Re: [PATCH v6 1/2] leds: trigger: netdev: display only supported link speed attribute

[Lee Jones]

A review from Andrew is always helpful for netdev related items.

On Thu, 21 Dec 2023, Christian Marangi wrote:

> With the addition of more link speed mode to the netdev trigger, it was
> pointed out that there may be a problem with bloating the attribute list
> with modes that won't ever be supported by the trigger as the attached
> device name doesn't support them.
> 
> To clear and address this problem, change the logic where these
> additional trigger modes are listed.
> 
> Since the netdev trigger REQUIRE a device name to be set, attach to the
> device name change function additional logic to parse the supported link
> speed modes using ethtool APIs and show only the supported link speed
> modes attribute.
> 
> Link speed attribute are refreshed on device_name set and on
> NETDEV_CHANGE events.
> 
> This only apply to the link speed modes and every other mode is still
> provided by default.
> 
> Signed-off-by: Christian Marangi <ansuelsmth@xxxxxxxxx>
> Reviewed-by: Marek Behún <kabel@xxxxxxxxxx>
> ---
> Took a while but I found a way to not use phy_speeds.
> 
> Saddly that is way too specific to PHYs and we can't add PHYLIB as
> a dependency for leds.
> 
> I instead found a handy way to keep everything to ethtool, it's a bit
> worse optimization wise but does the same work. (the perf penality
> is really minimal as we only parse supported speeds and it's difficult
> to have a device that have tons of speeds modes)
> 
> Changes v6:
> - Improve comments wording
> - Add Reviewed-by tag
> Changes v5:
> - Add macro to make code less ugly
> Changes v4:
> - Rework to use an alternative to phy_speeds API
> Changes v3:
> - Use phy_speeds API to parse the ethtool mask
> Changes v2:
> - Use is_visibile instead of removing/adding attr
> 
>  drivers/leds/trigger/ledtrig-netdev.c | 88 +++++++++++++++++++++++++--
>  1 file changed, 82 insertions(+), 6 deletions(-)

Generally fine, just a couple of nits.

> diff --git a/drivers/leds/trigger/ledtrig-netdev.c b/drivers/leds/trigger/ledtrig-netdev.c
> index 836610292b37..f082a952bd4d 100644
> --- a/drivers/leds/trigger/ledtrig-netdev.c
> +++ b/drivers/leds/trigger/ledtrig-netdev.c
> @@ -18,10 +18,12 @@
>  #include <linux/jiffies.h>
>  #include <linux/kernel.h>
>  #include <linux/leds.h>
> +#include <linux/linkmode.h>
>  #include <linux/list.h>
>  #include <linux/module.h>
>  #include <linux/netdevice.h>
>  #include <linux/mutex.h>
> +#include <linux/phy.h>
>  #include <linux/rtnetlink.h>
>  #include <linux/timer.h>
>  #include "../leds.h"
> @@ -65,12 +67,15 @@ struct led_netdev_data {
>  
>  	unsigned long mode;
>  	int link_speed;
> +	__ETHTOOL_DECLARE_LINK_MODE_MASK(supported_link_modes);
>  	u8 duplex;
>  
>  	bool carrier_link_up;
>  	bool hw_control;
>  };
>  
> +static const struct attribute_group netdev_trig_link_speed_attrs_group;
> +
>  static void set_baseline_state(struct led_netdev_data *trigger_data)
>  {
>  	int current_brightness;
> @@ -218,13 +223,19 @@ static void get_device_state(struct led_netdev_data *trigger_data)
>  	struct ethtool_link_ksettings cmd;
>  
>  	trigger_data->carrier_link_up = netif_carrier_ok(trigger_data->net_dev);
> -	if (!trigger_data->carrier_link_up)
> +
> +	if (__ethtool_get_link_ksettings(trigger_data->net_dev, &cmd))
>  		return;
>  
> -	if (!__ethtool_get_link_ksettings(trigger_data->net_dev, &cmd)) {
> +	if (trigger_data->carrier_link_up) {
>  		trigger_data->link_speed = cmd.base.speed;
>  		trigger_data->duplex = cmd.base.duplex;
>  	}
> +
> +	/* Have a local copy of the link speed supported to avoid rtnl lock every time
> +	 * modes are refreshed on any change event
> +	 */

Nit: Standard kernel comments throughout please.

This is not the Net subsystem.

> +	linkmode_copy(trigger_data->supported_link_modes, cmd.link_modes.supported);
>  }
>  
>  static ssize_t device_name_show(struct device *dev,
> @@ -292,6 +303,10 @@ static ssize_t device_name_store(struct device *dev,
>  
>  	if (ret < 0)
>  		return ret;
> +
> +	/* Refresh link_speed visibility */
> +	sysfs_update_group(&dev->kobj, &netdev_trig_link_speed_attrs_group);
> +
>  	return size;
>  }
>  
> @@ -455,15 +470,62 @@ static ssize_t offloaded_show(struct device *dev,
>  
>  static DEVICE_ATTR_RO(offloaded);
>  
> -static struct attribute *netdev_trig_attrs[] = {
> -	&dev_attr_device_name.attr,
> -	&dev_attr_link.attr,
> +#define CHECK_LINK_MODE_ATTR(link_speed) \
> +	do { \
> +		if (attr == &dev_attr_link_##link_speed.attr && \
> +		    link_ksettings.base.speed == SPEED_##link_speed) \
> +			return attr->mode; \
> +	} while (0)
> +
> +static umode_t netdev_trig_link_speed_visible(struct kobject *kobj,
> +					      struct attribute *attr, int n)
> +{
> +	struct device *dev = kobj_to_dev(kobj);
> +	struct led_netdev_data *trigger_data;
> +	unsigned long *supported_link_modes;
> +	u32 mode;
> +
> +	trigger_data = led_trigger_get_drvdata(dev);
> +	supported_link_modes = trigger_data->supported_link_modes;
> +
> +	/* Search in the supported link mode mask a matching supported mode.
> +	 * Stop at the first matching entry as we care only to check if a particular
> +	 * speed is supported and not the kind.
> +	 */

Here too.

> +	for_each_set_bit(mode, supported_link_modes, __ETHTOOL_LINK_MODE_MASK_NBITS) {
> +		struct ethtool_link_ksettings link_ksettings;
> +
> +		ethtool_params_from_link_mode(&link_ksettings, mode);
> +
> +		CHECK_LINK_MODE_ATTR(10);
> +		CHECK_LINK_MODE_ATTR(100);
> +		CHECK_LINK_MODE_ATTR(1000);
> +		CHECK_LINK_MODE_ATTR(2500);
> +		CHECK_LINK_MODE_ATTR(5000);
> +		CHECK_LINK_MODE_ATTR(10000);
> +	}
> +
> +	return 0;
> +}
> +
> +static struct attribute *netdev_trig_link_speed_attrs[] = {
>  	&dev_attr_link_10.attr,
>  	&dev_attr_link_100.attr,
>  	&dev_attr_link_1000.attr,
>  	&dev_attr_link_2500.attr,
>  	&dev_attr_link_5000.attr,
>  	&dev_attr_link_10000.attr,
> +	NULL
> +};
> +
> +static const struct attribute_group netdev_trig_link_speed_attrs_group = {
> +	.attrs = netdev_trig_link_speed_attrs,
> +	.is_visible = netdev_trig_link_speed_visible,
> +};
> +
> +static struct attribute *netdev_trig_attrs[] = {
> +	&dev_attr_device_name.attr,
> +	&dev_attr_link.attr,
>  	&dev_attr_full_duplex.attr,
>  	&dev_attr_half_duplex.attr,
>  	&dev_attr_rx.attr,
> @@ -472,7 +534,16 @@ static struct attribute *netdev_trig_attrs[] = {
>  	&dev_attr_offloaded.attr,
>  	NULL
>  };
> -ATTRIBUTE_GROUPS(netdev_trig);
> +
> +static const struct attribute_group netdev_trig_attrs_group = {
> +	.attrs = netdev_trig_attrs,
> +};
> +
> +static const struct attribute_group *netdev_trig_groups[] = {
> +	&netdev_trig_attrs_group,
> +	&netdev_trig_link_speed_attrs_group,
> +	NULL,
> +};
>  
>  static int netdev_trig_notify(struct notifier_block *nb,
>  			      unsigned long evt, void *dv)
> @@ -481,6 +552,7 @@ static int netdev_trig_notify(struct notifier_block *nb,
>  		netdev_notifier_info_to_dev((struct netdev_notifier_info *)dv);
>  	struct led_netdev_data *trigger_data =
>  		container_of(nb, struct led_netdev_data, notifier);
> +	struct led_classdev *led_cdev = trigger_data->led_cdev;
>  
>  	if (evt != NETDEV_UP && evt != NETDEV_DOWN && evt != NETDEV_CHANGE
>  	    && evt != NETDEV_REGISTER && evt != NETDEV_UNREGISTER
> @@ -515,6 +587,10 @@ static int netdev_trig_notify(struct notifier_block *nb,
>  	case NETDEV_UP:
>  	case NETDEV_CHANGE:
>  		get_device_state(trigger_data);
> +		/* Refresh link_speed visibility */
> +		if (evt == NETDEV_CHANGE)
> +			sysfs_update_group(&led_cdev->dev->kobj,
> +					   &netdev_trig_link_speed_attrs_group);
>  		break;
>  	}
>  
> -- 
> 2.40.1

-- 
Lee Jones [李琼斯]