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

From: Sowjanya Komatineni
Date: Mon Apr 06 2020 - 16:38:15 EST



On 4/6/20 1:37 PM, Dmitry Osipenko wrote:
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06.04.2020 23:20, Sowjanya Komatineni ÐÐÑÐÑ:
On 4/6/20 1:02 PM, Dmitry Osipenko wrote:
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04.04.2020 04:25, Sowjanya Komatineni ÐÐÑÐÑ:
...
+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