diff options
Diffstat (limited to 'include/linux/configfs.h')
| -rw-r--r-- | include/linux/configfs.h | 71 |
1 files changed, 68 insertions, 3 deletions
diff --git a/include/linux/configfs.h b/include/linux/configfs.h index 3ae65b1bf90..7f627775c94 100644 --- a/include/linux/configfs.h +++ b/include/linux/configfs.h @@ -40,6 +40,7 @@ #include <linux/list.h> #include <linux/kref.h> #include <linux/mutex.h> +#include <linux/err.h> #include <asm/atomic.h> @@ -129,8 +130,25 @@ struct configfs_attribute { /* * Users often need to create attribute structures for their configurable * attributes, containing a configfs_attribute member and function pointers - * for the show() and store() operations on that attribute. They can use - * this macro (similar to sysfs' __ATTR) to make defining attributes easier. + * for the show() and store() operations on that attribute. If they don't + * need anything else on the extended attribute structure, they can use + * this macro to define it The argument _item is the name of the + * config_item structure. + */ +#define CONFIGFS_ATTR_STRUCT(_item) \ +struct _item##_attribute { \ + struct configfs_attribute attr; \ + ssize_t (*show)(struct _item *, char *); \ + ssize_t (*store)(struct _item *, const char *, size_t); \ +} + +/* + * With the extended attribute structure, users can use this macro + * (similar to sysfs' __ATTR) to make defining attributes easier. + * An example: + * #define MYITEM_ATTR(_name, _mode, _show, _store) \ + * struct myitem_attribute childless_attr_##_name = \ + * __CONFIGFS_ATTR(_name, _mode, _show, _store) */ #define __CONFIGFS_ATTR(_name, _mode, _show, _store) \ { \ @@ -142,13 +160,60 @@ struct configfs_attribute { .show = _show, \ .store = _store, \ } +/* Here is a readonly version, only requiring a show() operation */ +#define __CONFIGFS_ATTR_RO(_name, _show) \ +{ \ + .attr = { \ + .ca_name = __stringify(_name), \ + .ca_mode = 0444, \ + .ca_owner = THIS_MODULE, \ + }, \ + .show = _show, \ +} + +/* + * With these extended attributes, the simple show_attribute() and + * store_attribute() operations need to call the show() and store() of the + * attributes. This is a common pattern, so we provide a macro to define + * them. The argument _item is the name of the config_item structure. + * This macro expects the attributes to be named "struct <name>_attribute" + * and the function to_<name>() to exist; + */ +#define CONFIGFS_ATTR_OPS(_item) \ +static ssize_t _item##_attr_show(struct config_item *item, \ + struct configfs_attribute *attr, \ + char *page) \ +{ \ + struct _item *_item = to_##_item(item); \ + struct _item##_attribute *_item##_attr = \ + container_of(attr, struct _item##_attribute, attr); \ + ssize_t ret = 0; \ + \ + if (_item##_attr->show) \ + ret = _item##_attr->show(_item, page); \ + return ret; \ +} \ +static ssize_t _item##_attr_store(struct config_item *item, \ + struct configfs_attribute *attr, \ + const char *page, size_t count) \ +{ \ + struct _item *_item = to_##_item(item); \ + struct _item##_attribute *_item##_attr = \ + container_of(attr, struct _item##_attribute, attr); \ + ssize_t ret = -EINVAL; \ + \ + if (_item##_attr->store) \ + ret = _item##_attr->store(_item, page, count); \ + return ret; \ +} /* * If allow_link() exists, the item can symlink(2) out to other * items. If the item is a group, it may support mkdir(2). * Groups supply one of make_group() and make_item(). If the * group supports make_group(), one can create group children. If it - * supports make_item(), one can create config_item children. If it has + * supports make_item(), one can create config_item children. make_group() + * and make_item() return ERR_PTR() on errors. If it has * default_groups on group->default_groups, it has automatically created * group children. default_groups may coexist alongsize make_group() or * make_item(), but if the group wishes to have only default_groups |