linux/fs/sysfs/group.c
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   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
  19static 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
  29static 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                umode_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
  59static 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        if (!grp->attrs) {
  71                WARN(1, "sysfs: attrs not set by subsystem for group: %s/%s\n",
  72                        kobj->name, grp->name ? "" : grp->name);
  73                return -EINVAL;
  74        }
  75        if (grp->name) {
  76                error = sysfs_create_subdir(kobj, grp->name, &sd);
  77                if (error)
  78                        return error;
  79        } else
  80                sd = kobj->sd;
  81        sysfs_get(sd);
  82        error = create_files(sd, kobj, grp, update);
  83        if (error) {
  84                if (grp->name)
  85                        sysfs_remove_subdir(sd);
  86        }
  87        sysfs_put(sd);
  88        return error;
  89}
  90
  91/**
  92 * sysfs_create_group - given a directory kobject, create an attribute group
  93 * @kobj:       The kobject to create the group on
  94 * @grp:        The attribute group to create
  95 *
  96 * This function creates a group for the first time.  It will explicitly
  97 * warn and error if any of the attribute files being created already exist.
  98 *
  99 * Returns 0 on success or error.
 100 */
 101int sysfs_create_group(struct kobject *kobj,
 102                       const struct attribute_group *grp)
 103{
 104        return internal_create_group(kobj, 0, grp);
 105}
 106
 107/**
 108 * sysfs_update_group - given a directory kobject, update an attribute group
 109 * @kobj:       The kobject to update the group on
 110 * @grp:        The attribute group to update
 111 *
 112 * This function updates an attribute group.  Unlike
 113 * sysfs_create_group(), it will explicitly not warn or error if any
 114 * of the attribute files being created already exist.  Furthermore,
 115 * if the visibility of the files has changed through the is_visible()
 116 * callback, it will update the permissions and add or remove the
 117 * relevant files.
 118 *
 119 * The primary use for this function is to call it after making a change
 120 * that affects group visibility.
 121 *
 122 * Returns 0 on success or error.
 123 */
 124int sysfs_update_group(struct kobject *kobj,
 125                       const struct attribute_group *grp)
 126{
 127        return internal_create_group(kobj, 1, grp);
 128}
 129
 130
 131
 132void sysfs_remove_group(struct kobject * kobj, 
 133                        const struct attribute_group * grp)
 134{
 135        struct sysfs_dirent *dir_sd = kobj->sd;
 136        struct sysfs_dirent *sd;
 137
 138        if (grp->name) {
 139                sd = sysfs_get_dirent(dir_sd, NULL, grp->name);
 140                if (!sd) {
 141                        WARN(!sd, KERN_WARNING "sysfs group %p not found for "
 142                                "kobject '%s'\n", grp, kobject_name(kobj));
 143                        return;
 144                }
 145        } else
 146                sd = sysfs_get(dir_sd);
 147
 148        remove_files(sd, kobj, grp);
 149        if (grp->name)
 150                sysfs_remove_subdir(sd);
 151
 152        sysfs_put(sd);
 153}
 154
 155/**
 156 * sysfs_merge_group - merge files into a pre-existing attribute group.
 157 * @kobj:       The kobject containing the group.
 158 * @grp:        The files to create and the attribute group they belong to.
 159 *
 160 * This function returns an error if the group doesn't exist or any of the
 161 * files already exist in that group, in which case none of the new files
 162 * are created.
 163 */
 164int sysfs_merge_group(struct kobject *kobj,
 165                       const struct attribute_group *grp)
 166{
 167        struct sysfs_dirent *dir_sd;
 168        int error = 0;
 169        struct attribute *const *attr;
 170        int i;
 171
 172        dir_sd = sysfs_get_dirent(kobj->sd, NULL, grp->name);
 173        if (!dir_sd)
 174                return -ENOENT;
 175
 176        for ((i = 0, attr = grp->attrs); *attr && !error; (++i, ++attr))
 177                error = sysfs_add_file(dir_sd, *attr, SYSFS_KOBJ_ATTR);
 178        if (error) {
 179                while (--i >= 0)
 180                        sysfs_hash_and_remove(dir_sd, NULL, (*--attr)->name);
 181        }
 182        sysfs_put(dir_sd);
 183
 184        return error;
 185}
 186EXPORT_SYMBOL_GPL(sysfs_merge_group);
 187
 188/**
 189 * sysfs_unmerge_group - remove files from a pre-existing attribute group.
 190 * @kobj:       The kobject containing the group.
 191 * @grp:        The files to remove and the attribute group they belong to.
 192 */
 193void sysfs_unmerge_group(struct kobject *kobj,
 194                       const struct attribute_group *grp)
 195{
 196        struct sysfs_dirent *dir_sd;
 197        struct attribute *const *attr;
 198
 199        dir_sd = sysfs_get_dirent(kobj->sd, NULL, grp->name);
 200        if (dir_sd) {
 201                for (attr = grp->attrs; *attr; ++attr)
 202                        sysfs_hash_and_remove(dir_sd, NULL, (*attr)->name);
 203                sysfs_put(dir_sd);
 204        }
 205}
 206EXPORT_SYMBOL_GPL(sysfs_unmerge_group);
 207
 208
 209EXPORT_SYMBOL_GPL(sysfs_create_group);
 210EXPORT_SYMBOL_GPL(sysfs_update_group);
 211EXPORT_SYMBOL_GPL(sysfs_remove_group);
 212
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