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

[Daniel Baluta]

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.
>>
>> This fixes the following compilation warning:
>>
>> drivers/iio/magnetometer/ak8975.c: In function âak8975_probeâ:
>> drivers/iio/magnetometer/ak8975.c:788:14: warning: âchipsetâ may be used
>> uninitialized in this function [-Wmaybe-uninitialized]
>>   data->def =ak_def_array[chipset];
>>
>> Reported-by: Octavian Purdila <octavian.purdila@xxxxxxxxx>
>> Signed-off-by: Daniel Baluta <daniel.baluta@xxxxxxxxx>
>> ---
>> This is a RFC because while I'm pretty sure that chipset should be initialized
>> with AK_MAX_TYPE in ak8975_match_acpi_device, I am not sure if we can live with
>> a NULL return value of ak8975_match_acpi_device. Current implementation ignores
>> return value of ak8975_match_acpi_device.
> This seems to be the actual problem: these _match_acpi_device functions return
> NULL on failure, and this should be checked for.

Ok, so this would acceptable?

diff --git a/drivers/iio/magnetometer/ak8975.c
b/drivers/iio/magnetometer/ak8975.c
index 0d10a4b..68d99e9 100644
--- a/drivers/iio/magnetometer/ak8975.c
+++ b/drivers/iio/magnetometer/ak8975.c
@@ -776,8 +776,9 @@ static int ak8975_probe(struct i2c_client *client,
                name = id->name;
        } else if (ACPI_HANDLE(&client->dev))
                name = ak8975_match_acpi_device(&client->dev, &chipset);
-       else
-               return -ENOSYS;
+
+       if (!name)
+               return -ENODEV;


I still have some doubts about return code in case of error.

For ak8975 we use -ENOSYS, but for kxcjk-1013 we use -ENODEV.

I will send a patch after we clear this out.

thanks,
Daniel.
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