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Commit a390d1f3 authored by Marcin Slusarz's avatar Marcin Slusarz Committed by David S. Miller
Browse files

phylib: convert state_queue work to delayed_work 



It closes a race in phy_stop_machine when reprogramming of phy_timer
(from phy_state_machine) happens between del_timer_sync and cancel_work_sync.

Without this change it could lead to crash if phy_device would be freed after
phy_stop_machine (timer would fire and schedule freed work).

Signed-off-by: default avatarMarcin Slusarz <marcin.slusarz@gmail.com>
Acked-by: default avatarJean Delvare <khali@linux-fr.org>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 34cd347c

drivers/net/phy/phy.c

+11 −30
Original line number Diff line number Diff line
@@ -414,7 +414,6 @@ EXPORT_SYMBOL(phy_start_aneg); 


static void phy_change(struct work_struct *work);

static void phy_state_machine(struct work_struct *work);

static void phy_timer(unsigned long data);



/**

 * phy_start_machine - start PHY state machine tracking
@@ -434,11 +433,8 @@ void phy_start_machine(struct phy_device *phydev, 
{

	phydev->adjust_state = handler;



	INIT_WORK(&phydev->state_queue, phy_state_machine);

	init_timer(&phydev->phy_timer);

	phydev->phy_timer.function = &phy_timer;

	phydev->phy_timer.data = (unsigned long) phydev;

	mod_timer(&phydev->phy_timer, jiffies + HZ);

	INIT_DELAYED_WORK(&phydev->state_queue, phy_state_machine);

	schedule_delayed_work(&phydev->state_queue, jiffies + HZ);

}



/**
@@ -451,8 +447,7 @@ void phy_start_machine(struct phy_device *phydev, 
 */

void phy_stop_machine(struct phy_device *phydev)

{

	del_timer_sync(&phydev->phy_timer);

	cancel_work_sync(&phydev->state_queue);

	cancel_delayed_work_sync(&phydev->state_queue);



	mutex_lock(&phydev->lock);

	if (phydev->state > PHY_UP)
@@ -680,11 +675,9 @@ static void phy_change(struct work_struct *work) 
	if (err)

		goto irq_enable_err;



	/* Stop timer and run the state queue now.  The work function for

	 * state_queue will start the timer up again.

	 */

	del_timer(&phydev->phy_timer);

	schedule_work(&phydev->state_queue);

	/* reschedule state queue work to run as soon as possible */

	cancel_delayed_work_sync(&phydev->state_queue);

	schedule_delayed_work(&phydev->state_queue, 0);



	return;
@@ -761,14 +754,13 @@ EXPORT_SYMBOL(phy_start); 
/**

 * phy_state_machine - Handle the state machine

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

 *

 * Description: Scheduled by the state_queue workqueue each time

 *   phy_timer is triggered.

 */

static void phy_state_machine(struct work_struct *work)

{

	struct delayed_work *dwork =

			container_of(work, struct delayed_work, work);

	struct phy_device *phydev =

			container_of(work, struct phy_device, state_queue);

			container_of(dwork, struct phy_device, state_queue);

	int needs_aneg = 0;

	int err = 0;
@@ -946,17 +938,6 @@ static void phy_state_machine(struct work_struct *work) 
	if (err < 0)

		phy_error(phydev);



	mod_timer(&phydev->phy_timer, jiffies + PHY_STATE_TIME * HZ);

}



/* PHY timer which schedules the state machine work */

static void phy_timer(unsigned long data)

{

	struct phy_device *phydev = (struct phy_device *)data;



	/*

	 * PHY I/O operations can potentially sleep so we ensure that

	 * it's done from a process context

	 */

	schedule_work(&phydev->state_queue);

	schedule_delayed_work(&phydev->state_queue,

				jiffies + PHY_STATE_TIME * HZ);

}

include/linux/phy.h

+1 −2
Original line number Diff line number Diff line
@@ -315,8 +315,7 @@ struct phy_device { 


	/* Interrupt and Polling infrastructure */

	struct work_struct phy_queue;

	struct work_struct state_queue;

	struct timer_list phy_timer;

	struct delayed_work state_queue;

	atomic_t irq_disable;



	struct mutex lock;