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, NULL, (*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, NULL, (*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, NULL, grp->name); 136 if (!sd) { 137 WARN(!sd, KERN_WARNING "sysfs group %p not found for " 138 "kobject '%s'\n", grp, kobject_name(kobj)); 139 return; 140 } 141 } else 142 sd = sysfs_get(dir_sd); 143 144 remove_files(sd, kobj, grp); 145 if (grp->name) 146 sysfs_remove_subdir(sd); 147 148 sysfs_put(sd); 149 } 150 151 152 EXPORT_SYMBOL_GPL(sysfs_create_group); 153 EXPORT_SYMBOL_GPL(sysfs_update_group); 154 EXPORT_SYMBOL_GPL(sysfs_remove_group); 155