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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 sd = sysfs_find_dirent(sd, NULL, dir);
470 if (sd && attr)
471 sd = sysfs_find_dirent(sd, NULL, attr);
472 if (sd)
473 sysfs_notify_dirent(sd);
474
475 mutex_unlock(&sysfs_mutex);
476}
477EXPORT_SYMBOL_GPL(sysfs_notify);
478
479const struct file_operations sysfs_file_operations = {
480 .read = sysfs_read_file,
481 .write = sysfs_write_file,
482 .llseek = generic_file_llseek,
483 .open = sysfs_open_file,
484 .release = sysfs_release,
485 .poll = sysfs_poll,
486};
487
488int sysfs_attr_ns(struct kobject *kobj, const struct attribute *attr,
489 const void **pns)
490{
491 struct sysfs_dirent *dir_sd = kobj->sd;
492 const struct sysfs_ops *ops;
493 const void *ns = NULL;
494 int err;
495
496 if (!dir_sd) {
497 WARN(1, KERN_ERR "sysfs: kobject %s without dirent\n",
498 kobject_name(kobj));
499 return -ENOENT;
500 }
501
502 err = 0;
503 if (!sysfs_ns_type(dir_sd))
504 goto out;
505
506 err = -EINVAL;
507 if (!kobj->ktype)
508 goto out;
509 ops = kobj->ktype->sysfs_ops;
510 if (!ops)
511 goto out;
512 if (!ops->namespace)
513 goto out;
514
515 err = 0;
516 ns = ops->namespace(kobj, attr);
517out:
518 if (err) {
519 WARN(1, KERN_ERR "missing sysfs namespace attribute operation for "
520 "kobject: %s\n", kobject_name(kobj));
521 }
522 *pns = ns;
523 return err;
524}
525
526int sysfs_add_file_mode(struct sysfs_dirent *dir_sd,
527 const struct attribute *attr, int type, umode_t amode)
528{
529 umode_t mode = (amode & S_IALLUGO) | S_IFREG;
530 struct sysfs_addrm_cxt acxt;
531 struct sysfs_dirent *sd;
532 const void *ns;
533 int rc;
534
535 rc = sysfs_attr_ns(dir_sd->s_dir.kobj, attr, &ns);
536 if (rc)
537 return rc;
538
539 sd = sysfs_new_dirent(attr->name, mode, type);
540 if (!sd)
541 return -ENOMEM;
542
543 sd->s_ns = ns;
544 sd->s_attr.attr = (void *)attr;
545 sysfs_dirent_init_lockdep(sd);
546
547 sysfs_addrm_start(&acxt, dir_sd);
548 rc = sysfs_add_one(&acxt, sd);
549 sysfs_addrm_finish(&acxt);
550
551 if (rc)
552 sysfs_put(sd);
553
554 return rc;
555}
556
557
558int sysfs_add_file(struct sysfs_dirent *dir_sd, const struct attribute *attr,
559 int type)
560{
561 return sysfs_add_file_mode(dir_sd, attr, type, attr->mode);
562}
563
564
565/**
566 * sysfs_create_file - create an attribute file for an object.
567 * @kobj: object we're creating for.
568 * @attr: attribute descriptor.
569 */
570
571int sysfs_create_file(struct kobject * kobj, const struct attribute * attr)
572{
573 BUG_ON(!kobj || !kobj->sd || !attr);
574
575 return sysfs_add_file(kobj->sd, attr, SYSFS_KOBJ_ATTR);
576
577}
578
579int sysfs_create_files(struct kobject *kobj, const struct attribute **ptr)
580{
581 int err = 0;
582 int i;
583
584 for (i = 0; ptr[i] && !err; i++)
585 err = sysfs_create_file(kobj, ptr[i]);
586 if (err)
587 while (--i >= 0)
588 sysfs_remove_file(kobj, ptr[i]);
589 return err;
590}
591
592/**
593 * sysfs_add_file_to_group - add an attribute file to a pre-existing group.
594 * @kobj: object we're acting for.
595 * @attr: attribute descriptor.
596 * @group: group name.
597 */
598int sysfs_add_file_to_group(struct kobject *kobj,
599 const struct attribute *attr, const char *group)
600{
601 struct sysfs_dirent *dir_sd;
602 int error;
603
604 if (group)
605 dir_sd = sysfs_get_dirent(kobj->sd, NULL, group);
606 else
607 dir_sd = sysfs_get(kobj->sd);
608
609 if (!dir_sd)
610 return -ENOENT;
611
612 error = sysfs_add_file(dir_sd, attr, SYSFS_KOBJ_ATTR);
613 sysfs_put(dir_sd);
614
615 return error;
616}
617EXPORT_SYMBOL_GPL(sysfs_add_file_to_group);
618
619/**
620 * sysfs_chmod_file - update the modified mode value on an object attribute.
621 * @kobj: object we're acting for.
622 * @attr: attribute descriptor.
623 * @mode: file permissions.
624 *
625 */
626int sysfs_chmod_file(struct kobject *kobj, const struct attribute *attr,
627 umode_t mode)
628{
629 struct sysfs_dirent *sd;
630 struct iattr newattrs;
631 const void *ns;
632 int rc;
633
634 rc = sysfs_attr_ns(kobj, attr, &ns);
635 if (rc)
636 return rc;
637
638 mutex_lock(&sysfs_mutex);
639
640 rc = -ENOENT;
641 sd = sysfs_find_dirent(kobj->sd, ns, attr->name);
642 if (!sd)
643 goto out;
644
645 newattrs.ia_mode = (mode & S_IALLUGO) | (sd->s_mode & ~S_IALLUGO);
646 newattrs.ia_valid = ATTR_MODE;
647 rc = sysfs_sd_setattr(sd, &newattrs);
648
649 out:
650 mutex_unlock(&sysfs_mutex);
651 return rc;
652}
653EXPORT_SYMBOL_GPL(sysfs_chmod_file);
654
655
656/**
657 * sysfs_remove_file - remove an object attribute.
658 * @kobj: object we're acting for.
659 * @attr: attribute descriptor.
660 *
661 * Hash the attribute name and kill the victim.
662 */
663
664void sysfs_remove_file(struct kobject * kobj, const struct attribute * attr)
665{
666 const void *ns;
667
668 if (sysfs_attr_ns(kobj, attr, &ns))
669 return;
670
671 sysfs_hash_and_remove(kobj->sd, ns, attr->name);
672}
673
674void sysfs_remove_files(struct kobject * kobj, const struct attribute **ptr)
675{
676 int i;
677 for (i = 0; ptr[i]; i++)
678 sysfs_remove_file(kobj, ptr[i]);
679}
680
681/**
682 * sysfs_remove_file_from_group - remove an attribute file from a group.
683 * @kobj: object we're acting for.
684 * @attr: attribute descriptor.
685 * @group: group name.
686 */
687void sysfs_remove_file_from_group(struct kobject *kobj,
688 const struct attribute *attr, const char *group)
689{
690 struct sysfs_dirent *dir_sd;
691
692 if (group)
693 dir_sd = sysfs_get_dirent(kobj->sd, NULL, group);
694 else
695 dir_sd = sysfs_get(kobj->sd);
696 if (dir_sd) {
697 sysfs_hash_and_remove(dir_sd, NULL, attr->name);
698 sysfs_put(dir_sd);
699 }
700}
701EXPORT_SYMBOL_GPL(sysfs_remove_file_from_group);
702
703struct sysfs_schedule_callback_struct {
704 struct list_head workq_list;
705 struct kobject *kobj;
706 void (*func)(void *);
707 void *data;
708 struct module *owner;
709 struct work_struct work;
710};
711
712static struct workqueue_struct *sysfs_workqueue;
713static DEFINE_MUTEX(sysfs_workq_mutex);
714static LIST_HEAD(sysfs_workq);
715static void sysfs_schedule_callback_work(struct work_struct *work)
716{
717 struct sysfs_schedule_callback_struct *ss = container_of(work,
718 struct sysfs_schedule_callback_struct, work);
719
720 (ss->func)(ss->data);
721 kobject_put(ss->kobj);
722 module_put(ss->owner);
723 mutex_lock(&sysfs_workq_mutex);
724 list_del(&ss->workq_list);
725 mutex_unlock(&sysfs_workq_mutex);
726 kfree(ss);
727}
728
729/**
730 * sysfs_schedule_callback - helper to schedule a callback for a kobject
731 * @kobj: object we're acting for.
732 * @func: callback function to invoke later.
733 * @data: argument to pass to @func.
734 * @owner: module owning the callback code
735 *
736 * sysfs attribute methods must not unregister themselves or their parent
737 * kobject (which would amount to the same thing). Attempts to do so will
738 * deadlock, since unregistration is mutually exclusive with driver
739 * callbacks.
740 *
741 * Instead methods can call this routine, which will attempt to allocate
742 * and schedule a workqueue request to call back @func with @data as its
743 * argument in the workqueue's process context. @kobj will be pinned
744 * until @func returns.
745 *
746 * Returns 0 if the request was submitted, -ENOMEM if storage could not
747 * be allocated, -ENODEV if a reference to @owner isn't available,
748 * -EAGAIN if a callback has already been scheduled for @kobj.
749 */
750int sysfs_schedule_callback(struct kobject *kobj, void (*func)(void *),
751 void *data, struct module *owner)
752{
753 struct sysfs_schedule_callback_struct *ss, *tmp;
754
755 if (!try_module_get(owner))
756 return -ENODEV;
757
758 mutex_lock(&sysfs_workq_mutex);
759 list_for_each_entry_safe(ss, tmp, &sysfs_workq, workq_list)
760 if (ss->kobj == kobj) {
761 module_put(owner);
762 mutex_unlock(&sysfs_workq_mutex);
763 return -EAGAIN;
764 }
765 mutex_unlock(&sysfs_workq_mutex);
766
767 if (sysfs_workqueue == NULL) {
768 sysfs_workqueue = create_singlethread_workqueue("sysfsd");
769 if (sysfs_workqueue == NULL) {
770 module_put(owner);
771 return -ENOMEM;
772 }
773 }
774
775 ss = kmalloc(sizeof(*ss), GFP_KERNEL);
776 if (!ss) {
777 module_put(owner);
778 return -ENOMEM;
779 }
780 kobject_get(kobj);
781 ss->kobj = kobj;
782 ss->func = func;
783 ss->data = data;
784 ss->owner = owner;
785 INIT_WORK(&ss->work, sysfs_schedule_callback_work);
786 INIT_LIST_HEAD(&ss->workq_list);
787 mutex_lock(&sysfs_workq_mutex);
788 list_add_tail(&ss->workq_list, &sysfs_workq);
789 mutex_unlock(&sysfs_workq_mutex);
790 queue_work(sysfs_workqueue, &ss->work);
791 return 0;
792}
793EXPORT_SYMBOL_GPL(sysfs_schedule_callback);
794
795
796EXPORT_SYMBOL_GPL(sysfs_create_file);
797EXPORT_SYMBOL_GPL(sysfs_remove_file);
798EXPORT_SYMBOL_GPL(sysfs_remove_files);
799EXPORT_SYMBOL_GPL(sysfs_create_files);