fs/sysfs/group.c

   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  * Copyright (c) 2013 Greg Kroah-Hartman
   7  * Copyright (c) 2013 The Linux Foundation
   8  *
   9  * This file is released undert the GPL v2.
  10  *
  11  */
  12
  13 #include <linux/kobject.h>
  14 #include <linux/module.h>
  15 #include <linux/dcache.h>
  16 #include <linux/namei.h>
  17 #include <linux/err.h>
  18 #include "sysfs.h"
  19
  20
  21 static void remove_files(struct sysfs_dirent *dir_sd, struct kobject *kobj,
  22                          const struct attribute_group *grp)
  23 {
  24         struct attribute *const *attr;
  25         struct bin_attribute *const *bin_attr;
  26
  27         if (grp->attrs)
  28                 for (attr = grp->attrs; *attr; attr++)
  29                         sysfs_hash_and_remove(dir_sd, NULL, (*attr)->name);
  30         if (grp->bin_attrs)
  31                 for (bin_attr = grp->bin_attrs; *bin_attr; bin_attr++)
  32                         sysfs_remove_bin_file(kobj, *bin_attr);
  33 }
  34
  35 static int create_files(struct sysfs_dirent *dir_sd, struct kobject *kobj,
  36                         const struct attribute_group *grp, int update)
  37 {
  38         struct attribute *const *attr;
  39         struct bin_attribute *const *bin_attr;
  40         int error = 0, i;
  41
  42         if (grp->attrs) {
  43                 for (i = 0, attr = grp->attrs; *attr && !error; i++, attr++) {
  44                         umode_t mode = 0;
  45
  46                         /*
  47                          * In update mode, we're changing the permissions or
  48                          * visibility.  Do this by first removing then
  49                          * re-adding (if required) the file.
  50                          */
  51                         if (update)
  52                                 sysfs_hash_and_remove(dir_sd, NULL,
  53                                                       (*attr)->name);
  54                         if (grp->is_visible) {
  55                                 mode = grp->is_visible(kobj, *attr, i);
  56                                 if (!mode)
  57                                         continue;
  58                         }
  59                         error = sysfs_add_file_mode(dir_sd, *attr,
  60                                                     SYSFS_KOBJ_ATTR,
  61                                                     (*attr)->mode | mode);
  62                         if (unlikely(error))
  63                                 break;
  64                 }
  65                 if (error) {
  66                         remove_files(dir_sd, kobj, grp);
  67                         goto exit;
  68                 }
  69         }
  70
  71         if (grp->bin_attrs) {
  72                 for (bin_attr = grp->bin_attrs; *bin_attr; bin_attr++) {
  73                         if (update)
  74                                 sysfs_remove_bin_file(kobj, *bin_attr);
  75                         error = sysfs_create_bin_file(kobj, *bin_attr);
  76                         if (error)
  77                                 break;
  78                 }
  79                 if (error)
  80                         remove_files(dir_sd, kobj, grp);
  81         }
  82 exit:
  83         return error;
  84 }
  85
  86
  87 static int internal_create_group(struct kobject *kobj, int update,
  88                                  const struct attribute_group *grp)
  89 {
  90         struct sysfs_dirent *sd;
  91         int error;
  92
  93         BUG_ON(!kobj || (!update && !kobj->sd));
  94
  95         /* Updates may happen before the object has been instantiated */
  96         if (unlikely(update && !kobj->sd))
  97                 return -EINVAL;
  98         if (!grp->attrs && !grp->bin_attrs) {
  99                 WARN(1, "sysfs: (bin_)attrs not set by subsystem for group: %s/%s\n",
 100                         kobj->name, grp->name ? "" : grp->name);
 101                 return -EINVAL;
 102         }
 103         if (grp->name) {
 104                 error = sysfs_create_subdir(kobj, grp->name, &sd);
 105                 if (error)
 106                         return error;
 107         } else
 108                 sd = kobj->sd;
 109         sysfs_get(sd);
 110         error = create_files(sd, kobj, grp, update);
 111         if (error) {
 112                 if (grp->name)
 113                         sysfs_remove_subdir(sd);
 114         }
 115         sysfs_put(sd);
 116         return error;
 117 }
 118
 119 /**
 120  * sysfs_create_group - given a directory kobject, create an attribute group
 121  * @kobj:       The kobject to create the group on
 122  * @grp:        The attribute group to create
 123  *
 124  * This function creates a group for the first time.  It will explicitly
 125  * warn and error if any of the attribute files being created already exist.
 126  *
 127  * Returns 0 on success or error.
 128  */
 129 int sysfs_create_group(struct kobject *kobj,
 130                        const struct attribute_group *grp)
 131 {
 132         return internal_create_group(kobj, 0, grp);
 133 }
 134 EXPORT_SYMBOL_GPL(sysfs_create_group);
 135
 136 /**
 137  * sysfs_create_groups - given a directory kobject, create a bunch of attribute groups
 138  * @kobj:       The kobject to create the group on
 139  * @groups:     The attribute groups to create, NULL terminated
 140  *
 141  * This function creates a bunch of attribute groups.  If an error occurs when
 142  * creating a group, all previously created groups will be removed, unwinding
 143  * everything back to the original state when this function was called.
 144  * It will explicitly warn and error if any of the attribute files being
 145  * created already exist.
 146  *
 147  * Returns 0 on success or error code from sysfs_create_group on error.
 148  */
 149 int sysfs_create_groups(struct kobject *kobj,
 150                         const struct attribute_group **groups)
 151 {
 152         int error = 0;
 153         int i;
 154
 155         if (!groups)
 156                 return 0;
 157
 158         for (i = 0; groups[i]; i++) {
 159                 error = sysfs_create_group(kobj, groups[i]);
 160                 if (error) {
 161                         while (--i >= 0)
 162                                 sysfs_remove_group(kobj, groups[i]);
 163                         break;
 164                 }
 165         }
 166         return error;
 167 }
 168 EXPORT_SYMBOL_GPL(sysfs_create_groups);
 169
 170 /**
 171  * sysfs_update_group - given a directory kobject, update an attribute group
 172  * @kobj:       The kobject to update the group on
 173  * @grp:        The attribute group to update
 174  *
 175  * This function updates an attribute group.  Unlike
 176  * sysfs_create_group(), it will explicitly not warn or error if any
 177  * of the attribute files being created already exist.  Furthermore,
 178  * if the visibility of the files has changed through the is_visible()
 179  * callback, it will update the permissions and add or remove the
 180  * relevant files.
 181  *
 182  * The primary use for this function is to call it after making a change
 183  * that affects group visibility.
 184  *
 185  * Returns 0 on success or error.
 186  */
 187 int sysfs_update_group(struct kobject *kobj,
 188                        const struct attribute_group *grp)
 189 {
 190         return internal_create_group(kobj, 1, grp);
 191 }
 192 EXPORT_SYMBOL_GPL(sysfs_update_group);
 193
 194 /**
 195  * sysfs_remove_group: remove a group from a kobject
 196  * @kobj:       kobject to remove the group from
 197  * @grp:        group to remove
 198  *
 199  * This function removes a group of attributes from a kobject.  The attributes
 200  * previously have to have been created for this group, otherwise it will fail.
 201  */
 202 void sysfs_remove_group(struct kobject *kobj,
 203                         const struct attribute_group *grp)
 204 {
 205         struct sysfs_dirent *dir_sd = kobj->sd;
 206         struct sysfs_dirent *sd;
 207
 208         if (grp->name) {
 209                 sd = sysfs_get_dirent(dir_sd, NULL, grp->name);
 210                 if (!sd) {
 211                         WARN(!sd, KERN_WARNING
 212                              "sysfs group %p not found for kobject '%s'\n",
 213                              grp, kobject_name(kobj));
 214                         return;
 215                 }
 216         } else
 217                 sd = sysfs_get(dir_sd);
 218
 219         remove_files(sd, kobj, grp);
 220         if (grp->name)
 221                 sysfs_remove_subdir(sd);
 222
 223         sysfs_put(sd);
 224 }
 225 EXPORT_SYMBOL_GPL(sysfs_remove_group);
 226
 227 /**
 228  * sysfs_remove_groups - remove a list of groups
 229  *
 230  * @kobj:       The kobject for the groups to be removed from
 231  * @groups:     NULL terminated list of groups to be removed
 232  *
 233  * If groups is not NULL, remove the specified groups from the kobject.
 234  */
 235 void sysfs_remove_groups(struct kobject *kobj,
 236                          const struct attribute_group **groups)
 237 {
 238         int i;
 239
 240         if (!groups)
 241                 return;
 242         for (i = 0; groups[i]; i++)
 243                 sysfs_remove_group(kobj, groups[i]);
 244 }
 245 EXPORT_SYMBOL_GPL(sysfs_remove_groups);
 246
 247 /**
 248  * sysfs_merge_group - merge files into a pre-existing attribute group.
 249  * @kobj:       The kobject containing the group.
 250  * @grp:        The files to create and the attribute group they belong to.
 251  *
 252  * This function returns an error if the group doesn't exist or any of the
 253  * files already exist in that group, in which case none of the new files
 254  * are created.
 255  */
 256 int sysfs_merge_group(struct kobject *kobj,
 257                        const struct attribute_group *grp)
 258 {
 259         struct sysfs_dirent *dir_sd;
 260         int error = 0;
 261         struct attribute *const *attr;
 262         int i;
 263
 264         dir_sd = sysfs_get_dirent(kobj->sd, NULL, grp->name);
 265         if (!dir_sd)
 266                 return -ENOENT;
 267
 268         for ((i = 0, attr = grp->attrs); *attr && !error; (++i, ++attr))
 269                 error = sysfs_add_file(dir_sd, *attr, SYSFS_KOBJ_ATTR);
 270         if (error) {
 271                 while (--i >= 0)
 272                         sysfs_hash_and_remove(dir_sd, NULL, (*--attr)->name);
 273         }
 274         sysfs_put(dir_sd);
 275
 276         return error;
 277 }
 278 EXPORT_SYMBOL_GPL(sysfs_merge_group);
 279
 280 /**
 281  * sysfs_unmerge_group - remove files from a pre-existing attribute group.
 282  * @kobj:       The kobject containing the group.
 283  * @grp:        The files to remove and the attribute group they belong to.
 284  */
 285 void sysfs_unmerge_group(struct kobject *kobj,
 286                        const struct attribute_group *grp)
 287 {
 288         struct sysfs_dirent *dir_sd;
 289         struct attribute *const *attr;
 290
 291         dir_sd = sysfs_get_dirent(kobj->sd, NULL, grp->name);
 292         if (dir_sd) {
 293                 for (attr = grp->attrs; *attr; ++attr)
 294                         sysfs_hash_and_remove(dir_sd, NULL, (*attr)->name);
 295                 sysfs_put(dir_sd);
 296         }
 297 }
 298 EXPORT_SYMBOL_GPL(sysfs_unmerge_group);
 299
 300 /**
 301  * sysfs_add_link_to_group - add a symlink to an attribute group.
 302  * @kobj:       The kobject containing the group.
 303  * @group_name: The name of the group.
 304  * @target:     The target kobject of the symlink to create.
 305  * @link_name:  The name of the symlink to create.
 306  */
 307 int sysfs_add_link_to_group(struct kobject *kobj, const char *group_name,
 308                             struct kobject *target, const char *link_name)
 309 {
 310         struct sysfs_dirent *dir_sd;
 311         int error = 0;
 312
 313         dir_sd = sysfs_get_dirent(kobj->sd, NULL, group_name);
 314         if (!dir_sd)
 315                 return -ENOENT;
 316
 317         error = sysfs_create_link_sd(dir_sd, target, link_name);
 318         sysfs_put(dir_sd);
 319
 320         return error;
 321 }
 322 EXPORT_SYMBOL_GPL(sysfs_add_link_to_group);
 323
 324 /**
 325  * sysfs_remove_link_from_group - remove a symlink from an attribute group.
 326  * @kobj:       The kobject containing the group.
 327  * @group_name: The name of the group.
 328  * @link_name:  The name of the symlink to remove.
 329  */
 330 void sysfs_remove_link_from_group(struct kobject *kobj, const char *group_name,
 331                                   const char *link_name)
 332 {
 333         struct sysfs_dirent *dir_sd;
 334
 335         dir_sd = sysfs_get_dirent(kobj->sd, NULL, group_name);
 336         if (dir_sd) {
 337                 sysfs_hash_and_remove(dir_sd, NULL, link_name);
 338                 sysfs_put(dir_sd);
 339         }
 340 }
 341 EXPORT_SYMBOL_GPL(sysfs_remove_link_from_group);