RE: [PATCH v3] rcutorture: Create nocb tasks only for CONFIG_RCU_NOCB_CPU=y kernels

[Zhang, Qiang1]

>When setting nocbs_nthreads to start rcutorture test with a non-zero value,
>the nocb tasks will be created and invoke rcu_nocb_cpu_offload/deoffload()
>to toggle CPU's callback-offload state, but for CONFIG_RCU_NOCB_CPU=n
>kernel, the rcu_nocb_cpu_offload/deoffload() is a no-op and this is also
>meaningless for torture_type is non-rcu.
>
>This commit therefore add member can_nocbs_toggle to rcu_torture_ops
>structure to avoid unnecessary nocb tasks creation.

Will change commit log next version.

Thanks
Zqiang

>
>Signed-off-by: Zqiang <qiang1.zhang@xxxxxxxxx>
>---
> kernel/rcu/rcutorture.c | 6 ++++++
> 1 file changed, 6 insertions(+)
>
>diff --git a/kernel/rcu/rcutorture.c b/kernel/rcu/rcutorture.c
>index 297da28ce92d..d01127e0e8cd 100644
>--- a/kernel/rcu/rcutorture.c
>+++ b/kernel/rcu/rcutorture.c
>@@ -3708,6 +3708,12 @@ rcu_torture_init(void)
> 		pr_alert("rcu-torture: ->fqs NULL and non-zero fqs_duration, fqs disabled.\n");
> 		fqs_duration = 0;
> 	}
>+	if (nocbs_nthreads != 0 && (cur_ops != &rcu_ops ||
>+					!IS_ENABLED(CONFIG_RCU_NOCB_CPU))) {
>+		pr_alert("rcu-torture types: %s and CONFIG_RCU_NOCB_CPU=%d, nocb toggle disabled.\n",
>+				cur_ops->name, IS_ENABLED(CONFIG_RCU_NOCB_CPU));
>+		nocbs_nthreads = 0;
>+	}
> 	if (cur_ops->init)
> 		cur_ops->init();
> 
>-- 
>2.25.1