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: Marcin Slusarz <marcin.slusarz@gmail.com>
Acked-by: Jean Delvare <khali@linux-fr.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 11 insertions, 30 deletions

diff --git a/drivers/net/phy/phy.c b/drivers/net/phy/phy.c
index e4ede6080c9d..58b73b08dde0 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);
 }