Re: [PATCH 1/4] power_supply: Cleanup power supply sysfs attribute list

From: Sebastian Reichel
Date: Fri May 01 2020 - 20:32:20 EST

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Hi,

On Fri, Apr 24, 2020 at 11:35:30AM -0600, Mathew King wrote:
> Make the device attribute list used to create sysfs attributes more
> robust by decoupling the list order from order of the enum defined in
> power_supply.h. This is done by using a designated initializer in the
> POWER_SUPPLY_ATTR macro.

Thanks for doing this :)

> Also properties not added to the list will still be created with
> name in the format "prop_*".

This is bad. We don't want to expose PROP_%d to userspace and risk
this becoming ABI. Instead it should not be registered and a warning
should be printed. This means we can drop the prop_name field and directly
use upper, which will always be in TEXT segment then.

For the lower case name, I think it's better to provide it as second
argument to POWER_SUPPLY_ATTR. Not very elegant solution, but it
means, that the string is in the TEXT segment and that we can
have the complete dev_attr initialized from the macro.

-- Sebastian

> Signed-off-by: Mathew King <mathewk@xxxxxxxxxxxx>
> ---
> drivers/power/supply/power_supply.h | 7 +-
> drivers/power/supply/power_supply_core.c | 9 +-
> drivers/power/supply/power_supply_sysfs.c | 290 +++++++++++++---------
> 3 files changed, 179 insertions(+), 127 deletions(-)
>
> diff --git a/drivers/power/supply/power_supply.h b/drivers/power/supply/power_supply.h
> index c310d4f36c10..e3475d35ec2a 100644
> --- a/drivers/power/supply/power_supply.h
> +++ b/drivers/power/supply/power_supply.h
> @@ -15,12 +15,15 @@ struct power_supply;
>
> #ifdef CONFIG_SYSFS
>
> -extern void power_supply_init_attrs(struct device_type *dev_type);
> +extern int power_supply_init_attrs(struct device_type *dev_type);
> +extern void power_supply_destroy_attrs(void);
> extern int power_supply_uevent(struct device *dev, struct kobj_uevent_env *env);
>
> #else
>
> -static inline void power_supply_init_attrs(struct device_type *dev_type) {}
> +static inline int power_supply_init_attrs(struct device_type *dev_type)
> +{ return 0; }
> +static void power_supply_destroy_attrs(void) {}
> #define power_supply_uevent NULL
>
> #endif /* CONFIG_SYSFS */
> diff --git a/drivers/power/supply/power_supply_core.c b/drivers/power/supply/power_supply_core.c
> index 1a9a9fae73d3..7fb99302b532 100644
> --- a/drivers/power/supply/power_supply_core.c
> +++ b/drivers/power/supply/power_supply_core.c
> @@ -1329,19 +1329,26 @@ EXPORT_SYMBOL_GPL(power_supply_get_drvdata);
>
> static int __init power_supply_class_init(void)
> {
> + int ret;
> power_supply_class = class_create(THIS_MODULE, "power_supply");
>
> if (IS_ERR(power_supply_class))
> return PTR_ERR(power_supply_class);
>
> power_supply_class->dev_uevent = power_supply_uevent;
> - power_supply_init_attrs(&power_supply_dev_type);
> +
> + ret = power_supply_init_attrs(&power_supply_dev_type);
> + if (ret) {
> + class_destroy(power_supply_class);
> + return ret;
> + }
>
> return 0;
> }
>
> static void __exit power_supply_class_exit(void)
> {
> + power_supply_destroy_attrs();
> class_destroy(power_supply_class);
> }
>
> diff --git a/drivers/power/supply/power_supply_sysfs.c b/drivers/power/supply/power_supply_sysfs.c
> index f37ad4eae60b..b579081599d7 100644
> --- a/drivers/power/supply/power_supply_sysfs.c
> +++ b/drivers/power/supply/power_supply_sysfs.c
> @@ -18,27 +18,22 @@
>
> #include "power_supply.h"
>
> -/*
> - * This is because the name "current" breaks the device attr macro.
> - * The "current" word resolves to "(get_current())" so instead of
> - * "current" "(get_current())" appears in the sysfs.
> - *
> - * The source of this definition is the device.h which calls __ATTR
> - * macro in sysfs.h which calls the __stringify macro.
> - *
> - * Only modification that the name is not tried to be resolved
> - * (as a macro let's say).
> - */
> +#define UNDEF_PROP_NAME_FMT "PROP_%d"
> +#define UNDEF_PROP_NAME_LEN (strlen(UNDEF_PROP_NAME_FMT) + 2)
> +
> +struct power_supply_attr {
> + const char *prop_name;
> + const char *upper_name;
> + const char *lower_name;
> + struct device_attribute dev_attr;
> +};
>
> -#define POWER_SUPPLY_ATTR(_name) \
> -{ \
> - .attr = { .name = #_name }, \
> - .show = power_supply_show_property, \
> - .store = power_supply_store_property, \
> +#define POWER_SUPPLY_ATTR(_name) \
> +[POWER_SUPPLY_PROP_ ## _name] = \
> +{ \
> + .prop_name = #_name \
> }
>
> -static struct device_attribute power_supply_attrs[];
> -
> static const char * const power_supply_type_text[] = {
> "Unknown", "Battery", "UPS", "Mains", "USB",
> "USB_DCP", "USB_CDP", "USB_ACA", "USB_C",
> @@ -77,6 +72,91 @@ static const char * const power_supply_scope_text[] = {
> "Unknown", "System", "Device"
> };
>
> +static struct power_supply_attr power_supply_attrs[] = {
> + /* Properties of type `int' */
> + POWER_SUPPLY_ATTR(STATUS),
> + POWER_SUPPLY_ATTR(CHARGE_TYPE),
> + POWER_SUPPLY_ATTR(HEALTH),
> + POWER_SUPPLY_ATTR(PRESENT),
> + POWER_SUPPLY_ATTR(ONLINE),
> + POWER_SUPPLY_ATTR(AUTHENTIC),
> + POWER_SUPPLY_ATTR(TECHNOLOGY),
> + POWER_SUPPLY_ATTR(CYCLE_COUNT),
> + POWER_SUPPLY_ATTR(VOLTAGE_MAX),
> + POWER_SUPPLY_ATTR(VOLTAGE_MIN),
> + POWER_SUPPLY_ATTR(VOLTAGE_MAX_DESIGN),
> + POWER_SUPPLY_ATTR(VOLTAGE_MIN_DESIGN),
> + POWER_SUPPLY_ATTR(VOLTAGE_NOW),
> + POWER_SUPPLY_ATTR(VOLTAGE_AVG),
> + POWER_SUPPLY_ATTR(VOLTAGE_OCV),
> + POWER_SUPPLY_ATTR(VOLTAGE_BOOT),
> + POWER_SUPPLY_ATTR(CURRENT_MAX),
> + POWER_SUPPLY_ATTR(CURRENT_NOW),
> + POWER_SUPPLY_ATTR(CURRENT_AVG),
> + POWER_SUPPLY_ATTR(CURRENT_BOOT),
> + POWER_SUPPLY_ATTR(POWER_NOW),
> + POWER_SUPPLY_ATTR(POWER_AVG),
> + POWER_SUPPLY_ATTR(CHARGE_FULL_DESIGN),
> + POWER_SUPPLY_ATTR(CHARGE_EMPTY_DESIGN),
> + POWER_SUPPLY_ATTR(CHARGE_FULL),
> + POWER_SUPPLY_ATTR(CHARGE_EMPTY),
> + POWER_SUPPLY_ATTR(CHARGE_NOW),
> + POWER_SUPPLY_ATTR(CHARGE_AVG),
> + POWER_SUPPLY_ATTR(CHARGE_COUNTER),
> + POWER_SUPPLY_ATTR(CONSTANT_CHARGE_CURRENT),
> + POWER_SUPPLY_ATTR(CONSTANT_CHARGE_CURRENT_MAX),
> + POWER_SUPPLY_ATTR(CONSTANT_CHARGE_VOLTAGE),
> + POWER_SUPPLY_ATTR(CONSTANT_CHARGE_VOLTAGE_MAX),
> + POWER_SUPPLY_ATTR(CHARGE_CONTROL_LIMIT),
> + POWER_SUPPLY_ATTR(CHARGE_CONTROL_LIMIT_MAX),
> + POWER_SUPPLY_ATTR(CHARGE_CONTROL_START_THRESHOLD),
> + POWER_SUPPLY_ATTR(CHARGE_CONTROL_END_THRESHOLD),
> + POWER_SUPPLY_ATTR(INPUT_CURRENT_LIMIT),
> + POWER_SUPPLY_ATTR(INPUT_VOLTAGE_LIMIT),
> + POWER_SUPPLY_ATTR(INPUT_POWER_LIMIT),
> + POWER_SUPPLY_ATTR(ENERGY_FULL_DESIGN),
> + POWER_SUPPLY_ATTR(ENERGY_EMPTY_DESIGN),
> + POWER_SUPPLY_ATTR(ENERGY_FULL),
> + POWER_SUPPLY_ATTR(ENERGY_EMPTY),
> + POWER_SUPPLY_ATTR(ENERGY_NOW),
> + POWER_SUPPLY_ATTR(ENERGY_AVG),
> + POWER_SUPPLY_ATTR(CAPACITY),
> + POWER_SUPPLY_ATTR(CAPACITY_ALERT_MIN),
> + POWER_SUPPLY_ATTR(CAPACITY_ALERT_MAX),
> + POWER_SUPPLY_ATTR(CAPACITY_LEVEL),
> + POWER_SUPPLY_ATTR(TEMP),
> + POWER_SUPPLY_ATTR(TEMP_MAX),
> + POWER_SUPPLY_ATTR(TEMP_MIN),
> + POWER_SUPPLY_ATTR(TEMP_ALERT_MIN),
> + POWER_SUPPLY_ATTR(TEMP_ALERT_MAX),
> + POWER_SUPPLY_ATTR(TEMP_AMBIENT),
> + POWER_SUPPLY_ATTR(TEMP_AMBIENT_ALERT_MIN),
> + POWER_SUPPLY_ATTR(TEMP_AMBIENT_ALERT_MAX),
> + POWER_SUPPLY_ATTR(TIME_TO_EMPTY_NOW),
> + POWER_SUPPLY_ATTR(TIME_TO_EMPTY_AVG),
> + POWER_SUPPLY_ATTR(TIME_TO_FULL_NOW),
> + POWER_SUPPLY_ATTR(TIME_TO_FULL_AVG),
> + POWER_SUPPLY_ATTR(TYPE),
> + POWER_SUPPLY_ATTR(USB_TYPE),
> + POWER_SUPPLY_ATTR(SCOPE),
> + POWER_SUPPLY_ATTR(PRECHARGE_CURRENT),
> + POWER_SUPPLY_ATTR(CHARGE_TERM_CURRENT),
> + POWER_SUPPLY_ATTR(CALIBRATE),
> + /* Properties of type `const char *' */
> + POWER_SUPPLY_ATTR(MODEL_NAME),
> + POWER_SUPPLY_ATTR(MANUFACTURER),
> + POWER_SUPPLY_ATTR(SERIAL_NUMBER),
> +};
> +
> +static struct attribute *
> +__power_supply_attrs[ARRAY_SIZE(power_supply_attrs) + 1];
> +
> +static enum power_supply_property dev_attr_psp(struct device_attribute *attr)
> +{
> + return container_of(attr, struct power_supply_attr, dev_attr) -
> + power_supply_attrs;
> +}
> +
> static ssize_t power_supply_show_usb_type(struct device *dev,
> enum power_supply_usb_type *usb_types,
> ssize_t num_usb_types,
> @@ -117,7 +197,7 @@ static ssize_t power_supply_show_property(struct device *dev,
> char *buf) {
> ssize_t ret;
> struct power_supply *psy = dev_get_drvdata(dev);
> - enum power_supply_property psp = attr - power_supply_attrs;
> + enum power_supply_property psp = dev_attr_psp(attr);
> union power_supply_propval value;
>
> if (psp == POWER_SUPPLY_PROP_TYPE) {
> @@ -186,7 +266,7 @@ static ssize_t power_supply_store_property(struct device *dev,
> const char *buf, size_t count) {
> ssize_t ret;
> struct power_supply *psy = dev_get_drvdata(dev);
> - enum power_supply_property psp = attr - power_supply_attrs;
> + enum power_supply_property psp = dev_attr_psp(attr);
> union power_supply_propval value;
>
> switch (psp) {
> @@ -235,86 +315,6 @@ static ssize_t power_supply_store_property(struct device *dev,
> return count;
> }
>
> -/* Must be in the same order as POWER_SUPPLY_PROP_* */
> -static struct device_attribute power_supply_attrs[] = {
> - /* Properties of type `int' */
> - POWER_SUPPLY_ATTR(status),
> - POWER_SUPPLY_ATTR(charge_type),
> - POWER_SUPPLY_ATTR(health),
> - POWER_SUPPLY_ATTR(present),
> - POWER_SUPPLY_ATTR(online),
> - POWER_SUPPLY_ATTR(authentic),
> - POWER_SUPPLY_ATTR(technology),
> - POWER_SUPPLY_ATTR(cycle_count),
> - POWER_SUPPLY_ATTR(voltage_max),
> - POWER_SUPPLY_ATTR(voltage_min),
> - POWER_SUPPLY_ATTR(voltage_max_design),
> - POWER_SUPPLY_ATTR(voltage_min_design),
> - POWER_SUPPLY_ATTR(voltage_now),
> - POWER_SUPPLY_ATTR(voltage_avg),
> - POWER_SUPPLY_ATTR(voltage_ocv),
> - POWER_SUPPLY_ATTR(voltage_boot),
> - POWER_SUPPLY_ATTR(current_max),
> - POWER_SUPPLY_ATTR(current_now),
> - POWER_SUPPLY_ATTR(current_avg),
> - POWER_SUPPLY_ATTR(current_boot),
> - POWER_SUPPLY_ATTR(power_now),
> - POWER_SUPPLY_ATTR(power_avg),
> - POWER_SUPPLY_ATTR(charge_full_design),
> - POWER_SUPPLY_ATTR(charge_empty_design),
> - POWER_SUPPLY_ATTR(charge_full),
> - POWER_SUPPLY_ATTR(charge_empty),
> - POWER_SUPPLY_ATTR(charge_now),
> - POWER_SUPPLY_ATTR(charge_avg),
> - POWER_SUPPLY_ATTR(charge_counter),
> - POWER_SUPPLY_ATTR(constant_charge_current),
> - POWER_SUPPLY_ATTR(constant_charge_current_max),
> - POWER_SUPPLY_ATTR(constant_charge_voltage),
> - POWER_SUPPLY_ATTR(constant_charge_voltage_max),
> - POWER_SUPPLY_ATTR(charge_control_limit),
> - POWER_SUPPLY_ATTR(charge_control_limit_max),
> - POWER_SUPPLY_ATTR(charge_control_start_threshold),
> - POWER_SUPPLY_ATTR(charge_control_end_threshold),
> - POWER_SUPPLY_ATTR(input_current_limit),
> - POWER_SUPPLY_ATTR(input_voltage_limit),
> - POWER_SUPPLY_ATTR(input_power_limit),
> - POWER_SUPPLY_ATTR(energy_full_design),
> - POWER_SUPPLY_ATTR(energy_empty_design),
> - POWER_SUPPLY_ATTR(energy_full),
> - POWER_SUPPLY_ATTR(energy_empty),
> - POWER_SUPPLY_ATTR(energy_now),
> - POWER_SUPPLY_ATTR(energy_avg),
> - POWER_SUPPLY_ATTR(capacity),
> - POWER_SUPPLY_ATTR(capacity_alert_min),
> - POWER_SUPPLY_ATTR(capacity_alert_max),
> - POWER_SUPPLY_ATTR(capacity_level),
> - POWER_SUPPLY_ATTR(temp),
> - POWER_SUPPLY_ATTR(temp_max),
> - POWER_SUPPLY_ATTR(temp_min),
> - POWER_SUPPLY_ATTR(temp_alert_min),
> - POWER_SUPPLY_ATTR(temp_alert_max),
> - POWER_SUPPLY_ATTR(temp_ambient),
> - POWER_SUPPLY_ATTR(temp_ambient_alert_min),
> - POWER_SUPPLY_ATTR(temp_ambient_alert_max),
> - POWER_SUPPLY_ATTR(time_to_empty_now),
> - POWER_SUPPLY_ATTR(time_to_empty_avg),
> - POWER_SUPPLY_ATTR(time_to_full_now),
> - POWER_SUPPLY_ATTR(time_to_full_avg),
> - POWER_SUPPLY_ATTR(type),
> - POWER_SUPPLY_ATTR(usb_type),
> - POWER_SUPPLY_ATTR(scope),
> - POWER_SUPPLY_ATTR(precharge_current),
> - POWER_SUPPLY_ATTR(charge_term_current),
> - POWER_SUPPLY_ATTR(calibrate),
> - /* Properties of type `const char *' */
> - POWER_SUPPLY_ATTR(model_name),
> - POWER_SUPPLY_ATTR(manufacturer),
> - POWER_SUPPLY_ATTR(serial_number),
> -};
> -
> -static struct attribute *
> -__power_supply_attrs[ARRAY_SIZE(power_supply_attrs) + 1];
> -
> static umode_t power_supply_attr_is_visible(struct kobject *kobj,
> struct attribute *attr,
> int attrno)
> @@ -352,17 +352,7 @@ static const struct attribute_group *power_supply_attr_groups[] = {
> NULL,
> };
>
> -void power_supply_init_attrs(struct device_type *dev_type)
> -{
> - int i;
> -
> - dev_type->groups = power_supply_attr_groups;
> -
> - for (i = 0; i < ARRAY_SIZE(power_supply_attrs); i++)
> - __power_supply_attrs[i] = &power_supply_attrs[i].attr;
> -}
> -
> -static char *kstruprdup(const char *str, gfp_t gfp)
> +static char *kstrlwrdup(const char *str, gfp_t gfp)
> {
> char *ret, *ustr;
>
> @@ -372,19 +362,75 @@ static char *kstruprdup(const char *str, gfp_t gfp)
> return NULL;
>
> while (*str)
> - *ustr++ = toupper(*str++);
> + *ustr++ = tolower(*str++);
>
> *ustr = 0;
>
> return ret;
> }
>
> +int power_supply_init_attrs(struct device_type *dev_type)
> +{
> + int i;
> +
> + dev_type->groups = power_supply_attr_groups;
> +
> + for (i = 0; i < ARRAY_SIZE(power_supply_attrs); i++) {
> + const char *upper, *lower;
> + struct device_attribute *attr;
> +
> + upper = power_supply_attrs[i].prop_name;
> +
> + if (!upper) {
> + char *name = kmalloc(UNDEF_PROP_NAME_LEN, GFP_KERNEL);
> +
> + if (!name)
> + goto err_no_mem;
> +
> + sprintf(name, UNDEF_PROP_NAME_FMT, i);
> + upper = name;
> + }
> +
> + lower = kstrlwrdup(upper, GFP_KERNEL);
> +
> + if (!lower)
> + goto err_no_mem;
> +
> + power_supply_attrs[i].upper_name = upper;
> + power_supply_attrs[i].lower_name = lower;
> +
> + attr = &power_supply_attrs[i].dev_attr;
> +
> + attr->attr.name = lower;
> + attr->show = power_supply_show_property;
> + attr->store = power_supply_store_property;
> + __power_supply_attrs[i] = &attr->attr;
> + }
> +
> + return 0;
> +
> +err_no_mem:
> + power_supply_destroy_attrs();
> + return -ENOMEM;
> +}
> +
> +void power_supply_destroy_attrs(void)
> +{
> + int i;
> +
> + for (i = 0; i < ARRAY_SIZE(power_supply_attrs); i++) {
> + kfree(power_supply_attrs[i].lower_name);
> +
> + if (!power_supply_attrs[i].prop_name)
> + kfree(power_supply_attrs[i].upper_name);
> + }
> +}
> +
> int power_supply_uevent(struct device *dev, struct kobj_uevent_env *env)
> {
> struct power_supply *psy = dev_get_drvdata(dev);
> int ret = 0, j;
> char *prop_buf;
> - char *attrname;
>
> if (!psy || !psy->desc) {
> dev_dbg(dev, "No power supply yet\n");
> @@ -400,12 +446,14 @@ int power_supply_uevent(struct device *dev, struct kobj_uevent_env *env)
> return -ENOMEM;
>
> for (j = 0; j < psy->desc->num_properties; j++) {
> - struct device_attribute *attr;
> + struct power_supply_attr *pwr_attr;
> + struct device_attribute *dev_attr;
> char *line;
>
> - attr = &power_supply_attrs[psy->desc->properties[j]];
> + pwr_attr = &power_supply_attrs[psy->desc->properties[j]];
> + dev_attr = &pwr_attr->dev_attr;
>
> - ret = power_supply_show_property(dev, attr, prop_buf);
> + ret = power_supply_show_property(dev, dev_attr, prop_buf);
> if (ret == -ENODEV || ret == -ENODATA) {
> /* When a battery is absent, we expect -ENODEV. Don't abort;
> send the uevent with at least the the PRESENT=0 property */
> @@ -420,14 +468,8 @@ int power_supply_uevent(struct device *dev, struct kobj_uevent_env *env)
> if (line)
> *line = 0;
>
> - attrname = kstruprdup(attr->attr.name, GFP_KERNEL);
> - if (!attrname) {
> - ret = -ENOMEM;
> - goto out;
> - }
> -
> - ret = add_uevent_var(env, "POWER_SUPPLY_%s=%s", attrname, prop_buf);
> - kfree(attrname);
> + ret = add_uevent_var(env, "POWER_SUPPLY_%s=%s",
> + pwr_attr->upper_name, prop_buf);
> if (ret)
> goto out;
> }
> --
> 2.26.2.303.gf8c07b1a785-goog
>

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