Merge branch 'net-phy-fix-locking-issue'

davem330 · davem330 · commit 61c4c0bcff87 · 2019-02-14T12:04:55.000-05:00
Heiner Kallweit says:

====================
net: phy: fix locking issue

Russell pointed out that the locking used in phy_is_started() isn't
needed and misleading. This locking also contributes to a race fixed
with patch 2.
====================

Signed-off-by: David S. Miller &lt;davem@davemloft.net&gt;
diff --git a/drivers/net/phy/phy.c b/drivers/net/phy/phy.c
@@ -553,7 +553,7 @@ int phy_start_aneg(struct phy_device *phydev)
 	if (err < 0)
 		goto out_unlock;
 
-	if (__phy_is_started(phydev)) {
+	if (phy_is_started(phydev)) {
 		if (phydev->autoneg == AUTONEG_ENABLE) {
 			err = phy_check_link_status(phydev);
 		} else {
@@ -709,7 +709,7 @@ void phy_stop_machine(struct phy_device *phydev)
 	cancel_delayed_work_sync(&phydev->state_queue);
 
 	mutex_lock(&phydev->lock);
-	if (__phy_is_started(phydev))
+	if (phy_is_started(phydev))
 		phydev->state = PHY_UP;
 	mutex_unlock(&phydev->lock);
 }
@@ -839,15 +839,14 @@ EXPORT_SYMBOL(phy_stop_interrupts);
  */
 void phy_stop(struct phy_device *phydev)
 {
-	mutex_lock(&phydev->lock);
-
-	if (!__phy_is_started(phydev)) {
+	if (!phy_is_started(phydev)) {
 		WARN(1, "called from state %s\n",
 		     phy_state_to_str(phydev->state));
-		mutex_unlock(&phydev->lock);
 		return;
 	}
 
+	mutex_lock(&phydev->lock);
+
 	if (phy_interrupt_is_valid(phydev))
 		phy_disable_interrupts(phydev);
 
@@ -986,8 +985,10 @@ void phy_state_machine(struct work_struct *work)
 	 * state machine would be pointless and possibly error prone when
 	 * called from phy_disconnect() synchronously.
 	 */
+	mutex_lock(&phydev->lock);
 	if (phy_polling_mode(phydev) && phy_is_started(phydev))
 		phy_queue_state_machine(phydev, PHY_STATE_TIME);
+	mutex_unlock(&phydev->lock);
 }
 
 /**
diff --git a/include/linux/phy.h b/include/linux/phy.h
@@ -674,26 +674,13 @@ phy_lookup_setting(int speed, int duplex, const unsigned long *mask,
 size_t phy_speeds(unsigned int *speeds, size_t size,
 		  unsigned long *mask);
 
-static inline bool __phy_is_started(struct phy_device *phydev)
-{
-	WARN_ON(!mutex_is_locked(&phydev->lock));
-
-	return phydev->state >= PHY_UP;
-}
-
 /**
  * phy_is_started - Convenience function to check whether PHY is started
  * @phydev: The phy_device struct
  */
 static inline bool phy_is_started(struct phy_device *phydev)
 {
-	bool started;
-
-	mutex_lock(&phydev->lock);
-	started = __phy_is_started(phydev);
-	mutex_unlock(&phydev->lock);
-
-	return started;
+	return phydev->state >= PHY_UP;
 }
 
 void phy_resolve_aneg_linkmode(struct phy_device *phydev);
