net: dsa: store CPU switch structure in the tree

Store a dsa_switch pointer to the CPU switch in the tree instead of only
its index. This avoids the need to initialize it to -1.

Signed-off-by: Vivien Didelot <[e-mail]>
Reviewed-by: Andrew Lunn <[e-mail]>
Reviewed-by: Florian Fainelli <[e-mail]>
Signed-off-by: David S. Miller <[e-mail]>

include/net/dsa.h

···
 	/*
 	 * The switch and port to which the CPU is attached.
 	 */
-	s8			cpu_switch;
+	struct dsa_switch	*cpu_switch;
 	s8			cpu_port;
 
 	/*
···
 
 static inline bool dsa_is_cpu_port(struct dsa_switch *ds, int p)
 {
-	return !!(ds->index == ds->dst->cpu_switch && p == ds->dst->cpu_port);
+	return !!(ds == ds->dst->cpu_switch && p == ds->dst->cpu_port);
 }
 
 static inline bool dsa_is_dsa_port(struct dsa_switch *ds, int p)
···
 	 * Else return the (DSA) port number that connects to the
 	 * switch that is one hop closer to the cpu.
 	 */
-	if (dst->cpu_switch == ds->index)
+	if (dst->cpu_switch == ds)
 		return dst->cpu_port;
 	else
-		return ds->rtable[dst->cpu_switch];
+		return ds->rtable[dst->cpu_switch->index];
 }
 
 struct switchdev_trans;

net/dsa/dsa.c

···
 			continue;
 
 		if (!strcmp(name, "cpu")) {
-			if (dst->cpu_switch != -1) {
+			if (!dst->cpu_switch) {
 				netdev_err(dst->master_netdev,
 					   "multiple cpu ports?!\n");
 				return -EINVAL;
 			}
-			dst->cpu_switch = index;
+			dst->cpu_switch = ds;
 			dst->cpu_port = i;
 			ds->cpu_port_mask |= 1 << i;
 		} else if (!strcmp(name, "dsa")) {
···
 	 * tagging protocol to the preferred tagging format of this
 	 * switch.
 	 */
-	if (dst->cpu_switch == index) {
+	if (dst->cpu_switch == ds) {
 		enum dsa_tag_protocol tag_protocol;
 
 		tag_protocol = ops->get_tag_protocol(ds);
···
 
 	dst->pd = pd;
 	dst->master_netdev = dev;
-	dst->cpu_switch = -1;
 	dst->cpu_port = -1;
 
 	for (i = 0; i < pd->nr_chips; i++) {

net/dsa/dsa2.c

···
 	if (!dst)
 		return NULL;
 	dst->tree = tree;
-	dst->cpu_switch = -1;
 	INIT_LIST_HEAD(&dst->list);
 	list_add_tail(&dsa_switch_trees, &dst->list);
 	kref_init(&dst->refcount);
···
 	if (!dst->master_netdev)
 		dst->master_netdev = ethernet_dev;
 
-	if (dst->cpu_switch == -1) {
-		dst->cpu_switch = ds->index;
+	if (!dst->cpu_switch) {
+		dst->cpu_switch = ds;
 		dst->cpu_port = index;
 	}