blob: 09a0611b3364a875929c22164487c07d306e28fa [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>
Christoph Hellwig5f45f1a2005-06-23 00:09:12 -070015#include <linux/namei.h>
NeilBrown4508a7a2006-03-20 17:53:53 +110016#include <linux/poll.h>
Oliver Neukum94bebf42006-12-20 10:52:44 +010017#include <linux/list.h>
Dave Young52e8c202007-07-26 11:03:54 +000018#include <linux/mutex.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070019#include <asm/uaccess.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070020
21#include "sysfs.h"
22
Greg Kroah-Hartman823bccf2007-04-13 13:15:19 -070023#define to_sattr(a) container_of(a,struct subsys_attribute, attr)
Linus Torvalds1da177e2005-04-16 15:20:36 -070024
Martin Waitz3d410882005-06-23 22:05:21 -070025/*
Linus Torvalds1da177e2005-04-16 15:20:36 -070026 * Subsystem file operations.
27 * These operations allow subsystems to have files that can be
28 * read/written.
29 */
30static ssize_t
31subsys_attr_show(struct kobject * kobj, struct attribute * attr, char * page)
32{
Greg Kroah-Hartman823bccf2007-04-13 13:15:19 -070033 struct kset *kset = to_kset(kobj);
Linus Torvalds1da177e2005-04-16 15:20:36 -070034 struct subsys_attribute * sattr = to_sattr(attr);
Dmitry Torokhovc76d0ab2005-04-29 01:22:00 -050035 ssize_t ret = -EIO;
Linus Torvalds1da177e2005-04-16 15:20:36 -070036
37 if (sattr->show)
Greg Kroah-Hartman823bccf2007-04-13 13:15:19 -070038 ret = sattr->show(kset, page);
Linus Torvalds1da177e2005-04-16 15:20:36 -070039 return ret;
40}
41
42static ssize_t
43subsys_attr_store(struct kobject * kobj, struct attribute * attr,
44 const char * page, size_t count)
45{
Greg Kroah-Hartman823bccf2007-04-13 13:15:19 -070046 struct kset *kset = to_kset(kobj);
Linus Torvalds1da177e2005-04-16 15:20:36 -070047 struct subsys_attribute * sattr = to_sattr(attr);
Dmitry Torokhovc76d0ab2005-04-29 01:22:00 -050048 ssize_t ret = -EIO;
Linus Torvalds1da177e2005-04-16 15:20:36 -070049
50 if (sattr->store)
Greg Kroah-Hartman823bccf2007-04-13 13:15:19 -070051 ret = sattr->store(kset, page, count);
Linus Torvalds1da177e2005-04-16 15:20:36 -070052 return ret;
53}
54
55static struct sysfs_ops subsys_sysfs_ops = {
56 .show = subsys_attr_show,
57 .store = subsys_attr_store,
58};
59
Tejun Heo85a4ffa2007-09-20 16:05:12 +090060/*
61 * There's one sysfs_buffer for each open file and one
62 * sysfs_open_dirent for each sysfs_dirent with one or more open
63 * files.
64 *
65 * filp->private_data points to sysfs_buffer and
66 * sysfs_dirent->s_attr.open points to sysfs_open_dirent. s_attr.open
67 * is protected by sysfs_open_dirent_lock.
68 */
Jiri Slabyd7b37882007-11-21 14:55:19 -080069static DEFINE_SPINLOCK(sysfs_open_dirent_lock);
Tejun Heo85a4ffa2007-09-20 16:05:12 +090070
71struct sysfs_open_dirent {
72 atomic_t refcnt;
Tejun Heoa4e8b912007-09-20 16:05:12 +090073 atomic_t event;
74 wait_queue_head_t poll;
Tejun Heo85a4ffa2007-09-20 16:05:12 +090075 struct list_head buffers; /* goes through sysfs_buffer.list */
76};
77
Tejun Heo73107cb2007-06-14 03:45:16 +090078struct sysfs_buffer {
79 size_t count;
80 loff_t pos;
81 char * page;
82 struct sysfs_ops * ops;
Dave Young52e8c202007-07-26 11:03:54 +000083 struct mutex mutex;
Tejun Heo73107cb2007-06-14 03:45:16 +090084 int needs_read_fill;
85 int event;
Tejun Heo85a4ffa2007-09-20 16:05:12 +090086 struct list_head list;
Tejun Heo73107cb2007-06-14 03:45:16 +090087};
Linus Torvalds1da177e2005-04-16 15:20:36 -070088
89/**
90 * fill_read_buffer - allocate and fill buffer from object.
91 * @dentry: dentry pointer.
92 * @buffer: data buffer for file.
93 *
94 * Allocate @buffer->page, if it hasn't been already, then call the
95 * kobject's show() method to fill the buffer with this attribute's
96 * data.
Oliver Neukum82244b12007-01-02 08:48:08 +010097 * This is called only once, on the file's first read unless an error
98 * is returned.
Linus Torvalds1da177e2005-04-16 15:20:36 -070099 */
100static int fill_read_buffer(struct dentry * dentry, struct sysfs_buffer * buffer)
101{
Tejun Heo0ab66082007-06-14 03:45:16 +0900102 struct sysfs_dirent *attr_sd = dentry->d_fsdata;
Tejun Heob1fc3d62007-09-20 16:05:11 +0900103 struct kobject *kobj = attr_sd->s_parent->s_dir.kobj;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700104 struct sysfs_ops * ops = buffer->ops;
105 int ret = 0;
106 ssize_t count;
107
108 if (!buffer->page)
109 buffer->page = (char *) get_zeroed_page(GFP_KERNEL);
110 if (!buffer->page)
111 return -ENOMEM;
112
Tejun Heo0ab66082007-06-14 03:45:16 +0900113 /* need attr_sd for attr and ops, its parent for kobj */
114 if (!sysfs_get_active_two(attr_sd))
115 return -ENODEV;
116
Tejun Heoa4e8b912007-09-20 16:05:12 +0900117 buffer->event = atomic_read(&attr_sd->s_attr.open->event);
Tejun Heob1fc3d62007-09-20 16:05:11 +0900118 count = ops->show(kobj, attr_sd->s_attr.attr, buffer->page);
Tejun Heo0ab66082007-06-14 03:45:16 +0900119
120 sysfs_put_active_two(attr_sd);
121
Miao Xie8118a852007-11-21 14:55:19 -0800122 /*
123 * The code works fine with PAGE_SIZE return but it's likely to
124 * indicate truncated result or overflow in normal use cases.
125 */
126 BUG_ON(count >= (ssize_t)PAGE_SIZE);
Oliver Neukum82244b12007-01-02 08:48:08 +0100127 if (count >= 0) {
128 buffer->needs_read_fill = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700129 buffer->count = count;
Oliver Neukum82244b12007-01-02 08:48:08 +0100130 } else {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700131 ret = count;
Oliver Neukum82244b12007-01-02 08:48:08 +0100132 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700133 return ret;
134}
135
Linus Torvalds1da177e2005-04-16 15:20:36 -0700136/**
137 * sysfs_read_file - read an attribute.
138 * @file: file pointer.
139 * @buf: buffer to fill.
140 * @count: number of bytes to read.
141 * @ppos: starting offset in file.
142 *
143 * Userspace wants to read an attribute file. The attribute descriptor
144 * is in the file's ->d_fsdata. The target object is in the directory's
145 * ->d_fsdata.
146 *
147 * We call fill_read_buffer() to allocate and fill the buffer from the
148 * object's show() method exactly once (if the read is happening from
149 * the beginning of the file). That should fill the entire buffer with
150 * all the data the object has to offer for that attribute.
151 * We then call flush_read_buffer() to copy the buffer to userspace
152 * in the increments specified.
153 */
154
155static ssize_t
156sysfs_read_file(struct file *file, char __user *buf, size_t count, loff_t *ppos)
157{
158 struct sysfs_buffer * buffer = file->private_data;
159 ssize_t retval = 0;
160
Dave Young52e8c202007-07-26 11:03:54 +0000161 mutex_lock(&buffer->mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700162 if (buffer->needs_read_fill) {
Tejun Heo73107cb2007-06-14 03:45:16 +0900163 retval = fill_read_buffer(file->f_path.dentry,buffer);
Alan Sterne7b0d262007-03-15 15:51:28 -0400164 if (retval)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700165 goto out;
166 }
Zach Brown5c1fdf42006-10-03 01:16:06 -0700167 pr_debug("%s: count = %zd, ppos = %lld, buf = %s\n",
168 __FUNCTION__, count, *ppos, buffer->page);
Akinobu Mita92f4c702007-05-09 02:33:32 -0700169 retval = simple_read_from_buffer(buf, count, ppos, buffer->page,
170 buffer->count);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700171out:
Dave Young52e8c202007-07-26 11:03:54 +0000172 mutex_unlock(&buffer->mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700173 return retval;
174}
175
Linus Torvalds1da177e2005-04-16 15:20:36 -0700176/**
177 * fill_write_buffer - copy buffer from userspace.
178 * @buffer: data buffer for file.
Martin Waitz67be2dd2005-05-01 08:59:26 -0700179 * @buf: data from user.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700180 * @count: number of bytes in @userbuf.
181 *
182 * Allocate @buffer->page if it hasn't been already, then
183 * copy the user-supplied buffer into it.
184 */
185
186static int
187fill_write_buffer(struct sysfs_buffer * buffer, const char __user * buf, size_t count)
188{
189 int error;
190
191 if (!buffer->page)
192 buffer->page = (char *)get_zeroed_page(GFP_KERNEL);
193 if (!buffer->page)
194 return -ENOMEM;
195
196 if (count >= PAGE_SIZE)
Greg Kroah-Hartman6e0dd742006-03-31 15:37:06 -0800197 count = PAGE_SIZE - 1;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700198 error = copy_from_user(buffer->page,buf,count);
199 buffer->needs_read_fill = 1;
Thomas Maier035ed7a2006-10-22 19:17:47 +0200200 /* if buf is assumed to contain a string, terminate it by \0,
201 so e.g. sscanf() can scan the string easily */
202 buffer->page[count] = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700203 return error ? -EFAULT : count;
204}
205
206
207/**
208 * flush_write_buffer - push buffer to kobject.
Martin Waitz3d410882005-06-23 22:05:21 -0700209 * @dentry: dentry to the attribute
Linus Torvalds1da177e2005-04-16 15:20:36 -0700210 * @buffer: data buffer for file.
Martin Waitz3d410882005-06-23 22:05:21 -0700211 * @count: number of bytes
Linus Torvalds1da177e2005-04-16 15:20:36 -0700212 *
213 * Get the correct pointers for the kobject and the attribute we're
214 * dealing with, then call the store() method for the attribute,
215 * passing the buffer that we acquired in fill_write_buffer().
216 */
217
Tejun Heo0ab66082007-06-14 03:45:16 +0900218static int
Linus Torvalds1da177e2005-04-16 15:20:36 -0700219flush_write_buffer(struct dentry * dentry, struct sysfs_buffer * buffer, size_t count)
220{
Tejun Heo3e519032007-06-14 03:45:15 +0900221 struct sysfs_dirent *attr_sd = dentry->d_fsdata;
Tejun Heob1fc3d62007-09-20 16:05:11 +0900222 struct kobject *kobj = attr_sd->s_parent->s_dir.kobj;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700223 struct sysfs_ops * ops = buffer->ops;
Tejun Heo0ab66082007-06-14 03:45:16 +0900224 int rc;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700225
Tejun Heo0ab66082007-06-14 03:45:16 +0900226 /* need attr_sd for attr and ops, its parent for kobj */
227 if (!sysfs_get_active_two(attr_sd))
228 return -ENODEV;
229
Tejun Heob1fc3d62007-09-20 16:05:11 +0900230 rc = ops->store(kobj, attr_sd->s_attr.attr, buffer->page, count);
Tejun Heo0ab66082007-06-14 03:45:16 +0900231
232 sysfs_put_active_two(attr_sd);
233
234 return rc;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700235}
236
237
238/**
239 * sysfs_write_file - write an attribute.
240 * @file: file pointer
241 * @buf: data to write
242 * @count: number of bytes
243 * @ppos: starting offset
244 *
245 * Similar to sysfs_read_file(), though working in the opposite direction.
246 * We allocate and fill the data from the user in fill_write_buffer(),
247 * then push it to the kobject in flush_write_buffer().
248 * There is no easy way for us to know if userspace is only doing a partial
249 * write, so we don't support them. We expect the entire buffer to come
250 * on the first write.
251 * Hint: if you're writing a value, first read the file, modify only the
252 * the value you're changing, then write entire buffer back.
253 */
254
255static ssize_t
256sysfs_write_file(struct file *file, const char __user *buf, size_t count, loff_t *ppos)
257{
258 struct sysfs_buffer * buffer = file->private_data;
259 ssize_t len;
260
Dave Young52e8c202007-07-26 11:03:54 +0000261 mutex_lock(&buffer->mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700262 len = fill_write_buffer(buffer, buf, count);
263 if (len > 0)
Josef "Jeff" Sipekf427f5d2006-12-08 02:36:36 -0800264 len = flush_write_buffer(file->f_path.dentry, buffer, len);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700265 if (len > 0)
266 *ppos += len;
Dave Young52e8c202007-07-26 11:03:54 +0000267 mutex_unlock(&buffer->mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700268 return len;
269}
270
Tejun Heo85a4ffa2007-09-20 16:05:12 +0900271/**
272 * sysfs_get_open_dirent - get or create sysfs_open_dirent
273 * @sd: target sysfs_dirent
274 * @buffer: sysfs_buffer for this instance of open
275 *
276 * If @sd->s_attr.open exists, increment its reference count;
277 * otherwise, create one. @buffer is chained to the buffers
278 * list.
279 *
280 * LOCKING:
281 * Kernel thread context (may sleep).
282 *
283 * RETURNS:
284 * 0 on success, -errno on failure.
285 */
286static int sysfs_get_open_dirent(struct sysfs_dirent *sd,
287 struct sysfs_buffer *buffer)
288{
289 struct sysfs_open_dirent *od, *new_od = NULL;
290
291 retry:
292 spin_lock(&sysfs_open_dirent_lock);
293
294 if (!sd->s_attr.open && new_od) {
295 sd->s_attr.open = new_od;
296 new_od = NULL;
297 }
298
299 od = sd->s_attr.open;
300 if (od) {
301 atomic_inc(&od->refcnt);
302 list_add_tail(&buffer->list, &od->buffers);
303 }
304
305 spin_unlock(&sysfs_open_dirent_lock);
306
307 if (od) {
308 kfree(new_od);
309 return 0;
310 }
311
312 /* not there, initialize a new one and retry */
313 new_od = kmalloc(sizeof(*new_od), GFP_KERNEL);
314 if (!new_od)
315 return -ENOMEM;
316
317 atomic_set(&new_od->refcnt, 0);
Tejun Heoa4e8b912007-09-20 16:05:12 +0900318 atomic_set(&new_od->event, 1);
319 init_waitqueue_head(&new_od->poll);
Tejun Heo85a4ffa2007-09-20 16:05:12 +0900320 INIT_LIST_HEAD(&new_od->buffers);
321 goto retry;
322}
323
324/**
325 * sysfs_put_open_dirent - put sysfs_open_dirent
326 * @sd: target sysfs_dirent
327 * @buffer: associated sysfs_buffer
328 *
329 * Put @sd->s_attr.open and unlink @buffer from the buffers list.
330 * If reference count reaches zero, disassociate and free it.
331 *
332 * LOCKING:
333 * None.
334 */
335static void sysfs_put_open_dirent(struct sysfs_dirent *sd,
336 struct sysfs_buffer *buffer)
337{
338 struct sysfs_open_dirent *od = sd->s_attr.open;
339
340 spin_lock(&sysfs_open_dirent_lock);
341
342 list_del(&buffer->list);
343 if (atomic_dec_and_test(&od->refcnt))
344 sd->s_attr.open = NULL;
345 else
346 od = NULL;
347
348 spin_unlock(&sysfs_open_dirent_lock);
349
350 kfree(od);
351}
352
Oliver Neukum94bebf42006-12-20 10:52:44 +0100353static int sysfs_open_file(struct inode *inode, struct file *file)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700354{
Tejun Heo3e519032007-06-14 03:45:15 +0900355 struct sysfs_dirent *attr_sd = file->f_path.dentry->d_fsdata;
Tejun Heob1fc3d62007-09-20 16:05:11 +0900356 struct kobject *kobj = attr_sd->s_parent->s_dir.kobj;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700357 struct sysfs_buffer * buffer;
358 struct sysfs_ops * ops = NULL;
Tejun Heo0ab66082007-06-14 03:45:16 +0900359 int error;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700360
Tejun Heo0ab66082007-06-14 03:45:16 +0900361 /* need attr_sd for attr and ops, its parent for kobj */
362 if (!sysfs_get_active_two(attr_sd))
363 return -ENODEV;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700364
Linus Torvalds1da177e2005-04-16 15:20:36 -0700365 /* if the kobject has no ktype, then we assume that it is a subsystem
366 * itself, and use ops for it.
367 */
368 if (kobj->kset && kobj->kset->ktype)
369 ops = kobj->kset->ktype->sysfs_ops;
370 else if (kobj->ktype)
371 ops = kobj->ktype->sysfs_ops;
372 else
373 ops = &subsys_sysfs_ops;
374
Tejun Heo73107cb2007-06-14 03:45:16 +0900375 error = -EACCES;
376
Linus Torvalds1da177e2005-04-16 15:20:36 -0700377 /* No sysfs operations, either from having no subsystem,
378 * or the subsystem have no operations.
379 */
380 if (!ops)
Tejun Heo7b595752007-06-14 03:45:17 +0900381 goto err_out;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700382
383 /* File needs write support.
384 * The inode's perms must say it's ok,
385 * and we must have a store method.
386 */
387 if (file->f_mode & FMODE_WRITE) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700388 if (!(inode->i_mode & S_IWUGO) || !ops->store)
Tejun Heo7b595752007-06-14 03:45:17 +0900389 goto err_out;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700390 }
391
392 /* File needs read support.
393 * The inode's perms must say it's ok, and we there
394 * must be a show method for it.
395 */
396 if (file->f_mode & FMODE_READ) {
397 if (!(inode->i_mode & S_IRUGO) || !ops->show)
Tejun Heo7b595752007-06-14 03:45:17 +0900398 goto err_out;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700399 }
400
401 /* No error? Great, allocate a buffer for the file, and store it
402 * it in file->private_data for easy access.
403 */
Tejun Heo0ab66082007-06-14 03:45:16 +0900404 error = -ENOMEM;
Eric Sesterhenn58d49282006-02-22 11:18:15 +0100405 buffer = kzalloc(sizeof(struct sysfs_buffer), GFP_KERNEL);
Tejun Heo0ab66082007-06-14 03:45:16 +0900406 if (!buffer)
Tejun Heo7b595752007-06-14 03:45:17 +0900407 goto err_out;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700408
Dave Young52e8c202007-07-26 11:03:54 +0000409 mutex_init(&buffer->mutex);
Tejun Heo0ab66082007-06-14 03:45:16 +0900410 buffer->needs_read_fill = 1;
411 buffer->ops = ops;
Tejun Heo0ab66082007-06-14 03:45:16 +0900412 file->private_data = buffer;
413
Tejun Heo85a4ffa2007-09-20 16:05:12 +0900414 /* make sure we have open dirent struct */
415 error = sysfs_get_open_dirent(attr_sd, buffer);
416 if (error)
417 goto err_free;
418
Tejun Heob05f0542007-09-20 16:05:10 +0900419 /* open succeeded, put active references */
Tejun Heo0ab66082007-06-14 03:45:16 +0900420 sysfs_put_active_two(attr_sd);
Tejun Heo0ab66082007-06-14 03:45:16 +0900421 return 0;
422
Tejun Heo85a4ffa2007-09-20 16:05:12 +0900423 err_free:
424 kfree(buffer);
Tejun Heo7b595752007-06-14 03:45:17 +0900425 err_out:
Tejun Heo0ab66082007-06-14 03:45:16 +0900426 sysfs_put_active_two(attr_sd);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700427 return error;
428}
429
Tejun Heo85a4ffa2007-09-20 16:05:12 +0900430static int sysfs_release(struct inode *inode, struct file *filp)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700431{
Tejun Heo85a4ffa2007-09-20 16:05:12 +0900432 struct sysfs_dirent *sd = filp->f_path.dentry->d_fsdata;
Tejun Heo73107cb2007-06-14 03:45:16 +0900433 struct sysfs_buffer *buffer = filp->private_data;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700434
Tejun Heo85a4ffa2007-09-20 16:05:12 +0900435 sysfs_put_open_dirent(sd, buffer);
436
Tejun Heo50ab1a72007-09-20 16:05:10 +0900437 if (buffer->page)
438 free_page((unsigned long)buffer->page);
439 kfree(buffer);
440
Linus Torvalds1da177e2005-04-16 15:20:36 -0700441 return 0;
442}
443
NeilBrown4508a7a2006-03-20 17:53:53 +1100444/* Sysfs attribute files are pollable. The idea is that you read
445 * the content and then you use 'poll' or 'select' to wait for
446 * the content to change. When the content changes (assuming the
447 * manager for the kobject supports notification), poll will
448 * return POLLERR|POLLPRI, and select will return the fd whether
449 * it is waiting for read, write, or exceptions.
450 * Once poll/select indicates that the value has changed, you
451 * need to close and re-open the file, as simply seeking and reading
452 * again will not get new data, or reset the state of 'poll'.
453 * Reminder: this only works for attributes which actively support
454 * it, and it is not possible to test an attribute from userspace
Rolf Eike Beera93720e2007-08-10 13:51:07 -0700455 * to see if it supports poll (Neither 'poll' nor 'select' return
NeilBrown4508a7a2006-03-20 17:53:53 +1100456 * an appropriate error code). When in doubt, set a suitable timeout value.
457 */
458static unsigned int sysfs_poll(struct file *filp, poll_table *wait)
459{
460 struct sysfs_buffer * buffer = filp->private_data;
Tejun Heo0ab66082007-06-14 03:45:16 +0900461 struct sysfs_dirent *attr_sd = filp->f_path.dentry->d_fsdata;
Tejun Heoa4e8b912007-09-20 16:05:12 +0900462 struct sysfs_open_dirent *od = attr_sd->s_attr.open;
Tejun Heo0ab66082007-06-14 03:45:16 +0900463
464 /* need parent for the kobj, grab both */
465 if (!sysfs_get_active_two(attr_sd))
466 goto trigger;
NeilBrown4508a7a2006-03-20 17:53:53 +1100467
Tejun Heoa4e8b912007-09-20 16:05:12 +0900468 poll_wait(filp, &od->poll, wait);
NeilBrown4508a7a2006-03-20 17:53:53 +1100469
Tejun Heo0ab66082007-06-14 03:45:16 +0900470 sysfs_put_active_two(attr_sd);
NeilBrown4508a7a2006-03-20 17:53:53 +1100471
Tejun Heoa4e8b912007-09-20 16:05:12 +0900472 if (buffer->event != atomic_read(&od->event))
Tejun Heo0ab66082007-06-14 03:45:16 +0900473 goto trigger;
474
475 return 0;
476
477 trigger:
478 buffer->needs_read_fill = 1;
479 return POLLERR|POLLPRI;
NeilBrown4508a7a2006-03-20 17:53:53 +1100480}
481
Tejun Heo51225032007-06-14 04:27:25 +0900482void sysfs_notify(struct kobject *k, char *dir, char *attr)
NeilBrown4508a7a2006-03-20 17:53:53 +1100483{
Tejun Heo51225032007-06-14 04:27:25 +0900484 struct sysfs_dirent *sd = k->sd;
NeilBrown4508a7a2006-03-20 17:53:53 +1100485
Tejun Heo51225032007-06-14 04:27:25 +0900486 mutex_lock(&sysfs_mutex);
NeilBrown4508a7a2006-03-20 17:53:53 +1100487
Tejun Heo51225032007-06-14 04:27:25 +0900488 if (sd && dir)
489 sd = sysfs_find_dirent(sd, dir);
490 if (sd && attr)
491 sd = sysfs_find_dirent(sd, attr);
492 if (sd) {
Tejun Heoa4e8b912007-09-20 16:05:12 +0900493 struct sysfs_open_dirent *od;
494
495 spin_lock(&sysfs_open_dirent_lock);
496
497 od = sd->s_attr.open;
498 if (od) {
499 atomic_inc(&od->event);
500 wake_up_interruptible(&od->poll);
501 }
502
503 spin_unlock(&sysfs_open_dirent_lock);
NeilBrown4508a7a2006-03-20 17:53:53 +1100504 }
Tejun Heo51225032007-06-14 04:27:25 +0900505
506 mutex_unlock(&sysfs_mutex);
NeilBrown4508a7a2006-03-20 17:53:53 +1100507}
508EXPORT_SYMBOL_GPL(sysfs_notify);
509
Arjan van de Ven4b6f5d22006-03-28 01:56:42 -0800510const struct file_operations sysfs_file_operations = {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700511 .read = sysfs_read_file,
512 .write = sysfs_write_file,
513 .llseek = generic_file_llseek,
514 .open = sysfs_open_file,
515 .release = sysfs_release,
NeilBrown4508a7a2006-03-20 17:53:53 +1100516 .poll = sysfs_poll,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700517};
518
519
Tejun Heo608e2662007-06-14 04:27:22 +0900520int sysfs_add_file(struct sysfs_dirent *dir_sd, const struct attribute *attr,
521 int type)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700522{
Linus Torvalds1da177e2005-04-16 15:20:36 -0700523 umode_t mode = (attr->mode & S_IALLUGO) | S_IFREG;
Tejun Heofb6896d2007-06-14 04:27:24 +0900524 struct sysfs_addrm_cxt acxt;
Tejun Heoa26cd722007-06-14 03:45:14 +0900525 struct sysfs_dirent *sd;
Tejun Heo23dc2792007-08-02 21:38:03 +0900526 int rc;
Tejun Heoa26cd722007-06-14 03:45:14 +0900527
Tejun Heo3e519032007-06-14 03:45:15 +0900528 sd = sysfs_new_dirent(attr->name, mode, type);
Tejun Heo3007e992007-06-14 04:27:23 +0900529 if (!sd)
530 return -ENOMEM;
Tejun Heob1fc3d62007-09-20 16:05:11 +0900531 sd->s_attr.attr = (void *)attr;
Tejun Heoa26cd722007-06-14 03:45:14 +0900532
Tejun Heofb6896d2007-06-14 04:27:24 +0900533 sysfs_addrm_start(&acxt, dir_sd);
Tejun Heo23dc2792007-08-02 21:38:03 +0900534 rc = sysfs_add_one(&acxt, sd);
535 sysfs_addrm_finish(&acxt);
Tejun Heo3007e992007-06-14 04:27:23 +0900536
Tejun Heo23dc2792007-08-02 21:38:03 +0900537 if (rc)
Tejun Heo967e35d2007-07-18 16:38:11 +0900538 sysfs_put(sd);
Tejun Heo3007e992007-06-14 04:27:23 +0900539
Tejun Heo23dc2792007-08-02 21:38:03 +0900540 return rc;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700541}
542
543
544/**
545 * sysfs_create_file - create an attribute file for an object.
546 * @kobj: object we're creating for.
Chris Malley3932bf62007-10-20 03:14:32 +0200547 * @attr: attribute descriptor.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700548 */
549
550int sysfs_create_file(struct kobject * kobj, const struct attribute * attr)
551{
Tejun Heo608e2662007-06-14 04:27:22 +0900552 BUG_ON(!kobj || !kobj->sd || !attr);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700553
Tejun Heo608e2662007-06-14 04:27:22 +0900554 return sysfs_add_file(kobj->sd, attr, SYSFS_KOBJ_ATTR);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700555
556}
557
558
559/**
Alan Sterndfa87c82007-02-20 15:02:44 -0500560 * sysfs_add_file_to_group - add an attribute file to a pre-existing group.
561 * @kobj: object we're acting for.
562 * @attr: attribute descriptor.
563 * @group: group name.
564 */
565int sysfs_add_file_to_group(struct kobject *kobj,
566 const struct attribute *attr, const char *group)
567{
Tejun Heo608e2662007-06-14 04:27:22 +0900568 struct sysfs_dirent *dir_sd;
Alan Sterndfa87c82007-02-20 15:02:44 -0500569 int error;
570
Tejun Heo608e2662007-06-14 04:27:22 +0900571 dir_sd = sysfs_get_dirent(kobj->sd, group);
572 if (!dir_sd)
573 return -ENOENT;
574
575 error = sysfs_add_file(dir_sd, attr, SYSFS_KOBJ_ATTR);
576 sysfs_put(dir_sd);
577
Alan Sterndfa87c82007-02-20 15:02:44 -0500578 return error;
579}
580EXPORT_SYMBOL_GPL(sysfs_add_file_to_group);
581
Linus Torvalds1da177e2005-04-16 15:20:36 -0700582/**
Kay Sievers31e5abe2005-04-18 21:57:32 -0700583 * sysfs_chmod_file - update the modified mode value on an object attribute.
584 * @kobj: object we're acting for.
585 * @attr: attribute descriptor.
586 * @mode: file permissions.
587 *
588 */
589int sysfs_chmod_file(struct kobject *kobj, struct attribute *attr, mode_t mode)
590{
Tejun Heo51225032007-06-14 04:27:25 +0900591 struct sysfs_dirent *victim_sd = NULL;
592 struct dentry *victim = NULL;
Maneesh Sonibc062b12005-07-29 12:13:35 -0700593 struct inode * inode;
594 struct iattr newattrs;
Tejun Heo51225032007-06-14 04:27:25 +0900595 int rc;
Kay Sievers31e5abe2005-04-18 21:57:32 -0700596
Tejun Heo51225032007-06-14 04:27:25 +0900597 rc = -ENOENT;
598 victim_sd = sysfs_get_dirent(kobj->sd, attr->name);
599 if (!victim_sd)
600 goto out;
601
Eric W. Biederman932ea2e2007-08-20 21:36:30 +0900602 mutex_lock(&sysfs_rename_mutex);
Tejun Heo51225032007-06-14 04:27:25 +0900603 victim = sysfs_get_dentry(victim_sd);
Eric W. Biederman932ea2e2007-08-20 21:36:30 +0900604 mutex_unlock(&sysfs_rename_mutex);
Tejun Heo51225032007-06-14 04:27:25 +0900605 if (IS_ERR(victim)) {
606 rc = PTR_ERR(victim);
607 victim = NULL;
608 goto out;
Kay Sievers31e5abe2005-04-18 21:57:32 -0700609 }
Kay Sievers31e5abe2005-04-18 21:57:32 -0700610
Tejun Heo51225032007-06-14 04:27:25 +0900611 inode = victim->d_inode;
Tejun Heof88123e2007-09-20 16:05:10 +0900612
Tejun Heo51225032007-06-14 04:27:25 +0900613 mutex_lock(&inode->i_mutex);
Tejun Heof88123e2007-09-20 16:05:10 +0900614
Tejun Heo51225032007-06-14 04:27:25 +0900615 newattrs.ia_mode = (mode & S_IALLUGO) | (inode->i_mode & ~S_IALLUGO);
616 newattrs.ia_valid = ATTR_MODE | ATTR_CTIME;
617 rc = notify_change(victim, &newattrs);
Tejun Heof88123e2007-09-20 16:05:10 +0900618
619 if (rc == 0) {
620 mutex_lock(&sysfs_mutex);
621 victim_sd->s_mode = newattrs.ia_mode;
622 mutex_unlock(&sysfs_mutex);
623 }
624
Tejun Heo51225032007-06-14 04:27:25 +0900625 mutex_unlock(&inode->i_mutex);
626 out:
627 dput(victim);
628 sysfs_put(victim_sd);
629 return rc;
Kay Sievers31e5abe2005-04-18 21:57:32 -0700630}
631EXPORT_SYMBOL_GPL(sysfs_chmod_file);
632
633
634/**
Linus Torvalds1da177e2005-04-16 15:20:36 -0700635 * sysfs_remove_file - remove an object attribute.
636 * @kobj: object we're acting for.
637 * @attr: attribute descriptor.
638 *
639 * Hash the attribute name and kill the victim.
640 */
641
642void sysfs_remove_file(struct kobject * kobj, const struct attribute * attr)
643{
Tejun Heo608e2662007-06-14 04:27:22 +0900644 sysfs_hash_and_remove(kobj->sd, attr->name);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700645}
646
647
Alan Sterndfa87c82007-02-20 15:02:44 -0500648/**
649 * sysfs_remove_file_from_group - remove an attribute file from a group.
650 * @kobj: object we're acting for.
651 * @attr: attribute descriptor.
652 * @group: group name.
653 */
654void sysfs_remove_file_from_group(struct kobject *kobj,
655 const struct attribute *attr, const char *group)
656{
Tejun Heo608e2662007-06-14 04:27:22 +0900657 struct sysfs_dirent *dir_sd;
Alan Sterndfa87c82007-02-20 15:02:44 -0500658
Tejun Heo608e2662007-06-14 04:27:22 +0900659 dir_sd = sysfs_get_dirent(kobj->sd, group);
660 if (dir_sd) {
661 sysfs_hash_and_remove(dir_sd, attr->name);
662 sysfs_put(dir_sd);
Alan Sterndfa87c82007-02-20 15:02:44 -0500663 }
664}
665EXPORT_SYMBOL_GPL(sysfs_remove_file_from_group);
666
Alan Sternd9a9cdf2007-03-15 15:50:34 -0400667struct sysfs_schedule_callback_struct {
668 struct kobject *kobj;
669 void (*func)(void *);
670 void *data;
Alan Stern523ded72007-04-26 00:12:04 -0700671 struct module *owner;
Alan Sternd9a9cdf2007-03-15 15:50:34 -0400672 struct work_struct work;
673};
674
675static void sysfs_schedule_callback_work(struct work_struct *work)
676{
677 struct sysfs_schedule_callback_struct *ss = container_of(work,
678 struct sysfs_schedule_callback_struct, work);
679
680 (ss->func)(ss->data);
681 kobject_put(ss->kobj);
Alan Stern523ded72007-04-26 00:12:04 -0700682 module_put(ss->owner);
Alan Sternd9a9cdf2007-03-15 15:50:34 -0400683 kfree(ss);
684}
685
686/**
687 * sysfs_schedule_callback - helper to schedule a callback for a kobject
688 * @kobj: object we're acting for.
689 * @func: callback function to invoke later.
690 * @data: argument to pass to @func.
Alan Stern523ded72007-04-26 00:12:04 -0700691 * @owner: module owning the callback code
Alan Sternd9a9cdf2007-03-15 15:50:34 -0400692 *
693 * sysfs attribute methods must not unregister themselves or their parent
694 * kobject (which would amount to the same thing). Attempts to do so will
695 * deadlock, since unregistration is mutually exclusive with driver
696 * callbacks.
697 *
698 * Instead methods can call this routine, which will attempt to allocate
699 * and schedule a workqueue request to call back @func with @data as its
700 * argument in the workqueue's process context. @kobj will be pinned
701 * until @func returns.
702 *
703 * Returns 0 if the request was submitted, -ENOMEM if storage could not
Alan Stern523ded72007-04-26 00:12:04 -0700704 * be allocated, -ENODEV if a reference to @owner isn't available.
Alan Sternd9a9cdf2007-03-15 15:50:34 -0400705 */
706int sysfs_schedule_callback(struct kobject *kobj, void (*func)(void *),
Alan Stern523ded72007-04-26 00:12:04 -0700707 void *data, struct module *owner)
Alan Sternd9a9cdf2007-03-15 15:50:34 -0400708{
709 struct sysfs_schedule_callback_struct *ss;
710
Alan Stern523ded72007-04-26 00:12:04 -0700711 if (!try_module_get(owner))
712 return -ENODEV;
Alan Sternd9a9cdf2007-03-15 15:50:34 -0400713 ss = kmalloc(sizeof(*ss), GFP_KERNEL);
Alan Stern523ded72007-04-26 00:12:04 -0700714 if (!ss) {
715 module_put(owner);
Alan Sternd9a9cdf2007-03-15 15:50:34 -0400716 return -ENOMEM;
Alan Stern523ded72007-04-26 00:12:04 -0700717 }
Alan Sternd9a9cdf2007-03-15 15:50:34 -0400718 kobject_get(kobj);
719 ss->kobj = kobj;
720 ss->func = func;
721 ss->data = data;
Alan Stern523ded72007-04-26 00:12:04 -0700722 ss->owner = owner;
Alan Sternd9a9cdf2007-03-15 15:50:34 -0400723 INIT_WORK(&ss->work, sysfs_schedule_callback_work);
724 schedule_work(&ss->work);
725 return 0;
726}
727EXPORT_SYMBOL_GPL(sysfs_schedule_callback);
728
Alan Sterndfa87c82007-02-20 15:02:44 -0500729
Linus Torvalds1da177e2005-04-16 15:20:36 -0700730EXPORT_SYMBOL_GPL(sysfs_create_file);
731EXPORT_SYMBOL_GPL(sysfs_remove_file);