Commit 9abefcb1 authored by Sergei Miroshnichenko's avatar Sergei Miroshnichenko Committed by Marc Kleine-Budde
Browse files

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: default avatarSergei Miroshnichenko <sergeimir@emcraft.com>
Cc: linux-stable <stable@vger.kernel.org>
Signed-off-by: default avatarMarc Kleine-Budde <mkl@pengutronix.de>
parent 7e32b443

drivers/net/can/dev.c

+17 −10
Original line number Diff line number Diff line
@@ -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);

include/linux/can/dev.h

+2 −1
Original line number Diff line number Diff line
@@ -32,6 +32,7 @@ enum can_mode { 
 * CAN common private data

 */

struct can_priv {

	struct net_device *dev;

	struct can_device_stats can_stats;



	struct can_bittiming bittiming, data_bittiming;
@@ -47,7 +48,7 @@ struct can_priv { 
	u32 ctrlmode_static;	/* static enabled options for driver/hardware */



	int restart_ms;

	struct timer_list restart_timer;

	struct delayed_work restart_work;



	int (*do_set_bittiming)(struct net_device *dev);

	int (*do_set_data_bittiming)(struct net_device *dev);

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