net: dsa: remove the "dsa_to_port in a loop" antipattern from the core

Ever since Vivien's conversion of the ds->ports array into a dst->ports
list, and the introduction of dsa_to_port, iterations through the ports
of a switch became quadratic whenever dsa_to_port was needed.

dsa_to_port can either be called directly, or indirectly through the
dsa_is_{user,cpu,dsa,unused}_port helpers.

Use the newly introduced dsa_switch_for_each_port() iteration macro
that works with the iterator variable being a struct dsa_port *dp
directly, and not an int i. It is an expensive variable to go from i to
dp, but cheap to go from dp to i.

This macro iterates through the entire ds->dst->ports list and filters
by the ports belonging just to the switch provided as argument.
Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/net/dsa.h

@@ -504,12 +504,11 @@ static inline bool dsa_is_user_port(struct dsa_switch *ds, int p)
 
 static inline u32 dsa_user_ports(struct dsa_switch *ds)
 {
+	struct dsa_port *dp;
 	u32 mask = 0;
-	int p;
 
-	for (p = 0; p < ds->num_ports; p++)
-		if (dsa_is_user_port(ds, p))
-			mask |= BIT(p);
+	dsa_switch_for_each_user_port(dp, ds)
+		mask |= BIT(dp->index);
 
 	return mask;
 }

net/dsa/dsa.c

@@ -280,23 +280,22 @@ static int dsa_switch_rcv(struct sk_buff *skb, struct net_device *dev,
 }
 
 #ifdef CONFIG_PM_SLEEP
-static bool dsa_is_port_initialized(struct dsa_switch *ds, int p)
+static bool dsa_port_is_initialized(const struct dsa_port *dp)
 {
-	const struct dsa_port *dp = dsa_to_port(ds, p);
-
 	return dp->type == DSA_PORT_TYPE_USER && dp->slave;
 }
 
 int dsa_switch_suspend(struct dsa_switch *ds)
 {
-	int i, ret = 0;
+	struct dsa_port *dp;
+	int ret = 0;
 
 	/* Suspend slave network devices */
-	for (i = 0; i < ds->num_ports; i++) {
-		if (!dsa_is_port_initialized(ds, i))
+	dsa_switch_for_each_port(dp, ds) {
+		if (!dsa_port_is_initialized(dp))
 			continue;
 
-		ret = dsa_slave_suspend(dsa_to_port(ds, i)->slave);
+		ret = dsa_slave_suspend(dp->slave);
 		if (ret)
 			return ret;
 	}
@@ -310,7 +309,8 @@ EXPORT_SYMBOL_GPL(dsa_switch_suspend);
 
 int dsa_switch_resume(struct dsa_switch *ds)
 {
-	int i, ret = 0;
+	struct dsa_port *dp;
+	int ret = 0;
 
 	if (ds->ops->resume)
 		ret = ds->ops->resume(ds);
@@ -319,11 +319,11 @@ int dsa_switch_resume(struct dsa_switch *ds)
 		return ret;
 
 	/* Resume slave network devices */
-	for (i = 0; i < ds->num_ports; i++) {
-		if (!dsa_is_port_initialized(ds, i))
+	dsa_switch_for_each_port(dp, ds) {
+		if (!dsa_port_is_initialized(dp))
 			continue;
 
-		ret = dsa_slave_resume(dsa_to_port(ds, i)->slave);
+		ret = dsa_slave_resume(dp->slave);
 		if (ret)
 			return ret;
 	}

net/dsa/dsa2.c

@@ -802,17 +802,16 @@ static int dsa_switch_setup_tag_protocol(struct dsa_switch *ds)
 {
 	const struct dsa_device_ops *tag_ops = ds->dst->tag_ops;
 	struct dsa_switch_tree *dst = ds->dst;
-	int port, err;
+	struct dsa_port *cpu_dp;
+	int err;
 
 	if (tag_ops->proto == dst->default_proto)
 		return 0;
 
-	for (port = 0; port < ds->num_ports; port++) {
-		if (!dsa_is_cpu_port(ds, port))
-			continue;
-
+	dsa_switch_for_each_cpu_port(cpu_dp, ds) {
 		rtnl_lock();
-		err = ds->ops->change_tag_protocol(ds, port, tag_ops->proto);
+		err = ds->ops->change_tag_protocol(ds, cpu_dp->index,
+						   tag_ops->proto);
 		rtnl_unlock();
 		if (err) {
 			dev_err(ds->dev, "Unable to use tag protocol \"%s\": %pe\n",
@@ -1150,7 +1149,7 @@ int dsa_tree_change_tag_proto(struct dsa_switch_tree *dst,
 		goto out_unlock;
 
 	list_for_each_entry(dp, &dst->ports, list) {
-		if (!dsa_is_user_port(dp->ds, dp->index))
+		if (!dsa_port_is_user(dp))
 			continue;
 
 		if (dp->slave->flags & IFF_UP)

net/dsa/port.c

@@ -515,7 +515,8 @@ static bool dsa_port_can_apply_vlan_filtering(struct dsa_port *dp,
 					      struct netlink_ext_ack *extack)
 {
 	struct dsa_switch *ds = dp->ds;
-	int err, i;
+	struct dsa_port *other_dp;
+	int err;
 
 	/* VLAN awareness was off, so the question is "can we turn it on".
 	 * We may have had 8021q uppers, those need to go. Make sure we don't
@@ -557,10 +558,10 @@ static bool dsa_port_can_apply_vlan_filtering(struct dsa_port *dp,
 	 * different ports of the same switch device and one of them has a
 	 * different setting than what is being requested.
 	 */
-	for (i = 0; i < ds->num_ports; i++) {
+	dsa_switch_for_each_port(other_dp, ds) {
 		struct net_device *other_bridge;
 
-		other_bridge = dsa_to_port(ds, i)->bridge_dev;
+		other_bridge = other_dp->bridge_dev;
 		if (!other_bridge)
 			continue;
 		/* If it's the same bridge, it also has same
@@ -607,20 +608,16 @@ int dsa_port_vlan_filtering(struct dsa_port *dp, bool vlan_filtering,
 		return err;
 
 	if (ds->vlan_filtering_is_global) {
-		int port;
+		struct dsa_port *other_dp;
 
 		ds->vlan_filtering = vlan_filtering;
 
-		for (port = 0; port < ds->num_ports; port++) {
-			struct net_device *slave;
-
-			if (!dsa_is_user_port(ds, port))
-				continue;
+		dsa_switch_for_each_user_port(other_dp, ds) {
+			struct net_device *slave = dp->slave;
 
 			/* We might be called in the unbind path, so not
 			 * all slave devices might still be registered.
 			 */
-			slave = dsa_to_port(ds, port)->slave;
 			if (!slave)
 				continue;
 

net/dsa/slave.c

@@ -2368,7 +2368,7 @@ static int dsa_slave_netdevice_event(struct notifier_block *nb,
 		dst = cpu_dp->ds->dst;
 
 		list_for_each_entry(dp, &dst->ports, list) {
-			if (!dsa_is_user_port(dp->ds, dp->index))
+			if (!dsa_port_is_user(dp))
 				continue;
 
 			list_add(&dp->slave->close_list, &close_list);

net/dsa/switch.c

@@ -17,14 +17,11 @@
 static unsigned int dsa_switch_fastest_ageing_time(struct dsa_switch *ds,
 						   unsigned int ageing_time)
 {
-	int i;
-
-	for (i = 0; i < ds->num_ports; ++i) {
-		struct dsa_port *dp = dsa_to_port(ds, i);
+	struct dsa_port *dp;
 
+	dsa_switch_for_each_port(dp, ds)
 		if (dp->ageing_time && dp->ageing_time < ageing_time)
 			ageing_time = dp->ageing_time;
-	}
 
 	return ageing_time;
 }
@@ -120,7 +117,8 @@ static int dsa_switch_bridge_leave(struct dsa_switch *ds,
 	struct netlink_ext_ack extack = {0};
 	bool change_vlan_filtering = false;
 	bool vlan_filtering;
-	int err, port;
+	struct dsa_port *dp;
+	int err;
 
 	if (dst->index == info->tree_index && ds->index == info->sw_index &&
 	    ds->ops->port_bridge_leave)
@@ -150,10 +148,10 @@ static int dsa_switch_bridge_leave(struct dsa_switch *ds,
 	 * VLAN-aware bridge.
 	 */
 	if (change_vlan_filtering && ds->vlan_filtering_is_global) {
-		for (port = 0; port < ds->num_ports; port++) {
+		dsa_switch_for_each_port(dp, ds) {
 			struct net_device *bridge_dev;
 
-			bridge_dev = dsa_to_port(ds, port)->bridge_dev;
+			bridge_dev = dp->bridge_dev;
 
 			if (bridge_dev && br_vlan_enabled(bridge_dev)) {
 				change_vlan_filtering = false;
@@ -579,38 +577,34 @@ static int dsa_switch_change_tag_proto(struct dsa_switch *ds,
 				       struct dsa_notifier_tag_proto_info *info)
 {
 	const struct dsa_device_ops *tag_ops = info->tag_ops;
-	int port, err;
+	struct dsa_port *dp, *cpu_dp;
+	int err;
 
 	if (!ds->ops->change_tag_protocol)
 		return -EOPNOTSUPP;
 
 	ASSERT_RTNL();
 
-	for (port = 0; port < ds->num_ports; port++) {
-		if (!dsa_is_cpu_port(ds, port))
-			continue;
-
-		err = ds->ops->change_tag_protocol(ds, port, tag_ops->proto);
+	dsa_switch_for_each_cpu_port(cpu_dp, ds) {
+		err = ds->ops->change_tag_protocol(ds, cpu_dp->index,
+						   tag_ops->proto);
 		if (err)
 			return err;
 
-		dsa_port_set_tag_protocol(dsa_to_port(ds, port), tag_ops);
+		dsa_port_set_tag_protocol(cpu_dp, tag_ops);
 	}
 
 	/* Now that changing the tag protocol can no longer fail, let's update
 	 * the remaining bits which are "duplicated for faster access", and the
 	 * bits that depend on the tagger, such as the MTU.
 	 */
-	for (port = 0; port < ds->num_ports; port++) {
-		if (dsa_is_user_port(ds, port)) {
-			struct net_device *slave;
+	dsa_switch_for_each_user_port(dp, ds) {
+		struct net_device *slave = dp->slave;
 
-			slave = dsa_to_port(ds, port)->slave;
-			dsa_slave_setup_tagger(slave);
+		dsa_slave_setup_tagger(slave);
 
-			/* rtnl_mutex is held in dsa_tree_change_tag_proto */
-			dsa_slave_change_mtu(slave, slave->mtu);
-		}
+		/* rtnl_mutex is held in dsa_tree_change_tag_proto */
+		dsa_slave_change_mtu(slave, slave->mtu);
 	}
 
 	return 0;