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SubjectPATCH] [ConfigFS]: Extend CONFIGFS_ATTR_STRUCT() and CONFIGFS_ATTR_OPS() macros
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Hi Joel,

What do you think..?

Also, here is the drivers/lio-core/iscsi_target_configfs.c commit to
convert to use to new parameters for CONFIGFS_ATTR_STRUCT() and
CONFIGFS_ATTR_OPS():

http://git.kernel.org/?p=linux/kernel/git/nab/lio-core-2.6.git;a=commitdiff;h=e305460ebaa92ce1f8542a55bd62648904fb2fd6

I don't see anyone except for drivers/lio-core and
Documentation/filesystems/configfs/ using these macros.. If I can get
an ACK I would be happy to update the examples.

--nab


>From 71fc659e337dcc5941f6f64f6c8abfb6b477fd7c Mon Sep 17 00:00:00 2001
From: Nicholas Bellinger <nab@linux-iscsi.org>
Date: Wed, 22 Oct 2008 14:49:01 -0700
Subject: [PATCH] [ConfigFS]: Extend CONFIGFS_ATTR_STRUCT() and CONFIGFS_ATTR_OPS() macros

Extend CONFIGFS_ATTR_STRUCT() and CONFIGFS_ATTR_OPS() macros to allow
multiple struct config_item or struct config_group to hang off the same
structure. This means the previous '_item' arguement gets split into
'_name' (for function and attribute structure names) and '_item' (the
struct _item used throughout the macros that contains
struct _item->my_config_group.

This patch also removed the requirement for code using these macros to
provide their own 'to_<name>()' function, which is now defined by
CONFIGFS_ATTR_OPS() by passing the '_item_member' argument which is
used inside of to_##_name() for locating struct _item *_item = container_of().

Signed-off-by: Nicholas A. Bellinger <nab@linux-iscsi.org>
---
include/linux/configfs.h | 51 ++++++++++++++++++++++++++++------------------
1 files changed, 31 insertions(+), 20 deletions(-)

diff --git a/include/linux/configfs.h b/include/linux/configfs.h
index 7f62777..2eab7ef 100644
--- a/include/linux/configfs.h
+++ b/include/linux/configfs.h
@@ -132,11 +132,13 @@ struct configfs_attribute {
* attributes, containing a configfs_attribute member and function pointers
* 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.
+ * this macro to define it. The argument _name isends up as
+ * 'struct _name_attribute, as well as names of to CONFIGFS_ATTR_OPS() below.
+ * The argument _item is the name of the structure containing the
+ * struct config_item or struct config_group structure members
*/
-#define CONFIGFS_ATTR_STRUCT(_item) \
-struct _item##_attribute { \
+#define CONFIGFS_ATTR_STRUCT(_name, _item) \
+struct _name##_attribute { \
struct configfs_attribute attr; \
ssize_t (*show)(struct _item *, char *); \
ssize_t (*store)(struct _item *, const char *, size_t); \
@@ -175,35 +177,44 @@ struct _item##_attribute { \
* 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;
+ * them. The argument _name is the name of the attribute defined by
+ * CONFIGFS_ATTR_STRUCT(). The argument _item is the name of the structure
+ * containing the struct config_item or struct config_group structure member.
+ * The argument _item_member is the actual name of the struct config_* struct
+ * in your _item structure. Meaning my_structure->some_config_group.
+ * ^^_item^^^^^ ^^_item_member^^^
+ * This macro expects the attributes to be named "struct <name>_attribute".
*/
-#define CONFIGFS_ATTR_OPS(_item) \
-static ssize_t _item##_attr_show(struct config_item *item, \
+#define CONFIGFS_ATTR_OPS(_name, _item, _item_member) \
+static struct _item *to_##_name(struct config_item *ci) \
+{ \
+ return((ci) ? container_of(to_config_group(ci), struct _item, \
+ _item_member) : NULL); \
+} \
+static ssize_t _name##_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); \
+ struct _item *_item = to_##_name(item); \
+ struct _name##_attribute *_name##_attr = \
+ container_of(attr, struct _name##_attribute, attr); \
ssize_t ret = 0; \
\
- if (_item##_attr->show) \
- ret = _item##_attr->show(_item, page); \
+ if (_name##_attr->show) \
+ ret = _name##_attr->show(_item, page); \
return ret; \
} \
-static ssize_t _item##_attr_store(struct config_item *item, \
+static ssize_t _name##_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); \
+ struct _item *_item = to_##_name(item); \
+ struct _name##_attribute *_name##_attr = \
+ container_of(attr, struct _name##_attribute, attr); \
ssize_t ret = -EINVAL; \
\
- if (_item##_attr->store) \
- ret = _item##_attr->store(_item, page, count); \
+ if (_name##_attr->store) \
+ ret = _name##_attr->store(_item, page, count); \
return ret; \
}

--
1.5.4.1




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