linux-kernel - Re: [PATCH v4 1/9] power: supply: sysfs: print single value in uevent for POWER_SUPPLY_PROP_CHARGE

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Message-ID: <d1e297c9-4abf-4df9-9112-3085175e1227@gmx.de>
Date: Sun, 24 Nov 2024 18:47:32 +0100
From: Armin Wolf <W_Armin@....de>
To: Thomas Weißschuh <linux@...ssschuh.net>,
 Sebastian Reichel <sre@...nel.org>, Hans de Goede <hdegoede@...hat.com>,
 Thomas Weißschuh <thomas@...ssschuh.net>,
 Benson Leung <bleung@...omium.org>, Guenter Roeck <groeck@...omium.org>
Cc: linux-pm@...r.kernel.org, linux-kernel@...r.kernel.org,
 chrome-platform@...ts.linux.dev
Subject: Re: [PATCH v4 1/9] power: supply: sysfs: print single value in uevent
 for POWER_SUPPLY_PROP_CHARGE_BEHAVIOUR

Am 11.11.24 um 22:40 schrieb Thomas Weißschuh:

> Currently an uevent contains the same string representation of a
> property as sysfs. However for POWER_SUPPLY_PROP_CHARGE_BEHAVIOUR this
> is specially formatted to indicate all possible values.
> This doesn't make sense for uevents and complicates parsing.
> Instead only include the currently active value in uevents.
>
> As currently no in-tree driver uses POWER_SUPPLY_PROP_CHARGE_BEHAVIOUR
> this change is not a problem.
> Soon the property will actually be used so fix the formatting before
> that happens.

AFAIK the cros-charge-behaviour driver does use POWER_SUPPLY_PROP_CHARGE_BEHAVIOUR,
so we have to make sure that no userspace application uses this uevent information.

Other than that:

Reviewed-by: Armin Wolf <W_Armin@....de>

> Signed-off-by: Thomas Weißschuh <linux@...ssschuh.net>
> ---
>   drivers/power/supply/power_supply_sysfs.c | 20 ++++++++++++++++----
>   1 file changed, 16 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/power/supply/power_supply_sysfs.c b/drivers/power/supply/power_supply_sysfs.c
> index 571de43fcca9827cf0fe3023e453defbf1eaec7d..a7351b9c8fe34a464a4e69b1a1a4a4179c1a4b4f 100644
> --- a/drivers/power/supply/power_supply_sysfs.c
> +++ b/drivers/power/supply/power_supply_sysfs.c
> @@ -268,9 +268,11 @@ static ssize_t power_supply_show_enum_with_available(
>   	return count;
>   }
>
> -static ssize_t power_supply_show_property(struct device *dev,
> -					  struct device_attribute *attr,
> -					  char *buf) {
> +static ssize_t power_supply_format_property(struct device *dev,
> +					    bool uevent,
> +					    struct device_attribute *attr,
> +					    char *buf)
> +{
>   	ssize_t ret;
>   	struct power_supply *psy = dev_get_drvdata(dev);
>   	const struct power_supply_attr *ps_attr = to_ps_attr(attr);
> @@ -303,6 +305,8 @@ static ssize_t power_supply_show_property(struct device *dev,
>   				psy->desc->usb_types, value.intval, buf);
>   		break;
>   	case POWER_SUPPLY_PROP_CHARGE_BEHAVIOUR:
> +		if (uevent) /* no possible values in uevents */
> +			goto default_format;
>   		ret = power_supply_charge_behaviour_show(dev, psy->desc->charge_behaviours,
>   							 value.intval, buf);
>   		break;
> @@ -310,6 +314,7 @@ static ssize_t power_supply_show_property(struct device *dev,
>   		ret = sysfs_emit(buf, "%s\n", value.strval);
>   		break;
>   	default:
> +default_format:
>   		if (ps_attr->text_values_len > 0 &&
>   				value.intval < ps_attr->text_values_len && value.intval >= 0) {
>   			ret = sysfs_emit(buf, "%s\n", ps_attr->text_values[value.intval]);
> @@ -321,6 +326,13 @@ static ssize_t power_supply_show_property(struct device *dev,
>   	return ret;
>   }
>
> +static ssize_t power_supply_show_property(struct device *dev,
> +					  struct device_attribute *attr,
> +					  char *buf)
> +{
> +	return power_supply_format_property(dev, false, attr, buf);
> +}
> +
>   static ssize_t power_supply_store_property(struct device *dev,
>   					   struct device_attribute *attr,
>   					   const char *buf, size_t count) {
> @@ -437,7 +449,7 @@ static int add_prop_uevent(const struct device *dev, struct kobj_uevent_env *env
>   	pwr_attr = &power_supply_attrs[prop];
>   	dev_attr = &pwr_attr->dev_attr;
>
> -	ret = power_supply_show_property((struct device *)dev, dev_attr, prop_buf);
> +	ret = power_supply_format_property((struct device *)dev, true, dev_attr, prop_buf);
>   	if (ret == -ENODEV || ret == -ENODATA) {
>   		/*
>   		 * When a battery is absent, we expect -ENODEV. Don't abort;
>