2 * fs/sysfs/file.c - sysfs regular (text) file implementation
4 * Copyright (c) 2001-3 Patrick Mochel
5 * Copyright (c) 2007 SUSE Linux Products GmbH
6 * Copyright (c) 2007 Tejun Heo <teheo@suse.de>
8 * This file is released under the GPLv2.
10 * Please see Documentation/filesystems/sysfs.txt for more information.
13 #include <linux/module.h>
14 #include <linux/kobject.h>
15 #include <linux/kallsyms.h>
16 #include <linux/slab.h>
17 #include <linux/list.h>
18 #include <linux/mutex.h>
19 #include <linux/seq_file.h>
22 #include "../kernfs/kernfs-internal.h"
25 * Determine ktype->sysfs_ops for the given kernfs_node. This function
26 * must be called while holding an active reference.
28 static const struct sysfs_ops *sysfs_file_ops(struct kernfs_node *kn)
30 struct kobject *kobj = kn->parent->priv;
32 if (kn->flags & KERNFS_LOCKDEP)
33 lockdep_assert_held(kn);
34 return kobj->ktype ? kobj->ktype->sysfs_ops : NULL;
38 * Reads on sysfs are handled through seq_file, which takes care of hairy
39 * details like buffering and seeking. The following function pipes
40 * sysfs_ops->show() result through seq_file.
42 static int sysfs_kf_seq_show(struct seq_file *sf, void *v)
44 struct kernfs_open_file *of = sf->private;
45 struct kobject *kobj = of->kn->parent->priv;
46 const struct sysfs_ops *ops = sysfs_file_ops(of->kn);
50 /* acquire buffer and ensure that it's >= PAGE_SIZE and clear */
51 count = seq_get_buf(sf, &buf);
52 if (count < PAGE_SIZE) {
56 memset(buf, 0, PAGE_SIZE);
59 * Invoke show(). Control may reach here via seq file lseek even
60 * if @ops->show() isn't implemented.
63 count = ops->show(kobj, of->kn->priv, buf);
69 * The code works fine with PAGE_SIZE return but it's likely to
70 * indicate truncated result or overflow in normal use cases.
72 if (count >= (ssize_t)PAGE_SIZE) {
73 print_symbol("fill_read_buffer: %s returned bad count\n",
74 (unsigned long)ops->show);
75 /* Try to struggle along */
76 count = PAGE_SIZE - 1;
78 seq_commit(sf, count);
82 static ssize_t sysfs_kf_bin_read(struct kernfs_open_file *of, char *buf,
83 size_t count, loff_t pos)
85 struct bin_attribute *battr = of->kn->priv;
86 struct kobject *kobj = of->kn->parent->priv;
87 loff_t size = file_inode(of->file)->i_size;
95 if (pos + count > size)
102 return battr->read(of->file, kobj, battr, buf, pos, count);
105 /* kernfs write callback for regular sysfs files */
106 static ssize_t sysfs_kf_write(struct kernfs_open_file *of, char *buf,
107 size_t count, loff_t pos)
109 const struct sysfs_ops *ops = sysfs_file_ops(of->kn);
110 struct kobject *kobj = of->kn->parent->priv;
115 return ops->store(kobj, of->kn->priv, buf, count);
118 /* kernfs write callback for bin sysfs files */
119 static ssize_t sysfs_kf_bin_write(struct kernfs_open_file *of, char *buf,
120 size_t count, loff_t pos)
122 struct bin_attribute *battr = of->kn->priv;
123 struct kobject *kobj = of->kn->parent->priv;
124 loff_t size = file_inode(of->file)->i_size;
129 count = min_t(ssize_t, count, size - pos);
137 return battr->write(of->file, kobj, battr, buf, pos, count);
140 static int sysfs_kf_bin_mmap(struct kernfs_open_file *of,
141 struct vm_area_struct *vma)
143 struct bin_attribute *battr = of->kn->priv;
144 struct kobject *kobj = of->kn->parent->priv;
146 return battr->mmap(of->file, kobj, battr, vma);
149 void sysfs_notify(struct kobject *kobj, const char *dir, const char *attr)
151 struct kernfs_node *kn = kobj->sd, *tmp;
154 kn = kernfs_find_and_get(kn, dir);
159 tmp = kernfs_find_and_get(kn, attr);
169 EXPORT_SYMBOL_GPL(sysfs_notify);
171 static const struct kernfs_ops sysfs_file_kfops_empty = {
174 static const struct kernfs_ops sysfs_file_kfops_ro = {
175 .seq_show = sysfs_kf_seq_show,
178 static const struct kernfs_ops sysfs_file_kfops_wo = {
179 .write = sysfs_kf_write,
182 static const struct kernfs_ops sysfs_file_kfops_rw = {
183 .seq_show = sysfs_kf_seq_show,
184 .write = sysfs_kf_write,
187 static const struct kernfs_ops sysfs_prealloc_kfops_wo = {
188 .write = sysfs_kf_write,
192 static const struct kernfs_ops sysfs_prealloc_kfops_rw = {
193 .seq_show = sysfs_kf_seq_show,
194 .write = sysfs_kf_write,
198 static const struct kernfs_ops sysfs_bin_kfops_ro = {
199 .read = sysfs_kf_bin_read,
202 static const struct kernfs_ops sysfs_bin_kfops_wo = {
203 .write = sysfs_kf_bin_write,
206 static const struct kernfs_ops sysfs_bin_kfops_rw = {
207 .read = sysfs_kf_bin_read,
208 .write = sysfs_kf_bin_write,
211 static const struct kernfs_ops sysfs_bin_kfops_mmap = {
212 .read = sysfs_kf_bin_read,
213 .write = sysfs_kf_bin_write,
214 .mmap = sysfs_kf_bin_mmap,
217 int sysfs_add_file_mode_ns(struct kernfs_node *parent,
218 const struct attribute *attr, bool is_bin,
219 umode_t mode, const void *ns)
221 struct lock_class_key *key = NULL;
222 const struct kernfs_ops *ops;
223 struct kernfs_node *kn;
227 struct kobject *kobj = parent->priv;
228 const struct sysfs_ops *sysfs_ops = kobj->ktype->sysfs_ops;
230 /* every kobject with an attribute needs a ktype assigned */
231 if (WARN(!sysfs_ops, KERN_ERR
232 "missing sysfs attribute operations for kobject: %s\n",
236 if (sysfs_ops->show && sysfs_ops->store) {
237 if (mode & SYSFS_PREALLOC)
238 ops = &sysfs_prealloc_kfops_rw;
240 ops = &sysfs_file_kfops_rw;
241 } else if (sysfs_ops->show)
242 ops = &sysfs_file_kfops_ro;
243 else if (sysfs_ops->store) {
244 if (mode & SYSFS_PREALLOC)
245 ops = &sysfs_prealloc_kfops_wo;
247 ops = &sysfs_file_kfops_wo;
249 ops = &sysfs_file_kfops_empty;
253 struct bin_attribute *battr = (void *)attr;
256 ops = &sysfs_bin_kfops_mmap;
257 else if (battr->read && battr->write)
258 ops = &sysfs_bin_kfops_rw;
259 else if (battr->read)
260 ops = &sysfs_bin_kfops_ro;
261 else if (battr->write)
262 ops = &sysfs_bin_kfops_wo;
264 ops = &sysfs_file_kfops_empty;
269 #ifdef CONFIG_DEBUG_LOCK_ALLOC
270 if (!attr->ignore_lockdep)
271 key = attr->key ?: (struct lock_class_key *)&attr->skey;
273 kn = __kernfs_create_file(parent, attr->name, mode & 0777, size, ops,
274 (void *)attr, ns, true, key);
276 if (PTR_ERR(kn) == -EEXIST)
277 sysfs_warn_dup(parent, attr->name);
283 int sysfs_add_file(struct kernfs_node *parent, const struct attribute *attr,
286 return sysfs_add_file_mode_ns(parent, attr, is_bin, attr->mode, NULL);
290 * sysfs_create_file_ns - create an attribute file for an object with custom ns
291 * @kobj: object we're creating for
292 * @attr: attribute descriptor
293 * @ns: namespace the new file should belong to
295 int sysfs_create_file_ns(struct kobject *kobj, const struct attribute *attr,
298 BUG_ON(!kobj || !kobj->sd || !attr);
300 return sysfs_add_file_mode_ns(kobj->sd, attr, false, attr->mode, ns);
303 EXPORT_SYMBOL_GPL(sysfs_create_file_ns);
305 int sysfs_create_files(struct kobject *kobj, const struct attribute **ptr)
310 for (i = 0; ptr[i] && !err; i++)
311 err = sysfs_create_file(kobj, ptr[i]);
314 sysfs_remove_file(kobj, ptr[i]);
317 EXPORT_SYMBOL_GPL(sysfs_create_files);
320 * sysfs_add_file_to_group - add an attribute file to a pre-existing group.
321 * @kobj: object we're acting for.
322 * @attr: attribute descriptor.
323 * @group: group name.
325 int sysfs_add_file_to_group(struct kobject *kobj,
326 const struct attribute *attr, const char *group)
328 struct kernfs_node *parent;
332 parent = kernfs_find_and_get(kobj->sd, group);
341 error = sysfs_add_file(parent, attr, false);
346 EXPORT_SYMBOL_GPL(sysfs_add_file_to_group);
349 * sysfs_chmod_file - update the modified mode value on an object attribute.
350 * @kobj: object we're acting for.
351 * @attr: attribute descriptor.
352 * @mode: file permissions.
355 int sysfs_chmod_file(struct kobject *kobj, const struct attribute *attr,
358 struct kernfs_node *kn;
359 struct iattr newattrs;
362 kn = kernfs_find_and_get(kobj->sd, attr->name);
366 newattrs.ia_mode = (mode & S_IALLUGO) | (kn->mode & ~S_IALLUGO);
367 newattrs.ia_valid = ATTR_MODE;
369 rc = kernfs_setattr(kn, &newattrs);
374 EXPORT_SYMBOL_GPL(sysfs_chmod_file);
377 * sysfs_remove_file_ns - remove an object attribute with a custom ns tag
378 * @kobj: object we're acting for
379 * @attr: attribute descriptor
380 * @ns: namespace tag of the file to remove
382 * Hash the attribute name and namespace tag and kill the victim.
384 void sysfs_remove_file_ns(struct kobject *kobj, const struct attribute *attr,
387 struct kernfs_node *parent = kobj->sd;
389 kernfs_remove_by_name_ns(parent, attr->name, ns);
391 EXPORT_SYMBOL_GPL(sysfs_remove_file_ns);
394 * sysfs_remove_file_self - remove an object attribute from its own method
395 * @kobj: object we're acting for
396 * @attr: attribute descriptor
398 * See kernfs_remove_self() for details.
400 bool sysfs_remove_file_self(struct kobject *kobj, const struct attribute *attr)
402 struct kernfs_node *parent = kobj->sd;
403 struct kernfs_node *kn;
406 kn = kernfs_find_and_get(parent, attr->name);
407 if (WARN_ON_ONCE(!kn))
410 ret = kernfs_remove_self(kn);
416 void sysfs_remove_files(struct kobject *kobj, const struct attribute **ptr)
419 for (i = 0; ptr[i]; i++)
420 sysfs_remove_file(kobj, ptr[i]);
422 EXPORT_SYMBOL_GPL(sysfs_remove_files);
425 * sysfs_remove_file_from_group - remove an attribute file from a group.
426 * @kobj: object we're acting for.
427 * @attr: attribute descriptor.
428 * @group: group name.
430 void sysfs_remove_file_from_group(struct kobject *kobj,
431 const struct attribute *attr, const char *group)
433 struct kernfs_node *parent;
436 parent = kernfs_find_and_get(kobj->sd, group);
443 kernfs_remove_by_name(parent, attr->name);
447 EXPORT_SYMBOL_GPL(sysfs_remove_file_from_group);
450 * sysfs_create_bin_file - create binary file for object.
452 * @attr: attribute descriptor.
454 int sysfs_create_bin_file(struct kobject *kobj,
455 const struct bin_attribute *attr)
457 BUG_ON(!kobj || !kobj->sd || !attr);
459 return sysfs_add_file(kobj->sd, &attr->attr, true);
461 EXPORT_SYMBOL_GPL(sysfs_create_bin_file);
464 * sysfs_remove_bin_file - remove binary file for object.
466 * @attr: attribute descriptor.
468 void sysfs_remove_bin_file(struct kobject *kobj,
469 const struct bin_attribute *attr)
471 kernfs_remove_by_name(kobj->sd, attr->attr.name);
473 EXPORT_SYMBOL_GPL(sysfs_remove_bin_file);