sysfs: Document sysfs_attr_init and sysfs_bin_attr_init

I have added a new requirement to the external sysfs interface
that dynamically allocated sysfs attributes must call sysfs_attr_init
if lockdep is enabled.  For the time being callying sysfs_attr_init
is only mandatory if lockdep is enabled, so we can live with a few
unconverted instances until we find them all.  As this is part of
the public interface of sysfs it is a good idea to document these
pseudo functions so someone inspeciting the code can find out
what has happened.

Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

include/linux/sysfs.h

@@ -36,6 +36,16 @@ struct attribute {
 #endif
 };
 
+/**
+ *	sysfs_attr_init - initialize a dynamically allocated sysfs attribute
+ *	@attr: struct attribute to initialize
+ *
+ *	Initialize a dynamically allocated struct attribute so we can
+ *	make lockdep happy.  This is a new requirement for attributes
+ *	and initially this is only needed when lockdep is enabled.
+ *	Lockdep gives a nice error when your attribute is added to
+ *	sysfs if you don't have this.
+ */
 #ifdef CONFIG_DEBUG_LOCK_ALLOC
 #define sysfs_attr_init(attr)				\
 do {							\
@@ -90,6 +100,16 @@ struct bin_attribute {
 		    struct vm_area_struct *vma);
 };
 
+/**
+ *	sysfs_bin_attr_init - initialize a dynamically allocated bin_attribute
+ *	@attr: struct bin_attribute to initialize
+ *
+ *	Initialize a dynamically allocated struct bin_attribute so we
+ *	can make lockdep happy.  This is a new requirement for
+ *	attributes and initially this is only needed when lockdep is
+ *	enabled.  Lockdep gives a nice error when your attribute is
+ *	added to sysfs if you don't have this.
+ */
 #define sysfs_bin_attr_init(bin_attr) sysfs_attr_init(&bin_attr->attr)
 
 struct sysfs_ops {