Re: [PATCH 1/2] kthread: convert worker lock to raw spinlock

[Petr Mladek]

On Tue 2019-02-12 17:25:53, Sebastian Andrzej Siewior wrote:
> From: Julia Cartwright <julia@xxxxxx>
> 
> In order to enable the queuing of kthread work items from hardirq
> context even when PREEMPT_RT_FULL is enabled, convert the worker
> spin_lock to a raw_spin_lock.
> 
> This is only acceptable to do because the work performed under the lock
> is well-bounded and minimal.

I could confirm that it is well-bounded and minimal. The most
expensive function probably is add_timer() called from
__kthread_queue_delayed_work(). It might spin a bit
to get timer->base->lock.

> Cc: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx>
> Cc: Guenter Roeck <linux@xxxxxxxxxxxx>
> Reported-and-tested-by: Steffen Trumtrar <s.trumtrar@xxxxxxxxxxxxxx>
> Reported-by: Tim Sander <tim@xxxxxxxxxxxxxxx>
> Signed-off-by: Julia Cartwright <julia@xxxxxx>
> Signed-off-by: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx>

Reviewed-by: Petr Mladek <pmladek@xxxxxxxx>

Best Regards,
Petr