Re: [RFC PATCH 09/16] dsa: dsa: Split up creating/destroying of DSA and CPU ports

On Fri, May 27, 2016 at 10:33:49AM -0400, Vivien Didelot wrote:

Hi Andrew,

Andrew Lunn [off-list ref] writes:

quoted

-static void dsa_switch_destroy(struct dsa_switch *ds)
+void dsa_cpu_dsa_destroy(struct device_node *port_dn)
 {
-	struct device_node *port_dn;
 	struct phy_device *phydev;
+
+	if (of_phy_is_fixed_link(port_dn)) {
+		phydev = of_phy_find_device(port_dn);
+		if (phydev) {
+			phy_device_free(phydev);
+			fixed_phy_unregister(phydev);
+		}
+	}
+}
+
+static void dsa_switch_destroy(struct dsa_switch *ds)
+{
 	int port;
 
 #ifdef CONFIG_NET_DSA_HWMON

@@ -445,17 +467,11 @@ static void dsa_switch_destroy(struct dsa_switch *ds)
 		dsa_slave_destroy(ds->ports[port].netdev);
 	}
 
-	/* Remove any fixed link PHYs */
+	/* Disable configuration of the CPU and DSA ports */
 	for (port = 0; port < DSA_MAX_PORTS; port++) {
-		port_dn = ds->ports[port].dn;
-		if (of_phy_is_fixed_link(port_dn)) {
-			phydev = of_phy_find_device(port_dn);
-			if (phydev) {
-				phy_device_free(phydev);
-				of_node_put(port_dn);

Why does dsa_cpu_dsa_destroy drop that of_node_put call?

The of node reference counting is broken. The DT maintainers actually
say not to care, the whole reference counting scheme is broken. Which
is a bit sad really. There was a discussion about this a couple of
months ago.

Anyway, the reference is taken in dsa_of_probe() as part of the
or_each_available_child_of_node(child, port). This reference has
nothing to do with the port being a fixed link or not. So freeing it
here is inappropriate. The correct place to free it would probably be
in dsa_of_remove.
 

quoted

-				fixed_phy_unregister(phydev);
-			}
-		}
+		if ((dsa_is_cpu_port(ds, port) || dsa_is_dsa_port(ds, port)))
+			continue;

Why do we skip DSA and CPU ports here? The previous code didn't.

quoted

+		dsa_cpu_dsa_destroy(ds->ports[port].dn);

They are now destroyed by the newly added dsa_cpu_dsa_destroy().  I'm
making the code more symmetrical and easier to re-use. The inverse of
this function is dsa_switch_setup_one() and it also uses a helper
function to setup the dsa and cpu ports, dsa_cpu_dsa_setups().

	 Andrew