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Date: Fri, 18 Jan 2008 08:04:48 +1100
From: Benjamin Herrenschmidt <benh@...nel.crashing.org>
To: Nate Case <ncase@...-inc.com>
Cc: Andy Fleming <afleming@...escale.com>,
netdev <netdev@...r.kernel.org>
Subject: Re: [PATCH] PHYLIB: Locking fixes for PHY I/O potentially sleeping
On Thu, 2008-01-03 at 17:36 -0600, Nate Case wrote:
> PHY read/write functions can potentially sleep (e.g., a PHY accessed
> via I2C). The following changes were made to account for this:
>
> * Change spin locks to mutex locks
> * Add a BUG_ON() to phy_read() phy_write() to warn against
> calling them from an interrupt context.
> * Use work queue for PHY state machine handling since
> it can potentially sleep
> * Change phydev lock from spinlock to mutex
>
> Signed-off-by: Nate Case <ncase@...-inc.com>
Excellent ! I've been wanting to do that for some time. I'll be able to
convert EMAC to phylib now :-) I'll review the patch in detail as I do
this convesion, maybe next week. Thanks !
Ben.
> ---
> drivers/net/phy/mdio_bus.c | 2 +-
> drivers/net/phy/phy.c | 68 ++++++++++++++++++++++++++++-------------
> drivers/net/phy/phy_device.c | 11 +++----
> include/linux/phy.h | 5 ++-
> 4 files changed, 55 insertions(+), 31 deletions(-)
>
> diff --git a/drivers/net/phy/mdio_bus.c b/drivers/net/phy/mdio_bus.c
> index c30196d..6e9f619 100644
> --- a/drivers/net/phy/mdio_bus.c
> +++ b/drivers/net/phy/mdio_bus.c
> @@ -49,7 +49,7 @@ int mdiobus_register(struct mii_bus *bus)
> int i;
> int err = 0;
>
> - spin_lock_init(&bus->mdio_lock);
> + mutex_init(&bus->mdio_lock);
>
> if (NULL == bus || NULL == bus->name ||
> NULL == bus->read ||
> diff --git a/drivers/net/phy/phy.c b/drivers/net/phy/phy.c
> index 7c9e6e3..12fccb1 100644
> --- a/drivers/net/phy/phy.c
> +++ b/drivers/net/phy/phy.c
> @@ -26,7 +26,6 @@
> #include <linux/netdevice.h>
> #include <linux/etherdevice.h>
> #include <linux/skbuff.h>
> -#include <linux/spinlock.h>
> #include <linux/mm.h>
> #include <linux/module.h>
> #include <linux/mii.h>
> @@ -72,9 +71,11 @@ int phy_read(struct phy_device *phydev, u16 regnum)
> int retval;
> struct mii_bus *bus = phydev->bus;
>
> - spin_lock_bh(&bus->mdio_lock);
> + BUG_ON(in_interrupt());
> +
> + mutex_lock(&bus->mdio_lock);
> retval = bus->read(bus, phydev->addr, regnum);
> - spin_unlock_bh(&bus->mdio_lock);
> + mutex_unlock(&bus->mdio_lock);
>
> return retval;
> }
> @@ -95,9 +96,11 @@ int phy_write(struct phy_device *phydev, u16 regnum, u16 val)
> int err;
> struct mii_bus *bus = phydev->bus;
>
> - spin_lock_bh(&bus->mdio_lock);
> + BUG_ON(in_interrupt());
> +
> + mutex_lock(&bus->mdio_lock);
> err = bus->write(bus, phydev->addr, regnum, val);
> - spin_unlock_bh(&bus->mdio_lock);
> + mutex_unlock(&bus->mdio_lock);
>
> return err;
> }
> @@ -428,7 +431,7 @@ int phy_start_aneg(struct phy_device *phydev)
> {
> int err;
>
> - spin_lock_bh(&phydev->lock);
> + mutex_lock(&phydev->lock);
>
> if (AUTONEG_DISABLE == phydev->autoneg)
> phy_sanitize_settings(phydev);
> @@ -449,13 +452,14 @@ int phy_start_aneg(struct phy_device *phydev)
> }
>
> out_unlock:
> - spin_unlock_bh(&phydev->lock);
> + mutex_unlock(&phydev->lock);
> return err;
> }
> 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);
>
> /**
> @@ -476,6 +480,7 @@ 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;
> @@ -493,11 +498,12 @@ 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);
>
> - spin_lock_bh(&phydev->lock);
> + mutex_lock(&phydev->lock);
> if (phydev->state > PHY_UP)
> phydev->state = PHY_UP;
> - spin_unlock_bh(&phydev->lock);
> + mutex_unlock(&phydev->lock);
>
> phydev->adjust_state = NULL;
> }
> @@ -541,9 +547,9 @@ static void phy_force_reduction(struct phy_device *phydev)
> */
> void phy_error(struct phy_device *phydev)
> {
> - spin_lock_bh(&phydev->lock);
> + mutex_lock(&phydev->lock);
> phydev->state = PHY_HALTED;
> - spin_unlock_bh(&phydev->lock);
> + mutex_unlock(&phydev->lock);
> }
>
> /**
> @@ -705,10 +711,10 @@ static void phy_change(struct work_struct *work)
> if (err)
> goto phy_err;
>
> - spin_lock_bh(&phydev->lock);
> + mutex_lock(&phydev->lock);
> if ((PHY_RUNNING == phydev->state) || (PHY_NOLINK == phydev->state))
> phydev->state = PHY_CHANGELINK;
> - spin_unlock_bh(&phydev->lock);
> + mutex_unlock(&phydev->lock);
>
> atomic_dec(&phydev->irq_disable);
> enable_irq(phydev->irq);
> @@ -735,7 +741,7 @@ phy_err:
> */
> void phy_stop(struct phy_device *phydev)
> {
> - spin_lock_bh(&phydev->lock);
> + mutex_lock(&phydev->lock);
>
> if (PHY_HALTED == phydev->state)
> goto out_unlock;
> @@ -751,7 +757,7 @@ void phy_stop(struct phy_device *phydev)
> phydev->state = PHY_HALTED;
>
> out_unlock:
> - spin_unlock_bh(&phydev->lock);
> + mutex_unlock(&phydev->lock);
>
> /*
> * Cannot call flush_scheduled_work() here as desired because
> @@ -773,7 +779,7 @@ out_unlock:
> */
> void phy_start(struct phy_device *phydev)
> {
> - spin_lock_bh(&phydev->lock);
> + mutex_lock(&phydev->lock);
>
> switch (phydev->state) {
> case PHY_STARTING:
> @@ -787,19 +793,26 @@ void phy_start(struct phy_device *phydev)
> default:
> break;
> }
> - spin_unlock_bh(&phydev->lock);
> + mutex_unlock(&phydev->lock);
> }
> EXPORT_SYMBOL(phy_stop);
> EXPORT_SYMBOL(phy_start);
>
> -/* PHY timer which handles the state machine */
> -static void phy_timer(unsigned long data)
> +/**
> + * 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 phy_device *phydev = (struct phy_device *)data;
> + struct phy_device *phydev =
> + container_of(work, struct phy_device, state_queue);
> int needs_aneg = 0;
> int err = 0;
>
> - spin_lock_bh(&phydev->lock);
> + mutex_lock(&phydev->lock);
>
> if (phydev->adjust_state)
> phydev->adjust_state(phydev->attached_dev);
> @@ -965,7 +978,7 @@ static void phy_timer(unsigned long data)
> break;
> }
>
> - spin_unlock_bh(&phydev->lock);
> + mutex_unlock(&phydev->lock);
>
> if (needs_aneg)
> err = phy_start_aneg(phydev);
> @@ -976,3 +989,14 @@ static void phy_timer(unsigned long data)
> 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);
> +}
> diff --git a/drivers/net/phy/phy_device.c b/drivers/net/phy/phy_device.c
> index 5b9e175..f4c4fd8 100644
> --- a/drivers/net/phy/phy_device.c
> +++ b/drivers/net/phy/phy_device.c
> @@ -25,7 +25,6 @@
> #include <linux/netdevice.h>
> #include <linux/etherdevice.h>
> #include <linux/skbuff.h>
> -#include <linux/spinlock.h>
> #include <linux/mm.h>
> #include <linux/module.h>
> #include <linux/mii.h>
> @@ -80,7 +79,7 @@ struct phy_device* phy_device_create(struct mii_bus *bus, int addr, int phy_id)
>
> dev->state = PHY_DOWN;
>
> - spin_lock_init(&dev->lock);
> + mutex_init(&dev->lock);
>
> return dev;
> }
> @@ -656,7 +655,7 @@ static int phy_probe(struct device *dev)
> if (!(phydrv->flags & PHY_HAS_INTERRUPT))
> phydev->irq = PHY_POLL;
>
> - spin_lock_bh(&phydev->lock);
> + mutex_lock(&phydev->lock);
>
> /* Start out supporting everything. Eventually,
> * a controller will attach, and may modify one
> @@ -670,7 +669,7 @@ static int phy_probe(struct device *dev)
> if (phydev->drv->probe)
> err = phydev->drv->probe(phydev);
>
> - spin_unlock_bh(&phydev->lock);
> + mutex_unlock(&phydev->lock);
>
> return err;
>
> @@ -682,9 +681,9 @@ static int phy_remove(struct device *dev)
>
> phydev = to_phy_device(dev);
>
> - spin_lock_bh(&phydev->lock);
> + mutex_lock(&phydev->lock);
> phydev->state = PHY_DOWN;
> - spin_unlock_bh(&phydev->lock);
> + mutex_unlock(&phydev->lock);
>
> if (phydev->drv->remove)
> phydev->drv->remove(phydev);
> diff --git a/include/linux/phy.h b/include/linux/phy.h
> index 554836e..5e43ae7 100644
> --- a/include/linux/phy.h
> +++ b/include/linux/phy.h
> @@ -88,7 +88,7 @@ struct mii_bus {
>
> /* A lock to ensure that only one thing can read/write
> * the MDIO bus at a time */
> - spinlock_t mdio_lock;
> + struct mutex mdio_lock;
>
> struct device *dev;
>
> @@ -284,10 +284,11 @@ struct phy_device {
>
> /* Interrupt and Polling infrastructure */
> struct work_struct phy_queue;
> + struct work_struct state_queue;
> struct timer_list phy_timer;
> atomic_t irq_disable;
>
> - spinlock_t lock;
> + struct mutex lock;
>
> struct net_device *attached_dev;
>
--
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