[PATCH v3 13/20] power_supply: Increment power supply use counter when obtaining references

Krzysztof Kozlowski
2015-01-30T14:47:51Z

Increment the power_supply.use_cnt usage counter on:
- power_supply_get_by_phandle()
- power_supply_get_by_name()
and decrement it on power_supply_put() call.

This helps tracking of valid usage of power supply instance by
consumers. The usage counter itself also allows safe calling of
power_supply_get_property-like functions even when driver unregisters
this power supply.

Signed-off-by: Krzysztof Kozlowski <k.kozlowski@samsung.com>
Reviewed-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
---
drivers/power/power_supply_core.c | 17 +++++++++++++++--
1 file changed, 15 insertions(+), 2 deletions(-)

diff --git a/drivers/power/power_supply_core.c b/drivers/power/power_supply_core.c
index 95aeae44c34a..acad7e87f754 100644
--- a/drivers/power/power_supply_core.c
+++ b/drivers/power/power_supply_core.c
@@ -349,10 +349,16 @@ static int power_supply_match_device_by_name(struct device *dev, const void *dat
*/
struct power_supply *power_supply_get_by_name(const char *name)
{
+ struct power_supply *psy = NULL;
struct device *dev = class_find_device(power_supply_class, NULL, name,
power_supply_match_device_by_name);

- return dev ? dev_get_drvdata(dev) : NULL;
+ if (dev) {
+ psy = dev_get_drvdata(dev);
+ atomic_inc(&psy->use_cnt);
+ }
+
+ return psy;
}
EXPORT_SYMBOL_GPL(power_supply_get_by_name);

@@ -367,6 +373,7 @@ void power_supply_put(struct power_supply *psy)
{
might_sleep();

+ atomic_dec(&psy->use_cnt);
put_device(&psy->dev);
}
EXPORT_SYMBOL_GPL(power_supply_put);
@@ -393,6 +400,7 @@ struct power_supply *power_supply_get_by_phandle(struct device_node *np,
const char *property)
{
struct device_node *power_supply_np;
+ struct power_supply *psy = NULL;
struct device *dev;

power_supply_np = of_parse_phandle(np, property, 0);
@@ -404,7 +412,12 @@ struct power_supply *power_supply_get_by_phandle(struct device_node *np,

of_node_put(power_supply_np);

- return dev ? dev_get_drvdata(dev) : NULL;
+ if (dev) {
+ psy = dev_get_drvdata(dev);
+ atomic_inc(&psy->use_cnt);
+ }
+
+ return psy;
}
EXPORT_SYMBOL_GPL(power_supply_get_by_phandle);
#endif /* CONFIG_OF */
--
1.9.1