[PATCH] sysfs: (rest) if show/store is missing return -EIO

sysfs: fix the rest of the kernel so if an attribute doesn't
       implement show or store method read/write will return
       -EIO instead of 0 or -EINVAL or -EPERM.

Signed-off-by: Dmitry Torokhov <dtor@mail.ru>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/infiniband/core/sysfs.c

@@ -71,7 +71,7 @@ static ssize_t port_attr_show(struct kobject *kobj,
 	struct ib_port *p = container_of(kobj, struct ib_port, kobj);
 
 	if (!port_attr->show)
-		return 0;
+		return -EIO;
 
 	return port_attr->show(p, port_attr, buf);
 }