Re: [RFC PATCH] iio: ak8975: Make sure chipset is always initialized

[Daniel Baluta]

On Mon, Jan 19, 2015 at 6:44 PM, Pandruvada, Srinivas
<srinivas.pandruvada@xxxxxxxxx> wrote:
> On Mon, 2015-01-19 at 16:40 +0200, Daniel Baluta wrote:
>> Hello,
>>
>> On Sat, Dec 20, 2014 at 11:29 PM, Pandruvada, Srinivas
>> <srinivas.pandruvada@xxxxxxxxx> wrote:
>> > +Mika
>> >
>> > On Sat, 2014-12-20 at 13:26 -0800, Srinivas Pandruvada wrote:
>> >> On Sat, 2014-12-20 at 00:25 +0200, Daniel Baluta wrote:
>> >> > On Sat, Dec 20, 2014 at 12:16 AM, Hartmut Knaack <knaack.h@xxxxxx> wrote:
>> >> > > Daniel Baluta schrieb am 18.12.2014 um 18:16:
>> >> > >> When using ACPI, if acpi_match_device fails then chipset enum will be
>> >> > >> uninitialized and &ak_def_array[chipset] will point to some bad address.
>> >> > >>
>> >> I am missing something. You are enumerated over i2c device, which was
>> >> created from ACPI PNP resource. There is a valid handle or and the
>> >> device has an ACPI companion at the least. If this failing, I have to
>> >> check the code for acpi i2c.
>> >> Can you check why this check failed? We may have bug in i2c handling.
>>
>> You are right about this. Under normal circumstances, if probe is called
>> then acpi_match_device will not fail. I even tried to remove the
>> device after probe
>> but before acpi_match_device, anyhow acpi_match_device was still successful :)
>>
>> This is more a matter of code correctness.
>>
>> In ak8975_match_acpi_device we have:
>>
>> Â       const struct acpi_device_id *id;
>>
>> Â       id = acpi_match_device(dev->driver->acpi_match_table, dev);
>> Â       if (!id)
>> Â       Â       return NULL;
>> Â       *chipset = (int)id->driver_data;
>>
>> Compiler complains on the fact that chipset might be uninitialized
>> if this returns NULL, and we shouldn't ignore this warning even this case
>> will never happen.
>>
> Will this fix?
> data->chipset = AK8975;
> before
> ak8975_match_acpi_device(&client->dev, &data->chipset);
>

Yes, this is done in the original patch:

+       *chipset = AK_MAX_TYPE;

.. and fixes the warning.

Daniel.
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