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Subject: Re: [PATCH] leds: trigger: Introduce a NETDEV trigger
To: Ben Whitten <ben.whitten@gmail.com>, rpurdie@rpsys.net, pavel@ucw.cz
References: <1511906058-30649-1-git-send-email-ben.whitten@gmail.com>
 <1511906058-30649-2-git-send-email-ben.whitten@gmail.com>
Cc: linux-leds@vger.kernel.org, linux-kernel@vger.kernel.org,
        netdev@vger.kernel.org
From: Jacek Anaszewski <jacek.anaszewski@gmail.com>
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Hi Ben,

Thanks for the patch. I have some comments in the code below.
Please take a look.

On 11/28/2017 10:54 PM, Ben Whitten wrote:
> This commit introduces a NETDEV trigger for named device
> activity. Available triggers are link, rx, and tx.
> 
> Signed-off-by: Ben Whitten <ben.whitten@gmail.com>
> ---
>  .../ABI/testing/sysfs-class-led-trigger-netdev     |  45 +++
>  drivers/leds/trigger/Kconfig                       |   7 +
>  drivers/leds/trigger/Makefile                      |   1 +
>  drivers/leds/trigger/ledtrig-netdev.c              | 428 +++++++++++++++++++++
>  4 files changed, 481 insertions(+)
>  create mode 100644 Documentation/ABI/testing/sysfs-class-led-trigger-netdev
>  create mode 100644 drivers/leds/trigger/ledtrig-netdev.c
> 
> diff --git a/Documentation/ABI/testing/sysfs-class-led-trigger-netdev b/Documentation/ABI/testing/sysfs-class-led-trigger-netdev
> new file mode 100644
> index 0000000..2c917df
> --- /dev/null
> +++ b/Documentation/ABI/testing/sysfs-class-led-trigger-netdev
> @@ -0,0 +1,45 @@
> +What:		/sys/class/leds/<led>/device_name
> +Date:		Nov 2017
> +KernelVersion:	4.15

Now it will be 4.16 presumably.

> +Contact:	linux-leds@vger.kernel.org
> +Description:
> +		Specifies the network device name to monitor.
> +
> +What:		/sys/class/leds/<led>/interval
> +Date:		Nov 2017
> +KernelVersion:	4.15
> +Contact:	linux-leds@vger.kernel.org
> +Description:
> +		Specifies the duration of the LED blink in milliseconds.
> +		Defaults to 50 ms.
> +
> +What:		/sys/class/leds/<led>/link
> +Date:		Nov 2017
> +KernelVersion:	4.15
> +Contact:	linux-leds@vger.kernel.org
> +Description:
> +		Signal the link state of the named network device.
> +		If set to 0 (default), the LED's normal state is off.
> +		If set to 1, the LED's normal state reflects the link state
> +		of the named network device.
> +		Setting this value also immediately changes the LED state.
> +
> +What:		/sys/class/leds/<led>/tx
> +Date:		Nov 2017
> +KernelVersion:	4.15
> +Contact:	linux-leds@vger.kernel.org
> +Description:
> +		Signal transmission of data on the named network device.
> +		If set to 0 (default), the LED will not blink on transmission.
> +		If set to 1, the LED will blink for the milliseconds specified
> +		in interval to signal transmission.
> +
> +What:		/sys/class/leds/<led>/rx
> +Date:		Nov 2017
> +KernelVersion:	4.15
> +Contact:	linux-leds@vger.kernel.org
> +Description:
> +		Signal reception of data on the named network device.
> +		If set to 0 (default), the LED will not blink on reception.
> +		If set to 1, the LED will blink for the milliseconds specified
> +		in interval to signal reception.
> diff --git a/drivers/leds/trigger/Kconfig b/drivers/leds/trigger/Kconfig
> index 3f9ddb9..4ec1853 100644
> --- a/drivers/leds/trigger/Kconfig
> +++ b/drivers/leds/trigger/Kconfig
> @@ -126,4 +126,11 @@ config LEDS_TRIGGER_PANIC
>  	  a different trigger.
>  	  If unsure, say Y.
>  
> +config LEDS_TRIGGER_NETDEV
> +	tristate "LED Netdev Trigger"
> +	depends on NET && LEDS_TRIGGERS
> +	help
> +	  This allows LEDs to be controlled by network device activity.
> +	  If unsure, say Y.
> +
>  endif # LEDS_TRIGGERS
> diff --git a/drivers/leds/trigger/Makefile b/drivers/leds/trigger/Makefile
> index 9f2e868..59e163d 100644
> --- a/drivers/leds/trigger/Makefile
> +++ b/drivers/leds/trigger/Makefile
> @@ -11,3 +11,4 @@ obj-$(CONFIG_LEDS_TRIGGER_DEFAULT_ON)	+= ledtrig-default-on.o
>  obj-$(CONFIG_LEDS_TRIGGER_TRANSIENT)	+= ledtrig-transient.o
>  obj-$(CONFIG_LEDS_TRIGGER_CAMERA)	+= ledtrig-camera.o
>  obj-$(CONFIG_LEDS_TRIGGER_PANIC)	+= ledtrig-panic.o
> +obj-$(CONFIG_LEDS_TRIGGER_NETDEV)	+= ledtrig-netdev.o
> diff --git a/drivers/leds/trigger/ledtrig-netdev.c b/drivers/leds/trigger/ledtrig-netdev.c
> new file mode 100644
> index 0000000..2953b41
> --- /dev/null
> +++ b/drivers/leds/trigger/ledtrig-netdev.c
> @@ -0,0 +1,428 @@
> +/*
> + * LED Kernel Netdev Trigger
> + *
> + * Toggles the LED to reflect the link and traffic state of a named net device
> + *
> + * Copyright 2017 Ben Whitten <ben.whitten@gmail.com>
> + *
> + * Copyright 2007 Oliver Jowett <oliver@opencloud.com>
> + *
> + * Derived from ledtrig-timer.c which is:
> + *  Copyright 2005-2006 Openedhand Ltd.
> + *  Author: Richard Purdie <rpurdie@openedhand.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/netdevice.h>
> +#include <linux/timer.h>
> +#include <linux/ctype.h>
> +#include <linux/atomic.h>
> +#include <linux/leds.h>

Please sort includes lexicographically.

> +/*
> + * Configurable sysfs attributes:
> + *
> + * device_name - network device name to monitor
> + *

Redundant empty line.

> + * interval - duration of LED blink, in milliseconds
> + *

Ditto.

> + * 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
> + *
> + */
> +
> +struct led_netdev_data {
> +	spinlock_t lock;
> +
> +	struct delayed_work work;
> +	struct notifier_block notifier;
> +
> +	struct led_classdev *led_cdev;
> +	struct net_device *net_dev;
> +
> +	char device_name[IFNAMSIZ];
> +	atomic_t interval;
> +	unsigned int last_activity;
> +
> +	unsigned long mode;
> +#define LED_BLINK_link	0
> +#define LED_BLINK_tx	1
> +#define LED_BLINK_rx	2

LED core already has LED_BLINK* family of macros. Please come up
with the prefix specific for this trigger e.g. NETDEV_LED.
Also let's use uppercase for the whole macro name.

> +#define LED_MODE_LINKUP	3

s/LED/NETDEV_LED/

> +};
> +
> +static void set_baseline_state(struct led_netdev_data *trigger_data)
> +{
> +	if (!test_bit(LED_MODE_LINKUP, &trigger_data->mode))
> +		led_set_brightness(trigger_data->led_cdev, LED_OFF);
> +	else {
> +		if (test_bit(LED_BLINK_link, &trigger_data->mode))
> +			led_set_brightness(trigger_data->led_cdev, LED_FULL);
> +
> +		if (test_bit(LED_BLINK_tx, &trigger_data->mode) ||
> +		    test_bit(LED_BLINK_rx, &trigger_data->mode))
> +			schedule_delayed_work(&trigger_data->work,
> +				atomic_read(&trigger_data->interval));

Now we have blink support in the LED core. Please use
led_blink_set_oneshot() instead.

Generally you can compare how ledtrig-timer is now implemented.

> +	}
> +}
> +
> +static ssize_t 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;
> +	ssize_t len;
> +
> +	spin_lock_bh(&trigger_data->lock);
> +	len = sprintf(buf, "%s\n", trigger_data->device_name);
> +	spin_unlock_bh(&trigger_data->lock);
> +
> +	return len;
> +}
> +
> +static ssize_t 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 >= IFNAMSIZ)
> +		return -EINVAL;
> +
> +	cancel_delayed_work_sync(&trigger_data->work);
> +
> +	spin_lock_bh(&trigger_data->lock);
> +
> +	if (trigger_data->net_dev) {
> +		dev_put(trigger_data->net_dev);
> +		trigger_data->net_dev = NULL;
> +	}
> +
> +	strncpy(trigger_data->device_name, buf, size);
> +	if (size > 0 && trigger_data->device_name[size - 1] == '\n')
> +		trigger_data->device_name[size - 1] = 0;
> +
> +	if (trigger_data->device_name[0] != 0)
> +		trigger_data->net_dev =
> +		    dev_get_by_name(&init_net, trigger_data->device_name);
> +
> +	clear_bit(LED_MODE_LINKUP, &trigger_data->mode);
> +	if (trigger_data->net_dev != NULL)
> +		if (netif_carrier_ok(trigger_data->net_dev))
> +			set_bit(LED_MODE_LINKUP, &trigger_data->mode);
> +
> +	trigger_data->last_activity = 0;
> +
> +	set_baseline_state(trigger_data);
> +	spin_unlock_bh(&trigger_data->lock);
> +
> +	return size;
> +}
> +
> +static DEVICE_ATTR_RW(device_name);
> +
> +#define led_mode_flags_attr(field)					\
> +static ssize_t field##_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;	\
> +									\
> +	return sprintf(buf, "%u\n", test_bit(LED_BLINK_##field,		\
> +					&trigger_data->mode));		\
> +}									\
> +static ssize_t field##_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;	\
> +	unsigned long state;						\
> +	int ret;							\
> +									\
> +	ret = kstrtoul(buf, 0, &state);					\
> +	if (ret)							\
> +		return ret;						\
> +									\
> +	cancel_delayed_work_sync(&trigger_data->work);			\
> +									\
> +	if (state)							\
> +		set_bit(LED_BLINK_##field, &trigger_data->mode);	\
> +	else								\
> +		clear_bit(LED_BLINK_##field, &trigger_data->mode);	\
> +									\
> +	set_baseline_state(trigger_data);				\
> +									\
> +	return size;							\
> +}									\
> +static DEVICE_ATTR_RW(field);

In order to get rid of this macro and avoid the need for camel case
macro name we could have one function that would accept an enum e.g.

enum netdev_led_attr {
	NETDEV_ATTR_LINK,
	NETDEV_ATTR_RX,
	NETDEV_ATTR_TX
};

The function would be called from each sysfs attr callback with the
related enum, and would alter the state of the related bit.

> +led_mode_flags_attr(link);
> +led_mode_flags_attr(rx);
> +led_mode_flags_attr(tx);
> +
> +static ssize_t 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;
> +
> +	return sprintf(buf, "%u\n",
> +		       jiffies_to_msecs(atomic_read(&trigger_data->interval)));
> +}
> +
> +static ssize_t 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;
> +	unsigned long value;
> +	int ret;
> +
> +	ret = kstrtoul(buf, 0, &value);
> +	if (ret)
> +		return ret;
> +
> +	/* impose some basic bounds on the timer interval */
> +	if (value >= 5 && value <= 10000) {
> +		cancel_delayed_work_sync(&trigger_data->work);
> +
> +		atomic_set(&trigger_data->interval, msecs_to_jiffies(value));
> +		set_baseline_state(trigger_data);	/* resets timer */
> +	}
> +
> +	return size;
> +}
> +
> +static DEVICE_ATTR_RW(interval);
> +
> +static int netdev_trig_notify(struct notifier_block *nb,
> +			      unsigned long evt, void *dv)
> +{
> +	struct net_device *dev =
> +		netdev_notifier_info_to_dev((struct netdev_notifier_info *)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
> +	    && evt != NETDEV_CHANGENAME)
> +		return NOTIFY_DONE;
> +
> +	if (strcmp(dev->name, trigger_data->device_name))
> +		return NOTIFY_DONE;
> +
> +	cancel_delayed_work_sync(&trigger_data->work);
> +
> +	spin_lock_bh(&trigger_data->lock);
> +
> +	clear_bit(LED_MODE_LINKUP, &trigger_data->mode);
> +	switch (evt) {
> +	case NETDEV_REGISTER:
> +		if (trigger_data->net_dev)
> +			dev_put(trigger_data->net_dev);
> +		dev_hold(dev);
> +		trigger_data->net_dev = dev;
> +		break;
> +	case NETDEV_CHANGENAME:
> +	case NETDEV_UNREGISTER:
> +		if (trigger_data->net_dev) {
> +			dev_put(trigger_data->net_dev);
> +			trigger_data->net_dev = NULL;
> +		}
> +		break;
> +	case NETDEV_UP:
> +	case NETDEV_CHANGE:
> +		if (netif_carrier_ok(dev))
> +			set_bit(LED_MODE_LINKUP, &trigger_data->mode);
> +		break;
> +	}
> +
> +	set_baseline_state(trigger_data);
> +
> +	spin_unlock_bh(&trigger_data->lock);
> +
> +	return NOTIFY_DONE;
> +}
> +
> +/* here's the real work! */
> +static void netdev_trig_work(struct work_struct *work)
> +{
> +	struct led_netdev_data *trigger_data = container_of(work,
> +							    struct
> +							    led_netdev_data,
> +							    work.work);
> +	struct rtnl_link_stats64 *dev_stats;
> +	unsigned int new_activity;
> +	struct rtnl_link_stats64 temp;
> +
> +	if (!test_bit(LED_MODE_LINKUP, &trigger_data->mode) ||
> +	    !trigger_data->net_dev ||
> +	    (!test_bit(LED_BLINK_tx, &trigger_data->mode) &&
> +	     !test_bit(LED_BLINK_rx, &trigger_data->mode))) {
> +		/* we don't need to do timer work, just reflect link state. */
> +		led_set_brightness(trigger_data->led_cdev,
> +				   (test_bit
> +				    (LED_BLINK_link, &trigger_data->mode)
> +				    && test_bit(LED_MODE_LINKUP,
> +						&trigger_data->mode
> +						) ? LED_FULL : LED_OFF));
> +		return;
> +	}
> +
> +	dev_stats = dev_get_stats(trigger_data->net_dev, &temp);
> +	new_activity =
> +	    (test_bit(LED_BLINK_tx, &trigger_data->mode) ?
> +		dev_stats->tx_packets : 0) +
> +	    (test_bit(LED_BLINK_rx, &trigger_data->mode) ?
> +		dev_stats->rx_packets : 0);
> +
> +	if (test_bit(LED_BLINK_link, &trigger_data->mode)) {
> +		/* 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;
> +	schedule_delayed_work(&trigger_data->work,
> +			      atomic_read(&trigger_data->interval));
> +}
> +
> +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;
> +
> +	spin_lock_init(&trigger_data->lock);
> +
> +	trigger_data->notifier.notifier_call = netdev_trig_notify;
> +	trigger_data->notifier.priority = 10;
> +
> +	INIT_DELAYED_WORK(&trigger_data->work, netdev_trig_work);
> +
> +	trigger_data->led_cdev = led_cdev;
> +	trigger_data->net_dev = NULL;
> +	trigger_data->device_name[0] = 0;
> +
> +	trigger_data->mode = 0;
> +	atomic_set(&trigger_data->interval, msecs_to_jiffies(50));
> +	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_link);
> +	if (rc)
> +		goto err_out_device_name;
> +	rc = device_create_file(led_cdev->dev, &dev_attr_rx);
> +	if (rc)
> +		goto err_out_link;
> +	rc = device_create_file(led_cdev->dev, &dev_attr_tx);
> +	if (rc)
> +		goto err_out_rx;
> +	rc = device_create_file(led_cdev->dev, &dev_attr_interval);
> +	if (rc)
> +		goto err_out_tx;
> +	rc = register_netdevice_notifier(&trigger_data->notifier);
> +	if (rc)
> +		goto err_out_interval;
> +	return;
> +
> +err_out_interval:
> +	device_remove_file(led_cdev->dev, &dev_attr_interval);
> +err_out_tx:
> +	device_remove_file(led_cdev->dev, &dev_attr_tx);
> +err_out_rx:
> +	device_remove_file(led_cdev->dev, &dev_attr_rx);
> +err_out_link:
> +	device_remove_file(led_cdev->dev, &dev_attr_link);
> +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_link);
> +		device_remove_file(led_cdev->dev, &dev_attr_rx);
> +		device_remove_file(led_cdev->dev, &dev_attr_tx);
> +		device_remove_file(led_cdev->dev, &dev_attr_interval);
> +
> +		cancel_delayed_work_sync(&trigger_data->work);
> +
> +		if (trigger_data->net_dev)
> +			dev_put(trigger_data->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_AUTHOR("Ben Whitten <ben.whitten@gmail.com>");
> +MODULE_AUTHOR("Oliver Jowett <oliver@opencloud.com>");
> +MODULE_DESCRIPTION("Netdev LED trigger");
> +MODULE_LICENSE("GPL");

"GPL v2" according to the licensing information from the top
of the file.

-- 
Best regards,
Jacek Anaszewski