| Message ID | 1433725788-13693-1-git-send-email-k.kozlowski@samsung.com (mailing list archive) |
|---|---|
| State | Not Applicable, archived |
| Headers | show |
Hi, On Mon, Jun 08, 2015 at 10:09:48AM +0900, Krzysztof Kozlowski wrote: > The fix for NULL pointer exception related to calling uevent for not > finished probe caused to set all writeable properties as non-writeable. > This was caused by checking if property is writeable before the initial > increase of power supply usage counter and in the same time using > wrapper over property_is_writeable(). The wrapper returns ENODEV if the > usage counter is still 0. > > The call trace looked like: > device probe: > power_supply_register() > use_cnt = 0; > device_add() > create sysfs entries > power_supply_attr_is_visible() > power_supply_property_is_writeable() > if (use_cnt == 0) return -ENODEV; > use_cnt++; > > Replace the usage of wrapper with direct call to property_is_writeable() > from driver. This should be safe call during device probe because > implementations of this callback just return 0/1 for different > properties and they do not access any of the driver's internal data. Thanks, queued. -- Sebastian
diff --git a/drivers/power/power_supply_sysfs.c b/drivers/power/power_supply_sysfs.c index af026806cba5..ed2d7fd0c734 100644 --- a/drivers/power/power_supply_sysfs.c +++ b/drivers/power/power_supply_sysfs.c @@ -223,7 +223,7 @@ static umode_t power_supply_attr_is_visible(struct kobject *kobj, if (property == attrno) { if (psy->desc->property_is_writeable && - power_supply_property_is_writeable(psy, property) > 0) + psy->desc->property_is_writeable(psy, property) > 0) mode |= S_IWUSR; return mode; diff --git a/include/linux/power_supply.h b/include/linux/power_supply.h index a80f1fd01ddb..0395bcb18ddb 100644 --- a/include/linux/power_supply.h +++ b/include/linux/power_supply.h @@ -206,6 +206,11 @@ struct power_supply_desc { int (*set_property)(struct power_supply *psy, enum power_supply_property psp, const union power_supply_propval *val); + /* + * property_is_writeable() will be called during registration + * of power supply. If this happens during device probe then it must + * not access internal data of device (because probe did not end). + */ int (*property_is_writeable)(struct power_supply *psy, enum power_supply_property psp); void (*external_power_changed)(struct power_supply *psy);
The fix for NULL pointer exception related to calling uevent for not finished probe caused to set all writeable properties as non-writeable. This was caused by checking if property is writeable before the initial increase of power supply usage counter and in the same time using wrapper over property_is_writeable(). The wrapper returns ENODEV if the usage counter is still 0. The call trace looked like: device probe: power_supply_register() use_cnt = 0; device_add() create sysfs entries power_supply_attr_is_visible() power_supply_property_is_writeable() if (use_cnt == 0) return -ENODEV; use_cnt++; Replace the usage of wrapper with direct call to property_is_writeable() from driver. This should be safe call during device probe because implementations of this callback just return 0/1 for different properties and they do not access any of the driver's internal data. Fixes: 8e59c7f23410 ("power_supply: Fix NULL pointer dereference during bq27x00_battery probe") Signed-off-by: Krzysztof Kozlowski <k.kozlowski@samsung.com> --- drivers/power/power_supply_sysfs.c | 2 +- include/linux/power_supply.h | 5 +++++ 2 files changed, 6 insertions(+), 1 deletion(-)