blob: 289c43a472634e5863c356502adeea451c0da882 [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
Andrew Mortonae87221d2007-08-24 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;
56 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;
Linus Torvalds1da177e2005-04-16 15:20:36 -070078 struct sysfs_ops * ops = buffer->ops;
79 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 */
88 if (!sysfs_get_active_two(attr_sd))
89 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
94 sysfs_put_active_two(attr_sd);
95
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;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700202 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 */
206 if (!sysfs_get_active_two(attr_sd))
207 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
211 sysfs_put_active_two(attr_sd);
212
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:
271 spin_lock(&sysfs_open_dirent_lock);
272
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
284 spin_unlock(&sysfs_open_dirent_lock);
285
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;
318
319 spin_lock(&sysfs_open_dirent_lock);
320
321 list_del(&buffer->list);
322 if (atomic_dec_and_test(&od->refcnt))
323 sd->s_attr.open = NULL;
324 else
325 od = NULL;
326
327 spin_unlock(&sysfs_open_dirent_lock);
328
329 kfree(od);
330}
331
Oliver Neukum94bebf42006-12-20 10:52:44 +0100332static int sysfs_open_file(struct inode *inode, struct file *file)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700333{
Tejun Heo3e519032007-06-14 03:45:15 +0900334 struct sysfs_dirent *attr_sd = file->f_path.dentry->d_fsdata;
Tejun Heob1fc3d62007-09-20 16:05:11 +0900335 struct kobject *kobj = attr_sd->s_parent->s_dir.kobj;
Kay Sievers000f2a42007-11-02 13:47:53 +0100336 struct sysfs_buffer *buffer;
337 struct sysfs_ops *ops;
338 int error = -EACCES;
Andrew Mortonae87221d2007-08-24 16:11:54 -0700339 char *p;
340
341 p = d_path(&file->f_path, last_sysfs_file, sizeof(last_sysfs_file));
342 if (p)
343 memmove(last_sysfs_file, p, strlen(p) + 1);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700344
Tejun Heo0ab66082007-06-14 03:45:16 +0900345 /* need attr_sd for attr and ops, its parent for kobj */
346 if (!sysfs_get_active_two(attr_sd))
347 return -ENODEV;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700348
Kay Sievers000f2a42007-11-02 13:47:53 +0100349 /* every kobject with an attribute needs a ktype assigned */
350 if (kobj->ktype && kobj->ktype->sysfs_ops)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700351 ops = kobj->ktype->sysfs_ops;
Kay Sievers000f2a42007-11-02 13:47:53 +0100352 else {
Arjan van de Ven99fcd772008-07-25 19:45:41 -0700353 WARN(1, KERN_ERR "missing sysfs attribute operations for "
Kay Sievers000f2a42007-11-02 13:47:53 +0100354 "kobject: %s\n", kobject_name(kobj));
Tejun Heo7b595752007-06-14 03:45:17 +0900355 goto err_out;
Kay Sievers000f2a42007-11-02 13:47:53 +0100356 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700357
358 /* File needs write support.
359 * The inode's perms must say it's ok,
360 * and we must have a store method.
361 */
362 if (file->f_mode & FMODE_WRITE) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700363 if (!(inode->i_mode & S_IWUGO) || !ops->store)
Tejun Heo7b595752007-06-14 03:45:17 +0900364 goto err_out;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700365 }
366
367 /* File needs read support.
368 * The inode's perms must say it's ok, and we there
369 * must be a show method for it.
370 */
371 if (file->f_mode & FMODE_READ) {
372 if (!(inode->i_mode & S_IRUGO) || !ops->show)
Tejun Heo7b595752007-06-14 03:45:17 +0900373 goto err_out;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700374 }
375
376 /* No error? Great, allocate a buffer for the file, and store it
377 * it in file->private_data for easy access.
378 */
Tejun Heo0ab66082007-06-14 03:45:16 +0900379 error = -ENOMEM;
Eric Sesterhenn58d49282006-02-22 11:18:15 +0100380 buffer = kzalloc(sizeof(struct sysfs_buffer), GFP_KERNEL);
Tejun Heo0ab66082007-06-14 03:45:16 +0900381 if (!buffer)
Tejun Heo7b595752007-06-14 03:45:17 +0900382 goto err_out;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700383
Dave Young52e8c202007-07-26 11:03:54 +0000384 mutex_init(&buffer->mutex);
Tejun Heo0ab66082007-06-14 03:45:16 +0900385 buffer->needs_read_fill = 1;
386 buffer->ops = ops;
Tejun Heo0ab66082007-06-14 03:45:16 +0900387 file->private_data = buffer;
388
Tejun Heo85a4ffa2007-09-20 16:05:12 +0900389 /* make sure we have open dirent struct */
390 error = sysfs_get_open_dirent(attr_sd, buffer);
391 if (error)
392 goto err_free;
393
Tejun Heob05f0542007-09-20 16:05:10 +0900394 /* open succeeded, put active references */
Tejun Heo0ab66082007-06-14 03:45:16 +0900395 sysfs_put_active_two(attr_sd);
Tejun Heo0ab66082007-06-14 03:45:16 +0900396 return 0;
397
Tejun Heo85a4ffa2007-09-20 16:05:12 +0900398 err_free:
399 kfree(buffer);
Tejun Heo7b595752007-06-14 03:45:17 +0900400 err_out:
Tejun Heo0ab66082007-06-14 03:45:16 +0900401 sysfs_put_active_two(attr_sd);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700402 return error;
403}
404
Tejun Heo85a4ffa2007-09-20 16:05:12 +0900405static int sysfs_release(struct inode *inode, struct file *filp)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700406{
Tejun Heo85a4ffa2007-09-20 16:05:12 +0900407 struct sysfs_dirent *sd = filp->f_path.dentry->d_fsdata;
Tejun Heo73107cb2007-06-14 03:45:16 +0900408 struct sysfs_buffer *buffer = filp->private_data;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700409
Tejun Heo85a4ffa2007-09-20 16:05:12 +0900410 sysfs_put_open_dirent(sd, buffer);
411
Tejun Heo50ab1a72007-09-20 16:05:10 +0900412 if (buffer->page)
413 free_page((unsigned long)buffer->page);
414 kfree(buffer);
415
Linus Torvalds1da177e2005-04-16 15:20:36 -0700416 return 0;
417}
418
NeilBrown4508a7a2006-03-20 17:53:53 +1100419/* Sysfs attribute files are pollable. The idea is that you read
420 * the content and then you use 'poll' or 'select' to wait for
421 * the content to change. When the content changes (assuming the
422 * manager for the kobject supports notification), poll will
423 * return POLLERR|POLLPRI, and select will return the fd whether
424 * it is waiting for read, write, or exceptions.
425 * Once poll/select indicates that the value has changed, you
Dan Williams2424b5d2008-04-07 15:35:01 -0700426 * need to close and re-open the file, or seek to 0 and read again.
NeilBrown4508a7a2006-03-20 17:53:53 +1100427 * Reminder: this only works for attributes which actively support
428 * it, and it is not possible to test an attribute from userspace
Rolf Eike Beera93720e2007-08-10 13:51:07 -0700429 * to see if it supports poll (Neither 'poll' nor 'select' return
NeilBrown4508a7a2006-03-20 17:53:53 +1100430 * an appropriate error code). When in doubt, set a suitable timeout value.
431 */
432static unsigned int sysfs_poll(struct file *filp, poll_table *wait)
433{
434 struct sysfs_buffer * buffer = filp->private_data;
Tejun Heo0ab66082007-06-14 03:45:16 +0900435 struct sysfs_dirent *attr_sd = filp->f_path.dentry->d_fsdata;
Tejun Heoa4e8b912007-09-20 16:05:12 +0900436 struct sysfs_open_dirent *od = attr_sd->s_attr.open;
Tejun Heo0ab66082007-06-14 03:45:16 +0900437
438 /* need parent for the kobj, grab both */
439 if (!sysfs_get_active_two(attr_sd))
440 goto trigger;
NeilBrown4508a7a2006-03-20 17:53:53 +1100441
Tejun Heoa4e8b912007-09-20 16:05:12 +0900442 poll_wait(filp, &od->poll, wait);
NeilBrown4508a7a2006-03-20 17:53:53 +1100443
Tejun Heo0ab66082007-06-14 03:45:16 +0900444 sysfs_put_active_two(attr_sd);
NeilBrown4508a7a2006-03-20 17:53:53 +1100445
Tejun Heoa4e8b912007-09-20 16:05:12 +0900446 if (buffer->event != atomic_read(&od->event))
Tejun Heo0ab66082007-06-14 03:45:16 +0900447 goto trigger;
448
449 return 0;
450
451 trigger:
452 buffer->needs_read_fill = 1;
453 return POLLERR|POLLPRI;
NeilBrown4508a7a2006-03-20 17:53:53 +1100454}
455
Neil Brownf1282c82008-07-16 08:58:04 +1000456void sysfs_notify_dirent(struct sysfs_dirent *sd)
457{
458 struct sysfs_open_dirent *od;
459
460 spin_lock(&sysfs_open_dirent_lock);
461
462 od = sd->s_attr.open;
463 if (od) {
464 atomic_inc(&od->event);
465 wake_up_interruptible(&od->poll);
466 }
467
468 spin_unlock(&sysfs_open_dirent_lock);
469}
470EXPORT_SYMBOL_GPL(sysfs_notify_dirent);
471
Trent Piepho8c0e3992008-09-25 16:45:13 -0700472void sysfs_notify(struct kobject *k, const char *dir, const char *attr)
NeilBrown4508a7a2006-03-20 17:53:53 +1100473{
Tejun Heo51225032007-06-14 04:27:25 +0900474 struct sysfs_dirent *sd = k->sd;
NeilBrown4508a7a2006-03-20 17:53:53 +1100475
Tejun Heo51225032007-06-14 04:27:25 +0900476 mutex_lock(&sysfs_mutex);
NeilBrown4508a7a2006-03-20 17:53:53 +1100477
Tejun Heo51225032007-06-14 04:27:25 +0900478 if (sd && dir)
479 sd = sysfs_find_dirent(sd, dir);
480 if (sd && attr)
481 sd = sysfs_find_dirent(sd, attr);
Neil Brownf1282c82008-07-16 08:58:04 +1000482 if (sd)
483 sysfs_notify_dirent(sd);
Tejun Heo51225032007-06-14 04:27:25 +0900484
485 mutex_unlock(&sysfs_mutex);
NeilBrown4508a7a2006-03-20 17:53:53 +1100486}
487EXPORT_SYMBOL_GPL(sysfs_notify);
488
Arjan van de Ven4b6f5d22006-03-28 01:56:42 -0800489const struct file_operations sysfs_file_operations = {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700490 .read = sysfs_read_file,
491 .write = sysfs_write_file,
492 .llseek = generic_file_llseek,
493 .open = sysfs_open_file,
494 .release = sysfs_release,
NeilBrown4508a7a2006-03-20 17:53:53 +1100495 .poll = sysfs_poll,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700496};
497
James Bottomley0f423892008-03-20 20:47:52 -0500498int sysfs_add_file_mode(struct sysfs_dirent *dir_sd,
499 const struct attribute *attr, int type, mode_t amode)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700500{
James Bottomley0f423892008-03-20 20:47:52 -0500501 umode_t mode = (amode & S_IALLUGO) | S_IFREG;
Tejun Heofb6896d2007-06-14 04:27:24 +0900502 struct sysfs_addrm_cxt acxt;
Tejun Heoa26cd722007-06-14 03:45:14 +0900503 struct sysfs_dirent *sd;
Tejun Heo23dc2792007-08-02 21:38:03 +0900504 int rc;
Tejun Heoa26cd722007-06-14 03:45:14 +0900505
Tejun Heo3e519032007-06-14 03:45:15 +0900506 sd = sysfs_new_dirent(attr->name, mode, type);
Tejun Heo3007e992007-06-14 04:27:23 +0900507 if (!sd)
508 return -ENOMEM;
Tejun Heob1fc3d62007-09-20 16:05:11 +0900509 sd->s_attr.attr = (void *)attr;
Tejun Heoa26cd722007-06-14 03:45:14 +0900510
Tejun Heofb6896d2007-06-14 04:27:24 +0900511 sysfs_addrm_start(&acxt, dir_sd);
Tejun Heo23dc2792007-08-02 21:38:03 +0900512 rc = sysfs_add_one(&acxt, sd);
513 sysfs_addrm_finish(&acxt);
Tejun Heo3007e992007-06-14 04:27:23 +0900514
Tejun Heo23dc2792007-08-02 21:38:03 +0900515 if (rc)
Tejun Heo967e35d2007-07-18 16:38:11 +0900516 sysfs_put(sd);
Tejun Heo3007e992007-06-14 04:27:23 +0900517
Tejun Heo23dc2792007-08-02 21:38:03 +0900518 return rc;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700519}
520
521
James Bottomley0f423892008-03-20 20:47:52 -0500522int sysfs_add_file(struct sysfs_dirent *dir_sd, const struct attribute *attr,
523 int type)
524{
525 return sysfs_add_file_mode(dir_sd, attr, type, attr->mode);
526}
527
528
Linus Torvalds1da177e2005-04-16 15:20:36 -0700529/**
530 * sysfs_create_file - create an attribute file for an object.
531 * @kobj: object we're creating for.
Chris Malley3932bf62007-10-20 03:14:32 +0200532 * @attr: attribute descriptor.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700533 */
534
535int sysfs_create_file(struct kobject * kobj, const struct attribute * attr)
536{
Tejun Heo608e2662007-06-14 04:27:22 +0900537 BUG_ON(!kobj || !kobj->sd || !attr);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700538
Tejun Heo608e2662007-06-14 04:27:22 +0900539 return sysfs_add_file(kobj->sd, attr, SYSFS_KOBJ_ATTR);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700540
541}
542
543
544/**
Alan Sterndfa87c82007-02-20 15:02:44 -0500545 * sysfs_add_file_to_group - add an attribute file to a pre-existing group.
546 * @kobj: object we're acting for.
547 * @attr: attribute descriptor.
548 * @group: group name.
549 */
550int sysfs_add_file_to_group(struct kobject *kobj,
551 const struct attribute *attr, const char *group)
552{
Tejun Heo608e2662007-06-14 04:27:22 +0900553 struct sysfs_dirent *dir_sd;
Alan Sterndfa87c82007-02-20 15:02:44 -0500554 int error;
555
James Bottomley11f24fb2008-01-02 18:44:05 -0600556 if (group)
557 dir_sd = sysfs_get_dirent(kobj->sd, group);
558 else
559 dir_sd = sysfs_get(kobj->sd);
560
Tejun Heo608e2662007-06-14 04:27:22 +0900561 if (!dir_sd)
562 return -ENOENT;
563
564 error = sysfs_add_file(dir_sd, attr, SYSFS_KOBJ_ATTR);
565 sysfs_put(dir_sd);
566
Alan Sterndfa87c82007-02-20 15:02:44 -0500567 return error;
568}
569EXPORT_SYMBOL_GPL(sysfs_add_file_to_group);
570
Linus Torvalds1da177e2005-04-16 15:20:36 -0700571/**
Kay Sievers31e5abe2005-04-18 21:57:32 -0700572 * sysfs_chmod_file - update the modified mode value on an object attribute.
573 * @kobj: object we're acting for.
574 * @attr: attribute descriptor.
575 * @mode: file permissions.
576 *
577 */
578int sysfs_chmod_file(struct kobject *kobj, struct attribute *attr, mode_t mode)
579{
Tejun Heo51225032007-06-14 04:27:25 +0900580 struct sysfs_dirent *victim_sd = NULL;
581 struct dentry *victim = NULL;
Maneesh Sonibc062b12005-07-29 12:13:35 -0700582 struct inode * inode;
583 struct iattr newattrs;
Tejun Heo51225032007-06-14 04:27:25 +0900584 int rc;
Kay Sievers31e5abe2005-04-18 21:57:32 -0700585
Tejun Heo51225032007-06-14 04:27:25 +0900586 rc = -ENOENT;
587 victim_sd = sysfs_get_dirent(kobj->sd, attr->name);
588 if (!victim_sd)
589 goto out;
590
Eric W. Biederman932ea2e2007-08-20 21:36:30 +0900591 mutex_lock(&sysfs_rename_mutex);
Tejun Heo51225032007-06-14 04:27:25 +0900592 victim = sysfs_get_dentry(victim_sd);
Eric W. Biederman932ea2e2007-08-20 21:36:30 +0900593 mutex_unlock(&sysfs_rename_mutex);
Tejun Heo51225032007-06-14 04:27:25 +0900594 if (IS_ERR(victim)) {
595 rc = PTR_ERR(victim);
596 victim = NULL;
597 goto out;
Kay Sievers31e5abe2005-04-18 21:57:32 -0700598 }
Kay Sievers31e5abe2005-04-18 21:57:32 -0700599
Tejun Heo51225032007-06-14 04:27:25 +0900600 inode = victim->d_inode;
Tejun Heof88123e2007-09-20 16:05:10 +0900601
Tejun Heo51225032007-06-14 04:27:25 +0900602 mutex_lock(&inode->i_mutex);
Tejun Heof88123e2007-09-20 16:05:10 +0900603
Tejun Heo51225032007-06-14 04:27:25 +0900604 newattrs.ia_mode = (mode & S_IALLUGO) | (inode->i_mode & ~S_IALLUGO);
605 newattrs.ia_valid = ATTR_MODE | ATTR_CTIME;
Miklos Szeredi93265d12008-06-16 13:46:47 +0200606 newattrs.ia_ctime = current_fs_time(inode->i_sb);
607 rc = sysfs_setattr(victim, &newattrs);
Tejun Heof88123e2007-09-20 16:05:10 +0900608
609 if (rc == 0) {
Miklos Szeredi93265d12008-06-16 13:46:47 +0200610 fsnotify_change(victim, newattrs.ia_valid);
Tejun Heof88123e2007-09-20 16:05:10 +0900611 mutex_lock(&sysfs_mutex);
612 victim_sd->s_mode = newattrs.ia_mode;
613 mutex_unlock(&sysfs_mutex);
614 }
615
Tejun Heo51225032007-06-14 04:27:25 +0900616 mutex_unlock(&inode->i_mutex);
617 out:
618 dput(victim);
619 sysfs_put(victim_sd);
620 return rc;
Kay Sievers31e5abe2005-04-18 21:57:32 -0700621}
622EXPORT_SYMBOL_GPL(sysfs_chmod_file);
623
624
625/**
Linus Torvalds1da177e2005-04-16 15:20:36 -0700626 * sysfs_remove_file - remove an object attribute.
627 * @kobj: object we're acting for.
628 * @attr: attribute descriptor.
629 *
630 * Hash the attribute name and kill the victim.
631 */
632
633void sysfs_remove_file(struct kobject * kobj, const struct attribute * attr)
634{
Tejun Heo608e2662007-06-14 04:27:22 +0900635 sysfs_hash_and_remove(kobj->sd, attr->name);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700636}
637
638
Alan Sterndfa87c82007-02-20 15:02:44 -0500639/**
640 * sysfs_remove_file_from_group - remove an attribute file from a group.
641 * @kobj: object we're acting for.
642 * @attr: attribute descriptor.
643 * @group: group name.
644 */
645void sysfs_remove_file_from_group(struct kobject *kobj,
646 const struct attribute *attr, const char *group)
647{
Tejun Heo608e2662007-06-14 04:27:22 +0900648 struct sysfs_dirent *dir_sd;
Alan Sterndfa87c82007-02-20 15:02:44 -0500649
James Bottomley11f24fb2008-01-02 18:44:05 -0600650 if (group)
651 dir_sd = sysfs_get_dirent(kobj->sd, group);
652 else
653 dir_sd = sysfs_get(kobj->sd);
Tejun Heo608e2662007-06-14 04:27:22 +0900654 if (dir_sd) {
655 sysfs_hash_and_remove(dir_sd, attr->name);
656 sysfs_put(dir_sd);
Alan Sterndfa87c82007-02-20 15:02:44 -0500657 }
658}
659EXPORT_SYMBOL_GPL(sysfs_remove_file_from_group);
660
Alan Sternd9a9cdf2007-03-15 15:50:34 -0400661struct sysfs_schedule_callback_struct {
Alex Chiang66942062009-03-13 12:07:36 -0600662 struct list_head workq_list;
663 struct kobject *kobj;
Alan Sternd9a9cdf2007-03-15 15:50:34 -0400664 void (*func)(void *);
665 void *data;
Alan Stern523ded72007-04-26 00:12:04 -0700666 struct module *owner;
Alan Sternd9a9cdf2007-03-15 15:50:34 -0400667 struct work_struct work;
668};
669
Alex Chiang66942062009-03-13 12:07:36 -0600670static DEFINE_MUTEX(sysfs_workq_mutex);
671static LIST_HEAD(sysfs_workq);
Alan Sternd9a9cdf2007-03-15 15:50:34 -0400672static void sysfs_schedule_callback_work(struct work_struct *work)
673{
674 struct sysfs_schedule_callback_struct *ss = container_of(work,
675 struct sysfs_schedule_callback_struct, work);
676
677 (ss->func)(ss->data);
678 kobject_put(ss->kobj);
Alan Stern523ded72007-04-26 00:12:04 -0700679 module_put(ss->owner);
Alex Chiang66942062009-03-13 12:07:36 -0600680 mutex_lock(&sysfs_workq_mutex);
681 list_del(&ss->workq_list);
682 mutex_unlock(&sysfs_workq_mutex);
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
Alex Chiang66942062009-03-13 12:07:36 -0600704 * be allocated, -ENODEV if a reference to @owner isn't available,
705 * -EAGAIN if a callback has already been scheduled for @kobj.
Alan Sternd9a9cdf2007-03-15 15:50:34 -0400706 */
707int sysfs_schedule_callback(struct kobject *kobj, void (*func)(void *),
Alan Stern523ded72007-04-26 00:12:04 -0700708 void *data, struct module *owner)
Alan Sternd9a9cdf2007-03-15 15:50:34 -0400709{
Alex Chiang66942062009-03-13 12:07:36 -0600710 struct sysfs_schedule_callback_struct *ss, *tmp;
Alan Sternd9a9cdf2007-03-15 15:50:34 -0400711
Alan Stern523ded72007-04-26 00:12:04 -0700712 if (!try_module_get(owner))
713 return -ENODEV;
Alex Chiang66942062009-03-13 12:07:36 -0600714
715 mutex_lock(&sysfs_workq_mutex);
716 list_for_each_entry_safe(ss, tmp, &sysfs_workq, workq_list)
717 if (ss->kobj == kobj) {
718 mutex_unlock(&sysfs_workq_mutex);
719 return -EAGAIN;
720 }
721 mutex_unlock(&sysfs_workq_mutex);
722
Alan Sternd9a9cdf2007-03-15 15:50:34 -0400723 ss = kmalloc(sizeof(*ss), GFP_KERNEL);
Alan Stern523ded72007-04-26 00:12:04 -0700724 if (!ss) {
725 module_put(owner);
Alan Sternd9a9cdf2007-03-15 15:50:34 -0400726 return -ENOMEM;
Alan Stern523ded72007-04-26 00:12:04 -0700727 }
Alan Sternd9a9cdf2007-03-15 15:50:34 -0400728 kobject_get(kobj);
729 ss->kobj = kobj;
730 ss->func = func;
731 ss->data = data;
Alan Stern523ded72007-04-26 00:12:04 -0700732 ss->owner = owner;
Alan Sternd9a9cdf2007-03-15 15:50:34 -0400733 INIT_WORK(&ss->work, sysfs_schedule_callback_work);
Alex Chiang66942062009-03-13 12:07:36 -0600734 INIT_LIST_HEAD(&ss->workq_list);
735 mutex_lock(&sysfs_workq_mutex);
736 list_add_tail(&ss->workq_list, &sysfs_workq);
737 mutex_unlock(&sysfs_workq_mutex);
Alan Sternd9a9cdf2007-03-15 15:50:34 -0400738 schedule_work(&ss->work);
739 return 0;
740}
741EXPORT_SYMBOL_GPL(sysfs_schedule_callback);
742
Alan Sterndfa87c82007-02-20 15:02:44 -0500743
Linus Torvalds1da177e2005-04-16 15:20:36 -0700744EXPORT_SYMBOL_GPL(sysfs_create_file);
745EXPORT_SYMBOL_GPL(sysfs_remove_file);