Unverified Commit 3ebed2fd authored by Armin Wolf's avatar Armin Wolf Committed by Ilpo Järvinen
Browse files

power: supply: core: Add power_supply_get/set_property_direct() 



Power supply extensions might want to interact with the underlying
power supply to retrieve data like serial numbers, charging status
and more. However doing so causes psy->extensions_sem to be locked
twice, possibly causing a deadlock.

Provide special variants of power_supply_get/set_property() that
ignore any power supply extensions and thus do not touch the
associated psy->extensions_sem lock.

Suggested-by: default avatarHans de Goede <hansg@kernel.org>
Signed-off-by: default avatarArmin Wolf <W_Armin@gmx.de>
Acked-by: default avatarSebastian Reichel <sebastian.reichel@collabora.com>
Reviewed-by: default avatarHans de Goede <hansg@kernel.org>
Link: https://lore.kernel.org/r/20250627205124.250433-1-W_Armin@gmx.de


Reviewed-by: default avatarIlpo Järvinen <ilpo.jarvinen@linux.intel.com>
Signed-off-by: default avatarIlpo Järvinen <ilpo.jarvinen@linux.intel.com>
parent 8346c6af

drivers/power/supply/power_supply_core.c

+70 −12
Original line number Diff line number Diff line
@@ -1235,9 +1235,8 @@ bool power_supply_has_property(struct power_supply *psy, 
	return false;

}



int power_supply_get_property(struct power_supply *psy,

			    enum power_supply_property psp,

			    union power_supply_propval *val)

static int __power_supply_get_property(struct power_supply *psy, enum power_supply_property psp,

				       union power_supply_propval *val, bool use_extensions)

{

	struct power_supply_ext_registration *reg;
@@ -1247,12 +1246,16 @@ int power_supply_get_property(struct power_supply *psy, 
		return -ENODEV;

	}



	if (use_extensions) {

		scoped_guard(rwsem_read, &psy->extensions_sem) {

			power_supply_for_each_extension(reg, psy) {

			if (power_supply_ext_has_property(reg->ext, psp))

				if (!power_supply_ext_has_property(reg->ext, psp))

					continue;



				return reg->ext->get_property(psy, reg->ext, reg->data, psp, val);

			}

		}

	}



	if (psy_desc_has_property(psy->desc, psp))

		return psy->desc->get_property(psy, psp, val);
@@ -1261,20 +1264,49 @@ int power_supply_get_property(struct power_supply *psy, 
	else

		return -EINVAL;

}



int power_supply_get_property(struct power_supply *psy, enum power_supply_property psp,

			      union power_supply_propval *val)

{

	return __power_supply_get_property(psy, psp, val, true);

}

EXPORT_SYMBOL_GPL(power_supply_get_property);



int power_supply_set_property(struct power_supply *psy,

			    enum power_supply_property psp,

			    const union power_supply_propval *val)

/**

 * power_supply_get_property_direct - Read a power supply property without checking for extensions

 * @psy: The power supply

 * @psp: The power supply property to read

 * @val: The resulting value of the power supply property

 *

 * Read a power supply property without taking into account any power supply extensions registered

 * on the given power supply. This is mostly useful for power supply extensions that want to access

 * their own power supply as using power_supply_get_property() directly will result in a potential

 * deadlock.

 *

 * Return: 0 on success or negative error code on failure.

 */

int power_supply_get_property_direct(struct power_supply *psy, enum power_supply_property psp,

				     union power_supply_propval *val)

{

        return __power_supply_get_property(psy, psp, val, false);

}

EXPORT_SYMBOL_GPL(power_supply_get_property_direct);





static int __power_supply_set_property(struct power_supply *psy, enum power_supply_property psp,

				       const union power_supply_propval *val, bool use_extensions)

{

	struct power_supply_ext_registration *reg;



	if (atomic_read(&psy->use_cnt) <= 0)

		return -ENODEV;



	if (use_extensions) {

		scoped_guard(rwsem_read, &psy->extensions_sem) {

			power_supply_for_each_extension(reg, psy) {

			if (power_supply_ext_has_property(reg->ext, psp)) {

				if (!power_supply_ext_has_property(reg->ext, psp))

					continue;



				if (reg->ext->set_property)

					return reg->ext->set_property(psy, reg->ext, reg->data,

								      psp, val);
@@ -1289,8 +1321,34 @@ int power_supply_set_property(struct power_supply *psy, 


	return psy->desc->set_property(psy, psp, val);

}



int power_supply_set_property(struct power_supply *psy, enum power_supply_property psp,

			      const union power_supply_propval *val)

{

	return __power_supply_set_property(psy, psp, val, true);

}

EXPORT_SYMBOL_GPL(power_supply_set_property);



/**

 * power_supply_set_property_direct - Write a power supply property without checking for extensions

 * @psy: The power supply

 * @psp: The power supply property to write

 * @val: The value to write to the power supply property

 *

 * Write a power supply property without taking into account any power supply extensions registered

 * on the given power supply. This is mostly useful for power supply extensions that want to access

 * their own power supply as using power_supply_set_property() directly will result in a potential

 * deadlock.

 *

 * Return: 0 on success or negative error code on failure.

 */

int power_supply_set_property_direct(struct power_supply *psy, enum power_supply_property psp,

				     const union power_supply_propval *val)

{

	return __power_supply_set_property(psy, psp, val, false);

}

EXPORT_SYMBOL_GPL(power_supply_set_property_direct);



int power_supply_property_is_writeable(struct power_supply *psy,

					enum power_supply_property psp)

{

include/linux/power_supply.h

+8 −0
Original line number Diff line number Diff line
@@ -888,15 +888,23 @@ static inline int power_supply_is_system_supplied(void) { return -ENOSYS; } 
extern int power_supply_get_property(struct power_supply *psy,

			    enum power_supply_property psp,

			    union power_supply_propval *val);

int power_supply_get_property_direct(struct power_supply *psy, enum power_supply_property psp,

				     union power_supply_propval *val);

#if IS_ENABLED(CONFIG_POWER_SUPPLY)

extern int power_supply_set_property(struct power_supply *psy,

			    enum power_supply_property psp,

			    const union power_supply_propval *val);

int power_supply_set_property_direct(struct power_supply *psy, enum power_supply_property psp,

				     const union power_supply_propval *val);

#else

static inline int power_supply_set_property(struct power_supply *psy,

			    enum power_supply_property psp,

			    const union power_supply_propval *val)

{ return 0; }

static inline int power_supply_set_property_direct(struct power_supply *psy,

						   enum power_supply_property psp,

						   const union power_supply_propval *val)

{ return 0; }

#endif

extern void power_supply_external_power_changed(struct power_supply *psy);