On 10/24/13 11:44, Lars-Peter Clausen wrote:
> On 10/24/2013 12:34 PM, Sebastian Andrzej Siewior wrote:
>> On 10/24/2013 11:41 AM, Lars-Peter Clausen wrote:
>>> The driver seems to be missing the iio_buffer_attach() call. Something like
>>> this should fix the problem:
>>>
>>> diff --git a/drivers/iio/adc/ti_am335x_adc.c b/drivers/iio/adc/ti_am335x_adc.c
>>> index ef54d8a..bf9c89c 100644
>>> --- a/drivers/iio/adc/ti_am335x_adc.c
>>> +++ b/drivers/iio/adc/ti_am335x_adc.c
>>> @@ -229,12 +229,15 @@ static int tiadc_iio_buffered_hardware_setup(struct
>>> iio_dev *indio_dev,
>>> unsigned long flags,
>>> const struct iio_buffer_setup_ops *setup_ops)
>>> {
>>> + struct iio_buffer *buffer;
>>> int ret;
>>>
>>> - indio_dev->buffer = iio_kfifo_allocate(indio_dev);
>>> - if (!indio_dev->buffer)
>>> + buffer = iio_kfifo_allocate(indio_dev);
>>> + if (!buffer)
>>> return -ENOMEM;
>>>
>>> + iio_device_attach_buffer(indio_dev, buffer);
>>> +
>>> ret = request_threaded_irq(irq, pollfunc_th, pollfunc_bh,
>>> flags, indio_dev->name, indio_dev);
>>> if (ret)
>>
>> Yep, that works, thanks.
>>
>> Shouldn't the two
>>
>> tiadc_iio_buffered_hardware_remove(indio_dev);
>> tiadc_channels_remove(indio_dev);
>>
>> in tiadc_remove() be reversed in their call order? The second alter is
>> accessing the buffer which is released by the former one.
>>
>
> As far as I can see tiadc_channels_remove() only does a
> kfree(indio_dev->channels), so it does not access the buffer at all.
Certainly seems to be true...
>
>> btw: is all this ref counting really required? I mean I would assume
>> allocate buffer in one place (at probe time) release it remove time
>> should be enough.
>
> It is required. Userspace may still be reading from the buffer when the
> driver frees it. So we need proper refcounting here.
Lars, can you do a clean version of the above with a reported-by from Sebastian
then Sebastian can you ack (if you are happy with it of course!)
Thanks,
Jonathan
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