On 6/9/2016 6:05 AM, Krzysztof Kozlowski wrote: > On 06/08/2016 05:26 PM, Rhyland Klein wrote: >> 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(). > > Right, currently it is not possible to differentiate these two cases. > After quick look, I think the difference with EAGAIN would be only in > error message printed or not. It is not critical so maybe keep it with > ENODEV? I'm ok with that. Sebastian, are you ok with that? If so, I'll post a v4 without the -EAGAIN change. -rhyland > > Best regards, > Krzysztof > -- nvpublic -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html