net: phy: Ensure state transitions are processed from phy_stop()

In the phy_disconnect() -> phy_stop() path, we will be forcibly setting
the PHY state machine to PHY_HALTED. This invalidates the old_state !=
phydev->state condition in phy_state_machine() such that we will neither
display the state change for debugging, nor will we invoke the
link_change_notify() callback.

Factor the code by introducing phy_process_state_change(), and ensure
that we process the state change from phy_stop() as well.

Fixes: 5c5f626b ("net: phy: improve handling link_change_notify callback")
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/phy/phy.c

@@ -57,6 +57,18 @@ static const char *phy_state_to_str(enum phy_state st)
 	return NULL;
 }
 
+static void phy_process_state_change(struct phy_device *phydev,
+				     enum phy_state old_state)
+{
+	if (old_state != phydev->state) {
+		phydev_dbg(phydev, "PHY state change %s -> %s\n",
+			   phy_state_to_str(old_state),
+			   phy_state_to_str(phydev->state));
+		if (phydev->drv && phydev->drv->link_change_notify)
+			phydev->drv->link_change_notify(phydev);
+	}
+}
+
 static void phy_link_up(struct phy_device *phydev)
 {
 	phydev->phy_link_change(phydev, true);
@@ -1301,6 +1313,7 @@ EXPORT_SYMBOL(phy_free_interrupt);
 void phy_stop(struct phy_device *phydev)
 {
 	struct net_device *dev = phydev->attached_dev;
+	enum phy_state old_state;
 
 	if (!phy_is_started(phydev) && phydev->state != PHY_DOWN) {
 		WARN(1, "called from state %s\n",
@@ -1309,6 +1322,7 @@ void phy_stop(struct phy_device *phydev)
 	}
 
 	mutex_lock(&phydev->lock);
+	old_state = phydev->state;
 
 	if (phydev->state == PHY_CABLETEST) {
 		phy_abort_cable_test(phydev);
@@ -1319,6 +1333,7 @@ void phy_stop(struct phy_device *phydev)
 		sfp_upstream_stop(phydev->sfp_bus);
 
 	phydev->state = PHY_HALTED;
+	phy_process_state_change(phydev, old_state);
 
 	mutex_unlock(&phydev->lock);
 
@@ -1436,13 +1451,7 @@ void phy_state_machine(struct work_struct *work)
 	if (err < 0)
 		phy_error(phydev);
 
-	if (old_state != phydev->state) {
-		phydev_dbg(phydev, "PHY state change %s -> %s\n",
-			   phy_state_to_str(old_state),
-			   phy_state_to_str(phydev->state));
-		if (phydev->drv && phydev->drv->link_change_notify)
-			phydev->drv->link_change_notify(phydev);
-	}
+	phy_process_state_change(phydev, old_state);
 
 	/* Only re-schedule a PHY state machine change if we are polling the
 	 * PHY, if PHY_MAC_INTERRUPT is set, then we will be moving