net: dsa: make dp->bridge_num one-based

I have seen too many bugs already due to the fact that we must encode an
invalid dp->bridge_num as a negative value, because the natural tendency
is to check that invalid value using (!dp->bridge_num). Latest example
can be seen in commit 1bec0f05062c ("net: dsa: fix bridge_num not
getting cleared after ports leaving the bridge").

Convert the existing users to assume that dp->bridge_num == 0 is the
encoding for invalid, and valid bridge numbers start from 1.

Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Reviewed-by: Alvin Šipraga <alsi@bang-olufsen.dk>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

1 files changed, 12 insertions, 12 deletions

diff --git a/net/dsa/dsa2.c b/net/dsa/dsa2.c
index 826957b6442b..9606e56710a5 100644
--- a/net/dsa/dsa2.c
+++ b/net/dsa/dsa2.c
@@ -141,23 +141,23 @@ static int dsa_bridge_num_find(const struct net_device *bridge_dev)
 	 */
 	list_for_each_entry(dst, &dsa_tree_list, list)
 		list_for_each_entry(dp, &dst->ports, list)
-			if (dp->bridge_dev == bridge_dev &&
-			    dp->bridge_num != -1)
+			if (dp->bridge_dev == bridge_dev && dp->bridge_num)
 				return dp->bridge_num;
 
-	return -1;
+	return 0;
 }
 
-int dsa_bridge_num_get(const struct net_device *bridge_dev, int max)
+unsigned int dsa_bridge_num_get(const struct net_device *bridge_dev, int max)
 {
-	int bridge_num = dsa_bridge_num_find(bridge_dev);
+	unsigned int bridge_num = dsa_bridge_num_find(bridge_dev);
 
-	if (bridge_num < 0) {
+	if (!bridge_num) {
 		/* First port that offloads TX forwarding for this bridge */
-		bridge_num = find_first_zero_bit(&dsa_fwd_offloading_bridges,
-						 DSA_MAX_NUM_OFFLOADING_BRIDGES);
+		bridge_num = find_next_zero_bit(&dsa_fwd_offloading_bridges,
+						DSA_MAX_NUM_OFFLOADING_BRIDGES,
+						1);
 		if (bridge_num >= max)
-			return -1;
+			return 0;
 
 		set_bit(bridge_num, &dsa_fwd_offloading_bridges);
 	}
@@ -165,12 +165,13 @@ int dsa_bridge_num_get(const struct net_device *bridge_dev, int max)
 	return bridge_num;
 }
 
-void dsa_bridge_num_put(const struct net_device *bridge_dev, int bridge_num)
+void dsa_bridge_num_put(const struct net_device *bridge_dev,
+			unsigned int bridge_num)
 {
 	/* Check if the bridge is still in use, otherwise it is time
 	 * to clean it up so we can reuse this bridge_num later.
 	 */
-	if (dsa_bridge_num_find(bridge_dev) < 0)
+	if (!dsa_bridge_num_find(bridge_dev))
 		clear_bit(bridge_num, &dsa_fwd_offloading_bridges);
 }
 
@@ -1184,7 +1185,6 @@ static struct dsa_port *dsa_port_touch(struct dsa_switch *ds, int index)
 
 	dp->ds = ds;
 	dp->index = index;
-	dp->bridge_num = -1;
 
 	INIT_LIST_HEAD(&dp->list);
 	list_add_tail(&dp->list, &dst->ports);