[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>
diff --git a/drivers/firmware/efivars.c b/drivers/firmware/efivars.c
index 0287ff6..a3451cb 100644
--- a/drivers/firmware/efivars.c
+++ b/drivers/firmware/efivars.c
@@ -352,7 +352,7 @@
 {
 	struct efivar_entry *var = to_efivar_entry(kobj);
 	struct efivar_attribute *efivar_attr = to_efivar_attr(attr);
-	ssize_t ret = 0;
+	ssize_t ret = -EIO;
 
 	if (!capable(CAP_SYS_ADMIN))
 		return -EACCES;
@@ -368,7 +368,7 @@
 {
 	struct efivar_entry *var = to_efivar_entry(kobj);
 	struct efivar_attribute *efivar_attr = to_efivar_attr(attr);
-	ssize_t ret = 0;
+	ssize_t ret = -EIO;
 
 	if (!capable(CAP_SYS_ADMIN))
 		return -EACCES;