xref: /openbmc/linux/fs/sysfs/group.c (revision 22246614)
1 /*
2  * fs/sysfs/group.c - Operations for adding/removing multiple files at once.
3  *
4  * Copyright (c) 2003 Patrick Mochel
5  * Copyright (c) 2003 Open Source Development Lab
6  *
7  * This file is released undert the GPL v2.
8  *
9  */
10 
11 #include <linux/kobject.h>
12 #include <linux/module.h>
13 #include <linux/dcache.h>
14 #include <linux/namei.h>
15 #include <linux/err.h>
16 #include "sysfs.h"
17 
18 
19 static void remove_files(struct sysfs_dirent *dir_sd, struct kobject *kobj,
20 			 const struct attribute_group *grp)
21 {
22 	struct attribute *const* attr;
23 	int i;
24 
25 	for (i = 0, attr = grp->attrs; *attr; i++, attr++)
26 		sysfs_hash_and_remove(dir_sd, (*attr)->name);
27 }
28 
29 static int create_files(struct sysfs_dirent *dir_sd, struct kobject *kobj,
30 			const struct attribute_group *grp, int update)
31 {
32 	struct attribute *const* attr;
33 	int error = 0, i;
34 
35 	for (i = 0, attr = grp->attrs; *attr && !error; i++, attr++) {
36 		mode_t mode = 0;
37 
38 		/* in update mode, we're changing the permissions or
39 		 * visibility.  Do this by first removing then
40 		 * re-adding (if required) the file */
41 		if (update)
42 			sysfs_hash_and_remove(dir_sd, (*attr)->name);
43 		if (grp->is_visible) {
44 			mode = grp->is_visible(kobj, *attr, i);
45 			if (!mode)
46 				continue;
47 		}
48 		error = sysfs_add_file_mode(dir_sd, *attr, SYSFS_KOBJ_ATTR,
49 					    (*attr)->mode | mode);
50 		if (unlikely(error))
51 			break;
52 	}
53 	if (error)
54 		remove_files(dir_sd, kobj, grp);
55 	return error;
56 }
57 
58 
59 static int internal_create_group(struct kobject *kobj, int update,
60 				 const struct attribute_group *grp)
61 {
62 	struct sysfs_dirent *sd;
63 	int error;
64 
65 	BUG_ON(!kobj || (!update && !kobj->sd));
66 
67 	/* Updates may happen before the object has been instantiated */
68 	if (unlikely(update && !kobj->sd))
69 		return -EINVAL;
70 
71 	if (grp->name) {
72 		error = sysfs_create_subdir(kobj, grp->name, &sd);
73 		if (error)
74 			return error;
75 	} else
76 		sd = kobj->sd;
77 	sysfs_get(sd);
78 	error = create_files(sd, kobj, grp, update);
79 	if (error) {
80 		if (grp->name)
81 			sysfs_remove_subdir(sd);
82 	}
83 	sysfs_put(sd);
84 	return error;
85 }
86 
87 /**
88  * sysfs_create_group - given a directory kobject, create an attribute group
89  * @kobj:	The kobject to create the group on
90  * @grp:	The attribute group to create
91  *
92  * This function creates a group for the first time.  It will explicitly
93  * warn and error if any of the attribute files being created already exist.
94  *
95  * Returns 0 on success or error.
96  */
97 int sysfs_create_group(struct kobject *kobj,
98 		       const struct attribute_group *grp)
99 {
100 	return internal_create_group(kobj, 0, grp);
101 }
102 
103 /**
104  * sysfs_update_group - given a directory kobject, create an attribute group
105  * @kobj:	The kobject to create the group on
106  * @grp:	The attribute group to create
107  *
108  * This function updates an attribute group.  Unlike
109  * sysfs_create_group(), it will explicitly not warn or error if any
110  * of the attribute files being created already exist.  Furthermore,
111  * if the visibility of the files has changed through the is_visible()
112  * callback, it will update the permissions and add or remove the
113  * relevant files.
114  *
115  * The primary use for this function is to call it after making a change
116  * that affects group visibility.
117  *
118  * Returns 0 on success or error.
119  */
120 int sysfs_update_group(struct kobject *kobj,
121 		       const struct attribute_group *grp)
122 {
123 	return internal_create_group(kobj, 1, grp);
124 }
125 
126 
127 
128 void sysfs_remove_group(struct kobject * kobj,
129 			const struct attribute_group * grp)
130 {
131 	struct sysfs_dirent *dir_sd = kobj->sd;
132 	struct sysfs_dirent *sd;
133 
134 	if (grp->name) {
135 		sd = sysfs_get_dirent(dir_sd, grp->name);
136 		if (!sd) {
137 			printk(KERN_WARNING "sysfs group %p not found for "
138 				"kobject '%s'\n", grp, kobject_name(kobj));
139 			WARN_ON(!sd);
140 			return;
141 		}
142 	} else
143 		sd = sysfs_get(dir_sd);
144 
145 	remove_files(sd, kobj, grp);
146 	if (grp->name)
147 		sysfs_remove_subdir(sd);
148 
149 	sysfs_put(sd);
150 }
151 
152 
153 EXPORT_SYMBOL_GPL(sysfs_create_group);
154 EXPORT_SYMBOL_GPL(sysfs_update_group);
155 EXPORT_SYMBOL_GPL(sysfs_remove_group);
156