Message-ID: <4CE1C511.60607@metafoo.de>
Date:	Tue, 16 Nov 2010 00:41:05 +0100
From:	Lars-Peter Clausen <lars@...afoo.de>
To:	Eric Cooper <ecc@....edu>
CC:	linux-kernel@...r.kernel.org, Richard Purdie <rpurdie@...ys.net>,
	Oliver Jowett <oliver@...ncloud.com>
Subject: Re: [PATCH] add netdev led trigger

Eric Cooper wrote:
> Add a netdev LED trigger for all Blinkenlights lovers...
> Originally taken from https://dev.openwrt.org/ticket/2776
> Slightly updated for 2.6.24 by Mickey Lauer <mickey@...nmoko.org>
> and for 2.6.36 by Eric Cooper <ecc@....edu>
>
> Signed-off-by: Eric Cooper <ecc@....edu>
> ---
>  drivers/leds/Kconfig          |    7 +
>  drivers/leds/Makefile         |    1 +
>  drivers/leds/ledtrig-netdev.c |  463 +++++++++++++++++++++++++++++++++++++++++
>  3 files changed, 471 insertions(+), 0 deletions(-)
>  create mode 100644 drivers/leds/ledtrig-netdev.c
>
> diff --git a/drivers/leds/Kconfig b/drivers/leds/Kconfig
> index 77b8fd2..8d81cd0 100644
> --- a/drivers/leds/Kconfig
> +++ b/drivers/leds/Kconfig
> @@ -374,6 +374,13 @@ config LEDS_TRIGGER_HEARTBEAT
>  	  load average.
>  	  If unsure, say Y.
>
> +config LEDS_TRIGGER_NETDEV
> +	tristate "LED Network Device Trigger"
> +	depends on NET
> +	help
> +	  This allows LEDs to be controlled by network device activity.
> +	  If unsure, say Y.
> +
>  config LEDS_TRIGGER_BACKLIGHT
>  	tristate "LED backlight Trigger"
>  	help
> diff --git a/drivers/leds/Makefile b/drivers/leds/Makefile
> index aae6989..a3bb67d 100644
> --- a/drivers/leds/Makefile
> +++ b/drivers/leds/Makefile
> @@ -49,6 +49,7 @@ obj-$(CONFIG_LEDS_DAC124S085)		+= leds-dac124s085.o
>  obj-$(CONFIG_LEDS_TRIGGER_TIMER)	+= ledtrig-timer.o
>  obj-$(CONFIG_LEDS_TRIGGER_IDE_DISK)	+= ledtrig-ide-disk.o
>  obj-$(CONFIG_LEDS_TRIGGER_HEARTBEAT)	+= ledtrig-heartbeat.o
> +obj-$(CONFIG_LEDS_TRIGGER_NETDEV)	+= ledtrig-netdev.o
>  obj-$(CONFIG_LEDS_TRIGGER_BACKLIGHT)	+= ledtrig-backlight.o
>  obj-$(CONFIG_LEDS_TRIGGER_GPIO)		+= ledtrig-gpio.o
>  obj-$(CONFIG_LEDS_TRIGGER_DEFAULT_ON)	+= ledtrig-default-on.o
> diff --git a/drivers/leds/ledtrig-netdev.c b/drivers/leds/ledtrig-netdev.c
> new file mode 100644
> index 0000000..ebf9b6b
> --- /dev/null
> +++ b/drivers/leds/ledtrig-netdev.c
> @@ -0,0 +1,463 @@
> +/*
> + * LED Kernel Netdev Trigger
> + *
> + * Toggles the LED to reflect the link and traffic state of a named net device
> + *
> + * Copyright 2007 Oliver Jowett <oliver@...ncloud.com>
> + *
> + * Derived from ledtrig-timer.c which is:
> + *  Copyright 2005-2006 Openedhand Ltd.
> + *  Author: Richard Purdie <rpurdie@...nedhand.com>
> + *
> + * 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
> + * published by the Free Software Foundation.
> + *
> + */
> +
> +#include <linux/module.h>
> +#include <linux/jiffies.h>
> +#include <linux/kernel.h>
> +#include <linux/init.h>
> +#include <linux/list.h>
> +#include <linux/spinlock.h>
> +#include <linux/device.h>
> +#include <linux/sysdev.h>
> +#include <linux/netdevice.h>
> +#include <linux/timer.h>
> +#include <linux/ctype.h>
> +#include <linux/leds.h>
> +#include <linux/version.h>
> +#include <net/net_namespace.h>
> +
> +#include "leds.h"
> +
> +/*
> + * Configurable sysfs attributes:
> + *
> + * device_name - network device name to monitor
> + *
> + * interval - duration of LED blink, in milliseconds
> + *
> + * mode - either "none" (LED is off) or a space separated list
> + * of one or more of:
> + *   link: LED's normal state reflects whether the link is up (has carrier)
> + *         or not
> + *   tx:   LED blinks on transmitted data
> + *   rx:   LED blinks on receive data
> + *
> + * Some suggestions:
> + *
> + *  Simple link status LED:
> + *  $ echo netdev >someled/trigger
> + *  $ echo eth0 >someled/device_name
> + *  $ echo link >someled/mode
> + *
> + *  Ethernet-style link/activity LED:
> + *  $ echo netdev >someled/trigger
> + *  $ echo eth0 >someled/device_name
> + *  $ echo "link tx rx" >someled/mode
> + *
> + *  Modem-style tx/rx LEDs:
> + *  $ echo netdev >led1/trigger
> + *  $ echo ppp0 >led1/device_name
> + *  $ echo tx >led1/mode
> + *  $ echo netdev >led2/trigger
> + *  $ echo ppp0 >led2/device_name
> + *  $ echo rx >led2/mode
> + *
> + */
> +
> +#define MODE_LINK 1
> +#define MODE_TX	  2
> +#define MODE_RX	  4
> +
A prefix for the defines would be a good idea.

> +struct led_netdev_data {
> +	rwlock_t lock;
> +
> +	struct timer_list timer;
> +	struct notifier_block notifier;
> +
> +	struct led_classdev *led_cdev;
You can easily drop the pointer to the led device if you use the led device as
callback data for the timer and notifier callback. The led device has a pointer to
your trigger data.

> +	struct net_device *net_dev;
> +
> +	char device_name[IFNAMSIZ];
> +	unsigned interval;
unsigned long
> +	unsigned mode;
> +	unsigned link_up;
bool
> +	unsigned last_activity;
> +};
> +
> +static void set_baseline_state(struct led_netdev_data *trigger_data)
netdev_trig_...
> +{
> +	if ((trigger_data->mode & MODE_LINK) != 0 && trigger_data->link_up)
> +		led_set_brightness(trigger_data->led_cdev, LED_FULL);
> +	else
> +		led_set_brightness(trigger_data->led_cdev, LED_OFF);
> +
> +	if ((trigger_data->mode & (MODE_TX | MODE_RX)) != 0 &&
> +	    trigger_data->link_up)
> +		mod_timer(&trigger_data->timer,
> +			  jiffies + trigger_data->interval);
> +	else
> +		del_timer(&trigger_data->timer);
> +}
> +
> +static ssize_t led_device_name_show(struct device *dev,
> +				    struct device_attribute *attr, char *buf)
> +{
> +	struct led_classdev *led_cdev = dev_get_drvdata(dev);
> +	struct led_netdev_data *trigger_data = led_cdev->trigger_data;
> +
> +	read_lock(&trigger_data->lock);
> +	sprintf(buf, "%s\n", trigger_data->device_name);
len =
> +	read_unlock(&trigger_data->lock);
> +
> +	return strlen(buf) + 1;
return len
> +}
> +
> +static ssize_t led_device_name_store(struct device *dev,
> +				     struct device_attribute *attr,
> +				     const char *buf, size_t size)
> +{
> +	struct led_classdev *led_cdev = dev_get_drvdata(dev);
> +	struct led_netdev_data *trigger_data = led_cdev->trigger_data;
> +
> +	if (size < 0 || size >= IFNAMSIZ)
Size can not be less then zero.
> +		return -EINVAL;
> +
> +	write_lock(&trigger_data->lock);
> +
> +	strcpy(trigger_data->device_name, buf);
> +	if (size > 0 && trigger_data->device_name[size-1] == '\n')
> +		trigger_data->device_name[size-1] = 0;
> +
> +	if (trigger_data->device_name[0] != 0) {
> +		/* check for existing device to update from */
> +		struct net_device *dev =
> +			dev_get_by_name(&init_net, trigger_data->device_name);
> +		if (dev != NULL) {
> +			unsigned int flags = dev_get_flags(dev);
> +			trigger_data->net_dev = dev;
If trigger_data->net_dev is already you have to put it, otherwise you'll leak an
reference. And you should update trigger_data->net_dev even if the new device does
not exists.

> +			trigger_data->link_up = (flags & IFF_LOWER_UP) != 0;
> +		}
else trigger_data->linkup = false;

> +		/* updates LEDs, may start timers */
> +		set_baseline_state(trigger_data);
> +	}
You should also unset trigger_dat->net_dev and update the led status if the device
name is empty.

I suggest to rewrite it like this:
if (net_dev)
	dev_put(net_dev)
dev = NULL
if (*device_name)
	dev = dev_get_by_name(...)
if (dev != NULL)
	linkup = dev_get_flags ...
else
	linkup = false
net_dev = dev
> +
> +	write_unlock(&trigger_data->lock);
> +	return size;
> +}
> +
> +static DEVICE_ATTR(device_name, 0644,
> +		   led_device_name_show, led_device_name_store);
> +
> +static ssize_t led_mode_show(struct device *dev,
> +			     struct device_attribute *attr, char *buf)
> +{
> +	struct led_classdev *led_cdev = dev_get_drvdata(dev);
> +	struct led_netdev_data *trigger_data = led_cdev->trigger_data;
> +
> +	read_lock(&trigger_data->lock);
> +
> +	if (trigger_data->mode == 0) {
> +		strcpy(buf, "none\n");
> +	} else {
> +		if (trigger_data->mode & MODE_LINK)
> +			strcat(buf, "link ");
> +		if (trigger_data->mode & MODE_TX)
> +			strcat(buf, "tx ");
> +		if (trigger_data->mode & MODE_RX)
> +			strcat(buf, "rx ");
> +		strcat(buf, "\n");
> +	}
> +
> +	read_unlock(&trigger_data->lock);
> +
> +	return strlen(buf)+1;

You should already know the length. Maybe using len += sprintf(buf+len, "...") is a
better idea for appending the strings.

> +}
> +
> +static ssize_t led_mode_store(struct device *dev,
> +			      struct device_attribute *attr,
> +			      const char *buf, size_t size)
> +{
> +	struct led_classdev *led_cdev = dev_get_drvdata(dev);
> +	struct led_netdev_data *trigger_data = led_cdev->trigger_data;
> +	char copybuf[32];
> +	int new_mode = -1;
> +	char *p, *token;
> +
> +	/* take a copy since we don't want to trash the inbound buffer
> +	   when using strsep */
> +	strncpy(copybuf, buf, sizeof(copybuf));
> +	copybuf[sizeof(copybuf) - 1] = '\0';
> +	p = copybuf;
> +
> +	while ((token = strsep(&p, " \t\n")) != NULL) {
> +		if (!*token)
> +			continue;
> +
> +		if (new_mode == -1)
> +			new_mode = 0;
> +
> +		if (!strcmp(token, "none"))
> +			new_mode = 0;
> +		else if (!strcmp(token, "tx"))
> +			new_mode |= MODE_TX;
> +		else if (!strcmp(token, "rx"))
> +			new_mode |= MODE_RX;
> +		else if (!strcmp(token, "link"))
> +			new_mode |= MODE_LINK;
> +		else
> +			return -EINVAL;
> +	}
> +
> +	if (new_mode == -1)
> +		return -EINVAL;
> +
> +	write_lock(&trigger_data->lock);
> +	trigger_data->mode = new_mode;
> +	set_baseline_state(trigger_data);
> +	write_unlock(&trigger_data->lock);
> +
> +	return size;
> +}
> +
> +static DEVICE_ATTR(mode, 0644, led_mode_show, led_mode_store);
> +
> +static ssize_t led_interval_show(struct device *dev,
> +				 struct device_attribute *attr,
> +				 char *buf)
> +{
> +	struct led_classdev *led_cdev = dev_get_drvdata(dev);
> +	struct led_netdev_data *trigger_data = led_cdev->trigger_data;
> +
> +	read_lock(&trigger_data->lock);
> +	sprintf(buf, "%u\n", jiffies_to_msecs(trigger_data->interval));
> +	read_unlock(&trigger_data->lock);
I don't think you need to take the lock here.

> +
> +	return strlen(buf) + 1;
> +}
> +
> +static ssize_t led_interval_store(struct device *dev,
> +				  struct device_attribute *attr,
> +				  const char *buf, size_t size)
> +{
> +	struct led_classdev *led_cdev = dev_get_drvdata(dev);
> +	struct led_netdev_data *trigger_data = led_cdev->trigger_data;
> +	int ret = -EINVAL;
> +	char *after;
> +	unsigned long value = simple_strtoul(buf, &after, 10);

strict_strtoul

> +	size_t count = after - buf;
> +
> +	if (*after && isspace(*after))
> +		count++;
> +
> +	/* impose some basic bounds on the timer interval */
> +	if (count == size && value >= 5 && value <= 10000) {
> +		write_lock(&trigger_data->lock);
> +		trigger_data->interval = msecs_to_jiffies(value);
> +		set_baseline_state(trigger_data);	/* resets timer */
> +		write_unlock(&trigger_data->lock);
> +		ret = count;
> +	}
> +
> +	return ret;
> +}
> +
> +static DEVICE_ATTR(interval, 0644, led_interval_show, led_interval_store);
> +
> +static int netdev_trig_notify(struct notifier_block *nb,
> +			      unsigned long evt,
> +			      void *dv)
> +{
> +	struct net_device *dev = dv;
> +	struct led_netdev_data *trigger_data =
> +		container_of(nb, struct led_netdev_data, notifier);
> +
> +	if (evt != NETDEV_UP && evt != NETDEV_DOWN && evt != NETDEV_CHANGE &&
> +	    evt != NETDEV_REGISTER && evt != NETDEV_UNREGISTER)
> +		return NOTIFY_DONE;
> +
> +	write_lock(&trigger_data->lock);
> +
> +	if (strcmp(dev->name, trigger_data->device_name))
> +		goto done;
> +
> +	if (evt == NETDEV_REGISTER) {
> +		if (trigger_data->net_dev != NULL)
> +			dev_put(trigger_data->net_dev);
> +		dev_hold(dev);
> +		trigger_data->net_dev = dev;
> +		trigger_data->link_up = 0;
> +		goto done;
> +	}
> +
> +	if (evt == NETDEV_UNREGISTER && trigger_data->net_dev != NULL) {
> +		dev_put(trigger_data->net_dev);
> +		trigger_data->net_dev = NULL;
> +		goto done;
> +	}
> +
> +	/* UP / DOWN / CHANGE */
> +
> +	trigger_data->link_up = (evt != NETDEV_DOWN && netif_carrier_ok(dev));
> +	set_baseline_state(trigger_data);

Maybe use an switch-case block here instead of gotos.

> +
> +done:
> +	write_unlock(&trigger_data->lock);
> +	return NOTIFY_DONE;
> +}
> +
> +/* here's the real work! */
> +static void netdev_trig_timer(unsigned long arg)
> +{
> +	struct led_netdev_data *trigger_data = (struct led_netdev_data *)arg;
> +	struct rtnl_link_stats64 temp;
> +	const struct rtnl_link_stats64 *dev_stats;
> +	unsigned new_activity;
> +
> +	write_lock(&trigger_data->lock);
> +
> +	if (!trigger_data->link_up || !trigger_data->net_dev ||
> +	    (trigger_data->mode & (MODE_TX | MODE_RX)) == 0) {
> +		/* we don't need to do timer work, just reflect link state. */
> +		int on = (trigger_data->mode & MODE_LINK) != 0 &&
> +			trigger_data->link_up;
> +		led_set_brightness(trigger_data->led_cdev,
> +				   on ? LED_FULL : LED_OFF);
> +		goto no_restart;
> +	}
> +
> +	dev_stats = dev_get_stats(trigger_data->net_dev, &temp);
> +
> +	new_activity =
> +		((trigger_data->mode & MODE_TX) ? dev_stats->tx_packets : 0) +
> +		((trigger_data->mode & MODE_RX) ? dev_stats->rx_packets : 0);
> +
> +	if (trigger_data->mode & MODE_LINK) {
> +		/* base state is ON (link present) */
> +		/* if there's no link, we don't get this far
> +		   and the LED is off */
> +
> +		/* OFF -> ON always */
> +		/* ON -> OFF on activity */
> +		if (trigger_data->led_cdev->brightness == LED_OFF)
> +			led_set_brightness(trigger_data->led_cdev, LED_FULL);
> +		else if (trigger_data->last_activity != new_activity)
> +			led_set_brightness(trigger_data->led_cdev, LED_OFF);
> +	} else {
> +		/* base state is OFF */
> +		/* ON -> OFF always */
> +		/* OFF -> ON on activity */
> +		if (trigger_data->led_cdev->brightness == LED_FULL)
> +			led_set_brightness(trigger_data->led_cdev, LED_OFF);
> +		else if (trigger_data->last_activity != new_activity)
> +			led_set_brightness(trigger_data->led_cdev, LED_FULL);
> +	}
> +
> +	trigger_data->last_activity = new_activity;
> +	mod_timer(&trigger_data->timer, jiffies + trigger_data->interval);
> +
> +no_restart:
> +	write_unlock(&trigger_data->lock);
> +}
> +
> +static void netdev_trig_activate(struct led_classdev *led_cdev)
> +{
> +	struct led_netdev_data *trigger_data;
> +	int rc;
> +
> +	trigger_data = kzalloc(sizeof(struct led_netdev_data), GFP_KERNEL);
> +	if (!trigger_data)
> +		return;
> +
> +	rwlock_init(&trigger_data->lock);
> +
> +	trigger_data->notifier.notifier_call = netdev_trig_notify;
> +	trigger_data->notifier.priority = 10;
> +
> +	setup_timer(&trigger_data->timer, netdev_trig_timer,
> +		    (unsigned long) trigger_data);
> +
> +	trigger_data->led_cdev = led_cdev;
> +	trigger_data->net_dev = NULL;
> +	trigger_data->device_name[0] = 0;
Since you are using kzalloc the fields are already initalized with '0', no need to do
it again.

> +
> +	trigger_data->mode = 0;
> +	trigger_data->interval = msecs_to_jiffies(50);
> +	trigger_data->link_up = 0;
> +	trigger_data->last_activity = 0;
> +
> +	led_cdev->trigger_data = trigger_data;
> +
> +	rc = device_create_file(led_cdev->dev, &dev_attr_device_name);
> +	if (rc)
> +		goto err_out;
> +	rc = device_create_file(led_cdev->dev, &dev_attr_mode);
> +	if (rc)
> +		goto err_out_device_name;
> +	rc = device_create_file(led_cdev->dev, &dev_attr_interval);
> +	if (rc)
> +		goto err_out_mode;
> +
> +	register_netdevice_notifier(&trigger_data->notifier);
You should check the return value of register_netdevice_notifier.

> +	return;
> +
> +err_out_mode:
> +	device_remove_file(led_cdev->dev, &dev_attr_mode);
> +err_out_device_name:
> +	device_remove_file(led_cdev->dev, &dev_attr_device_name);
> +err_out:
> +	led_cdev->trigger_data = NULL;
> +	kfree(trigger_data);
> +}
> +
> +static void netdev_trig_deactivate(struct led_classdev *led_cdev)
> +{
> +	struct led_netdev_data *trigger_data = led_cdev->trigger_data;
> +
> +	if (trigger_data) {
> +		unregister_netdevice_notifier(&trigger_data->notifier);
> +
> +		device_remove_file(led_cdev->dev, &dev_attr_device_name);
> +		device_remove_file(led_cdev->dev, &dev_attr_mode);
> +		device_remove_file(led_cdev->dev, &dev_attr_interval);
> +
> +		write_lock(&trigger_data->lock);
> +
> +		if (trigger_data->net_dev) {
> +			dev_put(trigger_data->net_dev);
> +			trigger_data->net_dev = NULL;
> +		}
> +
> +		write_unlock(&trigger_data->lock);
> +
> +		del_timer_sync(&trigger_data->timer);
It is a good idea to stop the timer before putting the net dev. You won't have to
take the lock then nor need to assign NULL to net_dev.
> +
> +		kfree(trigger_data);
> +	}
> +}
> +
> +static struct led_trigger netdev_led_trigger = {
> +	.name	  = "netdev",
> +	.activate = netdev_trig_activate,
> +	.deactivate = netdev_trig_deactivate,
> +};
> +
> +static int __init netdev_trig_init(void)
> +{
> +	return led_trigger_register(&netdev_led_trigger);
> +}
> +
> +static void __exit netdev_trig_exit(void)
> +{
> +	led_trigger_unregister(&netdev_led_trigger);
> +}
> +
> +module_init(netdev_trig_init);
> +module_exit(netdev_trig_exit);
module_{init,exit} should go right beneath the function they refer to.
> +
> +MODULE_AUTHOR("Oliver Jowett <oliver@...ncloud.com>");
> +MODULE_DESCRIPTION("Netdev LED trigger");
> +MODULE_LICENSE("GPL");

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