On 21 September 2015 09:18:39 BST, Karol Wrona <k.wrona@xxxxxxxxxxx> wrote:
>On 09/20/2015 09:18 PM, Jonathan Cameron wrote:
>> On 14/09/15 17:08, Vaishali Thakkar wrote:
>>> Use resourced managed function devm_iio_device_register to
>>> make error path simpler. To be compatible with the change,
>>> the remove function is removed as it is now redundant.
>>>
>>> Signed-off-by: Vaishali Thakkar <vthakkar1994@xxxxxxxxx>
>> This patch is reasonable, but makes me wonder if there is an issue
>> in the remove path for this driver. It relies on the ssp_sensors
>common
>> module. That in ssp_spi.c uses the fact ssp_register_consumer
>> has saved the struct iio_dev into a local array in the core driver.
>> I think this means that a remove of this function will leave a
>possible
>> null pointer de reference.
>You are right. In this case we need something like
>ssp_deregister_consumer(...) in ssp_dev.c. So I think that "remove
>func"
>should stay. Of course we can switch to devm iio register.
Not if you want to remove the userspace interface before doing you new function call. Doing so gives a nasty race.
>
>Also the same can (rather should) be done for accelerometer sensor
>(ssp_accel_sensor.c).
>
>Vaishali, if you want please feel free and send patch.
>
>>
>> Now I suspect that case doesn't actually occur because the relevant
>> device elements are disabled whenever this module is removed. Having
>> said that we might expect an ssp_unregister_consumer function that
>> sets the relevant pointer back to null on removal so as to avoid
>> any possible race conditions around driver removal / reprobing.
>> A spot of defensive programming rather than necessarily a bug to be
>> fixed!
>>
>> One little process thing. This driver was written by Karol so patches
>> should probably always cc Karol as well as the more general
>> maintainer / reviewers for IIO. Added cc.
>>
>> Jonathan
>>> ---
>>> drivers/iio/gyro/ssp_gyro_sensor.c | 12 +-----------
>>> 1 file changed, 1 insertion(+), 11 deletions(-)
>>>
>>> diff --git a/drivers/iio/gyro/ssp_gyro_sensor.c
>b/drivers/iio/gyro/ssp_gyro_sensor.c
>>> index 0a8afdd..ac88de7 100644
>>> --- a/drivers/iio/gyro/ssp_gyro_sensor.c
>>> +++ b/drivers/iio/gyro/ssp_gyro_sensor.c
>>> @@ -134,7 +134,7 @@ static int ssp_gyro_probe(struct platform_device
>*pdev)
>>>
>>> platform_set_drvdata(pdev, indio_dev);
>>>
>>> - ret = iio_device_register(indio_dev);
>>> + ret = devm_iio_device_register(&pdev->dev, indio_dev);
>>> if (ret < 0)
>>> return ret;
>>>
>>> @@ -144,21 +144,11 @@ static int ssp_gyro_probe(struct
>platform_device *pdev)
>>> return 0;
>>> }
>>>
>>> -static int ssp_gyro_remove(struct platform_device *pdev)
>>> -{
>>> - struct iio_dev *indio_dev = platform_get_drvdata(pdev);
>>> -
>>> - iio_device_unregister(indio_dev);
>>> -
>>> - return 0;
>>> -}
>>> -
>>> static struct platform_driver ssp_gyro_driver = {
>>> .driver = {
>>> .name = SSP_GYROSCOPE_NAME,
>>> },
>>> .probe = ssp_gyro_probe,
>>> - .remove = ssp_gyro_remove,
>>> };
>>>
>>> module_platform_driver(ssp_gyro_driver);
>>>
>>
>> --
>> To unsubscribe from this list: send the line "unsubscribe linux-iio"
>in
>> the body of a message to majordomo@xxxxxxxxxxxxxxx
>> More majordomo info at http://vger.kernel.org/majordomo-info.html
>>
--
Sent from my Android device with K-9 Mail. Please excuse my brevity.
--
To unsubscribe from this list: send the line "unsubscribe linux-iio" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
