linux-kernel - Re: [PATCH v3] can: rename LED trigger name on netdev renames

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Date:	Mon, 10 Sep 2012 20:25:50 +0200
From:	Oliver Hartkopp <socketcan@...tkopp.net>
To:	Fabio Baltieri <fabio.baltieri@...il.com>,
	Marc Kleine-Budde <mkl@...gutronix.de>,
	Wolfgang Grandegger <wg@...ndegger.com>,
	linux-kernel@...r.kernel.org, linux-can@...r.kernel.org
Subject: Re: [PATCH v3] can: rename LED trigger name on netdev renames

On 10.09.2012 16:28, Kurt Van Dijck wrote:

> can: rename LED trigger name on netdev renames
> 
> The LED trigger name for CAN devices is based on the initial
> CAN device name, but does never change. The LED trigger name
> is not guaranteed to be unique in case of hotplugging CAN devices.
> 
> This patch tries to address this problem by modifying the
> LED trigger name according to the CAN device name when
> the latter changes.
> 
> v1 - Kurt Van Dijck
> v2 - Fabio Baltieri
> - remove rename blocking if trigger is bound
> - use led-subsystem function for the actual rename (still WiP)
> - call init/exit functions from dev.c
> v3 - Kurt Van Dijck
> - safe operation for non-candev based devices (vcan, slcan)
> 	based on earlier patch
> 
> Signed-off-by: Kurt Van Dijck <kurt.van.dijck@....be>
> Signed-off-by: Fabio Baltieri <fabio.baltieri@...il.com>
> --
> 
> Fabio,
> 
> I followed all your contribution to this patch.
> 
> diff --git a/drivers/net/can/dev.c b/drivers/net/can/dev.c
> index 6c1e704..55ad320 100644
> --- a/drivers/net/can/dev.c
> +++ b/drivers/net/can/dev.c
> @@ -25,6 +25,7 @@
>  #include <linux/can.h>
>  #include <linux/can/dev.h>
>  #include <linux/can/netlink.h>
> +#include <linux/can/led.h>
>  #include <net/rtnetlink.h>
>  
>  #define MOD_DESC "CAN device driver interface"
> @@ -811,6 +812,10 @@ static __init int can_dev_init(void)
>  {
>  	int err;
>  
> +	can_led_notifier_init();
> +
> +	can_led_notifier_init();
> +


two times?

>  	err = rtnl_link_register(&can_link_ops);
>  	if (!err)
>  		printk(KERN_INFO MOD_DESC "\n");
> @@ -822,6 +827,8 @@ module_init(can_dev_init);
>  static __exit void can_dev_exit(void)
>  {
>  	rtnl_link_unregister(&can_link_ops);
> +
> +	can_led_notifier_exit();
>  }
>  module_exit(can_dev_exit);
>  
> diff --git a/drivers/net/can/led.c b/drivers/net/can/led.c
> index eaa14ac..1663b28 100644
> --- a/drivers/net/can/led.c
> +++ b/drivers/net/can/led.c
> @@ -1,5 +1,6 @@
>  /*
>   * Copyright 2012, Fabio Baltieri <fabio.baltieri@...il.com>
> + * Copyright 2012, Kurt Van Dijck <kurt.van.dijck@....be>
>   *
>   * This program is free software; you can redistribute it and/or modify
>   * it under the terms of the GNU General Public License version 2 as
> @@ -87,3 +88,39 @@ void devm_can_led_init(struct net_device *netdev)
>  	devres_add(&netdev->dev, res);
>  }
>  EXPORT_SYMBOL_GPL(devm_can_led_init);
> +
> +/*
> + * NETDEV rename notifier to rename the associated led triggers too
> + */
> +static int can_led_notifier(struct notifier_block *nb, unsigned long msg,
> +			void *data)
> +{
> +	struct net_device *netdev = data;
> +	struct can_priv *priv = safe_candev_priv(netdev);
> +	char name[CAN_LED_NAME_SZ];
> +


What about

if (!priv)
	return NOTIFY_DONE;

:-)

You created that nice function but you are accessing priv->tx_led_trig below
without checking the output of save_candev_priv() ...

Regards,
Oliver

> +	if (msg == NETDEV_CHANGENAME) {
> +		snprintf(name, sizeof(name), "%s-tx", netdev->name);
> +		led_trigger_rename_static(name, priv->tx_led_trig);
> +        
> +		snprintf(name, sizeof(name), "%s-rx", netdev->name);
> +		led_trigger_rename_static(name, priv->rx_led_trig);
> +	}
> +
> +	return NOTIFY_DONE;
> +}
> +
> +/* notifier block for netdevice event */
> +static struct notifier_block can_netdev_notifier __read_mostly = {
> +	.notifier_call = can_led_notifier,
> +};
> +
> +int __init can_led_notifier_init(void)
> +{
> +	return register_netdevice_notifier(&can_netdev_notifier);
> +}
> +
> +void __exit can_led_notifier_exit(void)
> +{
> +	unregister_netdevice_notifier(&can_netdev_notifier);
> +}
> diff --git a/include/linux/can/led.h b/include/linux/can/led.h
> index 12d5549..9c1167b 100644
> --- a/include/linux/can/led.h
> +++ b/include/linux/can/led.h
> @@ -26,6 +26,8 @@ enum can_led_event {
>  
>  void can_led_event(struct net_device *netdev, enum can_led_event event);
>  void devm_can_led_init(struct net_device *netdev);
> +int __init can_led_notifier_init(void);
> +void __exit can_led_notifier_exit(void);
>  
>  #else
>  
> @@ -36,6 +38,13 @@ static inline void can_led_event(struct net_device *netdev,
>  static inline void devm_can_led_init(struct net_device *netdev)
>  {
>  }
> +static inline int can_led_notifier_init(void)
> +{
> +	return 0;
> +}
> +static inline void can_led_notifier_exit(void)
> +{
> +}
>  
>  #endif
>  
> --
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