[RESEND PATCH v2] power_supply: power_supply_read_temp only if use_cnt > 0

Rhyland Klein
2016-06-06T16:58:19Z

Add check to power_supply_read_temp() to only use the power_supply
get_property() callback if the use_cnt is > 0. The use_cnt will
be incremented at the end of __power_supply_register, so this will
block to case where get_property can be called before the supply
is fully registered. This fixes the issue show in the stack below:

[ 1.452598] power_supply_read_temp+0x78/0x80
[ 1.458680] thermal_zone_get_temp+0x5c/0x11c
[ 1.464765] thermal_zone_device_update+0x34/0xb4
[ 1.471195] thermal_zone_device_register+0x87c/0x8cc
[ 1.477974] __power_supply_register+0x364/0x424
[ 1.484317] power_supply_register_no_ws+0x10/0x18
[ 1.490833] bq27xxx_battery_setup+0x10c/0x164
[ 1.497003] bq27xxx_battery_i2c_probe+0xd0/0x1b0
[ 1.503435] i2c_device_probe+0x174/0x240
[ 1.509172] driver_probe_device+0x1fc/0x29c
[ 1.515167] __driver_attach+0xa4/0xa8
[ 1.520643] bus_for_each_dev+0x58/0x98
[ 1.526204] driver_attach+0x20/0x28
[ 1.531505] bus_add_driver+0x1c8/0x22c
[ 1.537067] driver_register+0x68/0x108
[ 1.542630] i2c_register_driver+0x38/0x7c
[ 1.548457] bq27xxx_battery_i2c_driver_init+0x18/0x20
[ 1.555321] do_one_initcall+0x38/0x12c
[ 1.560886] kernel_init_freeable+0x148/0x1ec
[ 1.566972] kernel_init+0x10/0xfc
[ 1.572101] ret_from_fork+0x10/0x40

Cc: stable@vger.kernel.org
Signed-off-by: Rhyland Klein <rklein@nvidia.com>
---
v2:
- Added cc stable
- changed return to -EAGAIN in case of use_cnt < 1
- Removed WARNING
- return value check added in additional patch:
"thermal: helpers: Check return value of get_temp"

drivers/power/power_supply_core.c | 8 ++++++--
1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/drivers/power/power_supply_core.c b/drivers/power/power_supply_core.c
index 456987c88baa..bbd80631f31e 100644
--- a/drivers/power/power_supply_core.c
+++ b/drivers/power/power_supply_core.c
@@ -561,11 +561,15 @@ static int power_supply_read_temp(struct thermal_zone_device *tzd,
{
struct power_supply *psy;
union power_supply_propval val;
- int ret;
+ int ret = -EAGAIN;

WARN_ON(tzd == NULL);
+
psy = tzd->devdata;
- ret = psy->desc->get_property(psy, POWER_SUPPLY_PROP_TEMP, &val);
+
+ if (atomic_read(&psy->use_cnt) > 0)
+ ret = psy->desc->get_property(psy, POWER_SUPPLY_PROP_TEMP,
+ &val);

/* Convert tenths of degree Celsius to milli degree Celsius. */
if (!ret)
--
1.9.1