On 10/03, Peter Zijlstra wrote:
>
> On Thu, Oct 02, 2014 at 10:10:20PM +0200, Oleg Nesterov wrote:
>
> > As for rfcomm_run(), perhaps it can ise it too?
> >
> > set_kthread_wants_signal(true);
> >
> > add_wait_queue(&rfcomm_wq, &wait);
> > for (;;) {
> > // This is only possible if kthread_should_stop() == T
>
> True because kthreads SIG_IGN everything, right?
Yes,
> > if (signal_pending(current))
> > break;
> >
> > rfcomm_process_sessions();
> > wait_woken(TASK_INTERRUPTIBLE);
> > }
> >
> > Of course, this assumes that rfcomm_process_sessions() can't do something
> > "really bad" if signal_pending() is true.
>
> So from what I can think of, everything that does an INTERRUPTIBLE sleep
> will 'malfunction' after that, right? Which might be quite a lot
> actually.
Yes.
> > What do you think?
>
> Interesting approach, but somewhat risky I tihnk, due to that
> INTERRUPTIBLE thing.
OK, this is fixable. rfcomm_run() can do
add_wait_queue(&rfcomm_wq, &wait);
while (!kthread_should_stop()) {
rfcomm_process_sessions();
set_kthread_wants_signal(true);
wait_woken(TASK_INTERRUPTIBLE);
set_kthread_wants_signal(false);
}
remove_wait_queue(&rfcomm_wq, &wait);
Or. perhaps we can change wait_woken
- set_current_state(mode);
+ if (mode)
+ set_current_state(mode);
then rfcomm_run() can do
for (;;) {
rfcomm_process_sessions();
set_current_state(TASK_INTERRUPTIBLE);
if (kthread_should_stop())
break;
wait_woken(0);
}
Or perhaps we can split wait_woken() into 2 helpers,
static inline long wait_woken(wq, mode, timeout)
{
set_current_state(mode);
schedule_woken(wq, timeout); // does the rest
}
to avoid "mode == 0" hack; rfcomm_run() should use schedule_woken().
What do you think?
Oleg.
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