include/linux/configfs.h

0001 /* SPDX-License-Identifier: GPL-2.0-or-later */
0002 /*
0003  * configfs.h - definitions for the device driver filesystem
0004  *
0005  * Based on sysfs:
0006  *  sysfs is Copyright (C) 2001, 2002, 2003 Patrick Mochel
0007  *
0008  * Based on kobject.h:
0009  *      Copyright (c) 2002-2003 Patrick Mochel
0010  *      Copyright (c) 2002-2003 Open Source Development Labs
0011  *
0012  * configfs Copyright (C) 2005 Oracle.  All rights reserved.
0013  *
0014  * Please read Documentation/filesystems/configfs.rst before using
0015  * the configfs interface, ESPECIALLY the parts about reference counts and
0016  * item destructors.
0017  */
0018
0019 #ifndef _CONFIGFS_H_
0020 #define _CONFIGFS_H_
0021
0022 #include <linux/stat.h>   /* S_IRUGO */
0023 #include <linux/types.h>  /* ssize_t */
0024 #include <linux/list.h>   /* struct list_head */
0025 #include <linux/kref.h>   /* struct kref */
0026 #include <linux/mutex.h>  /* struct mutex */
0027
0028 #define CONFIGFS_ITEM_NAME_LEN  20
0029
0030 struct module;
0031
0032 struct configfs_item_operations;
0033 struct configfs_group_operations;
0034 struct configfs_attribute;
0035 struct configfs_bin_attribute;
0036 struct configfs_subsystem;
0037
0038 struct config_item {
0039     char            *ci_name;
0040     char            ci_namebuf[CONFIGFS_ITEM_NAME_LEN];
0041     struct kref     ci_kref;
0042     struct list_head    ci_entry;
0043     struct config_item  *ci_parent;
0044     struct config_group *ci_group;
0045     const struct config_item_type   *ci_type;
0046     struct dentry       *ci_dentry;
0047 };
0048
0049 extern __printf(2, 3)
0050 int config_item_set_name(struct config_item *, const char *, ...);
0051
0052 static inline char *config_item_name(struct config_item * item)
0053 {
0054     return item->ci_name;
0055 }
0056
0057 extern void config_item_init_type_name(struct config_item *item,
0058                        const char *name,
0059                        const struct config_item_type *type);
0060
0061 extern struct config_item *config_item_get(struct config_item *);
0062 extern struct config_item *config_item_get_unless_zero(struct config_item *);
0063 extern void config_item_put(struct config_item *);
0064
0065 struct config_item_type {
0066     struct module               *ct_owner;
0067     struct configfs_item_operations     *ct_item_ops;
0068     struct configfs_group_operations    *ct_group_ops;
0069     struct configfs_attribute       **ct_attrs;
0070     struct configfs_bin_attribute       **ct_bin_attrs;
0071 };
0072
0073 /**
0074  *  group - a group of config_items of a specific type, belonging
0075  *  to a specific subsystem.
0076  */
0077 struct config_group {
0078     struct config_item      cg_item;
0079     struct list_head        cg_children;
0080     struct configfs_subsystem   *cg_subsys;
0081     struct list_head        default_groups;
0082     struct list_head        group_entry;
0083 };
0084
0085 extern void config_group_init(struct config_group *group);
0086 extern void config_group_init_type_name(struct config_group *group,
0087                     const char *name,
0088                     const struct config_item_type *type);
0089
0090 static inline struct config_group *to_config_group(struct config_item *item)
0091 {
0092     return item ? container_of(item,struct config_group,cg_item) : NULL;
0093 }
0094
0095 static inline struct config_group *config_group_get(struct config_group *group)
0096 {
0097     return group ? to_config_group(config_item_get(&group->cg_item)) : NULL;
0098 }
0099
0100 static inline void config_group_put(struct config_group *group)
0101 {
0102     config_item_put(&group->cg_item);
0103 }
0104
0105 extern struct config_item *config_group_find_item(struct config_group *,
0106                           const char *);
0107
0108
0109 static inline void configfs_add_default_group(struct config_group *new_group,
0110         struct config_group *group)
0111 {
0112     list_add_tail(&new_group->group_entry, &group->default_groups);
0113 }
0114
0115 struct configfs_attribute {
0116     const char      *ca_name;
0117     struct module       *ca_owner;
0118     umode_t         ca_mode;
0119     ssize_t (*show)(struct config_item *, char *);
0120     ssize_t (*store)(struct config_item *, const char *, size_t);
0121 };
0122
0123 #define CONFIGFS_ATTR(_pfx, _name)          \
0124 static struct configfs_attribute _pfx##attr_##_name = { \
0125     .ca_name    = __stringify(_name),       \
0126     .ca_mode    = S_IRUGO | S_IWUSR,        \
0127     .ca_owner   = THIS_MODULE,          \
0128     .show       = _pfx##_name##_show,       \
0129     .store      = _pfx##_name##_store,      \
0130 }
0131
0132 #define CONFIGFS_ATTR_RO(_pfx, _name)           \
0133 static struct configfs_attribute _pfx##attr_##_name = { \
0134     .ca_name    = __stringify(_name),       \
0135     .ca_mode    = S_IRUGO,          \
0136     .ca_owner   = THIS_MODULE,          \
0137     .show       = _pfx##_name##_show,       \
0138 }
0139
0140 #define CONFIGFS_ATTR_WO(_pfx, _name)           \
0141 static struct configfs_attribute _pfx##attr_##_name = { \
0142     .ca_name    = __stringify(_name),       \
0143     .ca_mode    = S_IWUSR,          \
0144     .ca_owner   = THIS_MODULE,          \
0145     .store      = _pfx##_name##_store,      \
0146 }
0147
0148 struct file;
0149 struct vm_area_struct;
0150
0151 struct configfs_bin_attribute {
0152     struct configfs_attribute cb_attr;  /* std. attribute */
0153     void *cb_private;           /* for user       */
0154     size_t cb_max_size;         /* max core size  */
0155     ssize_t (*read)(struct config_item *, void *, size_t);
0156     ssize_t (*write)(struct config_item *, const void *, size_t);
0157 };
0158
0159 #define CONFIGFS_BIN_ATTR(_pfx, _name, _priv, _maxsz)       \
0160 static struct configfs_bin_attribute _pfx##attr_##_name = { \
0161     .cb_attr = {                        \
0162         .ca_name    = __stringify(_name),       \
0163         .ca_mode    = S_IRUGO | S_IWUSR,        \
0164         .ca_owner   = THIS_MODULE,          \
0165     },                          \
0166     .cb_private = _priv,                \
0167     .cb_max_size    = _maxsz,               \
0168     .read       = _pfx##_name##_read,           \
0169     .write      = _pfx##_name##_write,          \
0170 }
0171
0172 #define CONFIGFS_BIN_ATTR_RO(_pfx, _name, _priv, _maxsz)    \
0173 static struct configfs_bin_attribute _pfx##attr_##_name = { \
0174     .cb_attr = {                        \
0175         .ca_name    = __stringify(_name),       \
0176         .ca_mode    = S_IRUGO,          \
0177         .ca_owner   = THIS_MODULE,          \
0178     },                          \
0179     .cb_private = _priv,                \
0180     .cb_max_size    = _maxsz,               \
0181     .read       = _pfx##_name##_read,           \
0182 }
0183
0184 #define CONFIGFS_BIN_ATTR_WO(_pfx, _name, _priv, _maxsz)    \
0185 static struct configfs_bin_attribute _pfx##attr_##_name = { \
0186     .cb_attr = {                        \
0187         .ca_name    = __stringify(_name),       \
0188         .ca_mode    = S_IWUSR,          \
0189         .ca_owner   = THIS_MODULE,          \
0190     },                          \
0191     .cb_private = _priv,                \
0192     .cb_max_size    = _maxsz,               \
0193     .write      = _pfx##_name##_write,          \
0194 }
0195
0196 /*
0197  * If allow_link() exists, the item can symlink(2) out to other
0198  * items.  If the item is a group, it may support mkdir(2).
0199  * Groups supply one of make_group() and make_item().  If the
0200  * group supports make_group(), one can create group children.  If it
0201  * supports make_item(), one can create config_item children.  make_group()
0202  * and make_item() return ERR_PTR() on errors.  If it has
0203  * default_groups on group->default_groups, it has automatically created
0204  * group children.  default_groups may coexist alongsize make_group() or
0205  * make_item(), but if the group wishes to have only default_groups
0206  * children (disallowing mkdir(2)), it need not provide either function.
0207  * If the group has commit(), it supports pending and committed (active)
0208  * items.
0209  */
0210 struct configfs_item_operations {
0211     void (*release)(struct config_item *);
0212     int (*allow_link)(struct config_item *src, struct config_item *target);
0213     void (*drop_link)(struct config_item *src, struct config_item *target);
0214 };
0215
0216 struct configfs_group_operations {
0217     struct config_item *(*make_item)(struct config_group *group, const char *name);
0218     struct config_group *(*make_group)(struct config_group *group, const char *name);
0219     int (*commit_item)(struct config_item *item);
0220     void (*disconnect_notify)(struct config_group *group, struct config_item *item);
0221     void (*drop_item)(struct config_group *group, struct config_item *item);
0222 };
0223
0224 struct configfs_subsystem {
0225     struct config_group su_group;
0226     struct mutex        su_mutex;
0227 };
0228
0229 static inline struct configfs_subsystem *to_configfs_subsystem(struct config_group *group)
0230 {
0231     return group ?
0232         container_of(group, struct configfs_subsystem, su_group) :
0233         NULL;
0234 }
0235
0236 int configfs_register_subsystem(struct configfs_subsystem *subsys);
0237 void configfs_unregister_subsystem(struct configfs_subsystem *subsys);
0238
0239 int configfs_register_group(struct config_group *parent_group,
0240                 struct config_group *group);
0241 void configfs_unregister_group(struct config_group *group);
0242
0243 void configfs_remove_default_groups(struct config_group *group);
0244
0245 struct config_group *
0246 configfs_register_default_group(struct config_group *parent_group,
0247                 const char *name,
0248                 const struct config_item_type *item_type);
0249 void configfs_unregister_default_group(struct config_group *group);
0250
0251 /* These functions can sleep and can alloc with GFP_KERNEL */
0252 /* WARNING: These cannot be called underneath configfs callbacks!! */
0253 int configfs_depend_item(struct configfs_subsystem *subsys,
0254              struct config_item *target);
0255 void configfs_undepend_item(struct config_item *target);
0256
0257 /*
0258  * These functions can sleep and can alloc with GFP_KERNEL
0259  * NOTE: These should be called only underneath configfs callbacks.
0260  * NOTE: First parameter is a caller's subsystem, not target's.
0261  * WARNING: These cannot be called on newly created item
0262  *        (in make_group()/make_item() callback)
0263  */
0264 int configfs_depend_item_unlocked(struct configfs_subsystem *caller_subsys,
0265                   struct config_item *target);
0266
0267
0268 static inline void configfs_undepend_item_unlocked(struct config_item *target)
0269 {
0270     configfs_undepend_item(target);
0271 }
0272
0273 #endif /* _CONFIGFS_H_ */