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Date: Sat, 7 Mar 2009 10:46:20 +0100
From: Jean Delvare <khali@...ux-fr.org>
To: Marcin Slusarz <marcin.slusarz@...il.com>
Cc: netdev@...r.kernel.org, Andy Fleming <afleming@...escale.com>,
Trent Piepho <tpiepho@...escale.com>,
LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] phylib: convert state_queue work to delayed_work
On Fri, 6 Mar 2009 21:51:42 +0100, Marcin Slusarz wrote:
> 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: Marcin Slusarz <marcin.slusarz@...il.com>
> Cc: Andy Fleming <afleming@...escale.com>
> Cc: Trent Piepho <tpiepho@...escale.com>
> ---
>
> This patch was only compile tested.
Patch looks good.
Acked-by: Jean Delvare <khali@...ux-fr.org>
>
> ---
> drivers/net/phy/phy.c | 41 +++++++++++------------------------------
> include/linux/phy.h | 3 +--
> 2 files changed, 12 insertions(+), 32 deletions(-)
>
> diff --git a/drivers/net/phy/phy.c b/drivers/net/phy/phy.c
> index e4ede60..58b73b0 100644
> --- a/drivers/net/phy/phy.c
> +++ b/drivers/net/phy/phy.c
> @@ -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);
> }
> diff --git a/include/linux/phy.h b/include/linux/phy.h
> index d7e54d9..32cf14a 100644
> --- a/include/linux/phy.h
> +++ b/include/linux/phy.h
> @@ -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;
--
Jean Delvare
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