Re: [RFC PATCH v6 6/9] media: tegra: Add Tegra210 Video input driver

Sowjanya Komatineni
2020-04-06T20:38:18Z

On 4/6/20 1:37 PM, Dmitry Osipenko wrote:
> External email: Use caution opening links or attachments
>
>
> 06.04.2020 23:20, Sowjanya Komatineni пишет:
>> On 4/6/20 1:02 PM, Dmitry Osipenko wrote:
>>> External email: Use caution opening links or attachments
>>>
>>>
>>> 04.04.2020 04:25, Sowjanya Komatineni пишет:
>>> ...
>>>> +static int chan_capture_kthread_start(void *data)
>>>> +{
>>>> + struct tegra_vi_channel *chan = data;
>>>> + struct tegra_channel_buffer *buf;
>>>> + int err = 0;
>>>> + int caps_inflight;
>>>> +
>>>> + set_freezable();
>>>> +
>>>> + while (1) {
>>>> + try_to_freeze();
>>>> +
>>>> + wait_event_interruptible(chan->start_wait,
>>>> + !list_empty(&chan->capture) ||
>>>> + kthread_should_stop());
>>> Is it really okay that list_empty() isn't protected with a lock?
>>>
>>> Why wait_event is "interruptible"?
>> To allow it to sleep until wakeup on thread it to avoid constant
>> checking for condition even when no buffers are ready, basically to
>> prevent blocking.
> So the "interrupt" is for getting event about kthread_should_stop(),
> correct?
also to prevent blocking and to let is sleep and wakeup based on wait
queue to evaluate condition to proceed with the task
>