blob: d2bb7ed8fa74e772e8de3f112fdc16854ee6527d [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 Mortonae87221d2007-08-24 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
Tejun Heo85a4ffa2007-09-20 16:05:12 +090027/*
28 * There's one sysfs_buffer for each open file and one
29 * sysfs_open_dirent for each sysfs_dirent with one or more open
30 * files.
31 *
32 * filp->private_data points to sysfs_buffer and
33 * sysfs_dirent->s_attr.open points to sysfs_open_dirent. s_attr.open
34 * is protected by sysfs_open_dirent_lock.
35 */
Jiri Slabyd7b37882007-11-21 14:55:19 -080036static DEFINE_SPINLOCK(sysfs_open_dirent_lock);
Tejun Heo85a4ffa2007-09-20 16:05:12 +090037
38struct sysfs_open_dirent {
39 atomic_t refcnt;
Tejun Heoa4e8b912007-09-20 16:05:12 +090040 atomic_t event;
41 wait_queue_head_t poll;
Tejun Heo85a4ffa2007-09-20 16:05:12 +090042 struct list_head buffers; /* goes through sysfs_buffer.list */
43};
44
Tejun Heo73107cb2007-06-14 03:45:16 +090045struct sysfs_buffer {
46 size_t count;
47 loff_t pos;
48 char * page;
Emese Revfy52cf25d2010-01-19 02:58:23 +010049 const struct sysfs_ops * ops;
Dave Young52e8c202007-07-26 11:03:54 +000050 struct mutex mutex;
Tejun Heo73107cb2007-06-14 03:45:16 +090051 int needs_read_fill;
52 int event;
Tejun Heo85a4ffa2007-09-20 16:05:12 +090053 struct list_head list;
Tejun Heo73107cb2007-06-14 03:45:16 +090054};
Linus Torvalds1da177e2005-04-16 15:20:36 -070055
56/**
57 * fill_read_buffer - allocate and fill buffer from object.
58 * @dentry: dentry pointer.
59 * @buffer: data buffer for file.
60 *
61 * Allocate @buffer->page, if it hasn't been already, then call the
62 * kobject's show() method to fill the buffer with this attribute's
63 * data.
Oliver Neukum82244b12007-01-02 08:48:08 +010064 * This is called only once, on the file's first read unless an error
65 * is returned.
Linus Torvalds1da177e2005-04-16 15:20:36 -070066 */
67static int fill_read_buffer(struct dentry * dentry, struct sysfs_buffer * buffer)
68{
Tejun Heo0ab66082007-06-14 03:45:16 +090069 struct sysfs_dirent *attr_sd = dentry->d_fsdata;
Tejun Heob1fc3d62007-09-20 16:05:11 +090070 struct kobject *kobj = attr_sd->s_parent->s_dir.kobj;
Emese Revfy52cf25d2010-01-19 02:58:23 +010071 const struct sysfs_ops * ops = buffer->ops;
Linus Torvalds1da177e2005-04-16 15:20:36 -070072 int ret = 0;
73 ssize_t count;
74
75 if (!buffer->page)
76 buffer->page = (char *) get_zeroed_page(GFP_KERNEL);
77 if (!buffer->page)
78 return -ENOMEM;
79
Tejun Heo0ab66082007-06-14 03:45:16 +090080 /* need attr_sd for attr and ops, its parent for kobj */
Eric W. Biedermane72ceb82010-02-11 15:18:38 -080081 if (!sysfs_get_active(attr_sd))
Tejun Heo0ab66082007-06-14 03:45:16 +090082 return -ENODEV;
83
Tejun Heoa4e8b912007-09-20 16:05:12 +090084 buffer->event = atomic_read(&attr_sd->s_attr.open->event);
Tejun Heob1fc3d62007-09-20 16:05:11 +090085 count = ops->show(kobj, attr_sd->s_attr.attr, buffer->page);
Tejun Heo0ab66082007-06-14 03:45:16 +090086
Eric W. Biedermane72ceb82010-02-11 15:18:38 -080087 sysfs_put_active(attr_sd);
Tejun Heo0ab66082007-06-14 03:45:16 +090088
Miao Xie8118a852007-11-21 14:55:19 -080089 /*
90 * The code works fine with PAGE_SIZE return but it's likely to
91 * indicate truncated result or overflow in normal use cases.
92 */
Andrew Morton815d2d52008-03-04 15:09:07 -080093 if (count >= (ssize_t)PAGE_SIZE) {
94 print_symbol("fill_read_buffer: %s returned bad count\n",
95 (unsigned long)ops->show);
96 /* Try to struggle along */
97 count = PAGE_SIZE - 1;
98 }
Oliver Neukum82244b12007-01-02 08:48:08 +010099 if (count >= 0) {
100 buffer->needs_read_fill = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700101 buffer->count = count;
Oliver Neukum82244b12007-01-02 08:48:08 +0100102 } else {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700103 ret = count;
Oliver Neukum82244b12007-01-02 08:48:08 +0100104 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700105 return ret;
106}
107
Linus Torvalds1da177e2005-04-16 15:20:36 -0700108/**
109 * sysfs_read_file - read an attribute.
110 * @file: file pointer.
111 * @buf: buffer to fill.
112 * @count: number of bytes to read.
113 * @ppos: starting offset in file.
114 *
115 * Userspace wants to read an attribute file. The attribute descriptor
116 * is in the file's ->d_fsdata. The target object is in the directory's
117 * ->d_fsdata.
118 *
119 * We call fill_read_buffer() to allocate and fill the buffer from the
120 * object's show() method exactly once (if the read is happening from
121 * the beginning of the file). That should fill the entire buffer with
122 * all the data the object has to offer for that attribute.
123 * We then call flush_read_buffer() to copy the buffer to userspace
124 * in the increments specified.
125 */
126
127static ssize_t
128sysfs_read_file(struct file *file, char __user *buf, size_t count, loff_t *ppos)
129{
130 struct sysfs_buffer * buffer = file->private_data;
131 ssize_t retval = 0;
132
Dave Young52e8c202007-07-26 11:03:54 +0000133 mutex_lock(&buffer->mutex);
Dan Williams2424b5d2008-04-07 15:35:01 -0700134 if (buffer->needs_read_fill || *ppos == 0) {
Tejun Heo73107cb2007-06-14 03:45:16 +0900135 retval = fill_read_buffer(file->f_path.dentry,buffer);
Alan Sterne7b0d262007-03-15 15:51:28 -0400136 if (retval)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700137 goto out;
138 }
Zach Brown5c1fdf42006-10-03 01:16:06 -0700139 pr_debug("%s: count = %zd, ppos = %lld, buf = %s\n",
Harvey Harrison8e24eea2008-04-30 00:55:09 -0700140 __func__, count, *ppos, buffer->page);
Akinobu Mita92f4c702007-05-09 02:33:32 -0700141 retval = simple_read_from_buffer(buf, count, ppos, buffer->page,
142 buffer->count);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700143out:
Dave Young52e8c202007-07-26 11:03:54 +0000144 mutex_unlock(&buffer->mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700145 return retval;
146}
147
Linus Torvalds1da177e2005-04-16 15:20:36 -0700148/**
149 * fill_write_buffer - copy buffer from userspace.
150 * @buffer: data buffer for file.
Martin Waitz67be2dd2005-05-01 08:59:26 -0700151 * @buf: data from user.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700152 * @count: number of bytes in @userbuf.
153 *
154 * Allocate @buffer->page if it hasn't been already, then
155 * copy the user-supplied buffer into it.
156 */
157
158static int
159fill_write_buffer(struct sysfs_buffer * buffer, const char __user * buf, size_t count)
160{
161 int error;
162
163 if (!buffer->page)
164 buffer->page = (char *)get_zeroed_page(GFP_KERNEL);
165 if (!buffer->page)
166 return -ENOMEM;
167
168 if (count >= PAGE_SIZE)
Greg Kroah-Hartman6e0dd742006-03-31 15:37:06 -0800169 count = PAGE_SIZE - 1;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700170 error = copy_from_user(buffer->page,buf,count);
171 buffer->needs_read_fill = 1;
Thomas Maier035ed7a2006-10-22 19:17:47 +0200172 /* if buf is assumed to contain a string, terminate it by \0,
173 so e.g. sscanf() can scan the string easily */
174 buffer->page[count] = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700175 return error ? -EFAULT : count;
176}
177
178
179/**
180 * flush_write_buffer - push buffer to kobject.
Martin Waitz3d410882005-06-23 22:05:21 -0700181 * @dentry: dentry to the attribute
Linus Torvalds1da177e2005-04-16 15:20:36 -0700182 * @buffer: data buffer for file.
Martin Waitz3d410882005-06-23 22:05:21 -0700183 * @count: number of bytes
Linus Torvalds1da177e2005-04-16 15:20:36 -0700184 *
185 * Get the correct pointers for the kobject and the attribute we're
186 * dealing with, then call the store() method for the attribute,
187 * passing the buffer that we acquired in fill_write_buffer().
188 */
189
Tejun Heo0ab66082007-06-14 03:45:16 +0900190static int
Linus Torvalds1da177e2005-04-16 15:20:36 -0700191flush_write_buffer(struct dentry * dentry, struct sysfs_buffer * buffer, size_t count)
192{
Tejun Heo3e519032007-06-14 03:45:15 +0900193 struct sysfs_dirent *attr_sd = dentry->d_fsdata;
Tejun Heob1fc3d62007-09-20 16:05:11 +0900194 struct kobject *kobj = attr_sd->s_parent->s_dir.kobj;
Emese Revfy52cf25d2010-01-19 02:58:23 +0100195 const struct sysfs_ops * ops = buffer->ops;
Tejun Heo0ab66082007-06-14 03:45:16 +0900196 int rc;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700197
Tejun Heo0ab66082007-06-14 03:45:16 +0900198 /* need attr_sd for attr and ops, its parent for kobj */
Eric W. Biedermane72ceb82010-02-11 15:18:38 -0800199 if (!sysfs_get_active(attr_sd))
Tejun Heo0ab66082007-06-14 03:45:16 +0900200 return -ENODEV;
201
Tejun Heob1fc3d62007-09-20 16:05:11 +0900202 rc = ops->store(kobj, attr_sd->s_attr.attr, buffer->page, count);
Tejun Heo0ab66082007-06-14 03:45:16 +0900203
Eric W. Biedermane72ceb82010-02-11 15:18:38 -0800204 sysfs_put_active(attr_sd);
Tejun Heo0ab66082007-06-14 03:45:16 +0900205
206 return rc;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700207}
208
209
210/**
211 * sysfs_write_file - write an attribute.
212 * @file: file pointer
213 * @buf: data to write
214 * @count: number of bytes
215 * @ppos: starting offset
216 *
217 * Similar to sysfs_read_file(), though working in the opposite direction.
218 * We allocate and fill the data from the user in fill_write_buffer(),
219 * then push it to the kobject in flush_write_buffer().
220 * There is no easy way for us to know if userspace is only doing a partial
221 * write, so we don't support them. We expect the entire buffer to come
222 * on the first write.
223 * Hint: if you're writing a value, first read the file, modify only the
224 * the value you're changing, then write entire buffer back.
225 */
226
227static ssize_t
228sysfs_write_file(struct file *file, const char __user *buf, size_t count, loff_t *ppos)
229{
230 struct sysfs_buffer * buffer = file->private_data;
231 ssize_t len;
232
Dave Young52e8c202007-07-26 11:03:54 +0000233 mutex_lock(&buffer->mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700234 len = fill_write_buffer(buffer, buf, count);
235 if (len > 0)
Josef "Jeff" Sipekf427f5d2006-12-08 02:36:36 -0800236 len = flush_write_buffer(file->f_path.dentry, buffer, len);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700237 if (len > 0)
238 *ppos += len;
Dave Young52e8c202007-07-26 11:03:54 +0000239 mutex_unlock(&buffer->mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700240 return len;
241}
242
Tejun Heo85a4ffa2007-09-20 16:05:12 +0900243/**
244 * sysfs_get_open_dirent - get or create sysfs_open_dirent
245 * @sd: target sysfs_dirent
246 * @buffer: sysfs_buffer for this instance of open
247 *
248 * If @sd->s_attr.open exists, increment its reference count;
249 * otherwise, create one. @buffer is chained to the buffers
250 * list.
251 *
252 * LOCKING:
253 * Kernel thread context (may sleep).
254 *
255 * RETURNS:
256 * 0 on success, -errno on failure.
257 */
258static int sysfs_get_open_dirent(struct sysfs_dirent *sd,
259 struct sysfs_buffer *buffer)
260{
261 struct sysfs_open_dirent *od, *new_od = NULL;
262
263 retry:
Neil Brown83db93f2009-09-15 16:05:51 -0700264 spin_lock_irq(&sysfs_open_dirent_lock);
Tejun Heo85a4ffa2007-09-20 16:05:12 +0900265
266 if (!sd->s_attr.open && new_od) {
267 sd->s_attr.open = new_od;
268 new_od = NULL;
269 }
270
271 od = sd->s_attr.open;
272 if (od) {
273 atomic_inc(&od->refcnt);
274 list_add_tail(&buffer->list, &od->buffers);
275 }
276
Neil Brown83db93f2009-09-15 16:05:51 -0700277 spin_unlock_irq(&sysfs_open_dirent_lock);
Tejun Heo85a4ffa2007-09-20 16:05:12 +0900278
279 if (od) {
280 kfree(new_od);
281 return 0;
282 }
283
284 /* not there, initialize a new one and retry */
285 new_od = kmalloc(sizeof(*new_od), GFP_KERNEL);
286 if (!new_od)
287 return -ENOMEM;
288
289 atomic_set(&new_od->refcnt, 0);
Tejun Heoa4e8b912007-09-20 16:05:12 +0900290 atomic_set(&new_od->event, 1);
291 init_waitqueue_head(&new_od->poll);
Tejun Heo85a4ffa2007-09-20 16:05:12 +0900292 INIT_LIST_HEAD(&new_od->buffers);
293 goto retry;
294}
295
296/**
297 * sysfs_put_open_dirent - put sysfs_open_dirent
298 * @sd: target sysfs_dirent
299 * @buffer: associated sysfs_buffer
300 *
301 * Put @sd->s_attr.open and unlink @buffer from the buffers list.
302 * If reference count reaches zero, disassociate and free it.
303 *
304 * LOCKING:
305 * None.
306 */
307static void sysfs_put_open_dirent(struct sysfs_dirent *sd,
308 struct sysfs_buffer *buffer)
309{
310 struct sysfs_open_dirent *od = sd->s_attr.open;
Neil Brown83db93f2009-09-15 16:05:51 -0700311 unsigned long flags;
Tejun Heo85a4ffa2007-09-20 16:05:12 +0900312
Neil Brown83db93f2009-09-15 16:05:51 -0700313 spin_lock_irqsave(&sysfs_open_dirent_lock, flags);
Tejun Heo85a4ffa2007-09-20 16:05:12 +0900314
315 list_del(&buffer->list);
316 if (atomic_dec_and_test(&od->refcnt))
317 sd->s_attr.open = NULL;
318 else
319 od = NULL;
320
Neil Brown83db93f2009-09-15 16:05:51 -0700321 spin_unlock_irqrestore(&sysfs_open_dirent_lock, flags);
Tejun Heo85a4ffa2007-09-20 16:05:12 +0900322
323 kfree(od);
324}
325
Oliver Neukum94bebf42006-12-20 10:52:44 +0100326static int sysfs_open_file(struct inode *inode, struct file *file)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700327{
Tejun Heo3e519032007-06-14 03:45:15 +0900328 struct sysfs_dirent *attr_sd = file->f_path.dentry->d_fsdata;
Tejun Heob1fc3d62007-09-20 16:05:11 +0900329 struct kobject *kobj = attr_sd->s_parent->s_dir.kobj;
Kay Sievers000f2a42007-11-02 13:47:53 +0100330 struct sysfs_buffer *buffer;
Emese Revfy52cf25d2010-01-19 02:58:23 +0100331 const struct sysfs_ops *ops;
Kay Sievers000f2a42007-11-02 13:47:53 +0100332 int error = -EACCES;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700333
Tejun Heo0ab66082007-06-14 03:45:16 +0900334 /* need attr_sd for attr and ops, its parent for kobj */
Eric W. Biedermane72ceb82010-02-11 15:18:38 -0800335 if (!sysfs_get_active(attr_sd))
Tejun Heo0ab66082007-06-14 03:45:16 +0900336 return -ENODEV;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700337
Kay Sievers000f2a42007-11-02 13:47:53 +0100338 /* every kobject with an attribute needs a ktype assigned */
339 if (kobj->ktype && kobj->ktype->sysfs_ops)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700340 ops = kobj->ktype->sysfs_ops;
Kay Sievers000f2a42007-11-02 13:47:53 +0100341 else {
Arjan van de Ven99fcd772008-07-25 19:45:41 -0700342 WARN(1, KERN_ERR "missing sysfs attribute operations for "
Kay Sievers000f2a42007-11-02 13:47:53 +0100343 "kobject: %s\n", kobject_name(kobj));
Tejun Heo7b595752007-06-14 03:45:17 +0900344 goto err_out;
Kay Sievers000f2a42007-11-02 13:47:53 +0100345 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700346
347 /* File needs write support.
348 * The inode's perms must say it's ok,
349 * and we must have a store method.
350 */
351 if (file->f_mode & FMODE_WRITE) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700352 if (!(inode->i_mode & S_IWUGO) || !ops->store)
Tejun Heo7b595752007-06-14 03:45:17 +0900353 goto err_out;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700354 }
355
356 /* File needs read support.
357 * The inode's perms must say it's ok, and we there
358 * must be a show method for it.
359 */
360 if (file->f_mode & FMODE_READ) {
361 if (!(inode->i_mode & S_IRUGO) || !ops->show)
Tejun Heo7b595752007-06-14 03:45:17 +0900362 goto err_out;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700363 }
364
365 /* No error? Great, allocate a buffer for the file, and store it
366 * it in file->private_data for easy access.
367 */
Tejun Heo0ab66082007-06-14 03:45:16 +0900368 error = -ENOMEM;
Eric Sesterhenn58d49282006-02-22 11:18:15 +0100369 buffer = kzalloc(sizeof(struct sysfs_buffer), GFP_KERNEL);
Tejun Heo0ab66082007-06-14 03:45:16 +0900370 if (!buffer)
Tejun Heo7b595752007-06-14 03:45:17 +0900371 goto err_out;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700372
Dave Young52e8c202007-07-26 11:03:54 +0000373 mutex_init(&buffer->mutex);
Tejun Heo0ab66082007-06-14 03:45:16 +0900374 buffer->needs_read_fill = 1;
375 buffer->ops = ops;
Tejun Heo0ab66082007-06-14 03:45:16 +0900376 file->private_data = buffer;
377
Tejun Heo85a4ffa2007-09-20 16:05:12 +0900378 /* make sure we have open dirent struct */
379 error = sysfs_get_open_dirent(attr_sd, buffer);
380 if (error)
381 goto err_free;
382
Tejun Heob05f0542007-09-20 16:05:10 +0900383 /* open succeeded, put active references */
Eric W. Biedermane72ceb82010-02-11 15:18:38 -0800384 sysfs_put_active(attr_sd);
Tejun Heo0ab66082007-06-14 03:45:16 +0900385 return 0;
386
Tejun Heo85a4ffa2007-09-20 16:05:12 +0900387 err_free:
388 kfree(buffer);
Tejun Heo7b595752007-06-14 03:45:17 +0900389 err_out:
Eric W. Biedermane72ceb82010-02-11 15:18:38 -0800390 sysfs_put_active(attr_sd);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700391 return error;
392}
393
Tejun Heo85a4ffa2007-09-20 16:05:12 +0900394static int sysfs_release(struct inode *inode, struct file *filp)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700395{
Tejun Heo85a4ffa2007-09-20 16:05:12 +0900396 struct sysfs_dirent *sd = filp->f_path.dentry->d_fsdata;
Tejun Heo73107cb2007-06-14 03:45:16 +0900397 struct sysfs_buffer *buffer = filp->private_data;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700398
Tejun Heo85a4ffa2007-09-20 16:05:12 +0900399 sysfs_put_open_dirent(sd, buffer);
400
Tejun Heo50ab1a72007-09-20 16:05:10 +0900401 if (buffer->page)
402 free_page((unsigned long)buffer->page);
403 kfree(buffer);
404
Linus Torvalds1da177e2005-04-16 15:20:36 -0700405 return 0;
406}
407
NeilBrown4508a7a2006-03-20 17:53:53 +1100408/* Sysfs attribute files are pollable. The idea is that you read
409 * the content and then you use 'poll' or 'select' to wait for
410 * the content to change. When the content changes (assuming the
411 * manager for the kobject supports notification), poll will
412 * return POLLERR|POLLPRI, and select will return the fd whether
413 * it is waiting for read, write, or exceptions.
414 * Once poll/select indicates that the value has changed, you
Dan Williams2424b5d2008-04-07 15:35:01 -0700415 * need to close and re-open the file, or seek to 0 and read again.
NeilBrown4508a7a2006-03-20 17:53:53 +1100416 * Reminder: this only works for attributes which actively support
417 * it, and it is not possible to test an attribute from userspace
Rolf Eike Beera93720e2007-08-10 13:51:07 -0700418 * to see if it supports poll (Neither 'poll' nor 'select' return
NeilBrown4508a7a2006-03-20 17:53:53 +1100419 * an appropriate error code). When in doubt, set a suitable timeout value.
420 */
421static unsigned int sysfs_poll(struct file *filp, poll_table *wait)
422{
423 struct sysfs_buffer * buffer = filp->private_data;
Tejun Heo0ab66082007-06-14 03:45:16 +0900424 struct sysfs_dirent *attr_sd = filp->f_path.dentry->d_fsdata;
Tejun Heoa4e8b912007-09-20 16:05:12 +0900425 struct sysfs_open_dirent *od = attr_sd->s_attr.open;
Tejun Heo0ab66082007-06-14 03:45:16 +0900426
427 /* need parent for the kobj, grab both */
Eric W. Biedermane72ceb82010-02-11 15:18:38 -0800428 if (!sysfs_get_active(attr_sd))
Tejun Heo0ab66082007-06-14 03:45:16 +0900429 goto trigger;
NeilBrown4508a7a2006-03-20 17:53:53 +1100430
Tejun Heoa4e8b912007-09-20 16:05:12 +0900431 poll_wait(filp, &od->poll, wait);
NeilBrown4508a7a2006-03-20 17:53:53 +1100432
Eric W. Biedermane72ceb82010-02-11 15:18:38 -0800433 sysfs_put_active(attr_sd);
NeilBrown4508a7a2006-03-20 17:53:53 +1100434
Tejun Heoa4e8b912007-09-20 16:05:12 +0900435 if (buffer->event != atomic_read(&od->event))
Tejun Heo0ab66082007-06-14 03:45:16 +0900436 goto trigger;
437
KOSAKI Motohiro1af35572009-04-09 13:53:22 +0900438 return DEFAULT_POLLMASK;
Tejun Heo0ab66082007-06-14 03:45:16 +0900439
440 trigger:
441 buffer->needs_read_fill = 1;
KOSAKI Motohiro1af35572009-04-09 13:53:22 +0900442 return DEFAULT_POLLMASK|POLLERR|POLLPRI;
NeilBrown4508a7a2006-03-20 17:53:53 +1100443}
444
Neil Brownf1282c82008-07-16 08:58:04 +1000445void sysfs_notify_dirent(struct sysfs_dirent *sd)
446{
447 struct sysfs_open_dirent *od;
Neil Brown83db93f2009-09-15 16:05:51 -0700448 unsigned long flags;
Neil Brownf1282c82008-07-16 08:58:04 +1000449
Neil Brown83db93f2009-09-15 16:05:51 -0700450 spin_lock_irqsave(&sysfs_open_dirent_lock, flags);
Neil Brownf1282c82008-07-16 08:58:04 +1000451
Nick Dyerfc60bb82013-06-07 15:45:13 +0100452 if (!WARN_ON(sysfs_type(sd) != SYSFS_KOBJ_ATTR)) {
453 od = sd->s_attr.open;
454 if (od) {
455 atomic_inc(&od->event);
456 wake_up_interruptible(&od->poll);
457 }
Neil Brownf1282c82008-07-16 08:58:04 +1000458 }
459
Neil Brown83db93f2009-09-15 16:05:51 -0700460 spin_unlock_irqrestore(&sysfs_open_dirent_lock, flags);
Neil Brownf1282c82008-07-16 08:58:04 +1000461}
462EXPORT_SYMBOL_GPL(sysfs_notify_dirent);
463
Trent Piepho8c0e3992008-09-25 16:45:13 -0700464void sysfs_notify(struct kobject *k, const char *dir, const char *attr)
NeilBrown4508a7a2006-03-20 17:53:53 +1100465{
Tejun Heo51225032007-06-14 04:27:25 +0900466 struct sysfs_dirent *sd = k->sd;
NeilBrown4508a7a2006-03-20 17:53:53 +1100467
Tejun Heo51225032007-06-14 04:27:25 +0900468 mutex_lock(&sysfs_mutex);
NeilBrown4508a7a2006-03-20 17:53:53 +1100469
Tejun Heo51225032007-06-14 04:27:25 +0900470 if (sd && dir)
Eric W. Biederman3ff195b2010-03-30 11:31:26 -0700471 sd = sysfs_find_dirent(sd, NULL, dir);
Tejun Heo51225032007-06-14 04:27:25 +0900472 if (sd && attr)
Eric W. Biederman3ff195b2010-03-30 11:31:26 -0700473 sd = sysfs_find_dirent(sd, NULL, attr);
Neil Brownf1282c82008-07-16 08:58:04 +1000474 if (sd)
475 sysfs_notify_dirent(sd);
Tejun Heo51225032007-06-14 04:27:25 +0900476
477 mutex_unlock(&sysfs_mutex);
NeilBrown4508a7a2006-03-20 17:53:53 +1100478}
479EXPORT_SYMBOL_GPL(sysfs_notify);
480
Arjan van de Ven4b6f5d22006-03-28 01:56:42 -0800481const struct file_operations sysfs_file_operations = {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700482 .read = sysfs_read_file,
483 .write = sysfs_write_file,
484 .llseek = generic_file_llseek,
485 .open = sysfs_open_file,
486 .release = sysfs_release,
NeilBrown4508a7a2006-03-20 17:53:53 +1100487 .poll = sysfs_poll,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700488};
489
Josh Triplett1f20dfd2012-11-18 21:27:50 -0800490static int sysfs_attr_ns(struct kobject *kobj, const struct attribute *attr,
491 const void **pns)
Eric W. Biederman487505c2011-10-12 21:53:38 +0000492{
493 struct sysfs_dirent *dir_sd = kobj->sd;
494 const struct sysfs_ops *ops;
495 const void *ns = NULL;
496 int err;
497
Eric W. Biedermance597912012-01-13 21:32:59 -0800498 if (!dir_sd) {
499 WARN(1, KERN_ERR "sysfs: kobject %s without dirent\n",
500 kobject_name(kobj));
501 return -ENOENT;
502 }
503
Eric W. Biederman487505c2011-10-12 21:53:38 +0000504 err = 0;
505 if (!sysfs_ns_type(dir_sd))
506 goto out;
507
508 err = -EINVAL;
509 if (!kobj->ktype)
510 goto out;
511 ops = kobj->ktype->sysfs_ops;
512 if (!ops)
513 goto out;
514 if (!ops->namespace)
515 goto out;
516
517 err = 0;
518 ns = ops->namespace(kobj, attr);
519out:
520 if (err) {
521 WARN(1, KERN_ERR "missing sysfs namespace attribute operation for "
522 "kobject: %s\n", kobject_name(kobj));
523 }
524 *pns = ns;
525 return err;
526}
527
James Bottomley0f423892008-03-20 20:47:52 -0500528int sysfs_add_file_mode(struct sysfs_dirent *dir_sd,
Al Virofaef2b62011-07-24 23:44:53 -0400529 const struct attribute *attr, int type, umode_t amode)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700530{
James Bottomley0f423892008-03-20 20:47:52 -0500531 umode_t mode = (amode & S_IALLUGO) | S_IFREG;
Tejun Heofb6896d2007-06-14 04:27:24 +0900532 struct sysfs_addrm_cxt acxt;
Tejun Heoa26cd722007-06-14 03:45:14 +0900533 struct sysfs_dirent *sd;
Eric W. Biederman487505c2011-10-12 21:53:38 +0000534 const void *ns;
Tejun Heo23dc2792007-08-02 21:38:03 +0900535 int rc;
Tejun Heoa26cd722007-06-14 03:45:14 +0900536
Eric W. Biederman487505c2011-10-12 21:53:38 +0000537 rc = sysfs_attr_ns(dir_sd->s_dir.kobj, attr, &ns);
538 if (rc)
539 return rc;
540
Tejun Heo3e519032007-06-14 03:45:15 +0900541 sd = sysfs_new_dirent(attr->name, mode, type);
Tejun Heo3007e992007-06-14 04:27:23 +0900542 if (!sd)
543 return -ENOMEM;
Eric W. Biederman487505c2011-10-12 21:53:38 +0000544
545 sd->s_ns = ns;
Tejun Heob1fc3d62007-09-20 16:05:11 +0900546 sd->s_attr.attr = (void *)attr;
Eric W. Biedermana2db6842010-02-11 15:20:00 -0800547 sysfs_dirent_init_lockdep(sd);
Tejun Heoa26cd722007-06-14 03:45:14 +0900548
Tejun Heofb6896d2007-06-14 04:27:24 +0900549 sysfs_addrm_start(&acxt, dir_sd);
Tejun Heo23dc2792007-08-02 21:38:03 +0900550 rc = sysfs_add_one(&acxt, sd);
551 sysfs_addrm_finish(&acxt);
Tejun Heo3007e992007-06-14 04:27:23 +0900552
Tejun Heo23dc2792007-08-02 21:38:03 +0900553 if (rc)
Tejun Heo967e35d2007-07-18 16:38:11 +0900554 sysfs_put(sd);
Tejun Heo3007e992007-06-14 04:27:23 +0900555
Tejun Heo23dc2792007-08-02 21:38:03 +0900556 return rc;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700557}
558
559
James Bottomley0f423892008-03-20 20:47:52 -0500560int sysfs_add_file(struct sysfs_dirent *dir_sd, const struct attribute *attr,
561 int type)
562{
563 return sysfs_add_file_mode(dir_sd, attr, type, attr->mode);
564}
565
566
Linus Torvalds1da177e2005-04-16 15:20:36 -0700567/**
568 * sysfs_create_file - create an attribute file for an object.
569 * @kobj: object we're creating for.
Chris Malley3932bf62007-10-20 03:14:32 +0200570 * @attr: attribute descriptor.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700571 */
572
573int sysfs_create_file(struct kobject * kobj, const struct attribute * attr)
574{
Tejun Heo608e2662007-06-14 04:27:22 +0900575 BUG_ON(!kobj || !kobj->sd || !attr);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700576
Tejun Heo608e2662007-06-14 04:27:22 +0900577 return sysfs_add_file(kobj->sd, attr, SYSFS_KOBJ_ATTR);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700578
579}
580
Andi Kleen1c205ae2010-01-05 12:48:01 +0100581int sysfs_create_files(struct kobject *kobj, const struct attribute **ptr)
582{
583 int err = 0;
584 int i;
585
586 for (i = 0; ptr[i] && !err; i++)
587 err = sysfs_create_file(kobj, ptr[i]);
588 if (err)
589 while (--i >= 0)
590 sysfs_remove_file(kobj, ptr[i]);
591 return err;
592}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700593
594/**
Alan Sterndfa87c82007-02-20 15:02:44 -0500595 * sysfs_add_file_to_group - add an attribute file to a pre-existing group.
596 * @kobj: object we're acting for.
597 * @attr: attribute descriptor.
598 * @group: group name.
599 */
600int sysfs_add_file_to_group(struct kobject *kobj,
601 const struct attribute *attr, const char *group)
602{
Tejun Heo608e2662007-06-14 04:27:22 +0900603 struct sysfs_dirent *dir_sd;
Alan Sterndfa87c82007-02-20 15:02:44 -0500604 int error;
605
James Bottomley11f24fb2008-01-02 18:44:05 -0600606 if (group)
Eric W. Biederman3ff195b2010-03-30 11:31:26 -0700607 dir_sd = sysfs_get_dirent(kobj->sd, NULL, group);
James Bottomley11f24fb2008-01-02 18:44:05 -0600608 else
609 dir_sd = sysfs_get(kobj->sd);
610
Tejun Heo608e2662007-06-14 04:27:22 +0900611 if (!dir_sd)
612 return -ENOENT;
613
614 error = sysfs_add_file(dir_sd, attr, SYSFS_KOBJ_ATTR);
615 sysfs_put(dir_sd);
616
Alan Sterndfa87c82007-02-20 15:02:44 -0500617 return error;
618}
619EXPORT_SYMBOL_GPL(sysfs_add_file_to_group);
620
Linus Torvalds1da177e2005-04-16 15:20:36 -0700621/**
Kay Sievers31e5abe2005-04-18 21:57:32 -0700622 * sysfs_chmod_file - update the modified mode value on an object attribute.
623 * @kobj: object we're acting for.
624 * @attr: attribute descriptor.
625 * @mode: file permissions.
626 *
627 */
Jean Delvare49c19402010-07-02 16:54:05 +0200628int sysfs_chmod_file(struct kobject *kobj, const struct attribute *attr,
Al Viro48176a92011-07-24 03:40:40 -0400629 umode_t mode)
Kay Sievers31e5abe2005-04-18 21:57:32 -0700630{
Eric W. Biederman06fc0d62009-11-20 16:08:54 -0800631 struct sysfs_dirent *sd;
Maneesh Sonibc062b12005-07-29 12:13:35 -0700632 struct iattr newattrs;
Eric W. Biederman487505c2011-10-12 21:53:38 +0000633 const void *ns;
Tejun Heo51225032007-06-14 04:27:25 +0900634 int rc;
Kay Sievers31e5abe2005-04-18 21:57:32 -0700635
Eric W. Biederman487505c2011-10-12 21:53:38 +0000636 rc = sysfs_attr_ns(kobj, attr, &ns);
637 if (rc)
638 return rc;
639
Eric W. Biederman06fc0d62009-11-20 16:08:54 -0800640 mutex_lock(&sysfs_mutex);
641
Tejun Heo51225032007-06-14 04:27:25 +0900642 rc = -ENOENT;
Eric W. Biederman487505c2011-10-12 21:53:38 +0000643 sd = sysfs_find_dirent(kobj->sd, ns, attr->name);
Eric W. Biederman06fc0d62009-11-20 16:08:54 -0800644 if (!sd)
Tejun Heo51225032007-06-14 04:27:25 +0900645 goto out;
646
Eric W. Biederman06fc0d62009-11-20 16:08:54 -0800647 newattrs.ia_mode = (mode & S_IALLUGO) | (sd->s_mode & ~S_IALLUGO);
Eric W. Biederman4c6974f2009-11-07 23:27:02 -0800648 newattrs.ia_valid = ATTR_MODE;
Eric W. Biederman06fc0d62009-11-20 16:08:54 -0800649 rc = sysfs_sd_setattr(sd, &newattrs);
Tejun Heof88123e2007-09-20 16:05:10 +0900650
Tejun Heo51225032007-06-14 04:27:25 +0900651 out:
Eric W. Biederman06fc0d62009-11-20 16:08:54 -0800652 mutex_unlock(&sysfs_mutex);
Tejun Heo51225032007-06-14 04:27:25 +0900653 return rc;
Kay Sievers31e5abe2005-04-18 21:57:32 -0700654}
655EXPORT_SYMBOL_GPL(sysfs_chmod_file);
656
657
658/**
Linus Torvalds1da177e2005-04-16 15:20:36 -0700659 * sysfs_remove_file - remove an object attribute.
660 * @kobj: object we're acting for.
661 * @attr: attribute descriptor.
662 *
663 * Hash the attribute name and kill the victim.
664 */
665
666void sysfs_remove_file(struct kobject * kobj, const struct attribute * attr)
667{
Eric W. Biederman487505c2011-10-12 21:53:38 +0000668 const void *ns;
669
670 if (sysfs_attr_ns(kobj, attr, &ns))
671 return;
672
673 sysfs_hash_and_remove(kobj->sd, ns, attr->name);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700674}
675
Andi Kleen1c205ae2010-01-05 12:48:01 +0100676void sysfs_remove_files(struct kobject * kobj, const struct attribute **ptr)
677{
678 int i;
679 for (i = 0; ptr[i]; i++)
680 sysfs_remove_file(kobj, ptr[i]);
681}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700682
Alan Sterndfa87c82007-02-20 15:02:44 -0500683/**
684 * sysfs_remove_file_from_group - remove an attribute file from a group.
685 * @kobj: object we're acting for.
686 * @attr: attribute descriptor.
687 * @group: group name.
688 */
689void sysfs_remove_file_from_group(struct kobject *kobj,
690 const struct attribute *attr, const char *group)
691{
Tejun Heo608e2662007-06-14 04:27:22 +0900692 struct sysfs_dirent *dir_sd;
Alan Sterndfa87c82007-02-20 15:02:44 -0500693
James Bottomley11f24fb2008-01-02 18:44:05 -0600694 if (group)
Eric W. Biederman3ff195b2010-03-30 11:31:26 -0700695 dir_sd = sysfs_get_dirent(kobj->sd, NULL, group);
James Bottomley11f24fb2008-01-02 18:44:05 -0600696 else
697 dir_sd = sysfs_get(kobj->sd);
Tejun Heo608e2662007-06-14 04:27:22 +0900698 if (dir_sd) {
Eric W. Biederman3ff195b2010-03-30 11:31:26 -0700699 sysfs_hash_and_remove(dir_sd, NULL, attr->name);
Tejun Heo608e2662007-06-14 04:27:22 +0900700 sysfs_put(dir_sd);
Alan Sterndfa87c82007-02-20 15:02:44 -0500701 }
702}
703EXPORT_SYMBOL_GPL(sysfs_remove_file_from_group);
704
Alan Sternd9a9cdf2007-03-15 15:50:34 -0400705struct sysfs_schedule_callback_struct {
Alex Chiang66942062009-03-13 12:07:36 -0600706 struct list_head workq_list;
707 struct kobject *kobj;
Alan Sternd9a9cdf2007-03-15 15:50:34 -0400708 void (*func)(void *);
709 void *data;
Alan Stern523ded72007-04-26 00:12:04 -0700710 struct module *owner;
Alan Sternd9a9cdf2007-03-15 15:50:34 -0400711 struct work_struct work;
712};
713
Alex Chiangd1102712009-03-25 15:11:36 -0600714static struct workqueue_struct *sysfs_workqueue;
Alex Chiang66942062009-03-13 12:07:36 -0600715static DEFINE_MUTEX(sysfs_workq_mutex);
716static LIST_HEAD(sysfs_workq);
Alan Sternd9a9cdf2007-03-15 15:50:34 -0400717static void sysfs_schedule_callback_work(struct work_struct *work)
718{
719 struct sysfs_schedule_callback_struct *ss = container_of(work,
720 struct sysfs_schedule_callback_struct, work);
721
722 (ss->func)(ss->data);
723 kobject_put(ss->kobj);
Alan Stern523ded72007-04-26 00:12:04 -0700724 module_put(ss->owner);
Alex Chiang66942062009-03-13 12:07:36 -0600725 mutex_lock(&sysfs_workq_mutex);
726 list_del(&ss->workq_list);
727 mutex_unlock(&sysfs_workq_mutex);
Alan Sternd9a9cdf2007-03-15 15:50:34 -0400728 kfree(ss);
729}
730
731/**
732 * sysfs_schedule_callback - helper to schedule a callback for a kobject
733 * @kobj: object we're acting for.
734 * @func: callback function to invoke later.
735 * @data: argument to pass to @func.
Alan Stern523ded72007-04-26 00:12:04 -0700736 * @owner: module owning the callback code
Alan Sternd9a9cdf2007-03-15 15:50:34 -0400737 *
738 * sysfs attribute methods must not unregister themselves or their parent
739 * kobject (which would amount to the same thing). Attempts to do so will
740 * deadlock, since unregistration is mutually exclusive with driver
741 * callbacks.
742 *
743 * Instead methods can call this routine, which will attempt to allocate
744 * and schedule a workqueue request to call back @func with @data as its
745 * argument in the workqueue's process context. @kobj will be pinned
746 * until @func returns.
747 *
748 * Returns 0 if the request was submitted, -ENOMEM if storage could not
Alex Chiang66942062009-03-13 12:07:36 -0600749 * be allocated, -ENODEV if a reference to @owner isn't available,
750 * -EAGAIN if a callback has already been scheduled for @kobj.
Alan Sternd9a9cdf2007-03-15 15:50:34 -0400751 */
752int sysfs_schedule_callback(struct kobject *kobj, void (*func)(void *),
Alan Stern523ded72007-04-26 00:12:04 -0700753 void *data, struct module *owner)
Alan Sternd9a9cdf2007-03-15 15:50:34 -0400754{
Alex Chiang66942062009-03-13 12:07:36 -0600755 struct sysfs_schedule_callback_struct *ss, *tmp;
Alan Sternd9a9cdf2007-03-15 15:50:34 -0400756
Alan Stern523ded72007-04-26 00:12:04 -0700757 if (!try_module_get(owner))
758 return -ENODEV;
Alex Chiang66942062009-03-13 12:07:36 -0600759
760 mutex_lock(&sysfs_workq_mutex);
761 list_for_each_entry_safe(ss, tmp, &sysfs_workq, workq_list)
762 if (ss->kobj == kobj) {
Alex Chiangd1102712009-03-25 15:11:36 -0600763 module_put(owner);
Alex Chiang66942062009-03-13 12:07:36 -0600764 mutex_unlock(&sysfs_workq_mutex);
765 return -EAGAIN;
766 }
767 mutex_unlock(&sysfs_workq_mutex);
768
Alex Chiangd1102712009-03-25 15:11:36 -0600769 if (sysfs_workqueue == NULL) {
Andrew Morton086a3772009-05-07 12:36:53 -0700770 sysfs_workqueue = create_singlethread_workqueue("sysfsd");
Alex Chiangd1102712009-03-25 15:11:36 -0600771 if (sysfs_workqueue == NULL) {
772 module_put(owner);
773 return -ENOMEM;
774 }
775 }
776
Alan Sternd9a9cdf2007-03-15 15:50:34 -0400777 ss = kmalloc(sizeof(*ss), GFP_KERNEL);
Alan Stern523ded72007-04-26 00:12:04 -0700778 if (!ss) {
779 module_put(owner);
Alan Sternd9a9cdf2007-03-15 15:50:34 -0400780 return -ENOMEM;
Alan Stern523ded72007-04-26 00:12:04 -0700781 }
Alan Sternd9a9cdf2007-03-15 15:50:34 -0400782 kobject_get(kobj);
783 ss->kobj = kobj;
784 ss->func = func;
785 ss->data = data;
Alan Stern523ded72007-04-26 00:12:04 -0700786 ss->owner = owner;
Alan Sternd9a9cdf2007-03-15 15:50:34 -0400787 INIT_WORK(&ss->work, sysfs_schedule_callback_work);
Alex Chiang66942062009-03-13 12:07:36 -0600788 INIT_LIST_HEAD(&ss->workq_list);
789 mutex_lock(&sysfs_workq_mutex);
790 list_add_tail(&ss->workq_list, &sysfs_workq);
791 mutex_unlock(&sysfs_workq_mutex);
Alex Chiangd1102712009-03-25 15:11:36 -0600792 queue_work(sysfs_workqueue, &ss->work);
Alan Sternd9a9cdf2007-03-15 15:50:34 -0400793 return 0;
794}
795EXPORT_SYMBOL_GPL(sysfs_schedule_callback);
796
Alan Sterndfa87c82007-02-20 15:02:44 -0500797
Linus Torvalds1da177e2005-04-16 15:20:36 -0700798EXPORT_SYMBOL_GPL(sysfs_create_file);
799EXPORT_SYMBOL_GPL(sysfs_remove_file);
Andi Kleen1c205ae2010-01-05 12:48:01 +0100800EXPORT_SYMBOL_GPL(sysfs_remove_files);
801EXPORT_SYMBOL_GPL(sysfs_create_files);