ocelot: Dont allocate another multicast list, use __dev_mc_sync

Doing kmalloc in atomic context is always an issue,
more so for a list that can grow significantly.
Turns out that the driver only uses the duplicated
list of multicast mac addresses to keep track of
what addresses to delete from h/w before committing
the new list from kernel to h/w back again via set_rx_mode,
every time this list gets updated by the kernel.
Given that the h/w knows how to add and delete mac addresses
based on the mac address value alone, __dev_mc_sync should be
the much better choice of kernel API for these operations
avoiding the considerable overhead of maintaining a duplicated
list in the driver.

Signed-off-by: Claudiu Manoil <claudiu.manoil@nxp.com>
Tested-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Acked-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/mscc/ocelot.c

@@ -593,45 +593,25 @@ static int ocelot_port_xmit(struct sk_buff *skb, struct net_device *dev)
 	return NETDEV_TX_OK;
 }
 
-static void ocelot_mact_mc_reset(struct ocelot_port *port)
+static int ocelot_mc_unsync(struct net_device *dev, const unsigned char *addr)
 {
-	struct ocelot *ocelot = port->ocelot;
-	struct netdev_hw_addr *ha, *n;
+	struct ocelot_port *port = netdev_priv(dev);
 
-	/* Free and forget all the MAC addresses stored in the port private mc
-	 * list. These are mc addresses that were previously added by calling
-	 * ocelot_mact_mc_add().
-	 */
-	list_for_each_entry_safe(ha, n, &port->mc, list) {
-		ocelot_mact_forget(ocelot, ha->addr, port->pvid);
-		list_del(&ha->list);
-		kfree(ha);
-	}
+	return ocelot_mact_forget(port->ocelot, addr, port->pvid);
 }
 
-static int ocelot_mact_mc_add(struct ocelot_port *port,
-			      struct netdev_hw_addr *hw_addr)
+static int ocelot_mc_sync(struct net_device *dev, const unsigned char *addr)
 {
-	struct ocelot *ocelot = port->ocelot;
-	struct netdev_hw_addr *ha = kzalloc(sizeof(*ha), GFP_ATOMIC);
-
-	if (!ha)
-		return -ENOMEM;
-
-	memcpy(ha, hw_addr, sizeof(*ha));
-	list_add_tail(&ha->list, &port->mc);
-
-	ocelot_mact_learn(ocelot, PGID_CPU, ha->addr, port->pvid,
-			  ENTRYTYPE_LOCKED);
+	struct ocelot_port *port = netdev_priv(dev);
 
-	return 0;
+	return ocelot_mact_learn(port->ocelot, PGID_CPU, addr, port->pvid,
+				 ENTRYTYPE_LOCKED);
 }
 
 static void ocelot_set_rx_mode(struct net_device *dev)
 {
 	struct ocelot_port *port = netdev_priv(dev);
 	struct ocelot *ocelot = port->ocelot;
-	struct netdev_hw_addr *ha;
 	int i;
 	u32 val;
 
@@ -643,13 +623,7 @@ static void ocelot_set_rx_mode(struct net_device *dev)
 	for (i = ocelot->num_phys_ports + 1; i < PGID_CPU; i++)
 		ocelot_write_rix(ocelot, val, ANA_PGID_PGID, i);
 
-	/* Handle the device multicast addresses. First remove all the
-	 * previously installed addresses and then add the latest ones to the
-	 * mac table.
-	 */
-	ocelot_mact_mc_reset(port);
-	netdev_for_each_mc_addr(ha, dev)
-		ocelot_mact_mc_add(port, ha);
+	__dev_mc_sync(dev, ocelot_mc_sync, ocelot_mc_unsync);
 }
 
 static int ocelot_port_get_phys_port_name(struct net_device *dev,
@@ -1657,7 +1631,6 @@ int ocelot_probe_port(struct ocelot *ocelot, u8 port,
 	ocelot_port->regs = regs;
 	ocelot_port->chip_port = port;
 	ocelot_port->phy = phy;
-	INIT_LIST_HEAD(&ocelot_port->mc);
 	ocelot->ports[port] = ocelot_port;
 
 	dev->netdev_ops = &ocelot_port_netdev_ops;

drivers/net/ethernet/mscc/ocelot.h

@@ -441,10 +441,6 @@ struct ocelot_port {
 	struct phy_device *phy;
 	void __iomem *regs;
 	u8 chip_port;
-	/* Keep a track of the mc addresses added to the mac table, so that they
-	 * can be removed when needed.
-	 */
-	struct list_head mc;
 
 	/* Ingress default VLAN (pvid) */
 	u16 pvid;