On 06/05/15 17:25, Daniel Baluta wrote:
>
>
> On 05/05/2015 04:51 PM, Jonathan Cameron wrote:
>>
>>
>> On 4 May 2015 20:54:08 GMT+01:00, Lars-Peter Clausen <lars@xxxxxxxxxx> wrote:
>>> On 05/04/2015 12:50 PM, Daniel Baluta wrote:
>>> [...]
>>>> +IIO_HRTIMER_INFO_ATTR(sampling_frequency, S_IRUGO | S_IWUSR,
>>>> + iio_hrtimer_info_show_sampling_frequency,
>>>> + iio_hrtimer_info_store_sampling_frequency);
>>>
>>> I wonder if the sampling frequency should be configurable the regular
>>> IIO
>>> API, just like any other IIO device. But things like min/max sampling
>>> frequency should be configured in configfs.
>> Would have to be in the trigger dir rather than device... Makes sense to put it there.
>> Limits on it here seem like a sensible idea.
>
> But then each trigger will have sampling_frequency right? This is not what we want.
I'm confused now. Why not? Each hrtimer trigger created in configfs should have
it's own sampling frequency should it not?
>
>>>
>>> [...]
>>>> +#endif /* CONFIGFS_FS */
>>>> +
>>> [...]
>>>> +static struct iio_sw_trigger *iio_trig_hrtimer_probe(const char
>>> *name)
>>>> +{
>>> [...]
>>>> +#ifdef CONFIG_CONFIGFS_FS
>>>> + config_group_init_type_name(&trig_info->swt.group, name,
>>>> + &iio_hrtimer_type);
>>>> +#endif
>>>
>>> This should probably have a helper function in the sw trigger core,
>>> that
>>> gets stubbed out when CONFIG_FS is disabled. Otherwise we'll see the
>>> same
>>> #ifdef in every software trigger driver.
>>> [...]
>
> Agree with this. Will fix.
>
>>>> +}
>>>> +
>>>> +static int iio_trig_hrtimer_remove(struct iio_sw_trigger *swt)
>>>> +{
>>>> + struct iio_hrtimer_info *trig_info;
>>>> +
>>>> + trig_info = iio_trigger_get_drvdata(swt->trigger);
>>>> +
>>>> + hrtimer_cancel(&trig_info->timer);
>>>> +
>>>> + iio_trigger_unregister(swt->trigger);
>>>> + iio_trigger_free(swt->trigger);
>>>
>>> There is a bit of a race condition here. hrtimer_cancel() should be
>>> called
>>> between unregister and free, otherwise it might be re-armed before it
>>> is
>>> unregistered.
>
> So this can be re-armed only if the buffer is re-enabled between hrtimer_cancel and iio_trigger_unregister :). I'm trying to understand how the race can happen.
>
>
>>>
>>>> + kfree(trig_info);
>>>> +
>>>> + return 0;
>>>> +}
>>>> +
>>>> +struct iio_sw_trigger_ops iio_trig_hrtimer_ops = {
>>>
>>> const
>
> Agree.
>>>
>>>> + .probe = iio_trig_hrtimer_probe,
>>>> + .remove = iio_trig_hrtimer_remove,
>>>> +};
>>> [...]
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