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

Rhyland Klein
2016-06-07T16:46:01Z

On 6/7/2016 3:23 AM, Krzysztof Kozlowski wrote:
> On 06/06/2016 06:56 PM, 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
>>
>> Cc: stable@vger.kernel.org
>> Signed-off-by: Rhyland Klein <rklein@nvidia.com>
>
> And maybe:
> Fixes: 297d716f6260 ("power_supply: Change ownership from driver to core")

Sure, I wasn't sure which commit this should *fix*, but that makes sense.

>
>
>> ---
>> 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);
>
> How about using just power_supply_get_property() and convert return
> value to EAGAIN?

I like that. I'll swap it over to use that.

>
> Anyway probably such check should be present also on other
> get_property() calls, like thermal cooling path.

I'll look around and see what else I can find.

>
> Best regards,
> Krzysztof
>

-rhyland

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