Re: [RFC PATCH] sched/cputime: drop local_irq_safe() in vtime_init_idle()

[Sebastian Andrzej Siewior]

On 04/14/2016 03:18 PM, Frederic Weisbecker wrote:
> I think I tried this but I got lockdep warnings because the other updaters
> happen on IRQ.

I booted and played a little but lockdep didn't scream here so far.

> In practive we can't be interrupted since the idle task hasn't even started.
> 
> Now we can probably get rid of the write_seqcount_stuff here because what
> is initialized there is supposed to be visible by the idle task once it runs.
> 
> But I'm more worried about readers.

Most idle_thread_get() callers happen at boottime. Then I see two
during CPU-up (cpu-hotplug) at runtime. One from _cpu_up() via
idle_thread_get() and the second via bringup_cpu() and the second in
bringup_cpu().

Sebastian