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  *
   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                         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);