net: mscc: ocelot: drop the use of the "lags" array

We can now simplify the implementation by always using ocelot_get_bond_mask
to look up the other ports that are offloading the same bonding interface
as us.

In ocelot_set_aggr_pgids, the code had a way to uniquely iterate through
LAGs. We need to achieve the same behavior by marking each LAG as visited,
which we do now by using a temporary 32-bit "visited" bitmask. This is
ok and we do not need dynamic memory allocation, because we know that
this switch architecture will not have more than 32 ports (the PGID port
masks are 32-bit anyway).

Signed-off-by: Vladimir Oltean <[email protected]>
Signed-off-by: Jakub Kicinski <[email protected]>

drivers/net/ethernet/mscc/ocelot.c

@@ -957,21 +957,11 @@ void ocelot_apply_bridge_fwd_mask(struct ocelot *ocelot)
 			mask = GENMASK(ocelot->num_phys_ports - 1, 0);
 			mask &= ~cpu_fwd_mask;
 		} else if (ocelot->bridge_fwd_mask & BIT(port)) {
-			int lag;
+			struct net_device *bond = ocelot_port->bond;
 
 			mask = ocelot->bridge_fwd_mask & ~BIT(port);
-
-			for (lag = 0; lag < ocelot->num_phys_ports; lag++) {
-				unsigned long bond_mask = ocelot->lags[lag];
-
-				if (!bond_mask)
-					continue;
-
-				if (bond_mask & BIT(port)) {
-					mask &= ~bond_mask;
-					break;
-				}
-			}
+			if (bond)
+				mask &= ~ocelot_get_bond_mask(ocelot, bond);
 		} else {
 			/* Standalone ports forward only to DSA tag_8021q CPU
 			 * ports (if those exist), or to the hardware CPU port
@@ -1277,6 +1267,7 @@ EXPORT_SYMBOL(ocelot_port_bridge_leave);
 
 static void ocelot_set_aggr_pgids(struct ocelot *ocelot)
 {
+	unsigned long visited = GENMASK(ocelot->num_phys_ports - 1, 0);
 	int i, port, lag;
 
 	/* Reset destination and aggregation PGIDS */
@@ -1287,16 +1278,35 @@ static void ocelot_set_aggr_pgids(struct ocelot *ocelot)
 		ocelot_write_rix(ocelot, GENMASK(ocelot->num_phys_ports - 1, 0),
 				 ANA_PGID_PGID, i);
 
-	/* Now, set PGIDs for each LAG */
+	/* The visited ports bitmask holds the list of ports offloading any
+	 * bonding interface. Initially we mark all these ports as unvisited,
+	 * then every time we visit a port in this bitmask, we know that it is
+	 * the lowest numbered port, i.e. the one whose logical ID == physical
+	 * port ID == LAG ID. So we mark as visited all further ports in the
+	 * bitmask that are offloading the same bonding interface. This way,
+	 * we set up the aggregation PGIDs only once per bonding interface.
+	 */
+	for (port = 0; port < ocelot->num_phys_ports; port++) {
+		struct ocelot_port *ocelot_port = ocelot->ports[port];
+
+		if (!ocelot_port || !ocelot_port->bond)
+			continue;
+
+		visited &= ~BIT(port);
+	}
+
+	/* Now, set PGIDs for each active LAG */
 	for (lag = 0; lag < ocelot->num_phys_ports; lag++) {
+		struct net_device *bond = ocelot->ports[lag]->bond;
 		unsigned long bond_mask;
 		int aggr_count = 0;
 		u8 aggr_idx[16];
 
-		bond_mask = ocelot->lags[lag];
-		if (!bond_mask)
+		if (!bond || (visited & BIT(lag)))
 			continue;
 
+		bond_mask = ocelot_get_bond_mask(ocelot, bond);
+
 		for_each_set_bit(port, &bond_mask, ocelot->num_phys_ports) {
 			// Destination mask
 			ocelot_write_rix(ocelot, bond_mask,
@@ -1313,6 +1323,19 @@ static void ocelot_set_aggr_pgids(struct ocelot *ocelot)
 			ac |= BIT(aggr_idx[i % aggr_count]);
 			ocelot_write_rix(ocelot, ac, ANA_PGID_PGID, i);
 		}
+
+		/* Mark all ports in the same LAG as visited to avoid applying
+		 * the same config again.
+		 */
+		for (port = lag; port < ocelot->num_phys_ports; port++) {
+			struct ocelot_port *ocelot_port = ocelot->ports[port];
+
+			if (!ocelot_port)
+				continue;
+
+			if (ocelot_port->bond == bond)
+				visited |= BIT(port);
+		}
 	}
 }
 
@@ -1353,30 +1376,11 @@ int ocelot_port_lag_join(struct ocelot *ocelot, int port,
 			 struct net_device *bond,
 			 struct netdev_lag_upper_info *info)
 {
-	u32 bond_mask = 0;
-	int lag;
-
 	if (info->tx_type != NETDEV_LAG_TX_TYPE_HASH)
 		return -EOPNOTSUPP;
 
 	ocelot->ports[port]->bond = bond;
 
-	bond_mask = ocelot_get_bond_mask(ocelot, bond);
-
-	lag = __ffs(bond_mask);
-
-	/* If the new port is the lowest one, use it as the logical port from
-	 * now on
-	 */
-	if (port == lag) {
-		ocelot->lags[port] = bond_mask;
-		bond_mask &= ~BIT(port);
-		if (bond_mask)
-			ocelot->lags[__ffs(bond_mask)] = 0;
-	} else {
-		ocelot->lags[lag] |= BIT(port);
-	}
-
 	ocelot_setup_logical_port_ids(ocelot);
 	ocelot_apply_bridge_fwd_mask(ocelot);
 	ocelot_set_aggr_pgids(ocelot);
@@ -1388,24 +1392,8 @@ EXPORT_SYMBOL(ocelot_port_lag_join);
 void ocelot_port_lag_leave(struct ocelot *ocelot, int port,
 			   struct net_device *bond)
 {
-	int i;
-
 	ocelot->ports[port]->bond = NULL;
 
-	/* Remove port from any lag */
-	for (i = 0; i < ocelot->num_phys_ports; i++)
-		ocelot->lags[i] &= ~BIT(port);
-
-	/* if it was the logical port of the lag, move the lag config to the
-	 * next port
-	 */
-	if (ocelot->lags[port]) {
-		int n = __ffs(ocelot->lags[port]);
-
-		ocelot->lags[n] = ocelot->lags[port];
-		ocelot->lags[port] = 0;
-	}
-
 	ocelot_setup_logical_port_ids(ocelot);
 	ocelot_apply_bridge_fwd_mask(ocelot);
 	ocelot_set_aggr_pgids(ocelot);
@@ -1587,11 +1575,6 @@ int ocelot_init(struct ocelot *ocelot)
 		}
 	}
 
-	ocelot->lags = devm_kcalloc(ocelot->dev, ocelot->num_phys_ports,
-				    sizeof(u32), GFP_KERNEL);
-	if (!ocelot->lags)
-		return -ENOMEM;
-
 	ocelot->stats = devm_kcalloc(ocelot->dev,
 				     ocelot->num_phys_ports * ocelot->num_stats,
 				     sizeof(u64), GFP_KERNEL);

include/soc/mscc/ocelot.h

@@ -657,8 +657,6 @@ struct ocelot {
 	enum ocelot_tag_prefix		npi_inj_prefix;
 	enum ocelot_tag_prefix		npi_xtr_prefix;
 
-	u32				*lags;
-
 	struct list_head		multicast;
 	struct list_head		pgids;