Re: [PATCH 1/2] iio: adc: ti_am335x_adc: do not free the kfifo twice

[Jonathan Cameron <jic23@kernel.org>]

On 10/23/13 18:44, Lars-Peter Clausen wrote:
> The code is actually fine as it is. The iio_kfifo_free() function drops a reference, but does not free the buffer's memory if somebody else is still holding a reference.
> 
> - Lars
I'm guessing this came from a crash though.... Sebastian, what motivated the patch?
> 
> Sebastian Andrzej Siewior <bigeasy@linutronix.de> wrote:
> 
>> Since commit 9e69c9 ("iio: Add reference counting for buffers") the iio
>> core frees the buffer. So if the driver does it as well then bad things
>> will happen.
>>
>> Cc: Lars-Peter Clausen <lars@metafoo.de>
>> Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
>> ---
>>
>> By no means I am the expert here but the other users of iio_kfifo_free() like
>>
>> drivers/iio/industrialio-triggered-buffer.c:    iio_kfifo_free(indio_dev->buffer);
>> drivers/iio/industrialio-triggered-buffer.c:    iio_kfifo_free(indio_dev->buffer);
>>
>> are probably wrong, too. Not to mention staging. So *I* think iio_kfifo_free()
>> should vanish from the tree.
>>
>> drivers/iio/adc/ti_am335x_adc.c | 3 ---
>> 1 file changed, 3 deletions(-)
>>
>> diff --git a/drivers/iio/adc/ti_am335x_adc.c b/drivers/iio/adc/ti_am335x_adc.c
>> index f974dea..3d70f09 100644
>> --- a/drivers/iio/adc/ti_am335x_adc.c
>> +++ b/drivers/iio/adc/ti_am335x_adc.c
>> @@ -254,8 +254,6 @@ static int tiadc_iio_buffered_hardware_setup(struct iio_dev *indio_dev,
>>
>> error_free_irq:
>> 	free_irq(irq, indio_dev);
>> -error_kfifo_free:
>> -	iio_kfifo_free(indio_dev->buffer);
>> 	return ret;
>> }
>>
>> @@ -264,7 +262,6 @@ static void tiadc_iio_buffered_hardware_remove(struct iio_dev *indio_dev)
>> 	struct tiadc_device *adc_dev = iio_priv(indio_dev);
>>
>> 	free_irq(adc_dev->mfd_tscadc->irq, indio_dev);
>> -	iio_kfifo_free(indio_dev->buffer);
>> 	iio_buffer_unregister(indio_dev);
>> }
>>
>> -- 
>> 1.8.4.rc3
>>
>> --
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