On 6/8/2016 2:35 AM, Krzysztof Kozlowski wrote:
> On 06/07/2016 10:26 PM, Rhyland Klein wrote:
>> Change power_supply_read_temp() to use power_supply_get_property()
>> so that it will check the use_cnt and ensure it 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
>>
>> Also make the same change to ps_get_max_charge_cntl_limit() and
>> ps_get_cur_chrage_cntl_limit() to be safe. Lastly, change the return
>> value of power_supply_get_property() to -EAGAIN from -ENODEV if
>> use_cnt <= 0.
>>
>> Fixes: 297d716f6260 ("power_supply: Change ownership from driver to core")
>> Cc: stable@xxxxxxxxxxxxxxx
>> Signed-off-by: Rhyland Klein <rklein@xxxxxxxxxx>
>> ---
>> v3:
>> - Changed calls to ->get_property() to use common
>> power_supply_get_property()
>> - reworded description, added "Fixes" line
>> - Changed return value of power_supply_get_property() to -EAGAIN
>>
>> v2:
>> - Added cc stable
>> - changed return to -EAGAIN in case of use_cnt < 1
>> - Removed WARNING
>> - return value check added in additional patch:
>> https://lkml.org/lkml/2016/6/6/706
>>
>> drivers/power/power_supply_core.c | 26 ++++++++++++++++----------
>> 1 file changed, 16 insertions(+), 10 deletions(-)
>>
>> diff --git a/drivers/power/power_supply_core.c b/drivers/power/power_supply_core.c
>> index 456987c88baa..cccc630bd68e 100644
>> --- a/drivers/power/power_supply_core.c
>> +++ b/drivers/power/power_supply_core.c
>> @@ -492,7 +492,7 @@ int power_supply_get_property(struct power_supply *psy,
>> union power_supply_propval *val)
>> {
>> if (atomic_read(&psy->use_cnt) <= 0)
>> - return -ENODEV;
>> + return -EAGAIN;
>
> Wait, no. I was thinking of changing the return value in
> power_supply_read_temp() if we really want EAGAIN:
> ret = power_supply_get_property(...);
> if (ret)
> return -EAGAIN;
>
> On the other hand, here both return values look correct... the call can
> be executed too early (not very common) or too late after unbinding the
> driver (also kind of specific).
I did have it that way, but it seemed a little weird to me, since both
situations use the same condition (use_cnt <= 0) to trigger. I don't
think we can differentiate, unless I missed something, so I'm not sure
if it makes sense to override the return value after calling
power_supply_get_property() or not.
If I overrode the return value in get_temp, then assuming it was called
after unbinding, it would return the wrong thing (-EAGAIN). If we want
to support both EAGAIN and ENODEV, then maybe we need to use some
additional check to know which to return from power_supply_get_property().
>
>>
>> return psy->desc->get_property(psy, psp, val);
>> }
>> @@ -564,12 +564,14 @@ static int power_supply_read_temp(struct thermal_zone_device *tzd,
>> int ret;
>>
>> WARN_ON(tzd == NULL);
>> +
>> psy = tzd->devdata;
>> - ret = psy->desc->get_property(psy, POWER_SUPPLY_PROP_TEMP, &val);
>> + ret = power_supply_get_property(psy, POWER_SUPPLY_PROP_TEMP, &val);
>> + if (!ret)
>> + return ret;
>
> I think you wanted reverse:
> if (ret)
>
Indeed.
>>
>> /* Convert tenths of degree Celsius to milli degree Celsius. */
>> - if (!ret)
>> - *temp = val.intval * 100;
>> + *temp = val.intval * 100;
>>
>> return ret;
>> }
>> @@ -612,10 +614,12 @@ static int ps_get_max_charge_cntl_limit(struct thermal_cooling_device *tcd,
>> int ret;
>>
>> psy = tcd->devdata;
>> - ret = psy->desc->get_property(psy,
>> - POWER_SUPPLY_PROP_CHARGE_CONTROL_LIMIT_MAX, &val);
>> + ret = power_supply_get_property(psy,
>> + POWER_SUPPLY_PROP_CHARGE_CONTROL_LIMIT_MAX, &val);
>> if (!ret)
>> - *state = val.intval;
>> + return ret;
>
> Wait, again - why are you inverting the logic of 'ret'?a
>
copy/paste error repeated... <sigh>
-rhyland
--
nvpublic
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