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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/*
28 * There's one sysfs_buffer for each open file and one
29 * sysfs_open_dirent for each sysfs_dirent with one or more open
30 * files.
31 *
32 * filp->private_data points to sysfs_buffer and
33 * sysfs_dirent->s_attr.open points to sysfs_open_dirent. s_attr.open
34 * is protected by sysfs_open_dirent_lock.
35 */
36static DEFINE_SPINLOCK(sysfs_open_dirent_lock);
37
38struct sysfs_open_dirent {
39 atomic_t refcnt;
40 atomic_t event;
41 wait_queue_head_t poll;
42 struct list_head buffers; /* goes through sysfs_buffer.list */
43};
44
45struct sysfs_buffer {
46 size_t count;
47 loff_t pos;
48 char * page;
49 const struct sysfs_ops * ops;
50 struct mutex mutex;
51 int needs_read_fill;
52 int event;
53 struct list_head list;
54};
55
56/**
57 * fill_read_buffer - allocate and fill buffer from object.
58 * @dentry: dentry pointer.
59 * @buffer: data buffer for file.
60 *
61 * Allocate @buffer->page, if it hasn't been already, then call the
62 * kobject's show() method to fill the buffer with this attribute's
63 * data.
64 * This is called only once, on the file's first read unless an error
65 * is returned.
66 */
67static int fill_read_buffer(struct dentry * dentry, struct sysfs_buffer * buffer)
68{
69 struct sysfs_dirent *attr_sd = dentry->d_fsdata;
70 struct kobject *kobj = attr_sd->s_parent->s_dir.kobj;
71 const struct sysfs_ops * ops = buffer->ops;
72 int ret = 0;
73 ssize_t count;
74
75 if (!buffer->page)
76 buffer->page = (char *) get_zeroed_page(GFP_KERNEL);
77 if (!buffer->page)
78 return -ENOMEM;
79
80 /* need attr_sd for attr and ops, its parent for kobj */
81 if (!sysfs_get_active(attr_sd))
82 return -ENODEV;
83
84 buffer->event = atomic_read(&attr_sd->s_attr.open->event);
85 count = ops->show(kobj, attr_sd->s_attr.attr, buffer->page);
86
87 sysfs_put_active(attr_sd);
88
89 /*
90 * The code works fine with PAGE_SIZE return but it's likely to
91 * indicate truncated result or overflow in normal use cases.
92 */
93 if (count >= (ssize_t)PAGE_SIZE) {
94 print_symbol("fill_read_buffer: %s returned bad count\n",
95 (unsigned long)ops->show);
96 /* Try to struggle along */
97 count = PAGE_SIZE - 1;
98 }
99 if (count >= 0) {
100 buffer->needs_read_fill = 0;
101 buffer->count = count;
102 } else {
103 ret = count;
104 }
105 return ret;
106}
107
108/**
109 * sysfs_read_file - read an attribute.
110 * @file: file pointer.
111 * @buf: buffer to fill.
112 * @count: number of bytes to read.
113 * @ppos: starting offset in file.
114 *
115 * Userspace wants to read an attribute file. The attribute descriptor
116 * is in the file's ->d_fsdata. The target object is in the directory's
117 * ->d_fsdata.
118 *
119 * We call fill_read_buffer() to allocate and fill the buffer from the
120 * object's show() method exactly once (if the read is happening from
121 * the beginning of the file). That should fill the entire buffer with
122 * all the data the object has to offer for that attribute.
123 * We then call flush_read_buffer() to copy the buffer to userspace
124 * in the increments specified.
125 */
126
127static ssize_t
128sysfs_read_file(struct file *file, char __user *buf, size_t count, loff_t *ppos)
129{
130 struct sysfs_buffer * buffer = file->private_data;
131 ssize_t retval = 0;
132
133 mutex_lock(&buffer->mutex);
134 if (buffer->needs_read_fill || *ppos == 0) {
135 retval = fill_read_buffer(file->f_path.dentry,buffer);
136 if (retval)
137 goto out;
138 }
139 pr_debug("%s: count = %zd, ppos = %lld, buf = %s\n",
140 __func__, count, *ppos, buffer->page);
141 retval = simple_read_from_buffer(buf, count, ppos, buffer->page,
142 buffer->count);
143out:
144 mutex_unlock(&buffer->mutex);
145 return retval;
146}
147
148/**
149 * fill_write_buffer - copy buffer from userspace.
150 * @buffer: data buffer for file.
151 * @buf: data from user.
152 * @count: number of bytes in @userbuf.
153 *
154 * Allocate @buffer->page if it hasn't been already, then
155 * copy the user-supplied buffer into it.
156 */
157
158static int
159fill_write_buffer(struct sysfs_buffer * buffer, const char __user * buf, size_t count)
160{
161 int error;
162
163 if (!buffer->page)
164 buffer->page = (char *)get_zeroed_page(GFP_KERNEL);
165 if (!buffer->page)
166 return -ENOMEM;
167
168 if (count >= PAGE_SIZE)
169 count = PAGE_SIZE - 1;
170 error = copy_from_user(buffer->page,buf,count);
171 buffer->needs_read_fill = 1;
172 /* if buf is assumed to contain a string, terminate it by \0,
173 so e.g. sscanf() can scan the string easily */
174 buffer->page[count] = 0;
175 return error ? -EFAULT : count;
176}
177
178
179/**
180 * flush_write_buffer - push buffer to kobject.
181 * @dentry: dentry to the attribute
182 * @buffer: data buffer for file.
183 * @count: number of bytes
184 *
185 * Get the correct pointers for the kobject and the attribute we're
186 * dealing with, then call the store() method for the attribute,
187 * passing the buffer that we acquired in fill_write_buffer().
188 */
189
190static int
191flush_write_buffer(struct dentry * dentry, struct sysfs_buffer * buffer, size_t count)
192{
193 struct sysfs_dirent *attr_sd = dentry->d_fsdata;
194 struct kobject *kobj = attr_sd->s_parent->s_dir.kobj;
195 const struct sysfs_ops * ops = buffer->ops;
196 int rc;
197
198 /* need attr_sd for attr and ops, its parent for kobj */
199 if (!sysfs_get_active(attr_sd))
200 return -ENODEV;
201
202 rc = ops->store(kobj, attr_sd->s_attr.attr, buffer->page, count);
203
204 sysfs_put_active(attr_sd);
205
206 return rc;
207}
208
209
210/**
211 * sysfs_write_file - write an attribute.
212 * @file: file pointer
213 * @buf: data to write
214 * @count: number of bytes
215 * @ppos: starting offset
216 *
217 * Similar to sysfs_read_file(), though working in the opposite direction.
218 * We allocate and fill the data from the user in fill_write_buffer(),
219 * then push it to the kobject in flush_write_buffer().
220 * There is no easy way for us to know if userspace is only doing a partial
221 * write, so we don't support them. We expect the entire buffer to come
222 * on the first write.
223 * Hint: if you're writing a value, first read the file, modify only the
224 * the value you're changing, then write entire buffer back.
225 */
226
227static ssize_t
228sysfs_write_file(struct file *file, const char __user *buf, size_t count, loff_t *ppos)
229{
230 struct sysfs_buffer * buffer = file->private_data;
231 ssize_t len;
232
233 mutex_lock(&buffer->mutex);
234 len = fill_write_buffer(buffer, buf, count);
235 if (len > 0)
236 len = flush_write_buffer(file->f_path.dentry, buffer, len);
237 if (len > 0)
238 *ppos += len;
239 mutex_unlock(&buffer->mutex);
240 return len;
241}
242
243/**
244 * sysfs_get_open_dirent - get or create sysfs_open_dirent
245 * @sd: target sysfs_dirent
246 * @buffer: sysfs_buffer for this instance of open
247 *
248 * If @sd->s_attr.open exists, increment its reference count;
249 * otherwise, create one. @buffer is chained to the buffers
250 * list.
251 *
252 * LOCKING:
253 * Kernel thread context (may sleep).
254 *
255 * RETURNS:
256 * 0 on success, -errno on failure.
257 */
258static int sysfs_get_open_dirent(struct sysfs_dirent *sd,
259 struct sysfs_buffer *buffer)
260{
261 struct sysfs_open_dirent *od, *new_od = NULL;
262
263 retry:
264 spin_lock_irq(&sysfs_open_dirent_lock);
265
266 if (!sd->s_attr.open && new_od) {
267 sd->s_attr.open = new_od;
268 new_od = NULL;
269 }
270
271 od = sd->s_attr.open;
272 if (od) {
273 atomic_inc(&od->refcnt);
274 list_add_tail(&buffer->list, &od->buffers);
275 }
276
277 spin_unlock_irq(&sysfs_open_dirent_lock);
278
279 if (od) {
280 kfree(new_od);
281 return 0;
282 }
283
284 /* not there, initialize a new one and retry */
285 new_od = kmalloc(sizeof(*new_od), GFP_KERNEL);
286 if (!new_od)
287 return -ENOMEM;
288
289 atomic_set(&new_od->refcnt, 0);
290 atomic_set(&new_od->event, 1);
291 init_waitqueue_head(&new_od->poll);
292 INIT_LIST_HEAD(&new_od->buffers);
293 goto retry;
294}
295
296/**
297 * sysfs_put_open_dirent - put sysfs_open_dirent
298 * @sd: target sysfs_dirent
299 * @buffer: associated sysfs_buffer
300 *
301 * Put @sd->s_attr.open and unlink @buffer from the buffers list.
302 * If reference count reaches zero, disassociate and free it.
303 *
304 * LOCKING:
305 * None.
306 */
307static void sysfs_put_open_dirent(struct sysfs_dirent *sd,
308 struct sysfs_buffer *buffer)
309{
310 struct sysfs_open_dirent *od = sd->s_attr.open;
311 unsigned long flags;
312
313 spin_lock_irqsave(&sysfs_open_dirent_lock, flags);
314
315 list_del(&buffer->list);
316 if (atomic_dec_and_test(&od->refcnt))
317 sd->s_attr.open = NULL;
318 else
319 od = NULL;
320
321 spin_unlock_irqrestore(&sysfs_open_dirent_lock, flags);
322
323 kfree(od);
324}
325
326static int sysfs_open_file(struct inode *inode, struct file *file)
327{
328 struct sysfs_dirent *attr_sd = file->f_path.dentry->d_fsdata;
329 struct kobject *kobj = attr_sd->s_parent->s_dir.kobj;
330 struct sysfs_buffer *buffer;
331 const struct sysfs_ops *ops;
332 int error = -EACCES;
333
334 /* need attr_sd for attr and ops, its parent for kobj */
335 if (!sysfs_get_active(attr_sd))
336 return -ENODEV;
337
338 /* every kobject with an attribute needs a ktype assigned */
339 if (kobj->ktype && kobj->ktype->sysfs_ops)
340 ops = kobj->ktype->sysfs_ops;
341 else {
342 WARN(1, KERN_ERR "missing sysfs attribute operations for "
343 "kobject: %s\n", kobject_name(kobj));
344 goto err_out;
345 }
346
347 /* File needs write support.
348 * The inode's perms must say it's ok,
349 * and we must have a store method.
350 */
351 if (file->f_mode & FMODE_WRITE) {
352 if (!(inode->i_mode & S_IWUGO) || !ops->store)
353 goto err_out;
354 }
355
356 /* File needs read support.
357 * The inode's perms must say it's ok, and we there
358 * must be a show method for it.
359 */
360 if (file->f_mode & FMODE_READ) {
361 if (!(inode->i_mode & S_IRUGO) || !ops->show)
362 goto err_out;
363 }
364
365 /* No error? Great, allocate a buffer for the file, and store it
366 * it in file->private_data for easy access.
367 */
368 error = -ENOMEM;
369 buffer = kzalloc(sizeof(struct sysfs_buffer), GFP_KERNEL);
370 if (!buffer)
371 goto err_out;
372
373 mutex_init(&buffer->mutex);
374 buffer->needs_read_fill = 1;
375 buffer->ops = ops;
376 file->private_data = buffer;
377
378 /* make sure we have open dirent struct */
379 error = sysfs_get_open_dirent(attr_sd, buffer);
380 if (error)
381 goto err_free;
382
383 /* open succeeded, put active references */
384 sysfs_put_active(attr_sd);
385 return 0;
386
387 err_free:
388 kfree(buffer);
389 err_out:
390 sysfs_put_active(attr_sd);
391 return error;
392}
393
394static int sysfs_release(struct inode *inode, struct file *filp)
395{
396 struct sysfs_dirent *sd = filp->f_path.dentry->d_fsdata;
397 struct sysfs_buffer *buffer = filp->private_data;
398
399 sysfs_put_open_dirent(sd, buffer);
400
401 if (buffer->page)
402 free_page((unsigned long)buffer->page);
403 kfree(buffer);
404
405 return 0;
406}
407
408/* Sysfs attribute files are pollable. The idea is that you read
409 * the content and then you use 'poll' or 'select' to wait for
410 * the content to change. When the content changes (assuming the
411 * manager for the kobject supports notification), poll will
412 * return POLLERR|POLLPRI, and select will return the fd whether
413 * it is waiting for read, write, or exceptions.
414 * Once poll/select indicates that the value has changed, you
415 * need to close and re-open the file, or seek to 0 and read again.
416 * Reminder: this only works for attributes which actively support
417 * it, and it is not possible to test an attribute from userspace
418 * to see if it supports poll (Neither 'poll' nor 'select' return
419 * an appropriate error code). When in doubt, set a suitable timeout value.
420 */
421static unsigned int sysfs_poll(struct file *filp, poll_table *wait)
422{
423 struct sysfs_buffer * buffer = filp->private_data;
424 struct sysfs_dirent *attr_sd = filp->f_path.dentry->d_fsdata;
425 struct sysfs_open_dirent *od = attr_sd->s_attr.open;
426
427 /* need parent for the kobj, grab both */
428 if (!sysfs_get_active(attr_sd))
429 goto trigger;
430
431 poll_wait(filp, &od->poll, wait);
432
433 sysfs_put_active(attr_sd);
434
435 if (buffer->event != atomic_read(&od->event))
436 goto trigger;
437
438 return DEFAULT_POLLMASK;
439
440 trigger:
441 buffer->needs_read_fill = 1;
442 return DEFAULT_POLLMASK|POLLERR|POLLPRI;
443}
444
445void sysfs_notify_dirent(struct sysfs_dirent *sd)
446{
447 struct sysfs_open_dirent *od;
448 unsigned long flags;
449
450 spin_lock_irqsave(&sysfs_open_dirent_lock, flags);
451
452 od = sd->s_attr.open;
453 if (od) {
454 atomic_inc(&od->event);
455 wake_up_interruptible(&od->poll);
456 }
457
458 spin_unlock_irqrestore(&sysfs_open_dirent_lock, flags);
459}
460EXPORT_SYMBOL_GPL(sysfs_notify_dirent);
461
462void sysfs_notify(struct kobject *k, const char *dir, const char *attr)
463{
464 struct sysfs_dirent *sd = k->sd;
465
466 mutex_lock(&sysfs_mutex);
467
468 if (sd && dir)
469 /* Only directories are tagged, so no need to pass
470 * a tag explicitly.
471 */
472 sd = sysfs_find_dirent(sd, NULL, dir);
473 if (sd && attr)
474 sd = sysfs_find_dirent(sd, NULL, attr);
475 if (sd)
476 sysfs_notify_dirent(sd);
477
478 mutex_unlock(&sysfs_mutex);
479}
480EXPORT_SYMBOL_GPL(sysfs_notify);
481
482const struct file_operations sysfs_file_operations = {
483 .read = sysfs_read_file,
484 .write = sysfs_write_file,
485 .llseek = generic_file_llseek,
486 .open = sysfs_open_file,
487 .release = sysfs_release,
488 .poll = sysfs_poll,
489};
490
491int sysfs_add_file_mode(struct sysfs_dirent *dir_sd,
492 const struct attribute *attr, int type, mode_t amode)
493{
494 umode_t mode = (amode & S_IALLUGO) | S_IFREG;
495 struct sysfs_addrm_cxt acxt;
496 struct sysfs_dirent *sd;
497 int rc;
498
499 sd = sysfs_new_dirent(attr->name, mode, type);
500 if (!sd)
501 return -ENOMEM;
502 sd->s_attr.attr = (void *)attr;
503 sysfs_dirent_init_lockdep(sd);
504
505 sysfs_addrm_start(&acxt, dir_sd);
506 rc = sysfs_add_one(&acxt, sd);
507 sysfs_addrm_finish(&acxt);
508
509 if (rc)
510 sysfs_put(sd);
511
512 return rc;
513}
514
515
516int sysfs_add_file(struct sysfs_dirent *dir_sd, const struct attribute *attr,
517 int type)
518{
519 return sysfs_add_file_mode(dir_sd, attr, type, attr->mode);
520}
521
522
523/**
524 * sysfs_create_file - create an attribute file for an object.
525 * @kobj: object we're creating for.
526 * @attr: attribute descriptor.
527 */
528
529int sysfs_create_file(struct kobject * kobj, const struct attribute * attr)
530{
531 BUG_ON(!kobj || !kobj->sd || !attr);
532
533 return sysfs_add_file(kobj->sd, attr, SYSFS_KOBJ_ATTR);
534
535}
536
537int sysfs_create_files(struct kobject *kobj, const struct attribute **ptr)
538{
539 int err = 0;
540 int i;
541
542 for (i = 0; ptr[i] && !err; i++)
543 err = sysfs_create_file(kobj, ptr[i]);
544 if (err)
545 while (--i >= 0)
546 sysfs_remove_file(kobj, ptr[i]);
547 return err;
548}
549
550/**
551 * sysfs_add_file_to_group - add an attribute file to a pre-existing group.
552 * @kobj: object we're acting for.
553 * @attr: attribute descriptor.
554 * @group: group name.
555 */
556int sysfs_add_file_to_group(struct kobject *kobj,
557 const struct attribute *attr, const char *group)
558{
559 struct sysfs_dirent *dir_sd;
560 int error;
561
562 if (group)
563 dir_sd = sysfs_get_dirent(kobj->sd, NULL, group);
564 else
565 dir_sd = sysfs_get(kobj->sd);
566
567 if (!dir_sd)
568 return -ENOENT;
569
570 error = sysfs_add_file(dir_sd, attr, SYSFS_KOBJ_ATTR);
571 sysfs_put(dir_sd);
572
573 return error;
574}
575EXPORT_SYMBOL_GPL(sysfs_add_file_to_group);
576
577/**
578 * sysfs_chmod_file - update the modified mode value on an object attribute.
579 * @kobj: object we're acting for.
580 * @attr: attribute descriptor.
581 * @mode: file permissions.
582 *
583 */
584int sysfs_chmod_file(struct kobject *kobj, const struct attribute *attr,
585 mode_t mode)
586{
587 struct sysfs_dirent *sd;
588 struct iattr newattrs;
589 int rc;
590
591 mutex_lock(&sysfs_mutex);
592
593 rc = -ENOENT;
594 sd = sysfs_find_dirent(kobj->sd, NULL, attr->name);
595 if (!sd)
596 goto out;
597
598 newattrs.ia_mode = (mode & S_IALLUGO) | (sd->s_mode & ~S_IALLUGO);
599 newattrs.ia_valid = ATTR_MODE;
600 rc = sysfs_sd_setattr(sd, &newattrs);
601
602 out:
603 mutex_unlock(&sysfs_mutex);
604 return rc;
605}
606EXPORT_SYMBOL_GPL(sysfs_chmod_file);
607
608
609/**
610 * sysfs_remove_file - remove an object attribute.
611 * @kobj: object we're acting for.
612 * @attr: attribute descriptor.
613 *
614 * Hash the attribute name and kill the victim.
615 */
616
617void sysfs_remove_file(struct kobject * kobj, const struct attribute * attr)
618{
619 sysfs_hash_and_remove(kobj->sd, NULL, attr->name);
620}
621
622void sysfs_remove_files(struct kobject * kobj, const struct attribute **ptr)
623{
624 int i;
625 for (i = 0; ptr[i]; i++)
626 sysfs_remove_file(kobj, ptr[i]);
627}
628
629/**
630 * sysfs_remove_file_from_group - remove an attribute file from a group.
631 * @kobj: object we're acting for.
632 * @attr: attribute descriptor.
633 * @group: group name.
634 */
635void sysfs_remove_file_from_group(struct kobject *kobj,
636 const struct attribute *attr, const char *group)
637{
638 struct sysfs_dirent *dir_sd;
639
640 if (group)
641 dir_sd = sysfs_get_dirent(kobj->sd, NULL, group);
642 else
643 dir_sd = sysfs_get(kobj->sd);
644 if (dir_sd) {
645 sysfs_hash_and_remove(dir_sd, NULL, attr->name);
646 sysfs_put(dir_sd);
647 }
648}
649EXPORT_SYMBOL_GPL(sysfs_remove_file_from_group);
650
651struct sysfs_schedule_callback_struct {
652 struct list_head workq_list;
653 struct kobject *kobj;
654 void (*func)(void *);
655 void *data;
656 struct module *owner;
657 struct work_struct work;
658};
659
660static struct workqueue_struct *sysfs_workqueue;
661static DEFINE_MUTEX(sysfs_workq_mutex);
662static LIST_HEAD(sysfs_workq);
663static void sysfs_schedule_callback_work(struct work_struct *work)
664{
665 struct sysfs_schedule_callback_struct *ss = container_of(work,
666 struct sysfs_schedule_callback_struct, work);
667
668 (ss->func)(ss->data);
669 kobject_put(ss->kobj);
670 module_put(ss->owner);
671 mutex_lock(&sysfs_workq_mutex);
672 list_del(&ss->workq_list);
673 mutex_unlock(&sysfs_workq_mutex);
674 kfree(ss);
675}
676
677/**
678 * sysfs_schedule_callback - helper to schedule a callback for a kobject
679 * @kobj: object we're acting for.
680 * @func: callback function to invoke later.
681 * @data: argument to pass to @func.
682 * @owner: module owning the callback code
683 *
684 * sysfs attribute methods must not unregister themselves or their parent
685 * kobject (which would amount to the same thing). Attempts to do so will
686 * deadlock, since unregistration is mutually exclusive with driver
687 * callbacks.
688 *
689 * Instead methods can call this routine, which will attempt to allocate
690 * and schedule a workqueue request to call back @func with @data as its
691 * argument in the workqueue's process context. @kobj will be pinned
692 * until @func returns.
693 *
694 * Returns 0 if the request was submitted, -ENOMEM if storage could not
695 * be allocated, -ENODEV if a reference to @owner isn't available,
696 * -EAGAIN if a callback has already been scheduled for @kobj.
697 */
698int sysfs_schedule_callback(struct kobject *kobj, void (*func)(void *),
699 void *data, struct module *owner)
700{
701 struct sysfs_schedule_callback_struct *ss, *tmp;
702
703 if (!try_module_get(owner))
704 return -ENODEV;
705
706 mutex_lock(&sysfs_workq_mutex);
707 list_for_each_entry_safe(ss, tmp, &sysfs_workq, workq_list)
708 if (ss->kobj == kobj) {
709 module_put(owner);
710 mutex_unlock(&sysfs_workq_mutex);
711 return -EAGAIN;
712 }
713 mutex_unlock(&sysfs_workq_mutex);
714
715 if (sysfs_workqueue == NULL) {
716 sysfs_workqueue = create_singlethread_workqueue("sysfsd");
717 if (sysfs_workqueue == NULL) {
718 module_put(owner);
719 return -ENOMEM;
720 }
721 }
722
723 ss = kmalloc(sizeof(*ss), GFP_KERNEL);
724 if (!ss) {
725 module_put(owner);
726 return -ENOMEM;
727 }
728 kobject_get(kobj);
729 ss->kobj = kobj;
730 ss->func = func;
731 ss->data = data;
732 ss->owner = owner;
733 INIT_WORK(&ss->work, sysfs_schedule_callback_work);
734 INIT_LIST_HEAD(&ss->workq_list);
735 mutex_lock(&sysfs_workq_mutex);
736 list_add_tail(&ss->workq_list, &sysfs_workq);
737 mutex_unlock(&sysfs_workq_mutex);
738 queue_work(sysfs_workqueue, &ss->work);
739 return 0;
740}
741EXPORT_SYMBOL_GPL(sysfs_schedule_callback);
742
743
744EXPORT_SYMBOL_GPL(sysfs_create_file);
745EXPORT_SYMBOL_GPL(sysfs_remove_file);
746EXPORT_SYMBOL_GPL(sysfs_remove_files);
747EXPORT_SYMBOL_GPL(sysfs_create_files);
1// SPDX-License-Identifier: GPL-2.0
2/*
3 * fs/sysfs/file.c - sysfs regular (text) file implementation
4 *
5 * Copyright (c) 2001-3 Patrick Mochel
6 * Copyright (c) 2007 SUSE Linux Products GmbH
7 * Copyright (c) 2007 Tejun Heo <teheo@suse.de>
8 *
9 * Please see Documentation/filesystems/sysfs.txt for more information.
10 */
11
12#include <linux/module.h>
13#include <linux/kobject.h>
14#include <linux/slab.h>
15#include <linux/list.h>
16#include <linux/mutex.h>
17#include <linux/seq_file.h>
18
19#include "sysfs.h"
20#include "../kernfs/kernfs-internal.h"
21
22/*
23 * Determine ktype->sysfs_ops for the given kernfs_node. This function
24 * must be called while holding an active reference.
25 */
26static const struct sysfs_ops *sysfs_file_ops(struct kernfs_node *kn)
27{
28 struct kobject *kobj = kn->parent->priv;
29
30 if (kn->flags & KERNFS_LOCKDEP)
31 lockdep_assert_held(kn);
32 return kobj->ktype ? kobj->ktype->sysfs_ops : NULL;
33}
34
35/*
36 * Reads on sysfs are handled through seq_file, which takes care of hairy
37 * details like buffering and seeking. The following function pipes
38 * sysfs_ops->show() result through seq_file.
39 */
40static int sysfs_kf_seq_show(struct seq_file *sf, void *v)
41{
42 struct kernfs_open_file *of = sf->private;
43 struct kobject *kobj = of->kn->parent->priv;
44 const struct sysfs_ops *ops = sysfs_file_ops(of->kn);
45 ssize_t count;
46 char *buf;
47
48 /* acquire buffer and ensure that it's >= PAGE_SIZE and clear */
49 count = seq_get_buf(sf, &buf);
50 if (count < PAGE_SIZE) {
51 seq_commit(sf, -1);
52 return 0;
53 }
54 memset(buf, 0, PAGE_SIZE);
55
56 /*
57 * Invoke show(). Control may reach here via seq file lseek even
58 * if @ops->show() isn't implemented.
59 */
60 if (ops->show) {
61 count = ops->show(kobj, of->kn->priv, buf);
62 if (count < 0)
63 return count;
64 }
65
66 /*
67 * The code works fine with PAGE_SIZE return but it's likely to
68 * indicate truncated result or overflow in normal use cases.
69 */
70 if (count >= (ssize_t)PAGE_SIZE) {
71 printk("fill_read_buffer: %pS returned bad count\n",
72 ops->show);
73 /* Try to struggle along */
74 count = PAGE_SIZE - 1;
75 }
76 seq_commit(sf, count);
77 return 0;
78}
79
80static ssize_t sysfs_kf_bin_read(struct kernfs_open_file *of, char *buf,
81 size_t count, loff_t pos)
82{
83 struct bin_attribute *battr = of->kn->priv;
84 struct kobject *kobj = of->kn->parent->priv;
85 loff_t size = file_inode(of->file)->i_size;
86
87 if (!count)
88 return 0;
89
90 if (size) {
91 if (pos >= size)
92 return 0;
93 if (pos + count > size)
94 count = size - pos;
95 }
96
97 if (!battr->read)
98 return -EIO;
99
100 return battr->read(of->file, kobj, battr, buf, pos, count);
101}
102
103/* kernfs read callback for regular sysfs files with pre-alloc */
104static ssize_t sysfs_kf_read(struct kernfs_open_file *of, char *buf,
105 size_t count, loff_t pos)
106{
107 const struct sysfs_ops *ops = sysfs_file_ops(of->kn);
108 struct kobject *kobj = of->kn->parent->priv;
109 ssize_t len;
110
111 /*
112 * If buf != of->prealloc_buf, we don't know how
113 * large it is, so cannot safely pass it to ->show
114 */
115 if (WARN_ON_ONCE(buf != of->prealloc_buf))
116 return 0;
117 len = ops->show(kobj, of->kn->priv, buf);
118 if (len < 0)
119 return len;
120 if (pos) {
121 if (len <= pos)
122 return 0;
123 len -= pos;
124 memmove(buf, buf + pos, len);
125 }
126 return min_t(ssize_t, count, len);
127}
128
129/* kernfs write callback for regular sysfs files */
130static ssize_t sysfs_kf_write(struct kernfs_open_file *of, char *buf,
131 size_t count, loff_t pos)
132{
133 const struct sysfs_ops *ops = sysfs_file_ops(of->kn);
134 struct kobject *kobj = of->kn->parent->priv;
135
136 if (!count)
137 return 0;
138
139 return ops->store(kobj, of->kn->priv, buf, count);
140}
141
142/* kernfs write callback for bin sysfs files */
143static ssize_t sysfs_kf_bin_write(struct kernfs_open_file *of, char *buf,
144 size_t count, loff_t pos)
145{
146 struct bin_attribute *battr = of->kn->priv;
147 struct kobject *kobj = of->kn->parent->priv;
148 loff_t size = file_inode(of->file)->i_size;
149
150 if (size) {
151 if (size <= pos)
152 return -EFBIG;
153 count = min_t(ssize_t, count, size - pos);
154 }
155 if (!count)
156 return 0;
157
158 if (!battr->write)
159 return -EIO;
160
161 return battr->write(of->file, kobj, battr, buf, pos, count);
162}
163
164static int sysfs_kf_bin_mmap(struct kernfs_open_file *of,
165 struct vm_area_struct *vma)
166{
167 struct bin_attribute *battr = of->kn->priv;
168 struct kobject *kobj = of->kn->parent->priv;
169
170 return battr->mmap(of->file, kobj, battr, vma);
171}
172
173void sysfs_notify(struct kobject *kobj, const char *dir, const char *attr)
174{
175 struct kernfs_node *kn = kobj->sd, *tmp;
176
177 if (kn && dir)
178 kn = kernfs_find_and_get(kn, dir);
179 else
180 kernfs_get(kn);
181
182 if (kn && attr) {
183 tmp = kernfs_find_and_get(kn, attr);
184 kernfs_put(kn);
185 kn = tmp;
186 }
187
188 if (kn) {
189 kernfs_notify(kn);
190 kernfs_put(kn);
191 }
192}
193EXPORT_SYMBOL_GPL(sysfs_notify);
194
195static const struct kernfs_ops sysfs_file_kfops_empty = {
196};
197
198static const struct kernfs_ops sysfs_file_kfops_ro = {
199 .seq_show = sysfs_kf_seq_show,
200};
201
202static const struct kernfs_ops sysfs_file_kfops_wo = {
203 .write = sysfs_kf_write,
204};
205
206static const struct kernfs_ops sysfs_file_kfops_rw = {
207 .seq_show = sysfs_kf_seq_show,
208 .write = sysfs_kf_write,
209};
210
211static const struct kernfs_ops sysfs_prealloc_kfops_ro = {
212 .read = sysfs_kf_read,
213 .prealloc = true,
214};
215
216static const struct kernfs_ops sysfs_prealloc_kfops_wo = {
217 .write = sysfs_kf_write,
218 .prealloc = true,
219};
220
221static const struct kernfs_ops sysfs_prealloc_kfops_rw = {
222 .read = sysfs_kf_read,
223 .write = sysfs_kf_write,
224 .prealloc = true,
225};
226
227static const struct kernfs_ops sysfs_bin_kfops_ro = {
228 .read = sysfs_kf_bin_read,
229};
230
231static const struct kernfs_ops sysfs_bin_kfops_wo = {
232 .write = sysfs_kf_bin_write,
233};
234
235static const struct kernfs_ops sysfs_bin_kfops_rw = {
236 .read = sysfs_kf_bin_read,
237 .write = sysfs_kf_bin_write,
238};
239
240static const struct kernfs_ops sysfs_bin_kfops_mmap = {
241 .read = sysfs_kf_bin_read,
242 .write = sysfs_kf_bin_write,
243 .mmap = sysfs_kf_bin_mmap,
244};
245
246int sysfs_add_file_mode_ns(struct kernfs_node *parent,
247 const struct attribute *attr, bool is_bin,
248 umode_t mode, const void *ns)
249{
250 struct lock_class_key *key = NULL;
251 const struct kernfs_ops *ops;
252 struct kernfs_node *kn;
253 loff_t size;
254
255 if (!is_bin) {
256 struct kobject *kobj = parent->priv;
257 const struct sysfs_ops *sysfs_ops = kobj->ktype->sysfs_ops;
258
259 /* every kobject with an attribute needs a ktype assigned */
260 if (WARN(!sysfs_ops, KERN_ERR
261 "missing sysfs attribute operations for kobject: %s\n",
262 kobject_name(kobj)))
263 return -EINVAL;
264
265 if (sysfs_ops->show && sysfs_ops->store) {
266 if (mode & SYSFS_PREALLOC)
267 ops = &sysfs_prealloc_kfops_rw;
268 else
269 ops = &sysfs_file_kfops_rw;
270 } else if (sysfs_ops->show) {
271 if (mode & SYSFS_PREALLOC)
272 ops = &sysfs_prealloc_kfops_ro;
273 else
274 ops = &sysfs_file_kfops_ro;
275 } else if (sysfs_ops->store) {
276 if (mode & SYSFS_PREALLOC)
277 ops = &sysfs_prealloc_kfops_wo;
278 else
279 ops = &sysfs_file_kfops_wo;
280 } else
281 ops = &sysfs_file_kfops_empty;
282
283 size = PAGE_SIZE;
284 } else {
285 struct bin_attribute *battr = (void *)attr;
286
287 if (battr->mmap)
288 ops = &sysfs_bin_kfops_mmap;
289 else if (battr->read && battr->write)
290 ops = &sysfs_bin_kfops_rw;
291 else if (battr->read)
292 ops = &sysfs_bin_kfops_ro;
293 else if (battr->write)
294 ops = &sysfs_bin_kfops_wo;
295 else
296 ops = &sysfs_file_kfops_empty;
297
298 size = battr->size;
299 }
300
301#ifdef CONFIG_DEBUG_LOCK_ALLOC
302 if (!attr->ignore_lockdep)
303 key = attr->key ?: (struct lock_class_key *)&attr->skey;
304#endif
305 kn = __kernfs_create_file(parent, attr->name, mode & 0777, size, ops,
306 (void *)attr, ns, key);
307 if (IS_ERR(kn)) {
308 if (PTR_ERR(kn) == -EEXIST)
309 sysfs_warn_dup(parent, attr->name);
310 return PTR_ERR(kn);
311 }
312 return 0;
313}
314
315int sysfs_add_file(struct kernfs_node *parent, const struct attribute *attr,
316 bool is_bin)
317{
318 return sysfs_add_file_mode_ns(parent, attr, is_bin, attr->mode, NULL);
319}
320
321/**
322 * sysfs_create_file_ns - create an attribute file for an object with custom ns
323 * @kobj: object we're creating for
324 * @attr: attribute descriptor
325 * @ns: namespace the new file should belong to
326 */
327int sysfs_create_file_ns(struct kobject *kobj, const struct attribute *attr,
328 const void *ns)
329{
330 BUG_ON(!kobj || !kobj->sd || !attr);
331
332 return sysfs_add_file_mode_ns(kobj->sd, attr, false, attr->mode, ns);
333
334}
335EXPORT_SYMBOL_GPL(sysfs_create_file_ns);
336
337int sysfs_create_files(struct kobject *kobj, const struct attribute **ptr)
338{
339 int err = 0;
340 int i;
341
342 for (i = 0; ptr[i] && !err; i++)
343 err = sysfs_create_file(kobj, ptr[i]);
344 if (err)
345 while (--i >= 0)
346 sysfs_remove_file(kobj, ptr[i]);
347 return err;
348}
349EXPORT_SYMBOL_GPL(sysfs_create_files);
350
351/**
352 * sysfs_add_file_to_group - add an attribute file to a pre-existing group.
353 * @kobj: object we're acting for.
354 * @attr: attribute descriptor.
355 * @group: group name.
356 */
357int sysfs_add_file_to_group(struct kobject *kobj,
358 const struct attribute *attr, const char *group)
359{
360 struct kernfs_node *parent;
361 int error;
362
363 if (group) {
364 parent = kernfs_find_and_get(kobj->sd, group);
365 } else {
366 parent = kobj->sd;
367 kernfs_get(parent);
368 }
369
370 if (!parent)
371 return -ENOENT;
372
373 error = sysfs_add_file(parent, attr, false);
374 kernfs_put(parent);
375
376 return error;
377}
378EXPORT_SYMBOL_GPL(sysfs_add_file_to_group);
379
380/**
381 * sysfs_chmod_file - update the modified mode value on an object attribute.
382 * @kobj: object we're acting for.
383 * @attr: attribute descriptor.
384 * @mode: file permissions.
385 *
386 */
387int sysfs_chmod_file(struct kobject *kobj, const struct attribute *attr,
388 umode_t mode)
389{
390 struct kernfs_node *kn;
391 struct iattr newattrs;
392 int rc;
393
394 kn = kernfs_find_and_get(kobj->sd, attr->name);
395 if (!kn)
396 return -ENOENT;
397
398 newattrs.ia_mode = (mode & S_IALLUGO) | (kn->mode & ~S_IALLUGO);
399 newattrs.ia_valid = ATTR_MODE;
400
401 rc = kernfs_setattr(kn, &newattrs);
402
403 kernfs_put(kn);
404 return rc;
405}
406EXPORT_SYMBOL_GPL(sysfs_chmod_file);
407
408/**
409 * sysfs_remove_file_ns - remove an object attribute with a custom ns tag
410 * @kobj: object we're acting for
411 * @attr: attribute descriptor
412 * @ns: namespace tag of the file to remove
413 *
414 * Hash the attribute name and namespace tag and kill the victim.
415 */
416void sysfs_remove_file_ns(struct kobject *kobj, const struct attribute *attr,
417 const void *ns)
418{
419 struct kernfs_node *parent = kobj->sd;
420
421 kernfs_remove_by_name_ns(parent, attr->name, ns);
422}
423EXPORT_SYMBOL_GPL(sysfs_remove_file_ns);
424
425/**
426 * sysfs_remove_file_self - remove an object attribute from its own method
427 * @kobj: object we're acting for
428 * @attr: attribute descriptor
429 *
430 * See kernfs_remove_self() for details.
431 */
432bool sysfs_remove_file_self(struct kobject *kobj, const struct attribute *attr)
433{
434 struct kernfs_node *parent = kobj->sd;
435 struct kernfs_node *kn;
436 bool ret;
437
438 kn = kernfs_find_and_get(parent, attr->name);
439 if (WARN_ON_ONCE(!kn))
440 return false;
441
442 ret = kernfs_remove_self(kn);
443
444 kernfs_put(kn);
445 return ret;
446}
447
448void sysfs_remove_files(struct kobject *kobj, const struct attribute **ptr)
449{
450 int i;
451 for (i = 0; ptr[i]; i++)
452 sysfs_remove_file(kobj, ptr[i]);
453}
454EXPORT_SYMBOL_GPL(sysfs_remove_files);
455
456/**
457 * sysfs_remove_file_from_group - remove an attribute file from a group.
458 * @kobj: object we're acting for.
459 * @attr: attribute descriptor.
460 * @group: group name.
461 */
462void sysfs_remove_file_from_group(struct kobject *kobj,
463 const struct attribute *attr, const char *group)
464{
465 struct kernfs_node *parent;
466
467 if (group) {
468 parent = kernfs_find_and_get(kobj->sd, group);
469 } else {
470 parent = kobj->sd;
471 kernfs_get(parent);
472 }
473
474 if (parent) {
475 kernfs_remove_by_name(parent, attr->name);
476 kernfs_put(parent);
477 }
478}
479EXPORT_SYMBOL_GPL(sysfs_remove_file_from_group);
480
481/**
482 * sysfs_create_bin_file - create binary file for object.
483 * @kobj: object.
484 * @attr: attribute descriptor.
485 */
486int sysfs_create_bin_file(struct kobject *kobj,
487 const struct bin_attribute *attr)
488{
489 BUG_ON(!kobj || !kobj->sd || !attr);
490
491 return sysfs_add_file(kobj->sd, &attr->attr, true);
492}
493EXPORT_SYMBOL_GPL(sysfs_create_bin_file);
494
495/**
496 * sysfs_remove_bin_file - remove binary file for object.
497 * @kobj: object.
498 * @attr: attribute descriptor.
499 */
500void sysfs_remove_bin_file(struct kobject *kobj,
501 const struct bin_attribute *attr)
502{
503 kernfs_remove_by_name(kobj->sd, attr->attr.name);
504}
505EXPORT_SYMBOL_GPL(sysfs_remove_bin_file);