From: Sergei Miroshnichenko <sergei...@emcraft.com>

3.12-stable review patch.  If anyone has any objections, please let me know.

===============

commit 9abefcb1aaa58b9d5aa40a8bb12c87d02415e4c8 upstream.

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 <sergei...@emcraft.com>
Signed-off-by: Marc Kleine-Budde <m...@pengutronix.de>
Signed-off-by: Jiri Slaby <jsl...@suse.cz>
---
 drivers/net/can/dev.c   | 27 +++++++++++++++++----------
 include/linux/can/dev.h |  3 ++-
 2 files changed, 19 insertions(+), 11 deletions(-)

diff --git a/drivers/net/can/dev.c b/drivers/net/can/dev.c
index 464e5f66b66d..284d751ea97f 100644
--- a/drivers/net/can/dev.c
+++ b/drivers/net/can/dev.c
@@ -22,6 +22,7 @@
 #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>
@@ -394,9 +395,8 @@ 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;
@@ -436,6 +436,14 @@ 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);
@@ -449,8 +457,8 @@ 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;
 }
@@ -472,8 +480,8 @@ void can_bus_off(struct net_device *dev)
        priv->can_stats.bus_off++;
 
        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);
 
@@ -556,6 +564,7 @@ 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;
@@ -565,7 +574,7 @@ 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;
 }
@@ -599,8 +608,6 @@ 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);
@@ -615,7 +622,7 @@ 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);
diff --git a/include/linux/can/dev.h b/include/linux/can/dev.h
index fb0ab651a041..fb9fbe2f63e7 100644
--- a/include/linux/can/dev.h
+++ b/include/linux/can/dev.h
@@ -31,6 +31,7 @@ enum can_mode {
  * CAN common private data
  */
 struct can_priv {
+       struct net_device *dev;
        struct can_device_stats can_stats;
 
        struct can_bittiming bittiming;
@@ -42,7 +43,7 @@ struct can_priv {
        u32 ctrlmode_supported;
 
        int restart_ms;
-       struct timer_list restart_timer;
+       struct delayed_work restart_work;
 
        int (*do_set_bittiming)(struct net_device *dev);
        int (*do_set_mode)(struct net_device *dev, enum can_mode mode);
-- 
2.10.1

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