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TOMOYO Linux Cross Reference
Linux/fs/configfs/item.c

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  1 // SPDX-License-Identifier: GPL-2.0-or-later
  2 /* -*- mode: c; c-basic-offset: 8; -*-
  3  * vim: noexpandtab sw=8 ts=8 sts=0:
  4  *
  5  * item.c - library routines for handling generic config items
  6  *
  7  * Based on kobject:
  8  *      kobject is Copyright (c) 2002-2003 Patrick Mochel
  9  *
 10  * configfs Copyright (C) 2005 Oracle.  All rights reserved.
 11  *
 12  * Please see the file Documentation/filesystems/configfs/configfs.txt for
 13  * critical information about using the config_item interface.
 14  */
 15 
 16 #include <linux/string.h>
 17 #include <linux/module.h>
 18 #include <linux/stat.h>
 19 #include <linux/slab.h>
 20 
 21 #include <linux/configfs.h>
 22 
 23 
 24 static inline struct config_item *to_item(struct list_head *entry)
 25 {
 26         return container_of(entry, struct config_item, ci_entry);
 27 }
 28 
 29 /* Evil kernel */
 30 static void config_item_release(struct kref *kref);
 31 
 32 /**
 33  *      config_item_init - initialize item.
 34  *      @item:  item in question.
 35  */
 36 static void config_item_init(struct config_item *item)
 37 {
 38         kref_init(&item->ci_kref);
 39         INIT_LIST_HEAD(&item->ci_entry);
 40 }
 41 
 42 /**
 43  *      config_item_set_name - Set the name of an item
 44  *      @item:  item.
 45  *      @fmt:  The vsnprintf()'s format string.
 46  *
 47  *      If strlen(name) >= CONFIGFS_ITEM_NAME_LEN, then use a
 48  *      dynamically allocated string that @item->ci_name points to.
 49  *      Otherwise, use the static @item->ci_namebuf array.
 50  */
 51 int config_item_set_name(struct config_item *item, const char *fmt, ...)
 52 {
 53         int limit = CONFIGFS_ITEM_NAME_LEN;
 54         int need;
 55         va_list args;
 56         char *name;
 57 
 58         /*
 59          * First, try the static array
 60          */
 61         va_start(args, fmt);
 62         need = vsnprintf(item->ci_namebuf, limit, fmt, args);
 63         va_end(args);
 64         if (need < limit)
 65                 name = item->ci_namebuf;
 66         else {
 67                 va_start(args, fmt);
 68                 name = kvasprintf(GFP_KERNEL, fmt, args);
 69                 va_end(args);
 70                 if (!name)
 71                         return -EFAULT;
 72         }
 73 
 74         /* Free the old name, if necessary. */
 75         if (item->ci_name && item->ci_name != item->ci_namebuf)
 76                 kfree(item->ci_name);
 77 
 78         /* Now, set the new name */
 79         item->ci_name = name;
 80         return 0;
 81 }
 82 EXPORT_SYMBOL(config_item_set_name);
 83 
 84 void config_item_init_type_name(struct config_item *item,
 85                                 const char *name,
 86                                 const struct config_item_type *type)
 87 {
 88         config_item_set_name(item, "%s", name);
 89         item->ci_type = type;
 90         config_item_init(item);
 91 }
 92 EXPORT_SYMBOL(config_item_init_type_name);
 93 
 94 void config_group_init_type_name(struct config_group *group, const char *name,
 95                          const struct config_item_type *type)
 96 {
 97         config_item_set_name(&group->cg_item, "%s", name);
 98         group->cg_item.ci_type = type;
 99         config_group_init(group);
100 }
101 EXPORT_SYMBOL(config_group_init_type_name);
102 
103 struct config_item *config_item_get(struct config_item *item)
104 {
105         if (item)
106                 kref_get(&item->ci_kref);
107         return item;
108 }
109 EXPORT_SYMBOL(config_item_get);
110 
111 struct config_item *config_item_get_unless_zero(struct config_item *item)
112 {
113         if (item && kref_get_unless_zero(&item->ci_kref))
114                 return item;
115         return NULL;
116 }
117 EXPORT_SYMBOL(config_item_get_unless_zero);
118 
119 static void config_item_cleanup(struct config_item *item)
120 {
121         const struct config_item_type *t = item->ci_type;
122         struct config_group *s = item->ci_group;
123         struct config_item *parent = item->ci_parent;
124 
125         pr_debug("config_item %s: cleaning up\n", config_item_name(item));
126         if (item->ci_name != item->ci_namebuf)
127                 kfree(item->ci_name);
128         item->ci_name = NULL;
129         if (t && t->ct_item_ops && t->ct_item_ops->release)
130                 t->ct_item_ops->release(item);
131         if (s)
132                 config_group_put(s);
133         if (parent)
134                 config_item_put(parent);
135 }
136 
137 static void config_item_release(struct kref *kref)
138 {
139         config_item_cleanup(container_of(kref, struct config_item, ci_kref));
140 }
141 
142 /**
143  *      config_item_put - decrement refcount for item.
144  *      @item:  item.
145  *
146  *      Decrement the refcount, and if 0, call config_item_cleanup().
147  */
148 void config_item_put(struct config_item *item)
149 {
150         if (item)
151                 kref_put(&item->ci_kref, config_item_release);
152 }
153 EXPORT_SYMBOL(config_item_put);
154 
155 /**
156  *      config_group_init - initialize a group for use
157  *      @group: config_group
158  */
159 void config_group_init(struct config_group *group)
160 {
161         config_item_init(&group->cg_item);
162         INIT_LIST_HEAD(&group->cg_children);
163         INIT_LIST_HEAD(&group->default_groups);
164 }
165 EXPORT_SYMBOL(config_group_init);
166 
167 /**
168  *      config_group_find_item - search for item in group.
169  *      @group: group we're looking in.
170  *      @name:  item's name.
171  *
172  *      Iterate over @group->cg_list, looking for a matching config_item.
173  *      If matching item is found take a reference and return the item.
174  *      Caller must have locked group via @group->cg_subsys->su_mtx.
175  */
176 struct config_item *config_group_find_item(struct config_group *group,
177                                            const char *name)
178 {
179         struct list_head *entry;
180         struct config_item *ret = NULL;
181 
182         list_for_each(entry, &group->cg_children) {
183                 struct config_item *item = to_item(entry);
184                 if (config_item_name(item) &&
185                     !strcmp(config_item_name(item), name)) {
186                         ret = config_item_get(item);
187                         break;
188                 }
189         }
190         return ret;
191 }
192 EXPORT_SYMBOL(config_group_find_item);
193 

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