Commit a2004907 authored by Heiner Kallweit's avatar Heiner Kallweit Committed by David S. Miller

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: 2b3e88ea ("net: phy: improve phy state checking")
Reported-by: default avatarRussell King - ARM Linux admin <linux@armlinux.org.uk>
Signed-off-by: default avatarHeiner Kallweit <hkallweit1@gmail.com>
Reviewed-by: default avatarFlorian Fainelli <f.fainelli@gmail.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent a2fc9d7e
...@@ -985,8 +985,10 @@ void phy_state_machine(struct work_struct *work) ...@@ -985,8 +985,10 @@ void phy_state_machine(struct work_struct *work)
* state machine would be pointless and possibly error prone when * state machine would be pointless and possibly error prone when
* called from phy_disconnect() synchronously. * called from phy_disconnect() synchronously.
*/ */
mutex_lock(&phydev->lock);
if (phy_polling_mode(phydev) && phy_is_started(phydev)) if (phy_polling_mode(phydev) && phy_is_started(phydev))
phy_queue_state_machine(phydev, PHY_STATE_TIME); phy_queue_state_machine(phydev, PHY_STATE_TIME);
mutex_unlock(&phydev->lock);
} }
/** /**
......
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