Re: [PATCH] locktorture: Add raw_spinlock* torture tests for PREEMPT_RT kernels

[Davidlohr Bueso]

On Wed, 22 Feb 2023, Paul E. McKenney wrote:

> commit edc9d419ee8c22821ffd664466a5cf19208c3f02
> Author: Zqiang <qiang1.zhang@xxxxxxxxx>
> Date:   Wed Feb 15 14:10:35 2023 +0800
>
>    locktorture: Add raw_spinlock* torture tests for PREEMPT_RT kernels
>
>    In PREEMPT_RT kernels, both spin_lock() and spin_lock_irq() are converted
>    to sleepable rt_spin_lock().  This means that the interrupt related suffix
>    for spin_lock/unlock(_irq, irqsave/irqrestore) do not affect the CPU's
>    interrupt state. This commit therefore adds raw spin-lock torture tests.
>    This in turn permits pure spin locks to be tested in PREEMPT_RT kernels.
>
>    Signed-off-by: Zqiang <qiang1.zhang@xxxxxxxxx>
>    Signed-off-by: Paul E. McKenney <paulmck@xxxxxxxxxx>

This is a nice addition, thanks. Just one comment below.

> diff --git a/kernel/locking/locktorture.c b/kernel/locking/locktorture.c
> index 9425aff089365..ed8e5baafe49f 100644
> --- a/kernel/locking/locktorture.c
> +++ b/kernel/locking/locktorture.c
> @@ -257,6 +257,61 @@ static struct lock_torture_ops spin_lock_irq_ops = {
> 	.name		= "spin_lock_irq"
> };
>
> +#ifdef CONFIG_PREEMPT_RT
> +static DEFINE_RAW_SPINLOCK(torture_raw_spinlock);

How about leaving raw spinlocks regardless of preempt-rt, and instead
change the default lock (which is spin_lock) based on CONFIG_PREEMPT_RT
and use the raw one in that case?

Thanks,
Davidlohr