net: phy: don't reschedule state machine when PHY is halted

mainline inclusion
from mainline-v4.20-rc1
commit 075ddebc
category: bugfix
bugzilla: NA
CVE: NA

-------------------------------------------------

When being in state PHY_HALTED we don't have to reschedule the
state machine, phy_start() will start it again.
Signed-off-by: NHeiner Kallweit <hkallweit1@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
Signed-off-by: NYufeng Mo <moyufeng@huawei.com>
Reviewed-by: Nlinyunsheng <linyunsheng@huawei.com>
Signed-off-by: NYang Yingliang <yangyingliang@huawei.com>

drivers/net/phy/phy.c

@@ -1121,9 +1121,13 @@ void phy_state_machine(struct work_struct *work)
 
 	/* Only re-schedule a PHY state machine change if we are polling the
 	 * PHY, if PHY_IGNORE_INTERRUPT is set, then we will be moving
-	 * between states from phy_mac_interrupt()
+	 * between states from phy_mac_interrupt().
+	 *
+	 * In state PHY_HALTED the PHY gets suspended, so rescheduling the
+	 * state machine would be pointless and possibly error prone when
+	 * called from phy_disconnect() synchronously.
 	 */
-	if (phy_polling_mode(phydev))
+	if (phy_polling_mode(phydev) && old_state != PHY_HALTED)
 		queue_delayed_work(system_power_efficient_wq, &phydev->state_queue,
 				   PHY_STATE_TIME * HZ);
 }