Allow subsystem to have attributes, too.

This is really handy for subsystems that have any attributes they want
to export, esp. if they have just a few, since they don't have to define
all of the infrastructure for creating and tearing down the attributes 
for the high level type that they are. 

- define struct subsys_attribute for declaring attributes of subsystems
themselves. 

- define subsys_create_file() and subsys_remove_file().

- define subsys_sysfs_ops for forwarding sysfs reads and writes to the 
subsystem attribute callbacks. 

- Set the sysfs_ops to be the subsystem ones if the kobject doesn't belong
to a subsystem itself (meaning that it is a subsystem).

1 files changed, 34 insertions, 0 deletions

diff --git a/lib/kobject.c b/lib/kobject.c
index 33e4f8c9ce58c3..bdf6636d2b2ed9 100644
--- a/lib/kobject.c
+++ b/lib/kobject.c
@@ -229,6 +229,38 @@ void subsystem_unregister(struct subsystem * s)
 }
 
 
+/**
+ *	subsystem_create_file - export sysfs attribute file.
+ *	@s:	subsystem.
+ *	@a:	subsystem attribute descriptor.
+ */
+
+int subsys_create_file(struct subsystem * s, struct subsys_attribute * a)
+{
+	int error = 0;
+	if (subsys_get(s)) {
+		error = sysfs_create_file(&s->kobj,&a->attr);
+		subsys_put(s);
+	}
+	return error;
+}
+
+
+/**
+ *	subsystem_remove_file - remove sysfs attribute file.
+ *	@s:	subsystem.
+ *	@a:	attribute desciptor.
+ */
+
+void subsys_remove_file(struct subsystem * s, struct subsys_attribute * a)
+{
+	if (subsys_get(s)) {
+		sysfs_remove_file(&s->kobj,&a->attr);
+		subsys_put(s);
+	}
+}
+
+
 EXPORT_SYMBOL(kobject_init);
 EXPORT_SYMBOL(kobject_register);
 EXPORT_SYMBOL(kobject_unregister);
@@ -238,3 +270,5 @@ EXPORT_SYMBOL(kobject_put);
 EXPORT_SYMBOL(subsystem_init);
 EXPORT_SYMBOL(subsystem_register);
 EXPORT_SYMBOL(subsystem_unregister);
+EXPORT_SYMBOL(subsys_create_file);
+EXPORT_SYMBOL(subsys_remove_file);