On 4/6/20 1:54 PM, Dmitry Osipenko wrote:
External email: Use caution opening links or attachments
06.04.2020 23:38, Sowjanya Komatineni пишет:
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
This looks suspicious, the comment to wait_event_interruptible() says
that it will return ERESTARTSYS if signal is recieved..
Does this mean that I can send signal from userspace to wake it up?
The "interruptible" part looks wrong to me.
We are not checking for wait_event_interruptible to handle case when it
returns ERESTARTSYS.
So, signals sent from user space are ignore and we check if when wakeup
happens if kthread_stop has requested to stop thread.
