Eric Lee / smarc-fsl-linux-kernel

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Commit e071d93eb40c969dc8c578dde5ddd89a30fb01cb

Authored by Sven Eckelmann
Committed by Antonio Quartulli
1 parent 07a51cd379

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: Sven Eckelmann <sven@narfation.org>
Signed-off-by: Marek Lindner <mareklindner@neomailbox.ch>
Signed-off-by: Antonio Quartulli <antonio@meshcoding.com>

Showing 1 changed file with 1 additions and 5 deletions Side-by-side Diff

net/batman-adv/gateway_client.c
Diff comments   View file @ e071d93
... ... @@ -154,14 +154,10 @@
154 154 struct batadv_neigh_ifinfo *router_ifinfo;
155 155 struct batadv_gw_node *gw_node, *curr_gw = NULL;
156 156 uint32_t max_gw_factor = 0, tmp_gw_factor = 0;
157   - uint32_t gw_divisor;
158 157 uint8_t max_tq = 0;
159 158 uint8_t tq_avg;
160 159 struct batadv_orig_node *orig_node;
161 160  
162   - gw_divisor = BATADV_TQ_LOCAL_WINDOW_SIZE * BATADV_TQ_LOCAL_WINDOW_SIZE;
163   - gw_divisor *= 64;
164   -
165 161 rcu_read_lock();
166 162 hlist_for_each_entry_rcu(gw_node, &bat_priv->gw.list, list) {
167 163 if (gw_node->deleted)
... ... @@ -187,7 +183,7 @@
187 183 tmp_gw_factor = tq_avg * tq_avg;
188 184 tmp_gw_factor *= gw_node->bandwidth_down;
189 185 tmp_gw_factor *= 100 * 100;
190   - tmp_gw_factor /= gw_divisor;
  186 + tmp_gw_factor >>= 18;
191 187  
192 188 if ((tmp_gw_factor > max_gw_factor) ||
193 189 ((tmp_gw_factor == max_gw_factor) &&