drbd: Remove uninitialized_var() usage

Using uninitialized_var() is dangerous as it papers over real bugs[1]
(or can in the future), and suppresses unrelated compiler warnings (e.g.
"unused variable"). If the compiler thinks it is uninitialized, either
simply initialize the variable or make compiler changes. As a precursor
to removing[2] this[3] macro[4], just initialize this variable to NULL.

[1] https://lore.kernel.org/lkml/[email protected]/
[2] https://lore.kernel.org/lkml/CA+55aFw+Vbj0i=1TGqCR5vQkCzWJ0QxK6CernOU6eedsudAixw@mail.gmail.com/
[3] https://lore.kernel.org/lkml/CA+55aFwgbgqhbp1fkxvRKEpzyR5J8n1vKT1VZdz9knmPuXhOeg@mail.gmail.com/
[4] https://lore.kernel.org/lkml/CA+55aFz2500WfbKXAx8s67wrm9=yVJu65TpLgN_ybYNv0VEOKA@mail.gmail.com/

Fixes: a297284 ("drbd: Backport the "events2" command")
Reviewed-by: Nick Desaulniers <[email protected]>
Signed-off-by: Kees Cook <[email protected]>

Author: kees

drivers/block/drbd/drbd_state.c

@@ -1604,7 +1604,7 @@ static void broadcast_state_change(struct drbd_state_change *state_change)
 	unsigned int n_device, n_connection, n_peer_device, n_peer_devices;
 	void (*last_func)(struct sk_buff *, unsigned int, void *,
 			  enum drbd_notification_type) = NULL;
-	void *uninitialized_var(last_arg);
+	void *last_arg = NULL;
 
 #define HAS_CHANGED(state) ((state)[OLD] != (state)[NEW])
 #define FINAL_STATE_CHANGE(type) \