blob: fc4633378dc05e064e8d207babaebe2a917e2b78 [file] [log] [blame]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
2 * file.c - operations for regular (text) files.
3 */
4
5#include <linux/module.h>
Robert Love0eeca282005-07-12 17:06:03 -04006#include <linux/fsnotify.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -07007#include <linux/kobject.h>
Christoph Hellwig5f45f1a2005-06-23 00:09:12 -07008#include <linux/namei.h>
NeilBrown4508a7a2006-03-20 17:53:53 +11009#include <linux/poll.h>
Oliver Neukum94bebf42006-12-20 10:52:44 +010010#include <linux/list.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070011#include <asm/uaccess.h>
12#include <asm/semaphore.h>
13
14#include "sysfs.h"
15
16#define to_subsys(k) container_of(k,struct subsystem,kset.kobj)
17#define to_sattr(a) container_of(a,struct subsys_attribute,attr)
18
Martin Waitz3d410882005-06-23 22:05:21 -070019/*
Linus Torvalds1da177e2005-04-16 15:20:36 -070020 * Subsystem file operations.
21 * These operations allow subsystems to have files that can be
22 * read/written.
23 */
24static ssize_t
25subsys_attr_show(struct kobject * kobj, struct attribute * attr, char * page)
26{
27 struct subsystem * s = to_subsys(kobj);
28 struct subsys_attribute * sattr = to_sattr(attr);
Dmitry Torokhovc76d0ab2005-04-29 01:22:00 -050029 ssize_t ret = -EIO;
Linus Torvalds1da177e2005-04-16 15:20:36 -070030
31 if (sattr->show)
32 ret = sattr->show(s,page);
33 return ret;
34}
35
36static ssize_t
37subsys_attr_store(struct kobject * kobj, struct attribute * attr,
38 const char * page, size_t count)
39{
40 struct subsystem * s = to_subsys(kobj);
41 struct subsys_attribute * sattr = to_sattr(attr);
Dmitry Torokhovc76d0ab2005-04-29 01:22:00 -050042 ssize_t ret = -EIO;
Linus Torvalds1da177e2005-04-16 15:20:36 -070043
44 if (sattr->store)
45 ret = sattr->store(s,page,count);
46 return ret;
47}
48
49static struct sysfs_ops subsys_sysfs_ops = {
50 .show = subsys_attr_show,
51 .store = subsys_attr_store,
52};
53
Oliver Neukum94bebf42006-12-20 10:52:44 +010054/**
55 * add_to_collection - add buffer to a collection
56 * @buffer: buffer to be added
Randy Dunlapf95d8822007-02-10 14:41:56 -080057 * @node: inode of set to add to
Oliver Neukum94bebf42006-12-20 10:52:44 +010058 */
Linus Torvalds1da177e2005-04-16 15:20:36 -070059
Oliver Neukum94bebf42006-12-20 10:52:44 +010060static inline void
61add_to_collection(struct sysfs_buffer *buffer, struct inode *node)
62{
63 struct sysfs_buffer_collection *set = node->i_private;
Linus Torvalds1da177e2005-04-16 15:20:36 -070064
Oliver Neukum94bebf42006-12-20 10:52:44 +010065 mutex_lock(&node->i_mutex);
66 list_add(&buffer->associates, &set->associates);
67 mutex_unlock(&node->i_mutex);
68}
69
70static inline void
71remove_from_collection(struct sysfs_buffer *buffer, struct inode *node)
72{
73 mutex_lock(&node->i_mutex);
74 list_del(&buffer->associates);
75 mutex_unlock(&node->i_mutex);
76}
Linus Torvalds1da177e2005-04-16 15:20:36 -070077
78/**
79 * fill_read_buffer - allocate and fill buffer from object.
80 * @dentry: dentry pointer.
81 * @buffer: data buffer for file.
82 *
83 * Allocate @buffer->page, if it hasn't been already, then call the
84 * kobject's show() method to fill the buffer with this attribute's
85 * data.
Oliver Neukum82244b12007-01-02 08:48:08 +010086 * This is called only once, on the file's first read unless an error
87 * is returned.
Linus Torvalds1da177e2005-04-16 15:20:36 -070088 */
89static int fill_read_buffer(struct dentry * dentry, struct sysfs_buffer * buffer)
90{
NeilBrown4508a7a2006-03-20 17:53:53 +110091 struct sysfs_dirent * sd = dentry->d_fsdata;
Linus Torvalds1da177e2005-04-16 15:20:36 -070092 struct attribute * attr = to_attr(dentry);
93 struct kobject * kobj = to_kobj(dentry->d_parent);
94 struct sysfs_ops * ops = buffer->ops;
95 int ret = 0;
96 ssize_t count;
97
98 if (!buffer->page)
99 buffer->page = (char *) get_zeroed_page(GFP_KERNEL);
100 if (!buffer->page)
101 return -ENOMEM;
102
NeilBrown4508a7a2006-03-20 17:53:53 +1100103 buffer->event = atomic_read(&sd->s_event);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700104 count = ops->show(kobj,attr,buffer->page);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700105 BUG_ON(count > (ssize_t)PAGE_SIZE);
Oliver Neukum82244b12007-01-02 08:48:08 +0100106 if (count >= 0) {
107 buffer->needs_read_fill = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700108 buffer->count = count;
Oliver Neukum82244b12007-01-02 08:48:08 +0100109 } else {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700110 ret = count;
Oliver Neukum82244b12007-01-02 08:48:08 +0100111 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700112 return ret;
113}
114
115
116/**
117 * flush_read_buffer - push buffer to userspace.
118 * @buffer: data buffer for file.
Martin Waitz67be2dd2005-05-01 08:59:26 -0700119 * @buf: user-passed buffer.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700120 * @count: number of bytes requested.
121 * @ppos: file position.
122 *
123 * Copy the buffer we filled in fill_read_buffer() to userspace.
124 * This is done at the reader's leisure, copying and advancing
125 * the amount they specify each time.
126 * This may be called continuously until the buffer is empty.
127 */
128static int flush_read_buffer(struct sysfs_buffer * buffer, char __user * buf,
129 size_t count, loff_t * ppos)
130{
131 int error;
132
133 if (*ppos > buffer->count)
134 return 0;
135
136 if (count > (buffer->count - *ppos))
137 count = buffer->count - *ppos;
138
139 error = copy_to_user(buf,buffer->page + *ppos,count);
140 if (!error)
141 *ppos += count;
142 return error ? -EFAULT : count;
143}
144
145/**
146 * sysfs_read_file - read an attribute.
147 * @file: file pointer.
148 * @buf: buffer to fill.
149 * @count: number of bytes to read.
150 * @ppos: starting offset in file.
151 *
152 * Userspace wants to read an attribute file. The attribute descriptor
153 * is in the file's ->d_fsdata. The target object is in the directory's
154 * ->d_fsdata.
155 *
156 * We call fill_read_buffer() to allocate and fill the buffer from the
157 * object's show() method exactly once (if the read is happening from
158 * the beginning of the file). That should fill the entire buffer with
159 * all the data the object has to offer for that attribute.
160 * We then call flush_read_buffer() to copy the buffer to userspace
161 * in the increments specified.
162 */
163
164static ssize_t
165sysfs_read_file(struct file *file, char __user *buf, size_t count, loff_t *ppos)
166{
167 struct sysfs_buffer * buffer = file->private_data;
168 ssize_t retval = 0;
169
170 down(&buffer->sem);
171 if (buffer->needs_read_fill) {
Alan Sterne7b0d262007-03-15 15:51:28 -0400172 if (buffer->orphaned)
173 retval = -ENODEV;
174 else
175 retval = fill_read_buffer(file->f_path.dentry,buffer);
176 if (retval)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700177 goto out;
178 }
Zach Brown5c1fdf42006-10-03 01:16:06 -0700179 pr_debug("%s: count = %zd, ppos = %lld, buf = %s\n",
180 __FUNCTION__, count, *ppos, buffer->page);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700181 retval = flush_read_buffer(buffer,buf,count,ppos);
182out:
183 up(&buffer->sem);
184 return retval;
185}
186
Linus Torvalds1da177e2005-04-16 15:20:36 -0700187/**
188 * fill_write_buffer - copy buffer from userspace.
189 * @buffer: data buffer for file.
Martin Waitz67be2dd2005-05-01 08:59:26 -0700190 * @buf: data from user.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700191 * @count: number of bytes in @userbuf.
192 *
193 * Allocate @buffer->page if it hasn't been already, then
194 * copy the user-supplied buffer into it.
195 */
196
197static int
198fill_write_buffer(struct sysfs_buffer * buffer, const char __user * buf, size_t count)
199{
200 int error;
201
202 if (!buffer->page)
203 buffer->page = (char *)get_zeroed_page(GFP_KERNEL);
204 if (!buffer->page)
205 return -ENOMEM;
206
207 if (count >= PAGE_SIZE)
Greg Kroah-Hartman6e0dd742006-03-31 15:37:06 -0800208 count = PAGE_SIZE - 1;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700209 error = copy_from_user(buffer->page,buf,count);
210 buffer->needs_read_fill = 1;
Thomas Maier035ed7a2006-10-22 19:17:47 +0200211 /* if buf is assumed to contain a string, terminate it by \0,
212 so e.g. sscanf() can scan the string easily */
213 buffer->page[count] = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700214 return error ? -EFAULT : count;
215}
216
217
218/**
219 * flush_write_buffer - push buffer to kobject.
Martin Waitz3d410882005-06-23 22:05:21 -0700220 * @dentry: dentry to the attribute
Linus Torvalds1da177e2005-04-16 15:20:36 -0700221 * @buffer: data buffer for file.
Martin Waitz3d410882005-06-23 22:05:21 -0700222 * @count: number of bytes
Linus Torvalds1da177e2005-04-16 15:20:36 -0700223 *
224 * Get the correct pointers for the kobject and the attribute we're
225 * dealing with, then call the store() method for the attribute,
226 * passing the buffer that we acquired in fill_write_buffer().
227 */
228
229static int
230flush_write_buffer(struct dentry * dentry, struct sysfs_buffer * buffer, size_t count)
231{
232 struct attribute * attr = to_attr(dentry);
233 struct kobject * kobj = to_kobj(dentry->d_parent);
234 struct sysfs_ops * ops = buffer->ops;
235
236 return ops->store(kobj,attr,buffer->page,count);
237}
238
239
240/**
241 * sysfs_write_file - write an attribute.
242 * @file: file pointer
243 * @buf: data to write
244 * @count: number of bytes
245 * @ppos: starting offset
246 *
247 * Similar to sysfs_read_file(), though working in the opposite direction.
248 * We allocate and fill the data from the user in fill_write_buffer(),
249 * then push it to the kobject in flush_write_buffer().
250 * There is no easy way for us to know if userspace is only doing a partial
251 * write, so we don't support them. We expect the entire buffer to come
252 * on the first write.
253 * Hint: if you're writing a value, first read the file, modify only the
254 * the value you're changing, then write entire buffer back.
255 */
256
257static ssize_t
258sysfs_write_file(struct file *file, const char __user *buf, size_t count, loff_t *ppos)
259{
260 struct sysfs_buffer * buffer = file->private_data;
261 ssize_t len;
262
263 down(&buffer->sem);
Oliver Neukum94bebf42006-12-20 10:52:44 +0100264 if (buffer->orphaned) {
265 len = -ENODEV;
266 goto out;
267 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700268 len = fill_write_buffer(buffer, buf, count);
269 if (len > 0)
Josef "Jeff" Sipekf427f5d2006-12-08 02:36:36 -0800270 len = flush_write_buffer(file->f_path.dentry, buffer, len);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700271 if (len > 0)
272 *ppos += len;
Oliver Neukum94bebf42006-12-20 10:52:44 +0100273out:
Linus Torvalds1da177e2005-04-16 15:20:36 -0700274 up(&buffer->sem);
275 return len;
276}
277
Oliver Neukum94bebf42006-12-20 10:52:44 +0100278static int sysfs_open_file(struct inode *inode, struct file *file)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700279{
Josef "Jeff" Sipekf427f5d2006-12-08 02:36:36 -0800280 struct kobject *kobj = sysfs_get_kobject(file->f_path.dentry->d_parent);
281 struct attribute * attr = to_attr(file->f_path.dentry);
Oliver Neukum94bebf42006-12-20 10:52:44 +0100282 struct sysfs_buffer_collection *set;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700283 struct sysfs_buffer * buffer;
284 struct sysfs_ops * ops = NULL;
285 int error = 0;
286
287 if (!kobj || !attr)
288 goto Einval;
289
290 /* Grab the module reference for this attribute if we have one */
291 if (!try_module_get(attr->owner)) {
292 error = -ENODEV;
293 goto Done;
294 }
295
296 /* if the kobject has no ktype, then we assume that it is a subsystem
297 * itself, and use ops for it.
298 */
299 if (kobj->kset && kobj->kset->ktype)
300 ops = kobj->kset->ktype->sysfs_ops;
301 else if (kobj->ktype)
302 ops = kobj->ktype->sysfs_ops;
303 else
304 ops = &subsys_sysfs_ops;
305
306 /* No sysfs operations, either from having no subsystem,
307 * or the subsystem have no operations.
308 */
309 if (!ops)
310 goto Eaccess;
311
Oliver Neukum94bebf42006-12-20 10:52:44 +0100312 /* make sure we have a collection to add our buffers to */
313 mutex_lock(&inode->i_mutex);
314 if (!(set = inode->i_private)) {
315 if (!(set = inode->i_private = kmalloc(sizeof(struct sysfs_buffer_collection), GFP_KERNEL))) {
316 error = -ENOMEM;
317 goto Done;
318 } else {
319 INIT_LIST_HEAD(&set->associates);
320 }
321 }
322 mutex_unlock(&inode->i_mutex);
323
Linus Torvalds1da177e2005-04-16 15:20:36 -0700324 /* File needs write support.
325 * The inode's perms must say it's ok,
326 * and we must have a store method.
327 */
328 if (file->f_mode & FMODE_WRITE) {
329
330 if (!(inode->i_mode & S_IWUGO) || !ops->store)
331 goto Eaccess;
332
333 }
334
335 /* File needs read support.
336 * The inode's perms must say it's ok, and we there
337 * must be a show method for it.
338 */
339 if (file->f_mode & FMODE_READ) {
340 if (!(inode->i_mode & S_IRUGO) || !ops->show)
341 goto Eaccess;
342 }
343
344 /* No error? Great, allocate a buffer for the file, and store it
345 * it in file->private_data for easy access.
346 */
Eric Sesterhenn58d49282006-02-22 11:18:15 +0100347 buffer = kzalloc(sizeof(struct sysfs_buffer), GFP_KERNEL);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700348 if (buffer) {
Oliver Neukum94bebf42006-12-20 10:52:44 +0100349 INIT_LIST_HEAD(&buffer->associates);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700350 init_MUTEX(&buffer->sem);
351 buffer->needs_read_fill = 1;
352 buffer->ops = ops;
Oliver Neukum94bebf42006-12-20 10:52:44 +0100353 add_to_collection(buffer, inode);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700354 file->private_data = buffer;
355 } else
356 error = -ENOMEM;
357 goto Done;
358
359 Einval:
360 error = -EINVAL;
361 goto Done;
362 Eaccess:
363 error = -EACCES;
364 module_put(attr->owner);
365 Done:
Mariusz Kozlowskif7506532007-01-02 13:41:10 +0100366 if (error)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700367 kobject_put(kobj);
368 return error;
369}
370
Linus Torvalds1da177e2005-04-16 15:20:36 -0700371static int sysfs_release(struct inode * inode, struct file * filp)
372{
Josef "Jeff" Sipekf427f5d2006-12-08 02:36:36 -0800373 struct kobject * kobj = to_kobj(filp->f_path.dentry->d_parent);
374 struct attribute * attr = to_attr(filp->f_path.dentry);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700375 struct module * owner = attr->owner;
376 struct sysfs_buffer * buffer = filp->private_data;
377
Oliver Neukum94bebf42006-12-20 10:52:44 +0100378 if (buffer)
379 remove_from_collection(buffer, inode);
Mariusz Kozlowskif7506532007-01-02 13:41:10 +0100380 kobject_put(kobj);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700381 /* After this point, attr should not be accessed. */
382 module_put(owner);
383
384 if (buffer) {
385 if (buffer->page)
386 free_page((unsigned long)buffer->page);
387 kfree(buffer);
388 }
389 return 0;
390}
391
NeilBrown4508a7a2006-03-20 17:53:53 +1100392/* Sysfs attribute files are pollable. The idea is that you read
393 * the content and then you use 'poll' or 'select' to wait for
394 * the content to change. When the content changes (assuming the
395 * manager for the kobject supports notification), poll will
396 * return POLLERR|POLLPRI, and select will return the fd whether
397 * it is waiting for read, write, or exceptions.
398 * Once poll/select indicates that the value has changed, you
399 * need to close and re-open the file, as simply seeking and reading
400 * again will not get new data, or reset the state of 'poll'.
401 * Reminder: this only works for attributes which actively support
402 * it, and it is not possible to test an attribute from userspace
403 * to see if it supports poll (Nether 'poll' or 'select' return
404 * an appropriate error code). When in doubt, set a suitable timeout value.
405 */
406static unsigned int sysfs_poll(struct file *filp, poll_table *wait)
407{
408 struct sysfs_buffer * buffer = filp->private_data;
Josef "Jeff" Sipekf427f5d2006-12-08 02:36:36 -0800409 struct kobject * kobj = to_kobj(filp->f_path.dentry->d_parent);
410 struct sysfs_dirent * sd = filp->f_path.dentry->d_fsdata;
NeilBrown4508a7a2006-03-20 17:53:53 +1100411 int res = 0;
412
413 poll_wait(filp, &kobj->poll, wait);
414
415 if (buffer->event != atomic_read(&sd->s_event)) {
416 res = POLLERR|POLLPRI;
417 buffer->needs_read_fill = 1;
418 }
419
420 return res;
421}
422
423
424static struct dentry *step_down(struct dentry *dir, const char * name)
425{
426 struct dentry * de;
427
428 if (dir == NULL || dir->d_inode == NULL)
429 return NULL;
430
431 mutex_lock(&dir->d_inode->i_mutex);
432 de = lookup_one_len(name, dir, strlen(name));
433 mutex_unlock(&dir->d_inode->i_mutex);
434 dput(dir);
435 if (IS_ERR(de))
436 return NULL;
437 if (de->d_inode == NULL) {
438 dput(de);
439 return NULL;
440 }
441 return de;
442}
443
444void sysfs_notify(struct kobject * k, char *dir, char *attr)
445{
446 struct dentry *de = k->dentry;
447 if (de)
448 dget(de);
449 if (de && dir)
450 de = step_down(de, dir);
451 if (de && attr)
452 de = step_down(de, attr);
453 if (de) {
454 struct sysfs_dirent * sd = de->d_fsdata;
455 if (sd)
456 atomic_inc(&sd->s_event);
457 wake_up_interruptible(&k->poll);
458 dput(de);
459 }
460}
461EXPORT_SYMBOL_GPL(sysfs_notify);
462
Arjan van de Ven4b6f5d22006-03-28 01:56:42 -0800463const struct file_operations sysfs_file_operations = {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700464 .read = sysfs_read_file,
465 .write = sysfs_write_file,
466 .llseek = generic_file_llseek,
467 .open = sysfs_open_file,
468 .release = sysfs_release,
NeilBrown4508a7a2006-03-20 17:53:53 +1100469 .poll = sysfs_poll,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700470};
471
472
473int sysfs_add_file(struct dentry * dir, const struct attribute * attr, int type)
474{
475 struct sysfs_dirent * parent_sd = dir->d_fsdata;
476 umode_t mode = (attr->mode & S_IALLUGO) | S_IFREG;
Maneesh Sonic5168652006-03-09 19:40:14 +0530477 int error = -EEXIST;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700478
Jes Sorensen1b1dcc12006-01-09 15:59:24 -0800479 mutex_lock(&dir->d_inode->i_mutex);
Maneesh Sonic5168652006-03-09 19:40:14 +0530480 if (!sysfs_dirent_exist(parent_sd, attr->name))
481 error = sysfs_make_dirent(parent_sd, NULL, (void *)attr,
482 mode, type);
Jes Sorensen1b1dcc12006-01-09 15:59:24 -0800483 mutex_unlock(&dir->d_inode->i_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700484
485 return error;
486}
487
488
489/**
490 * sysfs_create_file - create an attribute file for an object.
491 * @kobj: object we're creating for.
492 * @attr: atrribute descriptor.
493 */
494
495int sysfs_create_file(struct kobject * kobj, const struct attribute * attr)
496{
497 BUG_ON(!kobj || !kobj->dentry || !attr);
498
499 return sysfs_add_file(kobj->dentry, attr, SYSFS_KOBJ_ATTR);
500
501}
502
503
504/**
Alan Sterndfa87c82007-02-20 15:02:44 -0500505 * sysfs_add_file_to_group - add an attribute file to a pre-existing group.
506 * @kobj: object we're acting for.
507 * @attr: attribute descriptor.
508 * @group: group name.
509 */
510int sysfs_add_file_to_group(struct kobject *kobj,
511 const struct attribute *attr, const char *group)
512{
513 struct dentry *dir;
514 int error;
515
516 dir = lookup_one_len(group, kobj->dentry, strlen(group));
517 if (IS_ERR(dir))
518 error = PTR_ERR(dir);
519 else {
520 error = sysfs_add_file(dir, attr, SYSFS_KOBJ_ATTR);
521 dput(dir);
522 }
523 return error;
524}
525EXPORT_SYMBOL_GPL(sysfs_add_file_to_group);
526
527
528/**
Linus Torvalds1da177e2005-04-16 15:20:36 -0700529 * sysfs_update_file - update the modified timestamp on an object attribute.
530 * @kobj: object we're acting for.
531 * @attr: attribute descriptor.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700532 */
533int sysfs_update_file(struct kobject * kobj, const struct attribute * attr)
534{
535 struct dentry * dir = kobj->dentry;
536 struct dentry * victim;
537 int res = -ENOENT;
538
Jes Sorensen1b1dcc12006-01-09 15:59:24 -0800539 mutex_lock(&dir->d_inode->i_mutex);
Christoph Hellwig5f45f1a2005-06-23 00:09:12 -0700540 victim = lookup_one_len(attr->name, dir, strlen(attr->name));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700541 if (!IS_ERR(victim)) {
542 /* make sure dentry is really there */
543 if (victim->d_inode &&
544 (victim->d_parent->d_inode == dir->d_inode)) {
545 victim->d_inode->i_mtime = CURRENT_TIME;
Robert Love0eeca282005-07-12 17:06:03 -0400546 fsnotify_modify(victim);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700547 res = 0;
548 } else
549 d_drop(victim);
550
551 /**
Hidetoshi Seto97a50182006-09-20 16:49:02 +0900552 * Drop the reference acquired from lookup_one_len() above.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700553 */
554 dput(victim);
555 }
Jes Sorensen1b1dcc12006-01-09 15:59:24 -0800556 mutex_unlock(&dir->d_inode->i_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700557
558 return res;
559}
560
561
562/**
Kay Sievers31e5abe2005-04-18 21:57:32 -0700563 * sysfs_chmod_file - update the modified mode value on an object attribute.
564 * @kobj: object we're acting for.
565 * @attr: attribute descriptor.
566 * @mode: file permissions.
567 *
568 */
569int sysfs_chmod_file(struct kobject *kobj, struct attribute *attr, mode_t mode)
570{
571 struct dentry *dir = kobj->dentry;
572 struct dentry *victim;
Maneesh Sonibc062b12005-07-29 12:13:35 -0700573 struct inode * inode;
574 struct iattr newattrs;
Kay Sievers31e5abe2005-04-18 21:57:32 -0700575 int res = -ENOENT;
576
Jes Sorensen1b1dcc12006-01-09 15:59:24 -0800577 mutex_lock(&dir->d_inode->i_mutex);
Christoph Hellwig5f45f1a2005-06-23 00:09:12 -0700578 victim = lookup_one_len(attr->name, dir, strlen(attr->name));
Kay Sievers31e5abe2005-04-18 21:57:32 -0700579 if (!IS_ERR(victim)) {
580 if (victim->d_inode &&
581 (victim->d_parent->d_inode == dir->d_inode)) {
Maneesh Sonibc062b12005-07-29 12:13:35 -0700582 inode = victim->d_inode;
Jes Sorensen1b1dcc12006-01-09 15:59:24 -0800583 mutex_lock(&inode->i_mutex);
Maneesh Sonibc062b12005-07-29 12:13:35 -0700584 newattrs.ia_mode = (mode & S_IALLUGO) |
585 (inode->i_mode & ~S_IALLUGO);
586 newattrs.ia_valid = ATTR_MODE | ATTR_CTIME;
587 res = notify_change(victim, &newattrs);
Jes Sorensen1b1dcc12006-01-09 15:59:24 -0800588 mutex_unlock(&inode->i_mutex);
Kay Sievers31e5abe2005-04-18 21:57:32 -0700589 }
Maneesh Sonibc062b12005-07-29 12:13:35 -0700590 dput(victim);
Kay Sievers31e5abe2005-04-18 21:57:32 -0700591 }
Jes Sorensen1b1dcc12006-01-09 15:59:24 -0800592 mutex_unlock(&dir->d_inode->i_mutex);
Kay Sievers31e5abe2005-04-18 21:57:32 -0700593
594 return res;
595}
596EXPORT_SYMBOL_GPL(sysfs_chmod_file);
597
598
599/**
Linus Torvalds1da177e2005-04-16 15:20:36 -0700600 * sysfs_remove_file - remove an object attribute.
601 * @kobj: object we're acting for.
602 * @attr: attribute descriptor.
603 *
604 * Hash the attribute name and kill the victim.
605 */
606
607void sysfs_remove_file(struct kobject * kobj, const struct attribute * attr)
608{
Oliver Neukum94bebf42006-12-20 10:52:44 +0100609 sysfs_hash_and_remove(kobj->dentry, attr->name);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700610}
611
612
Alan Sterndfa87c82007-02-20 15:02:44 -0500613/**
614 * sysfs_remove_file_from_group - remove an attribute file from a group.
615 * @kobj: object we're acting for.
616 * @attr: attribute descriptor.
617 * @group: group name.
618 */
619void sysfs_remove_file_from_group(struct kobject *kobj,
620 const struct attribute *attr, const char *group)
621{
622 struct dentry *dir;
623
624 dir = lookup_one_len(group, kobj->dentry, strlen(group));
625 if (!IS_ERR(dir)) {
626 sysfs_hash_and_remove(dir, attr->name);
627 dput(dir);
628 }
629}
630EXPORT_SYMBOL_GPL(sysfs_remove_file_from_group);
631
Alan Sternd9a9cdf2007-03-15 15:50:34 -0400632struct sysfs_schedule_callback_struct {
633 struct kobject *kobj;
634 void (*func)(void *);
635 void *data;
636 struct work_struct work;
637};
638
639static void sysfs_schedule_callback_work(struct work_struct *work)
640{
641 struct sysfs_schedule_callback_struct *ss = container_of(work,
642 struct sysfs_schedule_callback_struct, work);
643
644 (ss->func)(ss->data);
645 kobject_put(ss->kobj);
646 kfree(ss);
647}
648
649/**
650 * sysfs_schedule_callback - helper to schedule a callback for a kobject
651 * @kobj: object we're acting for.
652 * @func: callback function to invoke later.
653 * @data: argument to pass to @func.
654 *
655 * sysfs attribute methods must not unregister themselves or their parent
656 * kobject (which would amount to the same thing). Attempts to do so will
657 * deadlock, since unregistration is mutually exclusive with driver
658 * callbacks.
659 *
660 * Instead methods can call this routine, which will attempt to allocate
661 * and schedule a workqueue request to call back @func with @data as its
662 * argument in the workqueue's process context. @kobj will be pinned
663 * until @func returns.
664 *
665 * Returns 0 if the request was submitted, -ENOMEM if storage could not
666 * be allocated.
667 */
668int sysfs_schedule_callback(struct kobject *kobj, void (*func)(void *),
669 void *data)
670{
671 struct sysfs_schedule_callback_struct *ss;
672
673 ss = kmalloc(sizeof(*ss), GFP_KERNEL);
674 if (!ss)
675 return -ENOMEM;
676 kobject_get(kobj);
677 ss->kobj = kobj;
678 ss->func = func;
679 ss->data = data;
680 INIT_WORK(&ss->work, sysfs_schedule_callback_work);
681 schedule_work(&ss->work);
682 return 0;
683}
684EXPORT_SYMBOL_GPL(sysfs_schedule_callback);
685
Alan Sterndfa87c82007-02-20 15:02:44 -0500686
Linus Torvalds1da177e2005-04-16 15:20:36 -0700687EXPORT_SYMBOL_GPL(sysfs_create_file);
688EXPORT_SYMBOL_GPL(sysfs_remove_file);
689EXPORT_SYMBOL_GPL(sysfs_update_file);