On 6/4/2016 9:30 AM, Sebastian Reichel wrote:
> * PGP Signed by an unknown key
>
> Hi Rhyland,
>
> Thanks for the patch.
>
> On Fri, Jun 03, 2016 at 04:30:50PM -0400, Rhyland Klein wrote:
>> 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
>
> So I guess this should be backported to stable kernels.
That it would probably make sense.
>
>> Signed-off-by: Rhyland Klein <rkl...@nvidia.com>
>> ---
>> drivers/power/power_supply_core.c | 9 +++++++--
>> 1 file changed, 7 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/power/power_supply_core.c
>> b/drivers/power/power_supply_core.c
>> index 456987c88baa..070fec621d66 100644
>> --- a/drivers/power/power_supply_core.c
>> +++ b/drivers/power/power_supply_core.c
>> @@ -561,11 +561,16 @@ static int power_supply_read_temp(struct
>> thermal_zone_device *tzd,
>> {
>> struct power_supply *psy;
>> union power_supply_propval val;
>> - int ret;
>> + int ret = 0;
>
> ret should probably be initialized to -EAGAIN to avoid val being
> interpreted without get_property() having been called at all?
Sure, that makes more sense than a 0 temp which could be misinterpreted.
>
>> WARN_ON(tzd == NULL);
>> +
>> psy = tzd->devdata;
>> - ret = psy->desc->get_property(psy, POWER_SUPPLY_PROP_TEMP, &val);
>> + WARN_ON(atomic_read(&psy->use_cnt) == 0);
>
> I guess the warning can be dropped if error code is properly reported?
It looks like the thermal might not, but I will make a patch for that
too, since it is setup to handle it, but doesn't actually check it.
>
>> + 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)
>
> -- Sebastian
>
-rhyland
--
nvpublic
