sysdev: fix problem with sysdev_class being re-registered

We need to initialize the kobject for a sysdev_class as it could have
been recycled (stupid static kobjects...)

We also do the same thing in case sysdev devices are being
re-registered.

Thanks to Balaji Rao <balajirrao@gmail.com> for pointing out the
problem.

Signed-off-by: Balaji Rao <balajirrao@gmail.com>
Tested-by: Mikael Pettersson <mikpe@it.uu.se>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/base/sys.c

@@ -133,6 +133,7 @@ int sysdev_class_register(struct sysdev_class * cls)
 	pr_debug("Registering sysdev class '%s'\n",
 		 kobject_name(&cls->kset.kobj));
 	INIT_LIST_HEAD(&cls->drivers);
+	memset(&cls->kset.kobj, 0x00, sizeof(struct kobject));
 	cls->kset.kobj.parent = &system_kset->kobj;
 	cls->kset.kobj.ktype = &ktype_sysdev_class;
 	cls->kset.kobj.kset = system_kset;
@@ -227,6 +228,9 @@ int sysdev_register(struct sys_device * sysdev)
 
 	pr_debug("Registering sys device '%s'\n", kobject_name(&sysdev->kobj));
 
+	/* initialize the kobject to 0, in case it had previously been used */
+	memset(&sysdev->kobj, 0x00, sizeof(struct kobject));
+
 	/* Make sure the kset is set */
 	sysdev->kobj.kset = &cls->kset;