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 */
51 count
= seq_get_buf(sf
, &buf
);
52 if (count
< PAGE_SIZE
) {
58 * Invoke show(). Control may reach here via seq file lseek even
59 * if @ops->show() isn't implemented.
62 count
= ops
->show(kobj
, of
->kn
->priv
, buf
);
68 * The code works fine with PAGE_SIZE return but it's likely to
69 * indicate truncated result or overflow in normal use cases.
71 if (count
>= (ssize_t
)PAGE_SIZE
) {
72 print_symbol("fill_read_buffer: %s returned bad count\n",
73 (unsigned long)ops
->show
);
74 /* Try to struggle along */
75 count
= PAGE_SIZE
- 1;
77 seq_commit(sf
, count
);
81 static ssize_t
sysfs_kf_bin_read(struct kernfs_open_file
*of
, char *buf
,
82 size_t count
, loff_t pos
)
84 struct bin_attribute
*battr
= of
->kn
->priv
;
85 struct kobject
*kobj
= of
->kn
->parent
->priv
;
86 loff_t size
= file_inode(of
->file
)->i_size
;
94 if (pos
+ count
> size
)
101 return battr
->read(of
->file
, kobj
, battr
, buf
, pos
, count
);
104 /* kernfs write callback for regular sysfs files */
105 static ssize_t
sysfs_kf_write(struct kernfs_open_file
*of
, char *buf
,
106 size_t count
, loff_t pos
)
108 const struct sysfs_ops
*ops
= sysfs_file_ops(of
->kn
);
109 struct kobject
*kobj
= of
->kn
->parent
->priv
;
114 return ops
->store(kobj
, of
->kn
->priv
, buf
, count
);
117 /* kernfs write callback for bin sysfs files */
118 static ssize_t
sysfs_kf_bin_write(struct kernfs_open_file
*of
, char *buf
,
119 size_t count
, loff_t pos
)
121 struct bin_attribute
*battr
= of
->kn
->priv
;
122 struct kobject
*kobj
= of
->kn
->parent
->priv
;
123 loff_t size
= file_inode(of
->file
)->i_size
;
128 count
= min_t(ssize_t
, count
, size
- pos
);
136 return battr
->write(of
->file
, kobj
, battr
, buf
, pos
, count
);
139 static int sysfs_kf_bin_mmap(struct kernfs_open_file
*of
,
140 struct vm_area_struct
*vma
)
142 struct bin_attribute
*battr
= of
->kn
->priv
;
143 struct kobject
*kobj
= of
->kn
->parent
->priv
;
145 return battr
->mmap(of
->file
, kobj
, battr
, vma
);
148 void sysfs_notify(struct kobject
*kobj
, const char *dir
, const char *attr
)
150 struct kernfs_node
*kn
= kobj
->sd
, *tmp
;
153 kn
= kernfs_find_and_get(kn
, dir
);
158 tmp
= kernfs_find_and_get(kn
, attr
);
168 EXPORT_SYMBOL_GPL(sysfs_notify
);
170 static const struct kernfs_ops sysfs_file_kfops_empty
= {
173 static const struct kernfs_ops sysfs_file_kfops_ro
= {
174 .seq_show
= sysfs_kf_seq_show
,
177 static const struct kernfs_ops sysfs_file_kfops_wo
= {
178 .write
= sysfs_kf_write
,
181 static const struct kernfs_ops sysfs_file_kfops_rw
= {
182 .seq_show
= sysfs_kf_seq_show
,
183 .write
= sysfs_kf_write
,
186 static const struct kernfs_ops sysfs_bin_kfops_ro
= {
187 .read
= sysfs_kf_bin_read
,
190 static const struct kernfs_ops sysfs_bin_kfops_wo
= {
191 .write
= sysfs_kf_bin_write
,
194 static const struct kernfs_ops sysfs_bin_kfops_rw
= {
195 .read
= sysfs_kf_bin_read
,
196 .write
= sysfs_kf_bin_write
,
199 static const struct kernfs_ops sysfs_bin_kfops_mmap
= {
200 .read
= sysfs_kf_bin_read
,
201 .write
= sysfs_kf_bin_write
,
202 .mmap
= sysfs_kf_bin_mmap
,
205 int sysfs_add_file_mode_ns(struct kernfs_node
*parent
,
206 const struct attribute
*attr
, bool is_bin
,
207 umode_t mode
, const void *ns
)
209 struct lock_class_key
*key
= NULL
;
210 const struct kernfs_ops
*ops
;
211 struct kernfs_node
*kn
;
215 struct kobject
*kobj
= parent
->priv
;
216 const struct sysfs_ops
*sysfs_ops
= kobj
->ktype
->sysfs_ops
;
218 /* every kobject with an attribute needs a ktype assigned */
219 if (WARN(!sysfs_ops
, KERN_ERR
220 "missing sysfs attribute operations for kobject: %s\n",
224 if (sysfs_ops
->show
&& sysfs_ops
->store
)
225 ops
= &sysfs_file_kfops_rw
;
226 else if (sysfs_ops
->show
)
227 ops
= &sysfs_file_kfops_ro
;
228 else if (sysfs_ops
->store
)
229 ops
= &sysfs_file_kfops_wo
;
231 ops
= &sysfs_file_kfops_empty
;
235 struct bin_attribute
*battr
= (void *)attr
;
238 ops
= &sysfs_bin_kfops_mmap
;
239 else if (battr
->read
&& battr
->write
)
240 ops
= &sysfs_bin_kfops_rw
;
241 else if (battr
->read
)
242 ops
= &sysfs_bin_kfops_ro
;
243 else if (battr
->write
)
244 ops
= &sysfs_bin_kfops_wo
;
246 ops
= &sysfs_file_kfops_empty
;
251 #ifdef CONFIG_DEBUG_LOCK_ALLOC
252 if (!attr
->ignore_lockdep
)
253 key
= attr
->key
?: (struct lock_class_key
*)&attr
->skey
;
255 kn
= __kernfs_create_file(parent
, attr
->name
, mode
, size
, ops
,
256 (void *)attr
, ns
, true, key
);
258 if (PTR_ERR(kn
) == -EEXIST
)
259 sysfs_warn_dup(parent
, attr
->name
);
265 int sysfs_add_file(struct kernfs_node
*parent
, const struct attribute
*attr
,
268 return sysfs_add_file_mode_ns(parent
, attr
, is_bin
, attr
->mode
, NULL
);
272 * sysfs_create_file_ns - create an attribute file for an object with custom ns
273 * @kobj: object we're creating for
274 * @attr: attribute descriptor
275 * @ns: namespace the new file should belong to
277 int sysfs_create_file_ns(struct kobject
*kobj
, const struct attribute
*attr
,
280 BUG_ON(!kobj
|| !kobj
->sd
|| !attr
);
282 return sysfs_add_file_mode_ns(kobj
->sd
, attr
, false, attr
->mode
, ns
);
285 EXPORT_SYMBOL_GPL(sysfs_create_file_ns
);
287 int sysfs_create_files(struct kobject
*kobj
, const struct attribute
**ptr
)
292 for (i
= 0; ptr
[i
] && !err
; i
++)
293 err
= sysfs_create_file(kobj
, ptr
[i
]);
296 sysfs_remove_file(kobj
, ptr
[i
]);
299 EXPORT_SYMBOL_GPL(sysfs_create_files
);
302 * sysfs_add_file_to_group - add an attribute file to a pre-existing group.
303 * @kobj: object we're acting for.
304 * @attr: attribute descriptor.
305 * @group: group name.
307 int sysfs_add_file_to_group(struct kobject
*kobj
,
308 const struct attribute
*attr
, const char *group
)
310 struct kernfs_node
*parent
;
314 parent
= kernfs_find_and_get(kobj
->sd
, group
);
323 error
= sysfs_add_file(parent
, attr
, false);
328 EXPORT_SYMBOL_GPL(sysfs_add_file_to_group
);
331 * sysfs_chmod_file - update the modified mode value on an object attribute.
332 * @kobj: object we're acting for.
333 * @attr: attribute descriptor.
334 * @mode: file permissions.
337 int sysfs_chmod_file(struct kobject
*kobj
, const struct attribute
*attr
,
340 struct kernfs_node
*kn
;
341 struct iattr newattrs
;
344 kn
= kernfs_find_and_get(kobj
->sd
, attr
->name
);
348 newattrs
.ia_mode
= (mode
& S_IALLUGO
) | (kn
->mode
& ~S_IALLUGO
);
349 newattrs
.ia_valid
= ATTR_MODE
;
351 rc
= kernfs_setattr(kn
, &newattrs
);
356 EXPORT_SYMBOL_GPL(sysfs_chmod_file
);
359 * sysfs_remove_file_ns - remove an object attribute with a custom ns tag
360 * @kobj: object we're acting for
361 * @attr: attribute descriptor
362 * @ns: namespace tag of the file to remove
364 * Hash the attribute name and namespace tag and kill the victim.
366 void sysfs_remove_file_ns(struct kobject
*kobj
, const struct attribute
*attr
,
369 struct kernfs_node
*parent
= kobj
->sd
;
371 kernfs_remove_by_name_ns(parent
, attr
->name
, ns
);
373 EXPORT_SYMBOL_GPL(sysfs_remove_file_ns
);
375 void sysfs_remove_files(struct kobject
*kobj
, const struct attribute
**ptr
)
378 for (i
= 0; ptr
[i
]; i
++)
379 sysfs_remove_file(kobj
, ptr
[i
]);
381 EXPORT_SYMBOL_GPL(sysfs_remove_files
);
384 * sysfs_remove_file_from_group - remove an attribute file from a group.
385 * @kobj: object we're acting for.
386 * @attr: attribute descriptor.
387 * @group: group name.
389 void sysfs_remove_file_from_group(struct kobject
*kobj
,
390 const struct attribute
*attr
, const char *group
)
392 struct kernfs_node
*parent
;
395 parent
= kernfs_find_and_get(kobj
->sd
, group
);
402 kernfs_remove_by_name(parent
, attr
->name
);
406 EXPORT_SYMBOL_GPL(sysfs_remove_file_from_group
);
409 * sysfs_create_bin_file - create binary file for object.
411 * @attr: attribute descriptor.
413 int sysfs_create_bin_file(struct kobject
*kobj
,
414 const struct bin_attribute
*attr
)
416 BUG_ON(!kobj
|| !kobj
->sd
|| !attr
);
418 return sysfs_add_file(kobj
->sd
, &attr
->attr
, true);
420 EXPORT_SYMBOL_GPL(sysfs_create_bin_file
);
423 * sysfs_remove_bin_file - remove binary file for object.
425 * @attr: attribute descriptor.
427 void sysfs_remove_bin_file(struct kobject
*kobj
,
428 const struct bin_attribute
*attr
)
430 kernfs_remove_by_name(kobj
->sd
, attr
->attr
.name
);
432 EXPORT_SYMBOL_GPL(sysfs_remove_bin_file
);
434 struct sysfs_schedule_callback_struct
{
435 struct list_head workq_list
;
436 struct kobject
*kobj
;
437 void (*func
)(void *);
439 struct module
*owner
;
440 struct work_struct work
;
443 static struct workqueue_struct
*sysfs_workqueue
;
444 static DEFINE_MUTEX(sysfs_workq_mutex
);
445 static LIST_HEAD(sysfs_workq
);
446 static void sysfs_schedule_callback_work(struct work_struct
*work
)
448 struct sysfs_schedule_callback_struct
*ss
= container_of(work
,
449 struct sysfs_schedule_callback_struct
, work
);
451 (ss
->func
)(ss
->data
);
452 kobject_put(ss
->kobj
);
453 module_put(ss
->owner
);
454 mutex_lock(&sysfs_workq_mutex
);
455 list_del(&ss
->workq_list
);
456 mutex_unlock(&sysfs_workq_mutex
);
461 * sysfs_schedule_callback - helper to schedule a callback for a kobject
462 * @kobj: object we're acting for.
463 * @func: callback function to invoke later.
464 * @data: argument to pass to @func.
465 * @owner: module owning the callback code
467 * sysfs attribute methods must not unregister themselves or their parent
468 * kobject (which would amount to the same thing). Attempts to do so will
469 * deadlock, since unregistration is mutually exclusive with driver
472 * Instead methods can call this routine, which will attempt to allocate
473 * and schedule a workqueue request to call back @func with @data as its
474 * argument in the workqueue's process context. @kobj will be pinned
475 * until @func returns.
477 * Returns 0 if the request was submitted, -ENOMEM if storage could not
478 * be allocated, -ENODEV if a reference to @owner isn't available,
479 * -EAGAIN if a callback has already been scheduled for @kobj.
481 int sysfs_schedule_callback(struct kobject
*kobj
, void (*func
)(void *),
482 void *data
, struct module
*owner
)
484 struct sysfs_schedule_callback_struct
*ss
, *tmp
;
486 if (!try_module_get(owner
))
489 mutex_lock(&sysfs_workq_mutex
);
490 list_for_each_entry_safe(ss
, tmp
, &sysfs_workq
, workq_list
)
491 if (ss
->kobj
== kobj
) {
493 mutex_unlock(&sysfs_workq_mutex
);
496 mutex_unlock(&sysfs_workq_mutex
);
498 if (sysfs_workqueue
== NULL
) {
499 sysfs_workqueue
= create_singlethread_workqueue("sysfsd");
500 if (sysfs_workqueue
== NULL
) {
506 ss
= kmalloc(sizeof(*ss
), GFP_KERNEL
);
516 INIT_WORK(&ss
->work
, sysfs_schedule_callback_work
);
517 INIT_LIST_HEAD(&ss
->workq_list
);
518 mutex_lock(&sysfs_workq_mutex
);
519 list_add_tail(&ss
->workq_list
, &sysfs_workq
);
520 mutex_unlock(&sysfs_workq_mutex
);
521 queue_work(sysfs_workqueue
, &ss
->work
);
524 EXPORT_SYMBOL_GPL(sysfs_schedule_callback
);