From a20049071796691cf99eb6433968fc3c27632b95 Mon Sep 17 00:00:00 2001 From: Heiner Kallweit Date: Wed, 13 Feb 2019 20:12:54 +0100 Subject: [PATCH] net: phy: fix potential race in the phylib state machine Russell reported the following race in the phylib state machine (quoting from his mail): if (phy_polling_mode(phydev) && phy_is_started(phydev)) phy_queue_state_machine(phydev, PHY_STATE_TIME); state = PHY_UP thread 0 thread 1 phy_disconnect() +-phy_is_started() phy_is_started() | `-phy_stop() +-phydev->state = PHY_HALTED `-phy_stop_machine() `-cancel_delayed_work_sync() phy_queue_state_machine() `-mod_delayed_work() At this point, the phydev->state_queue() has been added back onto the system workqueue despite phy_stop_machine() having been called and cancel_delayed_work_sync() called on it. Fix this by protecting the complete operation in thread 0. Fixes: 2b3e88ea6528 ("net: phy: improve phy state checking") Reported-by: Russell King - ARM Linux admin Signed-off-by: Heiner Kallweit Reviewed-by: Florian Fainelli Signed-off-by: David S. Miller --- drivers/net/phy/phy.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/drivers/net/phy/phy.c b/drivers/net/phy/phy.c index 602816d70281..c5675df5fc6f 100644 --- a/drivers/net/phy/phy.c +++ b/drivers/net/phy/phy.c @@ -985,8 +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); } /**