| 1 | /* |
| 2 | * 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. |
| 11 | */ |
| 12 | |
| 13 | #include <linux/module.h> |
| 14 | #include <linux/kobject.h> |
| 15 | #include <linux/kallsyms.h> |
| 16 | #include <linux/slab.h> |
| 17 | #include <linux/fsnotify.h> |
| 18 | #include <linux/namei.h> |
| 19 | #include <linux/poll.h> |
| 20 | #include <linux/list.h> |
| 21 | #include <linux/mutex.h> |
| 22 | #include <linux/limits.h> |
| 23 | #include <asm/uaccess.h> |
| 24 | |
| 25 | #include "sysfs.h" |
| 26 | |
| 27 | /* used in crash dumps to help with debugging */ |
| 28 | static char last_sysfs_file[PATH_MAX]; |
| 29 | void sysfs_printk_last_file(void) |
| 30 | { |
| 31 | printk(KERN_EMERG "last sysfs file: %s\n", last_sysfs_file); |
| 32 | } |
| 33 | |
| 34 | /* |
| 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 | */ |
| 43 | static DEFINE_SPINLOCK(sysfs_open_dirent_lock); |
| 44 | |
| 45 | struct sysfs_open_dirent { |
| 46 | atomic_t refcnt; |
| 47 | atomic_t event; |
| 48 | wait_queue_head_t poll; |
| 49 | struct list_head buffers; /* goes through sysfs_buffer.list */ |
| 50 | }; |
| 51 | |
| 52 | struct sysfs_buffer { |
| 53 | size_t count; |
| 54 | loff_t pos; |
| 55 | char * page; |
| 56 | struct sysfs_ops * ops; |
| 57 | struct mutex mutex; |
| 58 | int needs_read_fill; |
| 59 | int event; |
| 60 | struct list_head list; |
| 61 | }; |
| 62 | |
| 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. |
| 71 | * This is called only once, on the file's first read unless an error |
| 72 | * is returned. |
| 73 | */ |
| 74 | static int fill_read_buffer(struct dentry * dentry, struct sysfs_buffer * buffer) |
| 75 | { |
| 76 | struct sysfs_dirent *attr_sd = dentry->d_fsdata; |
| 77 | struct kobject *kobj = attr_sd->s_parent->s_dir.kobj; |
| 78 | 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 | |
| 87 | /* need attr_sd for attr and ops, its parent for kobj */ |
| 88 | if (!sysfs_get_active_two(attr_sd)) |
| 89 | return -ENODEV; |
| 90 | |
| 91 | buffer->event = atomic_read(&attr_sd->s_attr.open->event); |
| 92 | count = ops->show(kobj, attr_sd->s_attr.attr, buffer->page); |
| 93 | |
| 94 | sysfs_put_active_two(attr_sd); |
| 95 | |
| 96 | /* |
| 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 | */ |
| 100 | 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 | } |
| 106 | if (count >= 0) { |
| 107 | buffer->needs_read_fill = 0; |
| 108 | buffer->count = count; |
| 109 | } else { |
| 110 | ret = count; |
| 111 | } |
| 112 | return ret; |
| 113 | } |
| 114 | |
| 115 | /** |
| 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 | |
| 134 | static ssize_t |
| 135 | sysfs_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 | |
| 140 | mutex_lock(&buffer->mutex); |
| 141 | if (buffer->needs_read_fill || *ppos == 0) { |
| 142 | retval = fill_read_buffer(file->f_path.dentry,buffer); |
| 143 | if (retval) |
| 144 | goto out; |
| 145 | } |
| 146 | pr_debug("%s: count = %zd, ppos = %lld, buf = %s\n", |
| 147 | __func__, count, *ppos, buffer->page); |
| 148 | retval = simple_read_from_buffer(buf, count, ppos, buffer->page, |
| 149 | buffer->count); |
| 150 | out: |
| 151 | mutex_unlock(&buffer->mutex); |
| 152 | return retval; |
| 153 | } |
| 154 | |
| 155 | /** |
| 156 | * fill_write_buffer - copy buffer from userspace. |
| 157 | * @buffer: data buffer for file. |
| 158 | * @buf: data from user. |
| 159 | * @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 | |
| 165 | static int |
| 166 | fill_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) |
| 176 | count = PAGE_SIZE - 1; |
| 177 | error = copy_from_user(buffer->page,buf,count); |
| 178 | buffer->needs_read_fill = 1; |
| 179 | /* 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; |
| 182 | return error ? -EFAULT : count; |
| 183 | } |
| 184 | |
| 185 | |
| 186 | /** |
| 187 | * flush_write_buffer - push buffer to kobject. |
| 188 | * @dentry: dentry to the attribute |
| 189 | * @buffer: data buffer for file. |
| 190 | * @count: number of bytes |
| 191 | * |
| 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 | |
| 197 | static int |
| 198 | flush_write_buffer(struct dentry * dentry, struct sysfs_buffer * buffer, size_t count) |
| 199 | { |
| 200 | struct sysfs_dirent *attr_sd = dentry->d_fsdata; |
| 201 | struct kobject *kobj = attr_sd->s_parent->s_dir.kobj; |
| 202 | struct sysfs_ops * ops = buffer->ops; |
| 203 | int rc; |
| 204 | |
| 205 | /* need attr_sd for attr and ops, its parent for kobj */ |
| 206 | if (!sysfs_get_active_two(attr_sd)) |
| 207 | return -ENODEV; |
| 208 | |
| 209 | rc = ops->store(kobj, attr_sd->s_attr.attr, buffer->page, count); |
| 210 | |
| 211 | sysfs_put_active_two(attr_sd); |
| 212 | |
| 213 | return rc; |
| 214 | } |
| 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 | |
| 234 | static ssize_t |
| 235 | sysfs_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 | |
| 240 | mutex_lock(&buffer->mutex); |
| 241 | len = fill_write_buffer(buffer, buf, count); |
| 242 | if (len > 0) |
| 243 | len = flush_write_buffer(file->f_path.dentry, buffer, len); |
| 244 | if (len > 0) |
| 245 | *ppos += len; |
| 246 | mutex_unlock(&buffer->mutex); |
| 247 | return len; |
| 248 | } |
| 249 | |
| 250 | /** |
| 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 | */ |
| 265 | static 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); |
| 297 | atomic_set(&new_od->event, 1); |
| 298 | init_waitqueue_head(&new_od->poll); |
| 299 | 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 | */ |
| 314 | static 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 | |
| 332 | static int sysfs_open_file(struct inode *inode, struct file *file) |
| 333 | { |
| 334 | struct sysfs_dirent *attr_sd = file->f_path.dentry->d_fsdata; |
| 335 | struct kobject *kobj = attr_sd->s_parent->s_dir.kobj; |
| 336 | struct sysfs_buffer *buffer; |
| 337 | struct sysfs_ops *ops; |
| 338 | int error = -EACCES; |
| 339 | 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); |
| 344 | |
| 345 | /* need attr_sd for attr and ops, its parent for kobj */ |
| 346 | if (!sysfs_get_active_two(attr_sd)) |
| 347 | return -ENODEV; |
| 348 | |
| 349 | /* every kobject with an attribute needs a ktype assigned */ |
| 350 | if (kobj->ktype && kobj->ktype->sysfs_ops) |
| 351 | ops = kobj->ktype->sysfs_ops; |
| 352 | else { |
| 353 | WARN(1, KERN_ERR "missing sysfs attribute operations for " |
| 354 | "kobject: %s\n", kobject_name(kobj)); |
| 355 | goto err_out; |
| 356 | } |
| 357 | |
| 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) { |
| 363 | if (!(inode->i_mode & S_IWUGO) || !ops->store) |
| 364 | goto err_out; |
| 365 | } |
| 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) |
| 373 | goto err_out; |
| 374 | } |
| 375 | |
| 376 | /* No error? Great, allocate a buffer for the file, and store it |
| 377 | * it in file->private_data for easy access. |
| 378 | */ |
| 379 | error = -ENOMEM; |
| 380 | buffer = kzalloc(sizeof(struct sysfs_buffer), GFP_KERNEL); |
| 381 | if (!buffer) |
| 382 | goto err_out; |
| 383 | |
| 384 | mutex_init(&buffer->mutex); |
| 385 | buffer->needs_read_fill = 1; |
| 386 | buffer->ops = ops; |
| 387 | file->private_data = buffer; |
| 388 | |
| 389 | /* make sure we have open dirent struct */ |
| 390 | error = sysfs_get_open_dirent(attr_sd, buffer); |
| 391 | if (error) |
| 392 | goto err_free; |
| 393 | |
| 394 | /* open succeeded, put active references */ |
| 395 | sysfs_put_active_two(attr_sd); |
| 396 | return 0; |
| 397 | |
| 398 | err_free: |
| 399 | kfree(buffer); |
| 400 | err_out: |
| 401 | sysfs_put_active_two(attr_sd); |
| 402 | return error; |
| 403 | } |
| 404 | |
| 405 | static int sysfs_release(struct inode *inode, struct file *filp) |
| 406 | { |
| 407 | struct sysfs_dirent *sd = filp->f_path.dentry->d_fsdata; |
| 408 | struct sysfs_buffer *buffer = filp->private_data; |
| 409 | |
| 410 | sysfs_put_open_dirent(sd, buffer); |
| 411 | |
| 412 | if (buffer->page) |
| 413 | free_page((unsigned long)buffer->page); |
| 414 | kfree(buffer); |
| 415 | |
| 416 | return 0; |
| 417 | } |
| 418 | |
| 419 | /* 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 |
| 426 | * need to close and re-open the file, or seek to 0 and read again. |
| 427 | * Reminder: this only works for attributes which actively support |
| 428 | * it, and it is not possible to test an attribute from userspace |
| 429 | * to see if it supports poll (Neither 'poll' nor 'select' return |
| 430 | * an appropriate error code). When in doubt, set a suitable timeout value. |
| 431 | */ |
| 432 | static unsigned int sysfs_poll(struct file *filp, poll_table *wait) |
| 433 | { |
| 434 | struct sysfs_buffer * buffer = filp->private_data; |
| 435 | struct sysfs_dirent *attr_sd = filp->f_path.dentry->d_fsdata; |
| 436 | struct sysfs_open_dirent *od = attr_sd->s_attr.open; |
| 437 | |
| 438 | /* need parent for the kobj, grab both */ |
| 439 | if (!sysfs_get_active_two(attr_sd)) |
| 440 | goto trigger; |
| 441 | |
| 442 | poll_wait(filp, &od->poll, wait); |
| 443 | |
| 444 | sysfs_put_active_two(attr_sd); |
| 445 | |
| 446 | if (buffer->event != atomic_read(&od->event)) |
| 447 | goto trigger; |
| 448 | |
| 449 | return 0; |
| 450 | |
| 451 | trigger: |
| 452 | buffer->needs_read_fill = 1; |
| 453 | return POLLERR|POLLPRI; |
| 454 | } |
| 455 | |
| 456 | void 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 | } |
| 470 | EXPORT_SYMBOL_GPL(sysfs_notify_dirent); |
| 471 | |
| 472 | void sysfs_notify(struct kobject *k, const char *dir, const char *attr) |
| 473 | { |
| 474 | struct sysfs_dirent *sd = k->sd; |
| 475 | |
| 476 | mutex_lock(&sysfs_mutex); |
| 477 | |
| 478 | if (sd && dir) |
| 479 | sd = sysfs_find_dirent(sd, dir); |
| 480 | if (sd && attr) |
| 481 | sd = sysfs_find_dirent(sd, attr); |
| 482 | if (sd) |
| 483 | sysfs_notify_dirent(sd); |
| 484 | |
| 485 | mutex_unlock(&sysfs_mutex); |
| 486 | } |
| 487 | EXPORT_SYMBOL_GPL(sysfs_notify); |
| 488 | |
| 489 | const struct file_operations sysfs_file_operations = { |
| 490 | .read = sysfs_read_file, |
| 491 | .write = sysfs_write_file, |
| 492 | .llseek = generic_file_llseek, |
| 493 | .open = sysfs_open_file, |
| 494 | .release = sysfs_release, |
| 495 | .poll = sysfs_poll, |
| 496 | }; |
| 497 | |
| 498 | int sysfs_add_file_mode(struct sysfs_dirent *dir_sd, |
| 499 | const struct attribute *attr, int type, mode_t amode) |
| 500 | { |
| 501 | umode_t mode = (amode & S_IALLUGO) | S_IFREG; |
| 502 | struct sysfs_addrm_cxt acxt; |
| 503 | struct sysfs_dirent *sd; |
| 504 | int rc; |
| 505 | |
| 506 | sd = sysfs_new_dirent(attr->name, mode, type); |
| 507 | if (!sd) |
| 508 | return -ENOMEM; |
| 509 | sd->s_attr.attr = (void *)attr; |
| 510 | |
| 511 | sysfs_addrm_start(&acxt, dir_sd); |
| 512 | rc = sysfs_add_one(&acxt, sd); |
| 513 | sysfs_addrm_finish(&acxt); |
| 514 | |
| 515 | if (rc) |
| 516 | sysfs_put(sd); |
| 517 | |
| 518 | return rc; |
| 519 | } |
| 520 | |
| 521 | |
| 522 | int 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 | |
| 529 | /** |
| 530 | * sysfs_create_file - create an attribute file for an object. |
| 531 | * @kobj: object we're creating for. |
| 532 | * @attr: attribute descriptor. |
| 533 | */ |
| 534 | |
| 535 | int sysfs_create_file(struct kobject * kobj, const struct attribute * attr) |
| 536 | { |
| 537 | BUG_ON(!kobj || !kobj->sd || !attr); |
| 538 | |
| 539 | return sysfs_add_file(kobj->sd, attr, SYSFS_KOBJ_ATTR); |
| 540 | |
| 541 | } |
| 542 | |
| 543 | |
| 544 | /** |
| 545 | * 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 | */ |
| 550 | int sysfs_add_file_to_group(struct kobject *kobj, |
| 551 | const struct attribute *attr, const char *group) |
| 552 | { |
| 553 | struct sysfs_dirent *dir_sd; |
| 554 | int error; |
| 555 | |
| 556 | if (group) |
| 557 | dir_sd = sysfs_get_dirent(kobj->sd, group); |
| 558 | else |
| 559 | dir_sd = sysfs_get(kobj->sd); |
| 560 | |
| 561 | if (!dir_sd) |
| 562 | return -ENOENT; |
| 563 | |
| 564 | error = sysfs_add_file(dir_sd, attr, SYSFS_KOBJ_ATTR); |
| 565 | sysfs_put(dir_sd); |
| 566 | |
| 567 | return error; |
| 568 | } |
| 569 | EXPORT_SYMBOL_GPL(sysfs_add_file_to_group); |
| 570 | |
| 571 | /** |
| 572 | * 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 | */ |
| 578 | int sysfs_chmod_file(struct kobject *kobj, struct attribute *attr, mode_t mode) |
| 579 | { |
| 580 | struct sysfs_dirent *victim_sd = NULL; |
| 581 | struct dentry *victim = NULL; |
| 582 | struct inode * inode; |
| 583 | struct iattr newattrs; |
| 584 | int rc; |
| 585 | |
| 586 | rc = -ENOENT; |
| 587 | victim_sd = sysfs_get_dirent(kobj->sd, attr->name); |
| 588 | if (!victim_sd) |
| 589 | goto out; |
| 590 | |
| 591 | mutex_lock(&sysfs_rename_mutex); |
| 592 | victim = sysfs_get_dentry(victim_sd); |
| 593 | mutex_unlock(&sysfs_rename_mutex); |
| 594 | if (IS_ERR(victim)) { |
| 595 | rc = PTR_ERR(victim); |
| 596 | victim = NULL; |
| 597 | goto out; |
| 598 | } |
| 599 | |
| 600 | inode = victim->d_inode; |
| 601 | |
| 602 | mutex_lock(&inode->i_mutex); |
| 603 | |
| 604 | newattrs.ia_mode = (mode & S_IALLUGO) | (inode->i_mode & ~S_IALLUGO); |
| 605 | newattrs.ia_valid = ATTR_MODE | ATTR_CTIME; |
| 606 | newattrs.ia_ctime = current_fs_time(inode->i_sb); |
| 607 | rc = sysfs_setattr(victim, &newattrs); |
| 608 | |
| 609 | if (rc == 0) { |
| 610 | fsnotify_change(victim, newattrs.ia_valid); |
| 611 | mutex_lock(&sysfs_mutex); |
| 612 | victim_sd->s_mode = newattrs.ia_mode; |
| 613 | mutex_unlock(&sysfs_mutex); |
| 614 | } |
| 615 | |
| 616 | mutex_unlock(&inode->i_mutex); |
| 617 | out: |
| 618 | dput(victim); |
| 619 | sysfs_put(victim_sd); |
| 620 | return rc; |
| 621 | } |
| 622 | EXPORT_SYMBOL_GPL(sysfs_chmod_file); |
| 623 | |
| 624 | |
| 625 | /** |
| 626 | * 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 | |
| 633 | void sysfs_remove_file(struct kobject * kobj, const struct attribute * attr) |
| 634 | { |
| 635 | sysfs_hash_and_remove(kobj->sd, attr->name); |
| 636 | } |
| 637 | |
| 638 | |
| 639 | /** |
| 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 | */ |
| 645 | void sysfs_remove_file_from_group(struct kobject *kobj, |
| 646 | const struct attribute *attr, const char *group) |
| 647 | { |
| 648 | struct sysfs_dirent *dir_sd; |
| 649 | |
| 650 | if (group) |
| 651 | dir_sd = sysfs_get_dirent(kobj->sd, group); |
| 652 | else |
| 653 | dir_sd = sysfs_get(kobj->sd); |
| 654 | if (dir_sd) { |
| 655 | sysfs_hash_and_remove(dir_sd, attr->name); |
| 656 | sysfs_put(dir_sd); |
| 657 | } |
| 658 | } |
| 659 | EXPORT_SYMBOL_GPL(sysfs_remove_file_from_group); |
| 660 | |
| 661 | struct sysfs_schedule_callback_struct { |
| 662 | struct kobject *kobj; |
| 663 | void (*func)(void *); |
| 664 | void *data; |
| 665 | struct module *owner; |
| 666 | struct work_struct work; |
| 667 | }; |
| 668 | |
| 669 | static void sysfs_schedule_callback_work(struct work_struct *work) |
| 670 | { |
| 671 | struct sysfs_schedule_callback_struct *ss = container_of(work, |
| 672 | struct sysfs_schedule_callback_struct, work); |
| 673 | |
| 674 | (ss->func)(ss->data); |
| 675 | kobject_put(ss->kobj); |
| 676 | module_put(ss->owner); |
| 677 | kfree(ss); |
| 678 | } |
| 679 | |
| 680 | /** |
| 681 | * sysfs_schedule_callback - helper to schedule a callback for a kobject |
| 682 | * @kobj: object we're acting for. |
| 683 | * @func: callback function to invoke later. |
| 684 | * @data: argument to pass to @func. |
| 685 | * @owner: module owning the callback code |
| 686 | * |
| 687 | * sysfs attribute methods must not unregister themselves or their parent |
| 688 | * kobject (which would amount to the same thing). Attempts to do so will |
| 689 | * deadlock, since unregistration is mutually exclusive with driver |
| 690 | * callbacks. |
| 691 | * |
| 692 | * Instead methods can call this routine, which will attempt to allocate |
| 693 | * and schedule a workqueue request to call back @func with @data as its |
| 694 | * argument in the workqueue's process context. @kobj will be pinned |
| 695 | * until @func returns. |
| 696 | * |
| 697 | * Returns 0 if the request was submitted, -ENOMEM if storage could not |
| 698 | * be allocated, -ENODEV if a reference to @owner isn't available. |
| 699 | */ |
| 700 | int sysfs_schedule_callback(struct kobject *kobj, void (*func)(void *), |
| 701 | void *data, struct module *owner) |
| 702 | { |
| 703 | struct sysfs_schedule_callback_struct *ss; |
| 704 | |
| 705 | if (!try_module_get(owner)) |
| 706 | return -ENODEV; |
| 707 | ss = kmalloc(sizeof(*ss), GFP_KERNEL); |
| 708 | if (!ss) { |
| 709 | module_put(owner); |
| 710 | return -ENOMEM; |
| 711 | } |
| 712 | kobject_get(kobj); |
| 713 | ss->kobj = kobj; |
| 714 | ss->func = func; |
| 715 | ss->data = data; |
| 716 | ss->owner = owner; |
| 717 | INIT_WORK(&ss->work, sysfs_schedule_callback_work); |
| 718 | schedule_work(&ss->work); |
| 719 | return 0; |
| 720 | } |
| 721 | EXPORT_SYMBOL_GPL(sysfs_schedule_callback); |
| 722 | |
| 723 | |
| 724 | EXPORT_SYMBOL_GPL(sysfs_create_file); |
| 725 | EXPORT_SYMBOL_GPL(sysfs_remove_file); |