blob: 1beaa739d0a6399c43ac28f8b986d2aaa544972c [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>
Miklos Szeredi93265d12008-06-16 13:46:47 +020017#include <linux/fsnotify.h>
Christoph Hellwig5f45f1a2005-06-23 00:09:12 -070018#include <linux/namei.h>
NeilBrown4508a7a2006-03-20 17:53:53 +110019#include <linux/poll.h>
Oliver Neukum94bebf42006-12-20 10:52:44 +010020#include <linux/list.h>
Dave Young52e8c202007-07-26 11:03:54 +000021#include <linux/mutex.h>
Andrew Mortonae872212007-08-24 16:11:54 -070022#include <linux/limits.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070023#include <asm/uaccess.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070024
25#include "sysfs.h"
26
Andrew Mortonae872212007-08-24 16:11:54 -070027/* used in crash dumps to help with debugging */
28static char last_sysfs_file[PATH_MAX];
29void sysfs_printk_last_file(void)
30{
31 printk(KERN_EMERG "last sysfs file: %s\n", last_sysfs_file);
32}
33
Tejun Heo85a4ffa2007-09-20 16:05:12 +090034/*
35 * There's one sysfs_buffer for each open file and one
36 * sysfs_open_dirent for each sysfs_dirent with one or more open
37 * files.
38 *
39 * filp->private_data points to sysfs_buffer and
40 * sysfs_dirent->s_attr.open points to sysfs_open_dirent. s_attr.open
41 * is protected by sysfs_open_dirent_lock.
42 */
Jiri Slabyd7b37882007-11-21 14:55:19 -080043static DEFINE_SPINLOCK(sysfs_open_dirent_lock);
Tejun Heo85a4ffa2007-09-20 16:05:12 +090044
45struct sysfs_open_dirent {
46 atomic_t refcnt;
Tejun Heoa4e8b912007-09-20 16:05:12 +090047 atomic_t event;
48 wait_queue_head_t poll;
Tejun Heo85a4ffa2007-09-20 16:05:12 +090049 struct list_head buffers; /* goes through sysfs_buffer.list */
50};
51
Tejun Heo73107cb2007-06-14 03:45:16 +090052struct sysfs_buffer {
53 size_t count;
54 loff_t pos;
55 char * page;
Emese Revfy52cf25d2010-01-19 02:58:23 +010056 const struct sysfs_ops * ops;
Dave Young52e8c202007-07-26 11:03:54 +000057 struct mutex mutex;
Tejun Heo73107cb2007-06-14 03:45:16 +090058 int needs_read_fill;
59 int event;
Tejun Heo85a4ffa2007-09-20 16:05:12 +090060 struct list_head list;
Tejun Heo73107cb2007-06-14 03:45:16 +090061};
Linus Torvalds1da177e2005-04-16 15:20:36 -070062
63/**
64 * fill_read_buffer - allocate and fill buffer from object.
65 * @dentry: dentry pointer.
66 * @buffer: data buffer for file.
67 *
68 * Allocate @buffer->page, if it hasn't been already, then call the
69 * kobject's show() method to fill the buffer with this attribute's
70 * data.
Oliver Neukum82244b12007-01-02 08:48:08 +010071 * This is called only once, on the file's first read unless an error
72 * is returned.
Linus Torvalds1da177e2005-04-16 15:20:36 -070073 */
74static int fill_read_buffer(struct dentry * dentry, struct sysfs_buffer * buffer)
75{
Tejun Heo0ab66082007-06-14 03:45:16 +090076 struct sysfs_dirent *attr_sd = dentry->d_fsdata;
Tejun Heob1fc3d62007-09-20 16:05:11 +090077 struct kobject *kobj = attr_sd->s_parent->s_dir.kobj;
Emese Revfy52cf25d2010-01-19 02:58:23 +010078 const struct sysfs_ops * ops = buffer->ops;
Linus Torvalds1da177e2005-04-16 15:20:36 -070079 int ret = 0;
80 ssize_t count;
81
82 if (!buffer->page)
83 buffer->page = (char *) get_zeroed_page(GFP_KERNEL);
84 if (!buffer->page)
85 return -ENOMEM;
86
Tejun Heo0ab66082007-06-14 03:45:16 +090087 /* need attr_sd for attr and ops, its parent for kobj */
Eric W. Biedermane72ceb82010-02-11 15:18:38 -080088 if (!sysfs_get_active(attr_sd))
Tejun Heo0ab66082007-06-14 03:45:16 +090089 return -ENODEV;
90
Tejun Heoa4e8b912007-09-20 16:05:12 +090091 buffer->event = atomic_read(&attr_sd->s_attr.open->event);
Tejun Heob1fc3d62007-09-20 16:05:11 +090092 count = ops->show(kobj, attr_sd->s_attr.attr, buffer->page);
Tejun Heo0ab66082007-06-14 03:45:16 +090093
Eric W. Biedermane72ceb82010-02-11 15:18:38 -080094 sysfs_put_active(attr_sd);
Tejun Heo0ab66082007-06-14 03:45:16 +090095
Miao Xie8118a852007-11-21 14:55:19 -080096 /*
97 * The code works fine with PAGE_SIZE return but it's likely to
98 * indicate truncated result or overflow in normal use cases.
99 */
Andrew Morton815d2d52008-03-04 15:09:07 -0800100 if (count >= (ssize_t)PAGE_SIZE) {
101 print_symbol("fill_read_buffer: %s returned bad count\n",
102 (unsigned long)ops->show);
103 /* Try to struggle along */
104 count = PAGE_SIZE - 1;
105 }
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
Linus Torvalds1da177e2005-04-16 15:20:36 -0700115/**
116 * sysfs_read_file - read an attribute.
117 * @file: file pointer.
118 * @buf: buffer to fill.
119 * @count: number of bytes to read.
120 * @ppos: starting offset in file.
121 *
122 * Userspace wants to read an attribute file. The attribute descriptor
123 * is in the file's ->d_fsdata. The target object is in the directory's
124 * ->d_fsdata.
125 *
126 * We call fill_read_buffer() to allocate and fill the buffer from the
127 * object's show() method exactly once (if the read is happening from
128 * the beginning of the file). That should fill the entire buffer with
129 * all the data the object has to offer for that attribute.
130 * We then call flush_read_buffer() to copy the buffer to userspace
131 * in the increments specified.
132 */
133
134static ssize_t
135sysfs_read_file(struct file *file, char __user *buf, size_t count, loff_t *ppos)
136{
137 struct sysfs_buffer * buffer = file->private_data;
138 ssize_t retval = 0;
139
Dave Young52e8c202007-07-26 11:03:54 +0000140 mutex_lock(&buffer->mutex);
Dan Williams2424b5d2008-04-07 15:35:01 -0700141 if (buffer->needs_read_fill || *ppos == 0) {
Tejun Heo73107cb2007-06-14 03:45:16 +0900142 retval = fill_read_buffer(file->f_path.dentry,buffer);
Alan Sterne7b0d262007-03-15 15:51:28 -0400143 if (retval)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700144 goto out;
145 }
Zach Brown5c1fdf42006-10-03 01:16:06 -0700146 pr_debug("%s: count = %zd, ppos = %lld, buf = %s\n",
Harvey Harrison8e24eea2008-04-30 00:55:09 -0700147 __func__, count, *ppos, buffer->page);
Akinobu Mita92f4c702007-05-09 02:33:32 -0700148 retval = simple_read_from_buffer(buf, count, ppos, buffer->page,
149 buffer->count);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700150out:
Dave Young52e8c202007-07-26 11:03:54 +0000151 mutex_unlock(&buffer->mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700152 return retval;
153}
154
Linus Torvalds1da177e2005-04-16 15:20:36 -0700155/**
156 * fill_write_buffer - copy buffer from userspace.
157 * @buffer: data buffer for file.
Martin Waitz67be2dd2005-05-01 08:59:26 -0700158 * @buf: data from user.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700159 * @count: number of bytes in @userbuf.
160 *
161 * Allocate @buffer->page if it hasn't been already, then
162 * copy the user-supplied buffer into it.
163 */
164
165static int
166fill_write_buffer(struct sysfs_buffer * buffer, const char __user * buf, size_t count)
167{
168 int error;
169
170 if (!buffer->page)
171 buffer->page = (char *)get_zeroed_page(GFP_KERNEL);
172 if (!buffer->page)
173 return -ENOMEM;
174
175 if (count >= PAGE_SIZE)
Greg Kroah-Hartman6e0dd742006-03-31 15:37:06 -0800176 count = PAGE_SIZE - 1;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700177 error = copy_from_user(buffer->page,buf,count);
178 buffer->needs_read_fill = 1;
Thomas Maier035ed7a2006-10-22 19:17:47 +0200179 /* if buf is assumed to contain a string, terminate it by \0,
180 so e.g. sscanf() can scan the string easily */
181 buffer->page[count] = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700182 return error ? -EFAULT : count;
183}
184
185
186/**
187 * flush_write_buffer - push buffer to kobject.
Martin Waitz3d410882005-06-23 22:05:21 -0700188 * @dentry: dentry to the attribute
Linus Torvalds1da177e2005-04-16 15:20:36 -0700189 * @buffer: data buffer for file.
Martin Waitz3d410882005-06-23 22:05:21 -0700190 * @count: number of bytes
Linus Torvalds1da177e2005-04-16 15:20:36 -0700191 *
192 * Get the correct pointers for the kobject and the attribute we're
193 * dealing with, then call the store() method for the attribute,
194 * passing the buffer that we acquired in fill_write_buffer().
195 */
196
Tejun Heo0ab66082007-06-14 03:45:16 +0900197static int
Linus Torvalds1da177e2005-04-16 15:20:36 -0700198flush_write_buffer(struct dentry * dentry, struct sysfs_buffer * buffer, size_t count)
199{
Tejun Heo3e519032007-06-14 03:45:15 +0900200 struct sysfs_dirent *attr_sd = dentry->d_fsdata;
Tejun Heob1fc3d62007-09-20 16:05:11 +0900201 struct kobject *kobj = attr_sd->s_parent->s_dir.kobj;
Emese Revfy52cf25d2010-01-19 02:58:23 +0100202 const struct sysfs_ops * ops = buffer->ops;
Tejun Heo0ab66082007-06-14 03:45:16 +0900203 int rc;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700204
Tejun Heo0ab66082007-06-14 03:45:16 +0900205 /* need attr_sd for attr and ops, its parent for kobj */
Eric W. Biedermane72ceb82010-02-11 15:18:38 -0800206 if (!sysfs_get_active(attr_sd))
Tejun Heo0ab66082007-06-14 03:45:16 +0900207 return -ENODEV;
208
Tejun Heob1fc3d62007-09-20 16:05:11 +0900209 rc = ops->store(kobj, attr_sd->s_attr.attr, buffer->page, count);
Tejun Heo0ab66082007-06-14 03:45:16 +0900210
Eric W. Biedermane72ceb82010-02-11 15:18:38 -0800211 sysfs_put_active(attr_sd);
Tejun Heo0ab66082007-06-14 03:45:16 +0900212
213 return rc;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700214}
215
216
217/**
218 * sysfs_write_file - write an attribute.
219 * @file: file pointer
220 * @buf: data to write
221 * @count: number of bytes
222 * @ppos: starting offset
223 *
224 * Similar to sysfs_read_file(), though working in the opposite direction.
225 * We allocate and fill the data from the user in fill_write_buffer(),
226 * then push it to the kobject in flush_write_buffer().
227 * There is no easy way for us to know if userspace is only doing a partial
228 * write, so we don't support them. We expect the entire buffer to come
229 * on the first write.
230 * Hint: if you're writing a value, first read the file, modify only the
231 * the value you're changing, then write entire buffer back.
232 */
233
234static ssize_t
235sysfs_write_file(struct file *file, const char __user *buf, size_t count, loff_t *ppos)
236{
237 struct sysfs_buffer * buffer = file->private_data;
238 ssize_t len;
239
Dave Young52e8c202007-07-26 11:03:54 +0000240 mutex_lock(&buffer->mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700241 len = fill_write_buffer(buffer, buf, count);
242 if (len > 0)
Josef "Jeff" Sipekf427f5d2006-12-08 02:36:36 -0800243 len = flush_write_buffer(file->f_path.dentry, buffer, len);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700244 if (len > 0)
245 *ppos += len;
Dave Young52e8c202007-07-26 11:03:54 +0000246 mutex_unlock(&buffer->mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700247 return len;
248}
249
Tejun Heo85a4ffa2007-09-20 16:05:12 +0900250/**
251 * sysfs_get_open_dirent - get or create sysfs_open_dirent
252 * @sd: target sysfs_dirent
253 * @buffer: sysfs_buffer for this instance of open
254 *
255 * If @sd->s_attr.open exists, increment its reference count;
256 * otherwise, create one. @buffer is chained to the buffers
257 * list.
258 *
259 * LOCKING:
260 * Kernel thread context (may sleep).
261 *
262 * RETURNS:
263 * 0 on success, -errno on failure.
264 */
265static int sysfs_get_open_dirent(struct sysfs_dirent *sd,
266 struct sysfs_buffer *buffer)
267{
268 struct sysfs_open_dirent *od, *new_od = NULL;
269
270 retry:
Neil Brown83db93f2009-09-15 16:05:51 -0700271 spin_lock_irq(&sysfs_open_dirent_lock);
Tejun Heo85a4ffa2007-09-20 16:05:12 +0900272
273 if (!sd->s_attr.open && new_od) {
274 sd->s_attr.open = new_od;
275 new_od = NULL;
276 }
277
278 od = sd->s_attr.open;
279 if (od) {
280 atomic_inc(&od->refcnt);
281 list_add_tail(&buffer->list, &od->buffers);
282 }
283
Neil Brown83db93f2009-09-15 16:05:51 -0700284 spin_unlock_irq(&sysfs_open_dirent_lock);
Tejun Heo85a4ffa2007-09-20 16:05:12 +0900285
286 if (od) {
287 kfree(new_od);
288 return 0;
289 }
290
291 /* not there, initialize a new one and retry */
292 new_od = kmalloc(sizeof(*new_od), GFP_KERNEL);
293 if (!new_od)
294 return -ENOMEM;
295
296 atomic_set(&new_od->refcnt, 0);
Tejun Heoa4e8b912007-09-20 16:05:12 +0900297 atomic_set(&new_od->event, 1);
298 init_waitqueue_head(&new_od->poll);
Tejun Heo85a4ffa2007-09-20 16:05:12 +0900299 INIT_LIST_HEAD(&new_od->buffers);
300 goto retry;
301}
302
303/**
304 * sysfs_put_open_dirent - put sysfs_open_dirent
305 * @sd: target sysfs_dirent
306 * @buffer: associated sysfs_buffer
307 *
308 * Put @sd->s_attr.open and unlink @buffer from the buffers list.
309 * If reference count reaches zero, disassociate and free it.
310 *
311 * LOCKING:
312 * None.
313 */
314static void sysfs_put_open_dirent(struct sysfs_dirent *sd,
315 struct sysfs_buffer *buffer)
316{
317 struct sysfs_open_dirent *od = sd->s_attr.open;
Neil Brown83db93f2009-09-15 16:05:51 -0700318 unsigned long flags;
Tejun Heo85a4ffa2007-09-20 16:05:12 +0900319
Neil Brown83db93f2009-09-15 16:05:51 -0700320 spin_lock_irqsave(&sysfs_open_dirent_lock, flags);
Tejun Heo85a4ffa2007-09-20 16:05:12 +0900321
322 list_del(&buffer->list);
323 if (atomic_dec_and_test(&od->refcnt))
324 sd->s_attr.open = NULL;
325 else
326 od = NULL;
327
Neil Brown83db93f2009-09-15 16:05:51 -0700328 spin_unlock_irqrestore(&sysfs_open_dirent_lock, flags);
Tejun Heo85a4ffa2007-09-20 16:05:12 +0900329
330 kfree(od);
331}
332
Oliver Neukum94bebf42006-12-20 10:52:44 +0100333static int sysfs_open_file(struct inode *inode, struct file *file)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700334{
Tejun Heo3e519032007-06-14 03:45:15 +0900335 struct sysfs_dirent *attr_sd = file->f_path.dentry->d_fsdata;
Tejun Heob1fc3d62007-09-20 16:05:11 +0900336 struct kobject *kobj = attr_sd->s_parent->s_dir.kobj;
Kay Sievers000f2a42007-11-02 13:47:53 +0100337 struct sysfs_buffer *buffer;
Emese Revfy52cf25d2010-01-19 02:58:23 +0100338 const struct sysfs_ops *ops;
Kay Sievers000f2a42007-11-02 13:47:53 +0100339 int error = -EACCES;
Andrew Mortonae872212007-08-24 16:11:54 -0700340 char *p;
341
342 p = d_path(&file->f_path, last_sysfs_file, sizeof(last_sysfs_file));
343 if (p)
344 memmove(last_sysfs_file, p, strlen(p) + 1);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700345
Tejun Heo0ab66082007-06-14 03:45:16 +0900346 /* need attr_sd for attr and ops, its parent for kobj */
Eric W. Biedermane72ceb82010-02-11 15:18:38 -0800347 if (!sysfs_get_active(attr_sd))
Tejun Heo0ab66082007-06-14 03:45:16 +0900348 return -ENODEV;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700349
Kay Sievers000f2a42007-11-02 13:47:53 +0100350 /* every kobject with an attribute needs a ktype assigned */
351 if (kobj->ktype && kobj->ktype->sysfs_ops)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700352 ops = kobj->ktype->sysfs_ops;
Kay Sievers000f2a42007-11-02 13:47:53 +0100353 else {
Arjan van de Ven99fcd772008-07-25 19:45:41 -0700354 WARN(1, KERN_ERR "missing sysfs attribute operations for "
Kay Sievers000f2a42007-11-02 13:47:53 +0100355 "kobject: %s\n", kobject_name(kobj));
Tejun Heo7b595752007-06-14 03:45:17 +0900356 goto err_out;
Kay Sievers000f2a42007-11-02 13:47:53 +0100357 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700358
359 /* File needs write support.
360 * The inode's perms must say it's ok,
361 * and we must have a store method.
362 */
363 if (file->f_mode & FMODE_WRITE) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700364 if (!(inode->i_mode & S_IWUGO) || !ops->store)
Tejun Heo7b595752007-06-14 03:45:17 +0900365 goto err_out;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700366 }
367
368 /* File needs read support.
369 * The inode's perms must say it's ok, and we there
370 * must be a show method for it.
371 */
372 if (file->f_mode & FMODE_READ) {
373 if (!(inode->i_mode & S_IRUGO) || !ops->show)
Tejun Heo7b595752007-06-14 03:45:17 +0900374 goto err_out;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700375 }
376
377 /* No error? Great, allocate a buffer for the file, and store it
378 * it in file->private_data for easy access.
379 */
Tejun Heo0ab66082007-06-14 03:45:16 +0900380 error = -ENOMEM;
Eric Sesterhenn58d49282006-02-22 11:18:15 +0100381 buffer = kzalloc(sizeof(struct sysfs_buffer), GFP_KERNEL);
Tejun Heo0ab66082007-06-14 03:45:16 +0900382 if (!buffer)
Tejun Heo7b595752007-06-14 03:45:17 +0900383 goto err_out;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700384
Dave Young52e8c202007-07-26 11:03:54 +0000385 mutex_init(&buffer->mutex);
Tejun Heo0ab66082007-06-14 03:45:16 +0900386 buffer->needs_read_fill = 1;
387 buffer->ops = ops;
Tejun Heo0ab66082007-06-14 03:45:16 +0900388 file->private_data = buffer;
389
Tejun Heo85a4ffa2007-09-20 16:05:12 +0900390 /* make sure we have open dirent struct */
391 error = sysfs_get_open_dirent(attr_sd, buffer);
392 if (error)
393 goto err_free;
394
Tejun Heob05f0542007-09-20 16:05:10 +0900395 /* open succeeded, put active references */
Eric W. Biedermane72ceb82010-02-11 15:18:38 -0800396 sysfs_put_active(attr_sd);
Tejun Heo0ab66082007-06-14 03:45:16 +0900397 return 0;
398
Tejun Heo85a4ffa2007-09-20 16:05:12 +0900399 err_free:
400 kfree(buffer);
Tejun Heo7b595752007-06-14 03:45:17 +0900401 err_out:
Eric W. Biedermane72ceb82010-02-11 15:18:38 -0800402 sysfs_put_active(attr_sd);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700403 return error;
404}
405
Tejun Heo85a4ffa2007-09-20 16:05:12 +0900406static int sysfs_release(struct inode *inode, struct file *filp)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700407{
Tejun Heo85a4ffa2007-09-20 16:05:12 +0900408 struct sysfs_dirent *sd = filp->f_path.dentry->d_fsdata;
Tejun Heo73107cb2007-06-14 03:45:16 +0900409 struct sysfs_buffer *buffer = filp->private_data;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700410
Tejun Heo85a4ffa2007-09-20 16:05:12 +0900411 sysfs_put_open_dirent(sd, buffer);
412
Tejun Heo50ab1a72007-09-20 16:05:10 +0900413 if (buffer->page)
414 free_page((unsigned long)buffer->page);
415 kfree(buffer);
416
Linus Torvalds1da177e2005-04-16 15:20:36 -0700417 return 0;
418}
419
NeilBrown4508a7a2006-03-20 17:53:53 +1100420/* Sysfs attribute files are pollable. The idea is that you read
421 * the content and then you use 'poll' or 'select' to wait for
422 * the content to change. When the content changes (assuming the
423 * manager for the kobject supports notification), poll will
424 * return POLLERR|POLLPRI, and select will return the fd whether
425 * it is waiting for read, write, or exceptions.
426 * Once poll/select indicates that the value has changed, you
Dan Williams2424b5d2008-04-07 15:35:01 -0700427 * need to close and re-open the file, or seek to 0 and read again.
NeilBrown4508a7a2006-03-20 17:53:53 +1100428 * Reminder: this only works for attributes which actively support
429 * it, and it is not possible to test an attribute from userspace
Rolf Eike Beera93720e2007-08-10 13:51:07 -0700430 * to see if it supports poll (Neither 'poll' nor 'select' return
NeilBrown4508a7a2006-03-20 17:53:53 +1100431 * an appropriate error code). When in doubt, set a suitable timeout value.
432 */
433static unsigned int sysfs_poll(struct file *filp, poll_table *wait)
434{
435 struct sysfs_buffer * buffer = filp->private_data;
Tejun Heo0ab66082007-06-14 03:45:16 +0900436 struct sysfs_dirent *attr_sd = filp->f_path.dentry->d_fsdata;
Tejun Heoa4e8b912007-09-20 16:05:12 +0900437 struct sysfs_open_dirent *od = attr_sd->s_attr.open;
Tejun Heo0ab66082007-06-14 03:45:16 +0900438
439 /* need parent for the kobj, grab both */
Eric W. Biedermane72ceb82010-02-11 15:18:38 -0800440 if (!sysfs_get_active(attr_sd))
Tejun Heo0ab66082007-06-14 03:45:16 +0900441 goto trigger;
NeilBrown4508a7a2006-03-20 17:53:53 +1100442
Tejun Heoa4e8b912007-09-20 16:05:12 +0900443 poll_wait(filp, &od->poll, wait);
NeilBrown4508a7a2006-03-20 17:53:53 +1100444
Eric W. Biedermane72ceb82010-02-11 15:18:38 -0800445 sysfs_put_active(attr_sd);
NeilBrown4508a7a2006-03-20 17:53:53 +1100446
Tejun Heoa4e8b912007-09-20 16:05:12 +0900447 if (buffer->event != atomic_read(&od->event))
Tejun Heo0ab66082007-06-14 03:45:16 +0900448 goto trigger;
449
KOSAKI Motohiro1af35572009-04-09 13:53:22 +0900450 return DEFAULT_POLLMASK;
Tejun Heo0ab66082007-06-14 03:45:16 +0900451
452 trigger:
453 buffer->needs_read_fill = 1;
KOSAKI Motohiro1af35572009-04-09 13:53:22 +0900454 return DEFAULT_POLLMASK|POLLERR|POLLPRI;
NeilBrown4508a7a2006-03-20 17:53:53 +1100455}
456
Neil Brownf1282c82008-07-16 08:58:04 +1000457void sysfs_notify_dirent(struct sysfs_dirent *sd)
458{
459 struct sysfs_open_dirent *od;
Neil Brown83db93f2009-09-15 16:05:51 -0700460 unsigned long flags;
Neil Brownf1282c82008-07-16 08:58:04 +1000461
Neil Brown83db93f2009-09-15 16:05:51 -0700462 spin_lock_irqsave(&sysfs_open_dirent_lock, flags);
Neil Brownf1282c82008-07-16 08:58:04 +1000463
464 od = sd->s_attr.open;
465 if (od) {
466 atomic_inc(&od->event);
467 wake_up_interruptible(&od->poll);
468 }
469
Neil Brown83db93f2009-09-15 16:05:51 -0700470 spin_unlock_irqrestore(&sysfs_open_dirent_lock, flags);
Neil Brownf1282c82008-07-16 08:58:04 +1000471}
472EXPORT_SYMBOL_GPL(sysfs_notify_dirent);
473
Trent Piepho8c0e3992008-09-25 16:45:13 -0700474void sysfs_notify(struct kobject *k, const char *dir, const char *attr)
NeilBrown4508a7a2006-03-20 17:53:53 +1100475{
Tejun Heo51225032007-06-14 04:27:25 +0900476 struct sysfs_dirent *sd = k->sd;
NeilBrown4508a7a2006-03-20 17:53:53 +1100477
Tejun Heo51225032007-06-14 04:27:25 +0900478 mutex_lock(&sysfs_mutex);
NeilBrown4508a7a2006-03-20 17:53:53 +1100479
Tejun Heo51225032007-06-14 04:27:25 +0900480 if (sd && dir)
Eric W. Biederman3ff195b2010-03-30 11:31:26 -0700481 /* Only directories are tagged, so no need to pass
482 * a tag explicitly.
483 */
484 sd = sysfs_find_dirent(sd, NULL, dir);
Tejun Heo51225032007-06-14 04:27:25 +0900485 if (sd && attr)
Eric W. Biederman3ff195b2010-03-30 11:31:26 -0700486 sd = sysfs_find_dirent(sd, NULL, attr);
Neil Brownf1282c82008-07-16 08:58:04 +1000487 if (sd)
488 sysfs_notify_dirent(sd);
Tejun Heo51225032007-06-14 04:27:25 +0900489
490 mutex_unlock(&sysfs_mutex);
NeilBrown4508a7a2006-03-20 17:53:53 +1100491}
492EXPORT_SYMBOL_GPL(sysfs_notify);
493
Arjan van de Ven4b6f5d22006-03-28 01:56:42 -0800494const struct file_operations sysfs_file_operations = {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700495 .read = sysfs_read_file,
496 .write = sysfs_write_file,
497 .llseek = generic_file_llseek,
498 .open = sysfs_open_file,
499 .release = sysfs_release,
NeilBrown4508a7a2006-03-20 17:53:53 +1100500 .poll = sysfs_poll,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700501};
502
James Bottomley0f423892008-03-20 20:47:52 -0500503int sysfs_add_file_mode(struct sysfs_dirent *dir_sd,
504 const struct attribute *attr, int type, mode_t amode)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700505{
James Bottomley0f423892008-03-20 20:47:52 -0500506 umode_t mode = (amode & S_IALLUGO) | S_IFREG;
Tejun Heofb6896d2007-06-14 04:27:24 +0900507 struct sysfs_addrm_cxt acxt;
Tejun Heoa26cd722007-06-14 03:45:14 +0900508 struct sysfs_dirent *sd;
Tejun Heo23dc2792007-08-02 21:38:03 +0900509 int rc;
Tejun Heoa26cd722007-06-14 03:45:14 +0900510
Tejun Heo3e519032007-06-14 03:45:15 +0900511 sd = sysfs_new_dirent(attr->name, mode, type);
Tejun Heo3007e992007-06-14 04:27:23 +0900512 if (!sd)
513 return -ENOMEM;
Tejun Heob1fc3d62007-09-20 16:05:11 +0900514 sd->s_attr.attr = (void *)attr;
Eric W. Biedermana2db6842010-02-11 15:20:00 -0800515 sysfs_dirent_init_lockdep(sd);
Tejun Heoa26cd722007-06-14 03:45:14 +0900516
Tejun Heofb6896d2007-06-14 04:27:24 +0900517 sysfs_addrm_start(&acxt, dir_sd);
Tejun Heo23dc2792007-08-02 21:38:03 +0900518 rc = sysfs_add_one(&acxt, sd);
519 sysfs_addrm_finish(&acxt);
Tejun Heo3007e992007-06-14 04:27:23 +0900520
Tejun Heo23dc2792007-08-02 21:38:03 +0900521 if (rc)
Tejun Heo967e35d2007-07-18 16:38:11 +0900522 sysfs_put(sd);
Tejun Heo3007e992007-06-14 04:27:23 +0900523
Tejun Heo23dc2792007-08-02 21:38:03 +0900524 return rc;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700525}
526
527
James Bottomley0f423892008-03-20 20:47:52 -0500528int sysfs_add_file(struct sysfs_dirent *dir_sd, const struct attribute *attr,
529 int type)
530{
531 return sysfs_add_file_mode(dir_sd, attr, type, attr->mode);
532}
533
534
Linus Torvalds1da177e2005-04-16 15:20:36 -0700535/**
536 * sysfs_create_file - create an attribute file for an object.
537 * @kobj: object we're creating for.
Chris Malley3932bf62007-10-20 03:14:32 +0200538 * @attr: attribute descriptor.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700539 */
540
541int sysfs_create_file(struct kobject * kobj, const struct attribute * attr)
542{
Tejun Heo608e2662007-06-14 04:27:22 +0900543 BUG_ON(!kobj || !kobj->sd || !attr);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700544
Tejun Heo608e2662007-06-14 04:27:22 +0900545 return sysfs_add_file(kobj->sd, attr, SYSFS_KOBJ_ATTR);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700546
547}
548
Andi Kleen1c205ae2010-01-05 12:48:01 +0100549int sysfs_create_files(struct kobject *kobj, const struct attribute **ptr)
550{
551 int err = 0;
552 int i;
553
554 for (i = 0; ptr[i] && !err; i++)
555 err = sysfs_create_file(kobj, ptr[i]);
556 if (err)
557 while (--i >= 0)
558 sysfs_remove_file(kobj, ptr[i]);
559 return err;
560}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700561
562/**
Alan Sterndfa87c82007-02-20 15:02:44 -0500563 * sysfs_add_file_to_group - add an attribute file to a pre-existing group.
564 * @kobj: object we're acting for.
565 * @attr: attribute descriptor.
566 * @group: group name.
567 */
568int sysfs_add_file_to_group(struct kobject *kobj,
569 const struct attribute *attr, const char *group)
570{
Tejun Heo608e2662007-06-14 04:27:22 +0900571 struct sysfs_dirent *dir_sd;
Alan Sterndfa87c82007-02-20 15:02:44 -0500572 int error;
573
James Bottomley11f24fb2008-01-02 18:44:05 -0600574 if (group)
Eric W. Biederman3ff195b2010-03-30 11:31:26 -0700575 dir_sd = sysfs_get_dirent(kobj->sd, NULL, group);
James Bottomley11f24fb2008-01-02 18:44:05 -0600576 else
577 dir_sd = sysfs_get(kobj->sd);
578
Tejun Heo608e2662007-06-14 04:27:22 +0900579 if (!dir_sd)
580 return -ENOENT;
581
582 error = sysfs_add_file(dir_sd, attr, SYSFS_KOBJ_ATTR);
583 sysfs_put(dir_sd);
584
Alan Sterndfa87c82007-02-20 15:02:44 -0500585 return error;
586}
587EXPORT_SYMBOL_GPL(sysfs_add_file_to_group);
588
Linus Torvalds1da177e2005-04-16 15:20:36 -0700589/**
Kay Sievers31e5abe2005-04-18 21:57:32 -0700590 * sysfs_chmod_file - update the modified mode value on an object attribute.
591 * @kobj: object we're acting for.
592 * @attr: attribute descriptor.
593 * @mode: file permissions.
594 *
595 */
596int sysfs_chmod_file(struct kobject *kobj, struct attribute *attr, mode_t mode)
597{
Eric W. Biederman06fc0d62009-11-20 16:08:54 -0800598 struct sysfs_dirent *sd;
Maneesh Sonibc062b12005-07-29 12:13:35 -0700599 struct iattr newattrs;
Tejun Heo51225032007-06-14 04:27:25 +0900600 int rc;
Kay Sievers31e5abe2005-04-18 21:57:32 -0700601
Eric W. Biederman06fc0d62009-11-20 16:08:54 -0800602 mutex_lock(&sysfs_mutex);
603
Tejun Heo51225032007-06-14 04:27:25 +0900604 rc = -ENOENT;
Eric W. Biederman3ff195b2010-03-30 11:31:26 -0700605 sd = sysfs_find_dirent(kobj->sd, NULL, attr->name);
Eric W. Biederman06fc0d62009-11-20 16:08:54 -0800606 if (!sd)
Tejun Heo51225032007-06-14 04:27:25 +0900607 goto out;
608
Eric W. Biederman06fc0d62009-11-20 16:08:54 -0800609 newattrs.ia_mode = (mode & S_IALLUGO) | (sd->s_mode & ~S_IALLUGO);
Eric W. Biederman4c6974f2009-11-07 23:27:02 -0800610 newattrs.ia_valid = ATTR_MODE;
Eric W. Biederman06fc0d62009-11-20 16:08:54 -0800611 rc = sysfs_sd_setattr(sd, &newattrs);
Tejun Heof88123e2007-09-20 16:05:10 +0900612
Tejun Heo51225032007-06-14 04:27:25 +0900613 out:
Eric W. Biederman06fc0d62009-11-20 16:08:54 -0800614 mutex_unlock(&sysfs_mutex);
Tejun Heo51225032007-06-14 04:27:25 +0900615 return rc;
Kay Sievers31e5abe2005-04-18 21:57:32 -0700616}
617EXPORT_SYMBOL_GPL(sysfs_chmod_file);
618
619
620/**
Linus Torvalds1da177e2005-04-16 15:20:36 -0700621 * sysfs_remove_file - remove an object attribute.
622 * @kobj: object we're acting for.
623 * @attr: attribute descriptor.
624 *
625 * Hash the attribute name and kill the victim.
626 */
627
628void sysfs_remove_file(struct kobject * kobj, const struct attribute * attr)
629{
Eric W. Biederman3ff195b2010-03-30 11:31:26 -0700630 sysfs_hash_and_remove(kobj->sd, NULL, attr->name);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700631}
632
Andi Kleen1c205ae2010-01-05 12:48:01 +0100633void sysfs_remove_files(struct kobject * kobj, const struct attribute **ptr)
634{
635 int i;
636 for (i = 0; ptr[i]; i++)
637 sysfs_remove_file(kobj, ptr[i]);
638}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700639
Alan Sterndfa87c82007-02-20 15:02:44 -0500640/**
641 * sysfs_remove_file_from_group - remove an attribute file from a group.
642 * @kobj: object we're acting for.
643 * @attr: attribute descriptor.
644 * @group: group name.
645 */
646void sysfs_remove_file_from_group(struct kobject *kobj,
647 const struct attribute *attr, const char *group)
648{
Tejun Heo608e2662007-06-14 04:27:22 +0900649 struct sysfs_dirent *dir_sd;
Alan Sterndfa87c82007-02-20 15:02:44 -0500650
James Bottomley11f24fb2008-01-02 18:44:05 -0600651 if (group)
Eric W. Biederman3ff195b2010-03-30 11:31:26 -0700652 dir_sd = sysfs_get_dirent(kobj->sd, NULL, group);
James Bottomley11f24fb2008-01-02 18:44:05 -0600653 else
654 dir_sd = sysfs_get(kobj->sd);
Tejun Heo608e2662007-06-14 04:27:22 +0900655 if (dir_sd) {
Eric W. Biederman3ff195b2010-03-30 11:31:26 -0700656 sysfs_hash_and_remove(dir_sd, NULL, attr->name);
Tejun Heo608e2662007-06-14 04:27:22 +0900657 sysfs_put(dir_sd);
Alan Sterndfa87c82007-02-20 15:02:44 -0500658 }
659}
660EXPORT_SYMBOL_GPL(sysfs_remove_file_from_group);
661
Alan Sternd9a9cdf2007-03-15 15:50:34 -0400662struct sysfs_schedule_callback_struct {
Alex Chiang66942062009-03-13 12:07:36 -0600663 struct list_head workq_list;
664 struct kobject *kobj;
Alan Sternd9a9cdf2007-03-15 15:50:34 -0400665 void (*func)(void *);
666 void *data;
Alan Stern523ded72007-04-26 00:12:04 -0700667 struct module *owner;
Alan Sternd9a9cdf2007-03-15 15:50:34 -0400668 struct work_struct work;
669};
670
Alex Chiangd1102712009-03-25 15:11:36 -0600671static struct workqueue_struct *sysfs_workqueue;
Alex Chiang66942062009-03-13 12:07:36 -0600672static DEFINE_MUTEX(sysfs_workq_mutex);
673static LIST_HEAD(sysfs_workq);
Alan Sternd9a9cdf2007-03-15 15:50:34 -0400674static void sysfs_schedule_callback_work(struct work_struct *work)
675{
676 struct sysfs_schedule_callback_struct *ss = container_of(work,
677 struct sysfs_schedule_callback_struct, work);
678
679 (ss->func)(ss->data);
680 kobject_put(ss->kobj);
Alan Stern523ded72007-04-26 00:12:04 -0700681 module_put(ss->owner);
Alex Chiang66942062009-03-13 12:07:36 -0600682 mutex_lock(&sysfs_workq_mutex);
683 list_del(&ss->workq_list);
684 mutex_unlock(&sysfs_workq_mutex);
Alan Sternd9a9cdf2007-03-15 15:50:34 -0400685 kfree(ss);
686}
687
688/**
689 * sysfs_schedule_callback - helper to schedule a callback for a kobject
690 * @kobj: object we're acting for.
691 * @func: callback function to invoke later.
692 * @data: argument to pass to @func.
Alan Stern523ded72007-04-26 00:12:04 -0700693 * @owner: module owning the callback code
Alan Sternd9a9cdf2007-03-15 15:50:34 -0400694 *
695 * sysfs attribute methods must not unregister themselves or their parent
696 * kobject (which would amount to the same thing). Attempts to do so will
697 * deadlock, since unregistration is mutually exclusive with driver
698 * callbacks.
699 *
700 * Instead methods can call this routine, which will attempt to allocate
701 * and schedule a workqueue request to call back @func with @data as its
702 * argument in the workqueue's process context. @kobj will be pinned
703 * until @func returns.
704 *
705 * Returns 0 if the request was submitted, -ENOMEM if storage could not
Alex Chiang66942062009-03-13 12:07:36 -0600706 * be allocated, -ENODEV if a reference to @owner isn't available,
707 * -EAGAIN if a callback has already been scheduled for @kobj.
Alan Sternd9a9cdf2007-03-15 15:50:34 -0400708 */
709int sysfs_schedule_callback(struct kobject *kobj, void (*func)(void *),
Alan Stern523ded72007-04-26 00:12:04 -0700710 void *data, struct module *owner)
Alan Sternd9a9cdf2007-03-15 15:50:34 -0400711{
Alex Chiang66942062009-03-13 12:07:36 -0600712 struct sysfs_schedule_callback_struct *ss, *tmp;
Alan Sternd9a9cdf2007-03-15 15:50:34 -0400713
Alan Stern523ded72007-04-26 00:12:04 -0700714 if (!try_module_get(owner))
715 return -ENODEV;
Alex Chiang66942062009-03-13 12:07:36 -0600716
717 mutex_lock(&sysfs_workq_mutex);
718 list_for_each_entry_safe(ss, tmp, &sysfs_workq, workq_list)
719 if (ss->kobj == kobj) {
Alex Chiangd1102712009-03-25 15:11:36 -0600720 module_put(owner);
Alex Chiang66942062009-03-13 12:07:36 -0600721 mutex_unlock(&sysfs_workq_mutex);
722 return -EAGAIN;
723 }
724 mutex_unlock(&sysfs_workq_mutex);
725
Alex Chiangd1102712009-03-25 15:11:36 -0600726 if (sysfs_workqueue == NULL) {
Andrew Morton086a3772009-05-07 12:36:53 -0700727 sysfs_workqueue = create_singlethread_workqueue("sysfsd");
Alex Chiangd1102712009-03-25 15:11:36 -0600728 if (sysfs_workqueue == NULL) {
729 module_put(owner);
730 return -ENOMEM;
731 }
732 }
733
Alan Sternd9a9cdf2007-03-15 15:50:34 -0400734 ss = kmalloc(sizeof(*ss), GFP_KERNEL);
Alan Stern523ded72007-04-26 00:12:04 -0700735 if (!ss) {
736 module_put(owner);
Alan Sternd9a9cdf2007-03-15 15:50:34 -0400737 return -ENOMEM;
Alan Stern523ded72007-04-26 00:12:04 -0700738 }
Alan Sternd9a9cdf2007-03-15 15:50:34 -0400739 kobject_get(kobj);
740 ss->kobj = kobj;
741 ss->func = func;
742 ss->data = data;
Alan Stern523ded72007-04-26 00:12:04 -0700743 ss->owner = owner;
Alan Sternd9a9cdf2007-03-15 15:50:34 -0400744 INIT_WORK(&ss->work, sysfs_schedule_callback_work);
Alex Chiang66942062009-03-13 12:07:36 -0600745 INIT_LIST_HEAD(&ss->workq_list);
746 mutex_lock(&sysfs_workq_mutex);
747 list_add_tail(&ss->workq_list, &sysfs_workq);
748 mutex_unlock(&sysfs_workq_mutex);
Alex Chiangd1102712009-03-25 15:11:36 -0600749 queue_work(sysfs_workqueue, &ss->work);
Alan Sternd9a9cdf2007-03-15 15:50:34 -0400750 return 0;
751}
752EXPORT_SYMBOL_GPL(sysfs_schedule_callback);
753
Alan Sterndfa87c82007-02-20 15:02:44 -0500754
Linus Torvalds1da177e2005-04-16 15:20:36 -0700755EXPORT_SYMBOL_GPL(sysfs_create_file);
756EXPORT_SYMBOL_GPL(sysfs_remove_file);
Andi Kleen1c205ae2010-01-05 12:48:01 +0100757EXPORT_SYMBOL_GPL(sysfs_remove_files);
758EXPORT_SYMBOL_GPL(sysfs_create_files);