blob: a859c32ff93a56b184c3d7a92ebec776d4d9eaa6 [file] [log] [blame]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
Tejun Heo6d66f5c2007-09-20 17:31:38 +09002 * 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.
Linus Torvalds1da177e2005-04-16 15:20:36 -070011 */
12
13#include <linux/module.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070014#include <linux/kobject.h>
Andrew Morton815d2d52008-03-04 15:09:07 -080015#include <linux/kallsyms.h>
Robert P. J. Dayc6f87732008-03-13 22:41:52 -040016#include <linux/slab.h>
Christoph Hellwig5f45f1a2005-06-23 00:09:12 -070017#include <linux/namei.h>
NeilBrown4508a7a2006-03-20 17:53:53 +110018#include <linux/poll.h>
Oliver Neukum94bebf42006-12-20 10:52:44 +010019#include <linux/list.h>
Dave Young52e8c202007-07-26 11:03:54 +000020#include <linux/mutex.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070021#include <asm/uaccess.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070022
23#include "sysfs.h"
24
Tejun Heo85a4ffa2007-09-20 16:05:12 +090025/*
26 * There's one sysfs_buffer for each open file and one
27 * sysfs_open_dirent for each sysfs_dirent with one or more open
28 * files.
29 *
30 * filp->private_data points to sysfs_buffer and
31 * sysfs_dirent->s_attr.open points to sysfs_open_dirent. s_attr.open
32 * is protected by sysfs_open_dirent_lock.
33 */
Jiri Slabyd7b37882007-11-21 14:55:19 -080034static DEFINE_SPINLOCK(sysfs_open_dirent_lock);
Tejun Heo85a4ffa2007-09-20 16:05:12 +090035
36struct sysfs_open_dirent {
37 atomic_t refcnt;
Tejun Heoa4e8b912007-09-20 16:05:12 +090038 atomic_t event;
39 wait_queue_head_t poll;
Tejun Heo85a4ffa2007-09-20 16:05:12 +090040 struct list_head buffers; /* goes through sysfs_buffer.list */
41};
42
Tejun Heo73107cb2007-06-14 03:45:16 +090043struct sysfs_buffer {
44 size_t count;
45 loff_t pos;
46 char * page;
47 struct sysfs_ops * ops;
Dave Young52e8c202007-07-26 11:03:54 +000048 struct mutex mutex;
Tejun Heo73107cb2007-06-14 03:45:16 +090049 int needs_read_fill;
50 int event;
Tejun Heo85a4ffa2007-09-20 16:05:12 +090051 struct list_head list;
Tejun Heo73107cb2007-06-14 03:45:16 +090052};
Linus Torvalds1da177e2005-04-16 15:20:36 -070053
54/**
55 * fill_read_buffer - allocate and fill buffer from object.
56 * @dentry: dentry pointer.
57 * @buffer: data buffer for file.
58 *
59 * Allocate @buffer->page, if it hasn't been already, then call the
60 * kobject's show() method to fill the buffer with this attribute's
61 * data.
Oliver Neukum82244b12007-01-02 08:48:08 +010062 * This is called only once, on the file's first read unless an error
63 * is returned.
Linus Torvalds1da177e2005-04-16 15:20:36 -070064 */
65static int fill_read_buffer(struct dentry * dentry, struct sysfs_buffer * buffer)
66{
Tejun Heo0ab66082007-06-14 03:45:16 +090067 struct sysfs_dirent *attr_sd = dentry->d_fsdata;
Tejun Heob1fc3d62007-09-20 16:05:11 +090068 struct kobject *kobj = attr_sd->s_parent->s_dir.kobj;
Linus Torvalds1da177e2005-04-16 15:20:36 -070069 struct sysfs_ops * ops = buffer->ops;
70 int ret = 0;
71 ssize_t count;
72
73 if (!buffer->page)
74 buffer->page = (char *) get_zeroed_page(GFP_KERNEL);
75 if (!buffer->page)
76 return -ENOMEM;
77
Tejun Heo0ab66082007-06-14 03:45:16 +090078 /* need attr_sd for attr and ops, its parent for kobj */
79 if (!sysfs_get_active_two(attr_sd))
80 return -ENODEV;
81
Tejun Heoa4e8b912007-09-20 16:05:12 +090082 buffer->event = atomic_read(&attr_sd->s_attr.open->event);
Tejun Heob1fc3d62007-09-20 16:05:11 +090083 count = ops->show(kobj, attr_sd->s_attr.attr, buffer->page);
Tejun Heo0ab66082007-06-14 03:45:16 +090084
85 sysfs_put_active_two(attr_sd);
86
Miao Xie8118a852007-11-21 14:55:19 -080087 /*
88 * The code works fine with PAGE_SIZE return but it's likely to
89 * indicate truncated result or overflow in normal use cases.
90 */
Andrew Morton815d2d52008-03-04 15:09:07 -080091 if (count >= (ssize_t)PAGE_SIZE) {
92 print_symbol("fill_read_buffer: %s returned bad count\n",
93 (unsigned long)ops->show);
94 /* Try to struggle along */
95 count = PAGE_SIZE - 1;
96 }
Oliver Neukum82244b12007-01-02 08:48:08 +010097 if (count >= 0) {
98 buffer->needs_read_fill = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -070099 buffer->count = count;
Oliver Neukum82244b12007-01-02 08:48:08 +0100100 } else {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700101 ret = count;
Oliver Neukum82244b12007-01-02 08:48:08 +0100102 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700103 return ret;
104}
105
Linus Torvalds1da177e2005-04-16 15:20:36 -0700106/**
107 * sysfs_read_file - read an attribute.
108 * @file: file pointer.
109 * @buf: buffer to fill.
110 * @count: number of bytes to read.
111 * @ppos: starting offset in file.
112 *
113 * Userspace wants to read an attribute file. The attribute descriptor
114 * is in the file's ->d_fsdata. The target object is in the directory's
115 * ->d_fsdata.
116 *
117 * We call fill_read_buffer() to allocate and fill the buffer from the
118 * object's show() method exactly once (if the read is happening from
119 * the beginning of the file). That should fill the entire buffer with
120 * all the data the object has to offer for that attribute.
121 * We then call flush_read_buffer() to copy the buffer to userspace
122 * in the increments specified.
123 */
124
125static ssize_t
126sysfs_read_file(struct file *file, char __user *buf, size_t count, loff_t *ppos)
127{
128 struct sysfs_buffer * buffer = file->private_data;
129 ssize_t retval = 0;
130
Dave Young52e8c202007-07-26 11:03:54 +0000131 mutex_lock(&buffer->mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700132 if (buffer->needs_read_fill) {
Tejun Heo73107cb2007-06-14 03:45:16 +0900133 retval = fill_read_buffer(file->f_path.dentry,buffer);
Alan Sterne7b0d262007-03-15 15:51:28 -0400134 if (retval)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700135 goto out;
136 }
Zach Brown5c1fdf42006-10-03 01:16:06 -0700137 pr_debug("%s: count = %zd, ppos = %lld, buf = %s\n",
138 __FUNCTION__, count, *ppos, buffer->page);
Akinobu Mita92f4c702007-05-09 02:33:32 -0700139 retval = simple_read_from_buffer(buf, count, ppos, buffer->page,
140 buffer->count);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700141out:
Dave Young52e8c202007-07-26 11:03:54 +0000142 mutex_unlock(&buffer->mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700143 return retval;
144}
145
Linus Torvalds1da177e2005-04-16 15:20:36 -0700146/**
147 * fill_write_buffer - copy buffer from userspace.
148 * @buffer: data buffer for file.
Martin Waitz67be2dd2005-05-01 08:59:26 -0700149 * @buf: data from user.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700150 * @count: number of bytes in @userbuf.
151 *
152 * Allocate @buffer->page if it hasn't been already, then
153 * copy the user-supplied buffer into it.
154 */
155
156static int
157fill_write_buffer(struct sysfs_buffer * buffer, const char __user * buf, size_t count)
158{
159 int error;
160
161 if (!buffer->page)
162 buffer->page = (char *)get_zeroed_page(GFP_KERNEL);
163 if (!buffer->page)
164 return -ENOMEM;
165
166 if (count >= PAGE_SIZE)
Greg Kroah-Hartman6e0dd742006-03-31 15:37:06 -0800167 count = PAGE_SIZE - 1;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700168 error = copy_from_user(buffer->page,buf,count);
169 buffer->needs_read_fill = 1;
Thomas Maier035ed7a2006-10-22 19:17:47 +0200170 /* if buf is assumed to contain a string, terminate it by \0,
171 so e.g. sscanf() can scan the string easily */
172 buffer->page[count] = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700173 return error ? -EFAULT : count;
174}
175
176
177/**
178 * flush_write_buffer - push buffer to kobject.
Martin Waitz3d410882005-06-23 22:05:21 -0700179 * @dentry: dentry to the attribute
Linus Torvalds1da177e2005-04-16 15:20:36 -0700180 * @buffer: data buffer for file.
Martin Waitz3d410882005-06-23 22:05:21 -0700181 * @count: number of bytes
Linus Torvalds1da177e2005-04-16 15:20:36 -0700182 *
183 * Get the correct pointers for the kobject and the attribute we're
184 * dealing with, then call the store() method for the attribute,
185 * passing the buffer that we acquired in fill_write_buffer().
186 */
187
Tejun Heo0ab66082007-06-14 03:45:16 +0900188static int
Linus Torvalds1da177e2005-04-16 15:20:36 -0700189flush_write_buffer(struct dentry * dentry, struct sysfs_buffer * buffer, size_t count)
190{
Tejun Heo3e519032007-06-14 03:45:15 +0900191 struct sysfs_dirent *attr_sd = dentry->d_fsdata;
Tejun Heob1fc3d62007-09-20 16:05:11 +0900192 struct kobject *kobj = attr_sd->s_parent->s_dir.kobj;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700193 struct sysfs_ops * ops = buffer->ops;
Tejun Heo0ab66082007-06-14 03:45:16 +0900194 int rc;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700195
Tejun Heo0ab66082007-06-14 03:45:16 +0900196 /* need attr_sd for attr and ops, its parent for kobj */
197 if (!sysfs_get_active_two(attr_sd))
198 return -ENODEV;
199
Tejun Heob1fc3d62007-09-20 16:05:11 +0900200 rc = ops->store(kobj, attr_sd->s_attr.attr, buffer->page, count);
Tejun Heo0ab66082007-06-14 03:45:16 +0900201
202 sysfs_put_active_two(attr_sd);
203
204 return rc;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700205}
206
207
208/**
209 * sysfs_write_file - write an attribute.
210 * @file: file pointer
211 * @buf: data to write
212 * @count: number of bytes
213 * @ppos: starting offset
214 *
215 * Similar to sysfs_read_file(), though working in the opposite direction.
216 * We allocate and fill the data from the user in fill_write_buffer(),
217 * then push it to the kobject in flush_write_buffer().
218 * There is no easy way for us to know if userspace is only doing a partial
219 * write, so we don't support them. We expect the entire buffer to come
220 * on the first write.
221 * Hint: if you're writing a value, first read the file, modify only the
222 * the value you're changing, then write entire buffer back.
223 */
224
225static ssize_t
226sysfs_write_file(struct file *file, const char __user *buf, size_t count, loff_t *ppos)
227{
228 struct sysfs_buffer * buffer = file->private_data;
229 ssize_t len;
230
Dave Young52e8c202007-07-26 11:03:54 +0000231 mutex_lock(&buffer->mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700232 len = fill_write_buffer(buffer, buf, count);
233 if (len > 0)
Josef "Jeff" Sipekf427f5d2006-12-08 02:36:36 -0800234 len = flush_write_buffer(file->f_path.dentry, buffer, len);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700235 if (len > 0)
236 *ppos += len;
Dave Young52e8c202007-07-26 11:03:54 +0000237 mutex_unlock(&buffer->mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700238 return len;
239}
240
Tejun Heo85a4ffa2007-09-20 16:05:12 +0900241/**
242 * sysfs_get_open_dirent - get or create sysfs_open_dirent
243 * @sd: target sysfs_dirent
244 * @buffer: sysfs_buffer for this instance of open
245 *
246 * If @sd->s_attr.open exists, increment its reference count;
247 * otherwise, create one. @buffer is chained to the buffers
248 * list.
249 *
250 * LOCKING:
251 * Kernel thread context (may sleep).
252 *
253 * RETURNS:
254 * 0 on success, -errno on failure.
255 */
256static int sysfs_get_open_dirent(struct sysfs_dirent *sd,
257 struct sysfs_buffer *buffer)
258{
259 struct sysfs_open_dirent *od, *new_od = NULL;
260
261 retry:
262 spin_lock(&sysfs_open_dirent_lock);
263
264 if (!sd->s_attr.open && new_od) {
265 sd->s_attr.open = new_od;
266 new_od = NULL;
267 }
268
269 od = sd->s_attr.open;
270 if (od) {
271 atomic_inc(&od->refcnt);
272 list_add_tail(&buffer->list, &od->buffers);
273 }
274
275 spin_unlock(&sysfs_open_dirent_lock);
276
277 if (od) {
278 kfree(new_od);
279 return 0;
280 }
281
282 /* not there, initialize a new one and retry */
283 new_od = kmalloc(sizeof(*new_od), GFP_KERNEL);
284 if (!new_od)
285 return -ENOMEM;
286
287 atomic_set(&new_od->refcnt, 0);
Tejun Heoa4e8b912007-09-20 16:05:12 +0900288 atomic_set(&new_od->event, 1);
289 init_waitqueue_head(&new_od->poll);
Tejun Heo85a4ffa2007-09-20 16:05:12 +0900290 INIT_LIST_HEAD(&new_od->buffers);
291 goto retry;
292}
293
294/**
295 * sysfs_put_open_dirent - put sysfs_open_dirent
296 * @sd: target sysfs_dirent
297 * @buffer: associated sysfs_buffer
298 *
299 * Put @sd->s_attr.open and unlink @buffer from the buffers list.
300 * If reference count reaches zero, disassociate and free it.
301 *
302 * LOCKING:
303 * None.
304 */
305static void sysfs_put_open_dirent(struct sysfs_dirent *sd,
306 struct sysfs_buffer *buffer)
307{
308 struct sysfs_open_dirent *od = sd->s_attr.open;
309
310 spin_lock(&sysfs_open_dirent_lock);
311
312 list_del(&buffer->list);
313 if (atomic_dec_and_test(&od->refcnt))
314 sd->s_attr.open = NULL;
315 else
316 od = NULL;
317
318 spin_unlock(&sysfs_open_dirent_lock);
319
320 kfree(od);
321}
322
Oliver Neukum94bebf42006-12-20 10:52:44 +0100323static int sysfs_open_file(struct inode *inode, struct file *file)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700324{
Tejun Heo3e519032007-06-14 03:45:15 +0900325 struct sysfs_dirent *attr_sd = file->f_path.dentry->d_fsdata;
Tejun Heob1fc3d62007-09-20 16:05:11 +0900326 struct kobject *kobj = attr_sd->s_parent->s_dir.kobj;
Kay Sievers000f2a42007-11-02 13:47:53 +0100327 struct sysfs_buffer *buffer;
328 struct sysfs_ops *ops;
329 int error = -EACCES;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700330
Tejun Heo0ab66082007-06-14 03:45:16 +0900331 /* need attr_sd for attr and ops, its parent for kobj */
332 if (!sysfs_get_active_two(attr_sd))
333 return -ENODEV;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700334
Kay Sievers000f2a42007-11-02 13:47:53 +0100335 /* every kobject with an attribute needs a ktype assigned */
336 if (kobj->ktype && kobj->ktype->sysfs_ops)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700337 ops = kobj->ktype->sysfs_ops;
Kay Sievers000f2a42007-11-02 13:47:53 +0100338 else {
339 printk(KERN_ERR "missing sysfs attribute operations for "
340 "kobject: %s\n", kobject_name(kobj));
341 WARN_ON(1);
Tejun Heo7b595752007-06-14 03:45:17 +0900342 goto err_out;
Kay Sievers000f2a42007-11-02 13:47:53 +0100343 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700344
345 /* File needs write support.
346 * The inode's perms must say it's ok,
347 * and we must have a store method.
348 */
349 if (file->f_mode & FMODE_WRITE) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700350 if (!(inode->i_mode & S_IWUGO) || !ops->store)
Tejun Heo7b595752007-06-14 03:45:17 +0900351 goto err_out;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700352 }
353
354 /* File needs read support.
355 * The inode's perms must say it's ok, and we there
356 * must be a show method for it.
357 */
358 if (file->f_mode & FMODE_READ) {
359 if (!(inode->i_mode & S_IRUGO) || !ops->show)
Tejun Heo7b595752007-06-14 03:45:17 +0900360 goto err_out;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700361 }
362
363 /* No error? Great, allocate a buffer for the file, and store it
364 * it in file->private_data for easy access.
365 */
Tejun Heo0ab66082007-06-14 03:45:16 +0900366 error = -ENOMEM;
Eric Sesterhenn58d49282006-02-22 11:18:15 +0100367 buffer = kzalloc(sizeof(struct sysfs_buffer), GFP_KERNEL);
Tejun Heo0ab66082007-06-14 03:45:16 +0900368 if (!buffer)
Tejun Heo7b595752007-06-14 03:45:17 +0900369 goto err_out;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700370
Dave Young52e8c202007-07-26 11:03:54 +0000371 mutex_init(&buffer->mutex);
Tejun Heo0ab66082007-06-14 03:45:16 +0900372 buffer->needs_read_fill = 1;
373 buffer->ops = ops;
Tejun Heo0ab66082007-06-14 03:45:16 +0900374 file->private_data = buffer;
375
Tejun Heo85a4ffa2007-09-20 16:05:12 +0900376 /* make sure we have open dirent struct */
377 error = sysfs_get_open_dirent(attr_sd, buffer);
378 if (error)
379 goto err_free;
380
Tejun Heob05f0542007-09-20 16:05:10 +0900381 /* open succeeded, put active references */
Tejun Heo0ab66082007-06-14 03:45:16 +0900382 sysfs_put_active_two(attr_sd);
Tejun Heo0ab66082007-06-14 03:45:16 +0900383 return 0;
384
Tejun Heo85a4ffa2007-09-20 16:05:12 +0900385 err_free:
386 kfree(buffer);
Tejun Heo7b595752007-06-14 03:45:17 +0900387 err_out:
Tejun Heo0ab66082007-06-14 03:45:16 +0900388 sysfs_put_active_two(attr_sd);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700389 return error;
390}
391
Tejun Heo85a4ffa2007-09-20 16:05:12 +0900392static int sysfs_release(struct inode *inode, struct file *filp)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700393{
Tejun Heo85a4ffa2007-09-20 16:05:12 +0900394 struct sysfs_dirent *sd = filp->f_path.dentry->d_fsdata;
Tejun Heo73107cb2007-06-14 03:45:16 +0900395 struct sysfs_buffer *buffer = filp->private_data;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700396
Tejun Heo85a4ffa2007-09-20 16:05:12 +0900397 sysfs_put_open_dirent(sd, buffer);
398
Tejun Heo50ab1a72007-09-20 16:05:10 +0900399 if (buffer->page)
400 free_page((unsigned long)buffer->page);
401 kfree(buffer);
402
Linus Torvalds1da177e2005-04-16 15:20:36 -0700403 return 0;
404}
405
NeilBrown4508a7a2006-03-20 17:53:53 +1100406/* Sysfs attribute files are pollable. The idea is that you read
407 * the content and then you use 'poll' or 'select' to wait for
408 * the content to change. When the content changes (assuming the
409 * manager for the kobject supports notification), poll will
410 * return POLLERR|POLLPRI, and select will return the fd whether
411 * it is waiting for read, write, or exceptions.
412 * Once poll/select indicates that the value has changed, you
413 * need to close and re-open the file, as simply seeking and reading
414 * again will not get new data, or reset the state of 'poll'.
415 * Reminder: this only works for attributes which actively support
416 * it, and it is not possible to test an attribute from userspace
Rolf Eike Beera93720e2007-08-10 13:51:07 -0700417 * to see if it supports poll (Neither 'poll' nor 'select' return
NeilBrown4508a7a2006-03-20 17:53:53 +1100418 * an appropriate error code). When in doubt, set a suitable timeout value.
419 */
420static unsigned int sysfs_poll(struct file *filp, poll_table *wait)
421{
422 struct sysfs_buffer * buffer = filp->private_data;
Tejun Heo0ab66082007-06-14 03:45:16 +0900423 struct sysfs_dirent *attr_sd = filp->f_path.dentry->d_fsdata;
Tejun Heoa4e8b912007-09-20 16:05:12 +0900424 struct sysfs_open_dirent *od = attr_sd->s_attr.open;
Tejun Heo0ab66082007-06-14 03:45:16 +0900425
426 /* need parent for the kobj, grab both */
427 if (!sysfs_get_active_two(attr_sd))
428 goto trigger;
NeilBrown4508a7a2006-03-20 17:53:53 +1100429
Tejun Heoa4e8b912007-09-20 16:05:12 +0900430 poll_wait(filp, &od->poll, wait);
NeilBrown4508a7a2006-03-20 17:53:53 +1100431
Tejun Heo0ab66082007-06-14 03:45:16 +0900432 sysfs_put_active_two(attr_sd);
NeilBrown4508a7a2006-03-20 17:53:53 +1100433
Tejun Heoa4e8b912007-09-20 16:05:12 +0900434 if (buffer->event != atomic_read(&od->event))
Tejun Heo0ab66082007-06-14 03:45:16 +0900435 goto trigger;
436
437 return 0;
438
439 trigger:
440 buffer->needs_read_fill = 1;
441 return POLLERR|POLLPRI;
NeilBrown4508a7a2006-03-20 17:53:53 +1100442}
443
Tejun Heo51225032007-06-14 04:27:25 +0900444void sysfs_notify(struct kobject *k, char *dir, char *attr)
NeilBrown4508a7a2006-03-20 17:53:53 +1100445{
Tejun Heo51225032007-06-14 04:27:25 +0900446 struct sysfs_dirent *sd = k->sd;
NeilBrown4508a7a2006-03-20 17:53:53 +1100447
Tejun Heo51225032007-06-14 04:27:25 +0900448 mutex_lock(&sysfs_mutex);
NeilBrown4508a7a2006-03-20 17:53:53 +1100449
Tejun Heo51225032007-06-14 04:27:25 +0900450 if (sd && dir)
451 sd = sysfs_find_dirent(sd, dir);
452 if (sd && attr)
453 sd = sysfs_find_dirent(sd, attr);
454 if (sd) {
Tejun Heoa4e8b912007-09-20 16:05:12 +0900455 struct sysfs_open_dirent *od;
456
457 spin_lock(&sysfs_open_dirent_lock);
458
459 od = sd->s_attr.open;
460 if (od) {
461 atomic_inc(&od->event);
462 wake_up_interruptible(&od->poll);
463 }
464
465 spin_unlock(&sysfs_open_dirent_lock);
NeilBrown4508a7a2006-03-20 17:53:53 +1100466 }
Tejun Heo51225032007-06-14 04:27:25 +0900467
468 mutex_unlock(&sysfs_mutex);
NeilBrown4508a7a2006-03-20 17:53:53 +1100469}
470EXPORT_SYMBOL_GPL(sysfs_notify);
471
Arjan van de Ven4b6f5d22006-03-28 01:56:42 -0800472const struct file_operations sysfs_file_operations = {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700473 .read = sysfs_read_file,
474 .write = sysfs_write_file,
475 .llseek = generic_file_llseek,
476 .open = sysfs_open_file,
477 .release = sysfs_release,
NeilBrown4508a7a2006-03-20 17:53:53 +1100478 .poll = sysfs_poll,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700479};
480
481
Tejun Heo608e2662007-06-14 04:27:22 +0900482int sysfs_add_file(struct sysfs_dirent *dir_sd, const struct attribute *attr,
483 int type)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700484{
Linus Torvalds1da177e2005-04-16 15:20:36 -0700485 umode_t mode = (attr->mode & S_IALLUGO) | S_IFREG;
Tejun Heofb6896d2007-06-14 04:27:24 +0900486 struct sysfs_addrm_cxt acxt;
Tejun Heoa26cd722007-06-14 03:45:14 +0900487 struct sysfs_dirent *sd;
Tejun Heo23dc2792007-08-02 21:38:03 +0900488 int rc;
Tejun Heoa26cd722007-06-14 03:45:14 +0900489
Tejun Heo3e519032007-06-14 03:45:15 +0900490 sd = sysfs_new_dirent(attr->name, mode, type);
Tejun Heo3007e992007-06-14 04:27:23 +0900491 if (!sd)
492 return -ENOMEM;
Tejun Heob1fc3d62007-09-20 16:05:11 +0900493 sd->s_attr.attr = (void *)attr;
Tejun Heoa26cd722007-06-14 03:45:14 +0900494
Tejun Heofb6896d2007-06-14 04:27:24 +0900495 sysfs_addrm_start(&acxt, dir_sd);
Tejun Heo23dc2792007-08-02 21:38:03 +0900496 rc = sysfs_add_one(&acxt, sd);
497 sysfs_addrm_finish(&acxt);
Tejun Heo3007e992007-06-14 04:27:23 +0900498
Tejun Heo23dc2792007-08-02 21:38:03 +0900499 if (rc)
Tejun Heo967e35d2007-07-18 16:38:11 +0900500 sysfs_put(sd);
Tejun Heo3007e992007-06-14 04:27:23 +0900501
Tejun Heo23dc2792007-08-02 21:38:03 +0900502 return rc;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700503}
504
505
506/**
507 * sysfs_create_file - create an attribute file for an object.
508 * @kobj: object we're creating for.
Chris Malley3932bf62007-10-20 03:14:32 +0200509 * @attr: attribute descriptor.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700510 */
511
512int sysfs_create_file(struct kobject * kobj, const struct attribute * attr)
513{
Tejun Heo608e2662007-06-14 04:27:22 +0900514 BUG_ON(!kobj || !kobj->sd || !attr);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700515
Tejun Heo608e2662007-06-14 04:27:22 +0900516 return sysfs_add_file(kobj->sd, attr, SYSFS_KOBJ_ATTR);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700517
518}
519
520
521/**
Alan Sterndfa87c82007-02-20 15:02:44 -0500522 * sysfs_add_file_to_group - add an attribute file to a pre-existing group.
523 * @kobj: object we're acting for.
524 * @attr: attribute descriptor.
525 * @group: group name.
526 */
527int sysfs_add_file_to_group(struct kobject *kobj,
528 const struct attribute *attr, const char *group)
529{
Tejun Heo608e2662007-06-14 04:27:22 +0900530 struct sysfs_dirent *dir_sd;
Alan Sterndfa87c82007-02-20 15:02:44 -0500531 int error;
532
James Bottomley11f24fb2008-01-02 18:44:05 -0600533 if (group)
534 dir_sd = sysfs_get_dirent(kobj->sd, group);
535 else
536 dir_sd = sysfs_get(kobj->sd);
537
Tejun Heo608e2662007-06-14 04:27:22 +0900538 if (!dir_sd)
539 return -ENOENT;
540
541 error = sysfs_add_file(dir_sd, attr, SYSFS_KOBJ_ATTR);
542 sysfs_put(dir_sd);
543
Alan Sterndfa87c82007-02-20 15:02:44 -0500544 return error;
545}
546EXPORT_SYMBOL_GPL(sysfs_add_file_to_group);
547
Linus Torvalds1da177e2005-04-16 15:20:36 -0700548/**
Kay Sievers31e5abe2005-04-18 21:57:32 -0700549 * sysfs_chmod_file - update the modified mode value on an object attribute.
550 * @kobj: object we're acting for.
551 * @attr: attribute descriptor.
552 * @mode: file permissions.
553 *
554 */
555int sysfs_chmod_file(struct kobject *kobj, struct attribute *attr, mode_t mode)
556{
Tejun Heo51225032007-06-14 04:27:25 +0900557 struct sysfs_dirent *victim_sd = NULL;
558 struct dentry *victim = NULL;
Maneesh Sonibc062b12005-07-29 12:13:35 -0700559 struct inode * inode;
560 struct iattr newattrs;
Tejun Heo51225032007-06-14 04:27:25 +0900561 int rc;
Kay Sievers31e5abe2005-04-18 21:57:32 -0700562
Tejun Heo51225032007-06-14 04:27:25 +0900563 rc = -ENOENT;
564 victim_sd = sysfs_get_dirent(kobj->sd, attr->name);
565 if (!victim_sd)
566 goto out;
567
Eric W. Biederman932ea2e2007-08-20 21:36:30 +0900568 mutex_lock(&sysfs_rename_mutex);
Tejun Heo51225032007-06-14 04:27:25 +0900569 victim = sysfs_get_dentry(victim_sd);
Eric W. Biederman932ea2e2007-08-20 21:36:30 +0900570 mutex_unlock(&sysfs_rename_mutex);
Tejun Heo51225032007-06-14 04:27:25 +0900571 if (IS_ERR(victim)) {
572 rc = PTR_ERR(victim);
573 victim = NULL;
574 goto out;
Kay Sievers31e5abe2005-04-18 21:57:32 -0700575 }
Kay Sievers31e5abe2005-04-18 21:57:32 -0700576
Tejun Heo51225032007-06-14 04:27:25 +0900577 inode = victim->d_inode;
Tejun Heof88123e2007-09-20 16:05:10 +0900578
Tejun Heo51225032007-06-14 04:27:25 +0900579 mutex_lock(&inode->i_mutex);
Tejun Heof88123e2007-09-20 16:05:10 +0900580
Tejun Heo51225032007-06-14 04:27:25 +0900581 newattrs.ia_mode = (mode & S_IALLUGO) | (inode->i_mode & ~S_IALLUGO);
582 newattrs.ia_valid = ATTR_MODE | ATTR_CTIME;
583 rc = notify_change(victim, &newattrs);
Tejun Heof88123e2007-09-20 16:05:10 +0900584
585 if (rc == 0) {
586 mutex_lock(&sysfs_mutex);
587 victim_sd->s_mode = newattrs.ia_mode;
588 mutex_unlock(&sysfs_mutex);
589 }
590
Tejun Heo51225032007-06-14 04:27:25 +0900591 mutex_unlock(&inode->i_mutex);
592 out:
593 dput(victim);
594 sysfs_put(victim_sd);
595 return rc;
Kay Sievers31e5abe2005-04-18 21:57:32 -0700596}
597EXPORT_SYMBOL_GPL(sysfs_chmod_file);
598
599
600/**
Linus Torvalds1da177e2005-04-16 15:20:36 -0700601 * sysfs_remove_file - remove an object attribute.
602 * @kobj: object we're acting for.
603 * @attr: attribute descriptor.
604 *
605 * Hash the attribute name and kill the victim.
606 */
607
608void sysfs_remove_file(struct kobject * kobj, const struct attribute * attr)
609{
Tejun Heo608e2662007-06-14 04:27:22 +0900610 sysfs_hash_and_remove(kobj->sd, attr->name);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700611}
612
613
Alan Sterndfa87c82007-02-20 15:02:44 -0500614/**
615 * sysfs_remove_file_from_group - remove an attribute file from a group.
616 * @kobj: object we're acting for.
617 * @attr: attribute descriptor.
618 * @group: group name.
619 */
620void sysfs_remove_file_from_group(struct kobject *kobj,
621 const struct attribute *attr, const char *group)
622{
Tejun Heo608e2662007-06-14 04:27:22 +0900623 struct sysfs_dirent *dir_sd;
Alan Sterndfa87c82007-02-20 15:02:44 -0500624
James Bottomley11f24fb2008-01-02 18:44:05 -0600625 if (group)
626 dir_sd = sysfs_get_dirent(kobj->sd, group);
627 else
628 dir_sd = sysfs_get(kobj->sd);
Tejun Heo608e2662007-06-14 04:27:22 +0900629 if (dir_sd) {
630 sysfs_hash_and_remove(dir_sd, attr->name);
631 sysfs_put(dir_sd);
Alan Sterndfa87c82007-02-20 15:02:44 -0500632 }
633}
634EXPORT_SYMBOL_GPL(sysfs_remove_file_from_group);
635
Alan Sternd9a9cdf2007-03-15 15:50:34 -0400636struct sysfs_schedule_callback_struct {
637 struct kobject *kobj;
638 void (*func)(void *);
639 void *data;
Alan Stern523ded72007-04-26 00:12:04 -0700640 struct module *owner;
Alan Sternd9a9cdf2007-03-15 15:50:34 -0400641 struct work_struct work;
642};
643
644static void sysfs_schedule_callback_work(struct work_struct *work)
645{
646 struct sysfs_schedule_callback_struct *ss = container_of(work,
647 struct sysfs_schedule_callback_struct, work);
648
649 (ss->func)(ss->data);
650 kobject_put(ss->kobj);
Alan Stern523ded72007-04-26 00:12:04 -0700651 module_put(ss->owner);
Alan Sternd9a9cdf2007-03-15 15:50:34 -0400652 kfree(ss);
653}
654
655/**
656 * sysfs_schedule_callback - helper to schedule a callback for a kobject
657 * @kobj: object we're acting for.
658 * @func: callback function to invoke later.
659 * @data: argument to pass to @func.
Alan Stern523ded72007-04-26 00:12:04 -0700660 * @owner: module owning the callback code
Alan Sternd9a9cdf2007-03-15 15:50:34 -0400661 *
662 * sysfs attribute methods must not unregister themselves or their parent
663 * kobject (which would amount to the same thing). Attempts to do so will
664 * deadlock, since unregistration is mutually exclusive with driver
665 * callbacks.
666 *
667 * Instead methods can call this routine, which will attempt to allocate
668 * and schedule a workqueue request to call back @func with @data as its
669 * argument in the workqueue's process context. @kobj will be pinned
670 * until @func returns.
671 *
672 * Returns 0 if the request was submitted, -ENOMEM if storage could not
Alan Stern523ded72007-04-26 00:12:04 -0700673 * be allocated, -ENODEV if a reference to @owner isn't available.
Alan Sternd9a9cdf2007-03-15 15:50:34 -0400674 */
675int sysfs_schedule_callback(struct kobject *kobj, void (*func)(void *),
Alan Stern523ded72007-04-26 00:12:04 -0700676 void *data, struct module *owner)
Alan Sternd9a9cdf2007-03-15 15:50:34 -0400677{
678 struct sysfs_schedule_callback_struct *ss;
679
Alan Stern523ded72007-04-26 00:12:04 -0700680 if (!try_module_get(owner))
681 return -ENODEV;
Alan Sternd9a9cdf2007-03-15 15:50:34 -0400682 ss = kmalloc(sizeof(*ss), GFP_KERNEL);
Alan Stern523ded72007-04-26 00:12:04 -0700683 if (!ss) {
684 module_put(owner);
Alan Sternd9a9cdf2007-03-15 15:50:34 -0400685 return -ENOMEM;
Alan Stern523ded72007-04-26 00:12:04 -0700686 }
Alan Sternd9a9cdf2007-03-15 15:50:34 -0400687 kobject_get(kobj);
688 ss->kobj = kobj;
689 ss->func = func;
690 ss->data = data;
Alan Stern523ded72007-04-26 00:12:04 -0700691 ss->owner = owner;
Alan Sternd9a9cdf2007-03-15 15:50:34 -0400692 INIT_WORK(&ss->work, sysfs_schedule_callback_work);
693 schedule_work(&ss->work);
694 return 0;
695}
696EXPORT_SYMBOL_GPL(sysfs_schedule_callback);
697
Alan Sterndfa87c82007-02-20 15:02:44 -0500698
Linus Torvalds1da177e2005-04-16 15:20:36 -0700699EXPORT_SYMBOL_GPL(sysfs_create_file);
700EXPORT_SYMBOL_GPL(sysfs_remove_file);