sysfs: Functions for adding/removing symlinks to/from attribute groups

The most convenient way to expose ACPI power resources lists of a
device is to put symbolic links to sysfs directories representing
those resources into special attribute groups in the device's sysfs
directory.  For this purpose, it is necessary to be able to add
symbolic links to attribute groups.

For this reason, add sysfs helper functions for adding/removing
symbolic links to/from attribute groups, sysfs_add_link_to_group()
and sysfs_remove_link_from_group(), respectively.

This change set includes a build fix from David Rientjes.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 16 insertions, 0 deletions

diff --git a/include/linux/sysfs.h b/include/linux/sysfs.h
index 381f06d..e2cee22 100644
--- a/include/linux/sysfs.h
+++ b/include/linux/sysfs.h
@@ -181,6 +181,10 @@ int sysfs_merge_group(struct kobject *kobj,
 		       const struct attribute_group *grp);
 void sysfs_unmerge_group(struct kobject *kobj,
 		       const struct attribute_group *grp);
+int sysfs_add_link_to_group(struct kobject *kobj, const char *group_name,
+			    struct kobject *target, const char *link_name);
+void sysfs_remove_link_from_group(struct kobject *kobj, const char *group_name,
+				  const char *link_name);
 
 void sysfs_notify(struct kobject *kobj, const char *dir, const char *attr);
 void sysfs_notify_dirent(struct sysfs_dirent *sd);
@@ -326,6 +330,18 @@ static inline void sysfs_unmerge_group(struct kobject *kobj,
 {
 }
 
+static inline int sysfs_add_link_to_group(struct kobject *kobj,
+		const char *group_name, struct kobject *target,
+		const char *link_name)
+{
+	return 0;
+}
+
+static inline void sysfs_remove_link_from_group(struct kobject *kobj,
+		const char *group_name, const char *link_name)
+{
+}
+
 static inline void sysfs_notify(struct kobject *kobj, const char *dir,
 				const char *attr)
 {