Commit e071d93e authored by Sven Eckelmann's avatar Sven Eckelmann Committed by Antonio Quartulli
Browse files

batman-adv: Replace gw_reselect divisor with simple shift 



The gw_factor is divided by BATADV_TQ_LOCAL_WINDOW_SIZE ** 2 * 64. But the
rest of the calculation has nothing to do with the tq window size and
therefore the calculation is just (tmp_gw_factor / (64 ** 3)).

Replace it with a simple shift to avoid a costly 64-bit divide when the
max_gw_factor is changed from u32 to u64. This type change is necessary
to avoid an overflow bug.

Signed-off-by: default avatarSven Eckelmann <sven@narfation.org>
Signed-off-by: default avatarMarek Lindner <mareklindner@neomailbox.ch>
Signed-off-by: default avatarAntonio Quartulli <antonio@meshcoding.com>
parent 07a51cd3

net/batman-adv/gateway_client.c

+1 −5
Original line number Diff line number Diff line
@@ -154,14 +154,10 @@ batadv_gw_get_best_gw_node(struct batadv_priv *bat_priv) 
	struct batadv_neigh_ifinfo *router_ifinfo;

	struct batadv_gw_node *gw_node, *curr_gw = NULL;

	uint32_t max_gw_factor = 0, tmp_gw_factor = 0;

	uint32_t gw_divisor;

	uint8_t max_tq = 0;

	uint8_t tq_avg;

	struct batadv_orig_node *orig_node;



	gw_divisor = BATADV_TQ_LOCAL_WINDOW_SIZE * BATADV_TQ_LOCAL_WINDOW_SIZE;

	gw_divisor *= 64;



	rcu_read_lock();

	hlist_for_each_entry_rcu(gw_node, &bat_priv->gw.list, list) {

		if (gw_node->deleted)
@@ -187,7 +183,7 @@ batadv_gw_get_best_gw_node(struct batadv_priv *bat_priv) 
			tmp_gw_factor = tq_avg * tq_avg;

			tmp_gw_factor *= gw_node->bandwidth_down;

			tmp_gw_factor *= 100 * 100;

			tmp_gw_factor /= gw_divisor;

			tmp_gw_factor >>= 18;



			if ((tmp_gw_factor > max_gw_factor) ||

			    ((tmp_gw_factor == max_gw_factor) &&