can: dev: fix deadlock reported after bus-off

A timer was used to restart after the bus-off state, leading to a
relatively large can_restart() executed in an interrupt context,
which in turn sets up pinctrl. When this happens during system boot,
there is a high probability of grabbing the pinctrl_list_mutex,
which is locked already by the probe() of other device, making the
kernel suspect a deadlock condition [1].

To resolve this issue, the restart_timer is replaced by a delayed
work.

[1] https://github.com/victronenergy/venus/issues/24

Signed-off-by: Sergei Miroshnichenko <sergeimir@emcraft.com>
Cc: linux-stable <stable@vger.kernel.org>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>

1 files changed, 17 insertions, 10 deletions

diff --git a/drivers/net/can/dev.c b/drivers/net/can/dev.c
index e21f7cc5ae4d..8d6208c0b400 100644
--- a/drivers/net/can/dev.c
+++ b/drivers/net/can/dev.c
@@ -21,6 +21,7 @@
 #include <linux/slab.h>
 #include <linux/netdevice.h>
 #include <linux/if_arp.h>
+#include <linux/workqueue.h>
 #include <linux/can.h>
 #include <linux/can/dev.h>
 #include <linux/can/skb.h>
@@ -501,9 +502,8 @@ EXPORT_SYMBOL_GPL(can_free_echo_skb);
 /*
  * CAN device restart for bus-off recovery
  */
-static void can_restart(unsigned long data)
+static void can_restart(struct net_device *dev)
 {
-        struct net_device *dev = (struct net_device *)data;
         struct can_priv *priv = netdev_priv(dev);
         struct net_device_stats *stats = &dev->stats;
         struct sk_buff *skb;
@@ -543,6 +543,14 @@ restart:
                 netdev_err(dev, "Error %d during restart", err);
 }
 
+static void can_restart_work(struct work_struct *work)
+{
+        struct delayed_work *dwork = to_delayed_work(work);
+        struct can_priv *priv = container_of(dwork, struct can_priv, restart_work);
+
+        can_restart(priv->dev);
+}
+
 int can_restart_now(struct net_device *dev)
 {
         struct can_priv *priv = netdev_priv(dev);
@@ -556,8 +564,8 @@ int can_restart_now(struct net_device *dev)
         if (priv->state != CAN_STATE_BUS_OFF)
                 return -EBUSY;
 
-        /* Runs as soon as possible in the timer context */
-        mod_timer(&priv->restart_timer, jiffies);
+        cancel_delayed_work_sync(&priv->restart_work);
+        can_restart(dev);
 
         return 0;
 }
@@ -578,8 +586,8 @@ void can_bus_off(struct net_device *dev)
         netif_carrier_off(dev);
 
         if (priv->restart_ms)
-                mod_timer(&priv->restart_timer,
-                          jiffies + (priv->restart_ms * HZ) / 1000);
+                schedule_delayed_work(&priv->restart_work,
+                                      msecs_to_jiffies(priv->restart_ms));
 }
 EXPORT_SYMBOL_GPL(can_bus_off);
 
@@ -688,6 +696,7 @@ struct net_device *alloc_candev(int sizeof_priv, unsigned int echo_skb_max)
                 return NULL;
 
         priv = netdev_priv(dev);
+        priv->dev = dev;
 
         if (echo_skb_max) {
                 priv->echo_skb_max = echo_skb_max;
@@ -697,7 +706,7 @@ struct net_device *alloc_candev(int sizeof_priv, unsigned int echo_skb_max)
 
         priv->state = CAN_STATE_STOPPED;
 
-        init_timer(&priv->restart_timer);
+        INIT_DELAYED_WORK(&priv->restart_work, can_restart_work);
 
         return dev;
 }
@@ -778,8 +787,6 @@ int open_candev(struct net_device *dev)
         if (!netif_carrier_ok(dev))
                 netif_carrier_on(dev);
 
-        setup_timer(&priv->restart_timer, can_restart, (unsigned long)dev);
-
         return 0;
 }
 EXPORT_SYMBOL_GPL(open_candev);
@@ -794,7 +801,7 @@ void close_candev(struct net_device *dev)
 {
         struct can_priv *priv = netdev_priv(dev);
 
-        del_timer_sync(&priv->restart_timer);
+        cancel_delayed_work_sync(&priv->restart_work);
         can_flush_echo_skb(dev);
 }
 EXPORT_SYMBOL_GPL(close_candev);