill the buffer with this attribute's | |
70 | * data. | |
71 | * This is called only once, on the file's first read unless an error | |
72 | * is returned. | |
73 | */ | |
74 | static int fill_read_buffer(struct dentry * dentry, struct sysfs_buffer * buffer) | |
75 | { | |
76 | struct sysfs_dirent *attr_sd = dentry->d_fsdata; | |
77 | struct kobject *kobj = attr_sd->s_parent->s_dir.kobj; | |
78 | const struct sysfs_ops * ops = buffer->ops; | |
79 | int ret = 0; | |
80 | ssize_t count; | |
81 | ||
82 | if (!buffer->page) | |
83 | buffer->page = (char *) get_zeroed_page(GFP_KERNEL); | |
84 | if (!buffer->page) | |
85 | return -ENOMEM; | |
86 | ||
87 | /* need attr_sd for attr and ops, its parent for kobj */ | |
88 | if (!sysfs_get_active(attr_sd)) | |
89 | return -ENODEV; | |
90 | ||
91 | buffer->event = atomic_read(&attr_sd->s_attr.open->event); | |
92 | count = ops->show(kobj, attr_sd->s_attr.attr, buffer->page); | |
93 | ||
94 | sysfs_put_active(attr_sd); | |
95 | ||
96 | /* | |
97 | * The code works fine with PAGE_SIZE return but it's likely to | |
98 | * indicate truncated result or overflow in normal use cases. | |
99 | */ | |
100 | if (count >= (ssize_t)PAGE_SIZE) { | |
101 | print_symbol("fill_read_buffer: %s returned bad count\n", | |
102 | (unsigned long)ops->show); | |
103 | /* Try to struggle along */ | |
104 | count = PAGE_SIZE - 1; | |
105 | } | |
106 | if (count >= 0) { | |
107 | buffer->needs_read_fill = 0; | |
108 | buffer->count = count; | |
109 | } else { | |
110 | ret = count; | |
111 | } | |
112 | return ret; | |
113 | } | |
114 | ||
115 | /** | |
116 | * sysfs_read_file - read an attribute. | |
117 | * @file: file pointer. | |
118 | * @buf: buffer to fill. | |
119 | * @count: number of bytes to read. | |
120 | * @ppos: starting offset in file. | |
121 | * | |
122 | * Userspace wants to read an attribute file. The attribute descriptor | |
123 | * is in the file's ->d_fsdata. The target object is in the directory's | |
124 | * ->d_fsdata. | |
125 | * | |
126 | * We call fill_read_buffer() to allocate and fill the buffer from the | |
127 | * object's show() method exactly once (if the read is happening from | |
128 | * the beginning of the file). That should fill the entire buffer with | |
129 | * all the data the object has to offer for that attribute. | |
130 | * We then call flush_read_buffer() to copy the buffer to userspace | |
131 | * in the increments specified. | |
132 | */ | |
133 | ||
134 | static ssize_t | |
135 | sysfs_read_file(struct file *file, char __user *buf, size_t count, loff_t *ppos) | |
136 | { | |
137 | struct sysfs_buffer * buffer = file->private_data; | |
138 | ssize_t retval = 0; | |
139 | ||
140 | mutex_lock(&buffer->mutex); | |
141 | if (buffer->needs_read_fill || *ppos == 0) { | |
142 | retval = fill_read_buffer(file->f_path.dentry,buffer); | |
143 | if (retval) | |
144 | goto out; | |
145 | } | |
146 | pr_debug("%s: count = %zd, ppos = %lld, buf = %s\n", | |
147 | __func__, count, *ppos, buffer->page); | |
148 | retval = simple_read_from_buffer(buf, count, ppos, buffer->page, | |
149 | buffer->count); | |
150 | out: | |
151 | mutex_unlock(&buffer->mutex); | |
152 | return retval; | |
153 | } | |
154 | ||
155 | /** | |
156 | * fill_write_buffer - copy buffer from userspace. | |
157 | * @buffer: data buffer for file. | |
158 | * @buf: data from user. | |
159 | * @count: number of bytes in @userbuf. | |
160 | * | |
161 | * Allocate @buffer->page if it hasn't been already, then | |
162 | * copy the user-supplied buffer into it. | |
163 | */ | |
164 | ||
165 | static int | |
166 | fill_write_buffer(struct sysfs_buffer * buffer, const char __user * buf, size_t count) | |
167 | { | |
168 | int error; | |
169 | ||
170 | if (!buffer->page) | |
171 | buffer->page = (char *)get_zeroed_page(GFP_KERNEL); | |
172 | if (!buffer->page) | |
173 | return -ENOMEM; | |
174 | ||
175 | if (count >= PAGE_SIZE) | |
176 | count = PAGE_SIZE - 1; | |
177 | error = copy_from_user(buffer->page,buf,count); | |
178 | buffer->needs_read_fill = 1; | |
179 | /* if buf is assumed to contain a string, terminate it by \0, | |
180 | so e.g. sscanf() can scan the string easily */ | |
181 | buffer->page[count] = 0; | |
182 | return error ? -EFAULT : count; | |
183 | } | |
184 | ||
185 | ||
186 | /** | |
187 | * flush_write_buffer - push buffer to kobject. | |
188 | * @dentry: dentry to the attribute | |
189 | * @buffer: data buffer for file. | |
190 | * @count: number of bytes | |
191 | * | |
192 | * Get the correct pointers for the kobject and the attribute we're | |
193 | * dealing with, then call the store() method for the attribute, | |
194 | * passing the buffer that we acquired in fill_write_buffer(). | |
195 | */ | |
196 | ||
197 | static int | |
198 | flush_write_buffer(struct dentry * dentry, struct sysfs_buffer * buffer, size_t count) | |
199 | { | |
200 | struct sysfs_dirent *attr_sd = dentry->d_fsdata; | |
201 | struct kobject *kobj = attr_sd->s_parent->s_dir.kobj; | |
202 | const struct sysfs_ops * ops = buffer->ops; | |
203 | int rc; | |
204 | ||
205 | /* need attr_sd for attr and ops, its parent for kobj */ | |
206 | if (!sysfs_get_active(attr_sd)) | |
207 | return -ENODEV; | |
208 | ||
209 | rc = ops->store(kobj, attr_sd->s_attr.attr, buffer->page, count); | |
210 | ||
211 | sysfs_put_active(attr_sd); | |
212 | ||
213 | return rc; | |
214 | } | |
215 | ||
216 | ||
217 | /** | |
218 | * sysfs_write_file - write an attribute. | |
219 | * @file: file pointer | |
220 | * @buf: data to write | |
221 | * @count: number of bytes | |
222 | * @ppos: starting offset | |
223 | * | |
224 | * Similar to sysfs_read_file(), though working in the opposite direction. | |
225 | * We allocate and fill the data from the user in fill_write_buffer(), | |
226 | * then push it to the kobject in flush_write_buffer(). | |
227 | * There is no easy way for us to know if userspace is only doing a partial | |
228 | * write, so we don't support them. We expect the entire buffer to come | |
229 | * on the first write. | |
230 | * Hint: if you're writing a value, first read the file, modify only the | |
231 | * the value you're changing, then write entire buffer back. | |
232 | */ | |
233 | ||
234 | static ssize_t | |
235 | sysfs_write_file(struct file *file, const char __user *buf, size_t count, loff_t *ppos) | |
236 | { | |
237 | struct sysfs_buffer * buffer = file->private_data; | |
238 | ssize_t len; | |
239 | ||
240 | mutex_lock(&buffer->mutex); | |
241 | len = fill_write_buffer(buffer, buf, count); | |
242 | if (len > 0) | |
243 | len = flush_write_buffer(file->f_path.dentry, buffer, len); | |
244 | if (len > 0) | |
245 | *ppos += len; | |
246 | mutex_unlock(&buffer->mutex); | |
247 | return len; | |
248 | } | |
249 | ||
250 | /** | |
251 | * sysfs_get_open_dirent - get or create sysfs_open_dirent | |
252 | * @sd: target sysfs_dirent | |
253 | * @buffer: sysfs_buffer for this instance of open | |
254 | * | |
255 | * If @sd->s_attr.open exists, increment its reference count; | |
256 | * otherwise, create one. @buffer is chained to the buffers | |
257 | * list. | |
258 | * | |
259 | * LOCKING: | |
260 | * Kernel thread context (may sleep). | |
261 | * | |
262 | * RETURNS: | |
263 | * 0 on success, -errno on failure. | |
264 | */ | |
265 | static int sysfs_get_open_dirent(struct sysfs_dirent *sd, | |
266 | struct sysfs_buffer *buffer) | |
267 | { | |
268 | struct sysfs_open_dirent *od, *new_od = NULL; | |
269 | ||
270 | retry: | |
271 | spin_lock_irq(&sysfs_open_dirent_lock); | |
272 | ||
273 | if (!sd->s_attr.open && new_od) { | |
274 | sd->s_attr.open = new_od; | |
275 | new_od = NULL; | |
276 | } | |
277 | ||
278 | od = sd->s_attr.open; | |
279 | if (od) { | |
280 | atomic_inc(&od->refcnt); | |
281 | list_add_tail(&buffer->list, &od->buffers); | |
282 | } | |
283 | ||
284 | spin_unlock_irq(&sysfs_open_dirent_lock); | |
285 | ||
286 | if (od) { | |
287 | kfree(new_od); | |
288 | return 0; | |
289 | } | |
290 | ||
291 | /* not there, initialize a new one and retry */ | |
292 | new_od = kmalloc(sizeof(*new_od), GFP_KERNEL); | |
293 | if (!new_od) | |
294 | return -ENOMEM; | |
295 | ||
296 | atomic_set(&new_od->refcnt, 0); | |
297 | atomic_set(&new_od->event, 1); | |
298 | init_waitqueue_head(&new_od->poll); | |
299 | INIT_LIST_HEAD(&new_od->buffers); | |
300 | goto retry; | |
301 | } | |
302 | ||
303 | /** | |
304 | * sysfs_put_open_dirent - put sysfs_open_dirent | |
305 | * @sd: target sysfs_dirent | |
306 | * @buffer: associated sysfs_buffer | |
307 | * | |
308 | * Put @sd->s_attr.open and unlink @buffer from the buffers list. | |
309 | * If reference count reaches zero, disassociate and free it. | |
310 | * | |
311 | * LOCKING: | |
312 | * None. | |
313 | */ | |
314 | static void sysfs_put_open_dirent(struct sysfs_dirent *sd, | |
315 | struct sysfs_buffer *buffer) | |
316 | { | |
317 | struct sysfs_open_dirent *od = sd->s_attr.open; | |
318 | unsigned long flags; | |
319 | ||
320 | spin_lock_irqsave(&sysfs_open_dirent_lock, flags); | |
321 | ||
322 | list_del(&buffer->list); | |
323 | if (atomic_dec_and_test(&od->refcnt)) | |
324 | sd->s_attr.open = NULL; | |
325 | else | |
326 | od = NULL; | |
327 | ||
328 | spin_unlock_irqrestore(&sysfs_open_dirent_lock, flags); | |
329 | ||
330 | kfree(od); | |
331 | } | |
332 | ||
333 | static int sysfs_open_file(struct inode *inode, struct file *file) | |
334 | { | |
335 | struct sysfs_dirent *attr_sd = file->f_path.dentry->d_fsdata; | |
336 | struct kobject *kobj = attr_sd->s_parent->s_dir.kobj; | |
337 | struct sysfs_buffer *buffer; | |
338 | const struct sysfs_ops *ops; | |
339 | int error = -EACCES; | |
340 | char *p; | |
341 | ||
342 | p = d_path(&file->f_path, last_sysfs_file, sizeof(last_sysfs_file)); | |
343 | if (p) | |
344 | memmove(last_sysfs_file, p, strlen(p) + 1); | |
345 | ||
346 | /* need attr_sd for attr and ops, its parent for kobj */ | |
347 | if (!sysfs_get_active(attr_sd)) | |
348 | return -ENODEV; | |
349 | ||
350 | /* every kobject with an attribute needs a ktype assigned */ | |
351 | if (kobj->ktype && kobj->ktype->sysfs_ops) | |
352 | ops = kobj->ktype->sysfs_ops; | |
353 | else { | |
354 | WARN(1, KERN_ERR "missing sysfs attribute operations for " | |
355 | "kobject: %s\n", kobject_name(kobj)); | |
356 | goto err_out; | |
357 | } | |
358 | ||
359 | /* File needs write support. | |
360 | * The inode's perms must say it's ok, | |
361 | * and we must have a store method. | |
362 | */ | |
363 | if (file->f_mode & FMODE_WRITE) { | |
364 | if (!(inode->i_mode & S_IWUGO) || !ops->store) | |
365 | goto err_out; | |
366 | } | |
367 | ||
368 | /* File needs read support. | |
369 | * The inode's perms must say it's ok, and we there | |
370 | * must be a show method for it. | |
371 | */ | |
372 | if (file->f_mode & FMODE_READ) { | |
373 | if (!(inode->i_mode & S_IRUGO) || !ops->show) | |
374 | goto err_out; | |
375 | } | |
376 | ||
377 | /* No error? Great, allocate a buffer for the file, and store it | |
378 | * it in file->private_data for easy access. | |
379 | */ | |
380 | error = -ENOMEM; | |
381 | buffer = kzalloc(sizeof(struct sysfs_buffer), GFP_KERNEL); | |
382 | if (!buffer) | |
383 | goto err_out; | |
384 | ||
385 | mutex_init(&buffer->mutex); | |
386 | buffer->needs_read_fill = 1; | |
387 | buffer->ops = ops; | |
388 | file->private_data = buffer; | |
389 | ||
390 | /* make sure we have open dirent struct */ | |
391 | error = sysfs_get_open_dirent(attr_sd, buffer); | |
392 | if (error) | |
393 | goto err_free; | |
394 | ||
395 | /* open succeeded, put active references */ | |
396 | sysfs_put_active(attr_sd); | |
397 | return 0; | |
398 | ||
399 | err_free: | |
400 | kfree(buffer); | |
401 | err_out: | |
402 | sysfs_put_active(attr_sd); | |
403 | return error; | |
404 | } | |
405 | ||
406 | static int sysfs_release(struct inode *inode, struct file *filp) | |
407 | { | |
408 | struct sysfs_dirent *sd = filp->f_path.dentry->d_fsdata; | |
409 | struct sysfs_buffer *buffer = filp->private_data; | |
410 | ||
411 | sysfs_put_open_dirent(sd, buffer); | |
412 | ||
413 | if (buffer->page) | |
414 | free_page((unsigned long)buffer->page); | |
415 | kfree(buffer); | |
416 | ||
417 | return 0; | |
418 | } | |
419 | ||
420 | /* Sysfs attribute files are pollable. The idea is that you read | |
421 | * the content and then you use 'poll' or 'select' to wait for | |
422 | * the content to change. When the content changes (assuming the | |
423 | * manager for the kobject supports notification), poll will | |
424 | * return POLLERR|POLLPRI, and select will return the fd whether | |
425 | * it is waiting for read, write, or exceptions. | |
426 | * Once poll/select indicates that the value has changed, you | |
427 | * need to close and re-open the file, or seek to 0 and read again. | |
428 | * Reminder: this only works for attributes which actively support | |
429 | * it, and it is not possible to test an attribute from userspace | |
430 | * to see if it supports poll (Neither 'poll' nor 'select' return | |
431 | * an appropriate error code). When in doubt, set a suitable timeout value. | |
432 | */ | |
433 | static unsigned int sysfs_poll(struct file *filp, poll_table *wait) | |
434 | { | |
435 | struct sysfs_buffer * buffer = filp->private_data; | |
436 | struct sysfs_dirent *attr_sd = filp->f_path.dentry->d_fsdata; | |
437 | struct sysfs_open_dirent *od = attr_sd->s_attr.open; | |
438 | ||
439 | /* need parent for the kobj, grab both */ | |
440 | if (!sysfs_get_active(attr_sd)) | |
441 | goto trigger; | |
442 | ||
443 | poll_wait(filp, &od->poll, wait); | |
444 | ||
445 | sysfs_put_active(attr_sd); | |
446 | ||
447 | if (buffer->event != atomic_read(&od->event)) | |
448 | goto trigger; | |
449 | ||
450 | return DEFAULT_POLLMASK; | |
451 | ||
452 | trigger: | |
453 | buffer->needs_read_fill = 1; | |
454 | return DEFAULT_POLLMASK|POLLERR|POLLPRI; | |
455 | } | |
456 | ||
457 | void sysfs_notify_dirent(struct sysfs_dirent *sd) | |
458 | { | |
459 | struct sysfs_open_dirent *od; | |
460 | unsigned long flags; | |
461 | ||
462 | spin_lock_irqsave(&sysfs_open_dirent_lock, flags); | |
463 | ||
464 | od = sd->s_attr.open; | |
465 | if (od) { | |
466 | atomic_inc(&od->event); | |
467 | wake_up_interruptible(&od->poll); | |
468 | } | |
469 | ||
470 | spin_unlock_irqrestore(&sysfs_open_dirent_lock, flags); | |
471 | } | |
472 | EXPORT_SYMBOL_GPL(sysfs_notify_dirent); | |
473 | ||
474 | void sysfs_notify(struct kobject *k, const char *dir, const char *attr) | |
475 | { | |
476 | struct sysfs_dirent *sd = k->sd; | |
477 | ||
478 | mutex_lock(&sysfs_mutex); | |
479 | ||
480 | if (sd && dir) | |
481 | /* Only directories are tagged, so no need to pass | |
482 | * a tag explicitly. | |
483 | */ | |
484 | sd = sysfs_find_dirent(sd, NULL, dir); | |
485 | if (sd && attr) | |
486 | sd = sysfs_find_dirent(sd, NULL, attr); | |
487 | if (sd) | |
488 | sysfs_notify_dirent(sd); | |
489 | ||
490 | mutex_unlock(&sysfs_mutex); | |
491 | } | |
492 | EXPORT_SYMBOL_GPL(sysfs_notify); | |
493 | ||
494 | const struct file_operations sysfs_file_operations = { | |
495 | .read = sysfs_read_file, | |
496 | .write = sysfs_write_file, | |
497 | .llseek = generic_file_llseek, | |
498 | .open = sysfs_open_file, | |
499 | .release = sysfs_release, | |
500 | .poll = sysfs_poll, | |
501 | }; | |
502 | ||
503 | int sysfs_add_file_mode(struct sysfs_dirent *dir_sd, | |
504 | const struct attribute *attr, int type, mode_t amode) | |
505 | { | |
506 | umode_t mode = (amode & S_IALLUGO) | S_IFREG; | |
507 | struct sysfs_addrm_cxt acxt; | |
508 | struct sysfs_dirent *sd; | |
509 | int rc; | |
510 | ||
511 | sd = sysfs_new_dirent(attr->name, mode, type); | |
512 | if (!sd) | |
513 | return -ENOMEM; | |
514 | sd->s_attr.attr = (void *)attr; | |
515 | sysfs_dirent_init_lockdep(sd); | |
516 | ||
517 | sysfs_addrm_start(&acxt, dir_sd); | |
518 | rc = sysfs_add_one(&acxt, sd); | |
519 | sysfs_addrm_finish(&acxt); | |
520 | ||
521 | if (rc) | |
522 | sysfs_put(sd); | |
523 | ||
524 | return rc; | |
525 | } | |
526 | ||
527 | ||
528 | int sysfs_add_file(struct sysfs_dirent *dir_sd, const struct attribute *attr, | |
529 | int type) | |
530 | { | |
531 | return sysfs_add_file_mode(dir_sd, attr, type, attr->mode); | |
532 | } | |
533 | ||
534 | ||
535 | /** | |
536 | * sysfs_create_file - create an attribute file for an object. | |
537 | * @kobj: object we're creating for. | |
538 | * @attr: attribute descriptor. | |
539 | */ | |
540 | ||
541 | int sysfs_create_file(struct kobject * kobj, const struct attribute * attr) | |
542 | { | |
543 | BUG_ON(!kobj || !kobj->sd || !attr); | |
544 | ||
545 | return sysfs_add_file(kobj->sd, attr, SYSFS_KOBJ_ATTR); | |
546 | ||
547 | } | |
548 | ||
549 | int sysfs_create_files(struct kobject *kobj, const struct attribute **ptr) | |
550 | { | |
551 | int err = 0; | |
552 | int i; | |
553 | ||
554 | for (i = 0; ptr[i] && !err; i++) | |
555 | err = sysfs_create_file(kobj, ptr[i]); | |
556 | if (err) | |
557 | while (--i >= 0) | |
558 | sysfs_remove_file(kobj, ptr[i]); | |
559 | return err; | |
560 | } | |
561 | ||
562 | /** | |
563 | * sysfs_add_file_to_group - add an attribute file to a pre-existing group. | |
564 | * @kobj: object we're acting for. | |
565 | * @attr: attribute descriptor. | |
566 | * @group: group name. | |
567 | */ | |
568 | int sysfs_add_file_to_group(struct kobject *kobj, | |
569 | const struct attribute *attr, const char *group) | |
570 | { | |
571 | struct sysfs_dirent *dir_sd; | |
572 | int error; | |
573 | ||
574 | if (group) | |
575 | dir_sd = sysfs_get_dirent(kobj->sd, NULL, group); | |
576 | else | |
577 | dir_sd = sysfs_get(kobj->sd); | |
578 | ||
579 | if (!dir_sd) | |
580 | return -ENOENT; | |
581 | ||
582 | error = sysfs_add_file(dir_sd, attr, SYSFS_KOBJ_ATTR); | |
583 | sysfs_put(dir_sd); | |
584 | ||
585 | return error; | |
586 | } | |
587 | EXPORT_SYMBOL_GPL(sysfs_add_file_to_group); | |
588 | ||
589 | /** | |
590 | * sysfs_chmod_file - update the modified mode value on an object attribute. | |
591 | * @kobj: object we're acting for. | |
592 | * @attr: attribute descriptor. | |
593 | * @mode: file permissions. | |
594 | * | |
595 | */ | |
596 | int sysfs_chmod_file(struct kobject *kobj, struct attribute *attr, mode_t mode) | |
597 | { | |
598 | struct sysfs_dirent *sd; | |
599 | struct iattr newattrs; | |
600 | int rc; | |
601 | ||
602 | mutex_lock(&sysfs_mutex); | |
603 | ||
604 | rc = -ENOENT; | |
605 | sd = sysfs_find_dirent(kobj->sd, NULL, attr->name); | |
606 | if (!sd) | |
607 | goto out; | |
608 | ||
609 | newattrs.ia_mode = (mode & S_IALLUGO) | (sd->s_mode & ~S_IALLUGO); | |
610 | newattrs.ia_valid = ATTR_MODE; | |
611 | rc = sysfs_sd_setattr(sd, &newattrs); | |
612 | ||
613 | out: | |
614 | mutex_unlock(&sysfs_mutex); | |
615 | return rc; | |
616 | } | |
617 | EXPORT_SYMBOL_GPL(sysfs_chmod_file); | |
618 | ||
619 | ||
620 | /** | |
621 | * sysfs_remove_file - remove an object attribute. | |
622 | * @kobj: object we're acting for. | |
623 | * @attr: attribute descriptor. | |
624 | * | |
625 | * Hash the attribute name and kill the victim. | |
626 | */ | |
627 | ||
628 | void sysfs_remove_file(struct kobject * kobj, const struct attribute * attr) | |
629 | { | |
630 | sysfs_hash_and_remove(kobj->sd, NULL, attr->name); | |
631 | } | |
632 | ||
633 | void sysfs_remove_files(struct kobject * kobj, const struct attribute **ptr) | |
634 | { | |
635 | int i; | |
636 | for (i = 0; ptr[i]; i++) | |
637 | sysfs_remove_file(kobj, ptr[i]); | |
638 | } | |
639 | ||
640 | /** | |
641 | * sysfs_remove_file_from_group - remove an attribute file from a group. | |
642 | * @kobj: object we're acting for. | |
643 | * @attr: attribute descriptor. | |
644 | * @group: group name. | |
645 | */ | |
646 | void sysfs_remove_file_from_group(struct kobject *kobj, | |
647 | const struct attribute *attr, const char *group) | |
648 | { | |
649 | struct sysfs_dirent *dir_sd; | |
650 | ||
651 | if (group) | |
652 | dir_sd = sysfs_get_dirent(kobj->sd, NULL, group); | |
653 | else | |
654 | dir_sd = sysfs_get(kobj->sd); | |
655 | if (dir_sd) { | |
656 | sysfs_hash_and_remove(dir_sd, NULL, attr->name); | |
657 | sysfs_put(dir_sd); | |
658 | } | |
659 | } | |
660 | EXPORT_SYMBOL_GPL(sysfs_remove_file_from_group); | |
661 | ||
662 | struct sysfs_schedule_callback_struct { | |
663 | struct list_head workq_list; | |
664 | struct kobject *kobj; | |
665 | void (*func)(void *); | |
666 | void *data; | |
667 | struct module *owner; | |
668 | struct work_struct work; | |
669 | }; | |
670 | ||
671 | static struct workqueue_struct *sysfs_workqueue; | |
672 | static DEFINE_MUTEX(sysfs_workq_mutex); | |
673 | static LIST_HEAD(sysfs_workq); | |
674 | static void sysfs_schedule_callback_work(struct work_struct *work) | |
675 | { | |
676 | struct sysfs_schedule_callback_struct *ss = container_of(work, | |
677 | struct sysfs_schedule_callback_struct, work); | |
678 | ||
679 | (ss->func)(ss->data); | |
680 | kobject_put(ss->kobj); | |
681 | module_put(ss->owner); | |
682 | mutex_lock(&sysfs_workq_mutex); | |
683 | list_del(&ss->workq_list); | |
684 | mutex_unlock(&sysfs_workq_mutex); | |
685 | kfree(ss); | |
686 | } | |
687 | ||
688 | /** | |
689 | * sysfs_schedule_callback - helper to schedule a callback for a kobject | |
690 | * @kobj: object we're acting for. | |
691 | * @func: callback function to invoke later. | |
692 | * @data: argument to pass to @func. | |
693 | * @owner: module owning the callback code | |
694 | * | |
695 | * sysfs attribute methods must not unregister themselves or their parent | |
696 | * kobject (which would amount to the same thing). Attempts to do so will | |
697 | * deadlock, since unregistration is mutually exclusive with driver | |
698 | * callbacks. | |
699 | * | |
700 | * Instead methods can call this routine, which will attempt to allocate | |
701 | * and schedule a workqueue request to call back @func with @data as its | |
702 | * argument in the workqueue's process context. @kobj will be pinned | |
703 | * until @func returns. | |
704 | * | |
705 | * Returns 0 if the request was submitted, -ENOMEM if storage could not | |
706 | * be allocated, -ENODEV if a reference to @owner isn't available, | |
707 | * -EAGAIN if a callback has already been scheduled for @kobj. | |
708 | */ | |
709 | int sysfs_schedule_callback(struct kobject *kobj, void (*func)(void *), | |
710 | void *data, struct module *owner) | |
711 | { | |
712 | struct sysfs_schedule_callback_struct *ss, *tmp; | |
713 | ||
714 | if (!try_module_get(owner)) | |
715 | return -ENODEV; | |
716 | ||
717 | mutex_lock(&sysfs_workq_mutex); | |
718 | list_for_each_entry_safe(ss, tmp, &sysfs_workq, workq_list) | |
719 | if (ss->kobj == kobj) { | |
720 | module_put(owner); | |
721 | mutex_unlock(&sysfs_workq_mutex); | |
722 | return -EAGAIN; | |
723 | } | |
724 | mutex_unlock(&sysfs_workq_mutex); | |
725 | ||
726 | if (sysfs_workqueue == NULL) { | |
727 | sysfs_workqueue = create_singlethread_workqueue("sysfsd"); | |
728 | if (sysfs_workqueue == NULL) { | |
729 | module_put(owner); | |
730 | return -ENOMEM; | |
731 | } | |
732 | } | |
733 | ||
734 | ss = kmalloc(sizeof(*ss), GFP_KERNEL); | |
735 | if (!ss) { | |
736 | module_put(owner); | |
737 | return -ENOMEM; | |
738 | } | |
739 | kobject_get(kobj); | |
740 | ss->kobj = kobj; | |
741 | ss->func = func; | |
742 | ss->data = data; | |
743 | ss->owner = owner; | |
744 | INIT_WORK(&ss->work, sysfs_schedule_callback_work); | |
745 | INIT_LIST_HEAD(&ss->workq_list); | |
746 | mutex_lock(&sysfs_workq_mutex); | |
747 | list_add_tail(&ss->workq_list, &sysfs_workq); | |
748 | mutex_unlock(&sysfs_workq_mutex); | |
749 | queue_work(sysfs_workqueue, &ss->work); | |
750 | return 0; | |
751 | } | |
752 | EXPORT_SYMBOL_GPL(sysfs_schedule_callback); | |
753 | ||
754 | ||
755 | EXPORT_SYMBOL_GPL(sysfs_create_file); | |
756 | EXPORT_SYMBOL_GPL(sysfs_remove_file); | |
757 | EXPORT_SYMBOL_GPL(sysfs_remove_files); | |
758 | EXPORT_SYMBOL_GPL(sysfs_create_files); |