Commit 4f9c85a1 authored by Anton Vorontsov's avatar Anton Vorontsov Committed by David S. Miller
Browse files

phylib: Move workqueue initialization to a proper place 



commit 541cd3ee ("phylib: Fix deadlock
on resume") caused TI DaVinci EMAC ethernet driver to oops upon resume:

 PM: resume of devices complete after 237.098 msecs
 Restarting tasks ... done.
 kernel BUG at kernel/workqueue.c:354!
 Unable to handle kernel NULL pointer dereference at virtual address 00000000
 [...]
 Backtrace:
 [<c002c598>] (__bug+0x0/0x2c) from [<c0052a54>] (queue_delayed_work_on+0x74/0xf8)
 [<c00529e0>] (queue_delayed_work_on+0x0/0xf8) from [<c0052b30>] (queue_delayed_work+0x2c/0x30)

The oops pops up because TI DaVinci EMAC driver detaches PHY on
suspend and attaches it back on resume. Attaching makes phylib call
phy_start_machine() that initializes a workqueue. On the other hand,
PHY's resume routine will call phy_start_machine() again, and that
will cause the oops since we just destroyed the already scheduled
workqueue.

This patch fixes the issue by moving workqueue initialization to
phy_device_create().

p.s. We don't see this oops with ucc_geth and gianfar drivers because
they perform a fine-grained suspend, i.e. they just stop the PHYs
without detaching.

Reported-by: default avatarSekhar Nori <nsekhar@ti.com>
Signed-off-by: default avatarAnton Vorontsov <avorontsov@ru.mvista.com>
Tested-by: default avatarSekhar Nori <nsekhar@ti.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent de4ef86c

drivers/net/phy/phy.c

+1 −3
Original line number Diff line number Diff line
@@ -410,7 +410,6 @@ EXPORT_SYMBOL(phy_start_aneg); 




static void phy_change(struct work_struct *work);

static void phy_state_machine(struct work_struct *work);



/**

 * phy_start_machine - start PHY state machine tracking
@@ -430,7 +429,6 @@ void phy_start_machine(struct phy_device *phydev, 
{

	phydev->adjust_state = handler;



	INIT_DELAYED_WORK(&phydev->state_queue, phy_state_machine);

	schedule_delayed_work(&phydev->state_queue, HZ);

}
@@ -761,7 +759,7 @@ EXPORT_SYMBOL(phy_start); 
 * phy_state_machine - Handle the state machine

 * @work: work_struct that describes the work to be done

 */

static void phy_state_machine(struct work_struct *work)

void phy_state_machine(struct work_struct *work)

{

	struct delayed_work *dwork = to_delayed_work(work);

	struct phy_device *phydev =

drivers/net/phy/phy_device.c

+1 −0
Original line number Diff line number Diff line
@@ -177,6 +177,7 @@ struct phy_device* phy_device_create(struct mii_bus *bus, int addr, int phy_id) 
	dev->state = PHY_DOWN;



	mutex_init(&dev->lock);

	INIT_DELAYED_WORK(&dev->state_queue, phy_state_machine);



	return dev;

}

include/linux/phy.h

+1 −0
Original line number Diff line number Diff line
@@ -485,6 +485,7 @@ void phy_driver_unregister(struct phy_driver *drv); 
int phy_driver_register(struct phy_driver *new_driver);

void phy_prepare_link(struct phy_device *phydev,

		void (*adjust_link)(struct net_device *));

void phy_state_machine(struct work_struct *work);

void phy_start_machine(struct phy_device *phydev,

		void (*handler)(struct net_device *));

void phy_stop_machine(struct phy_device *phydev);

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