>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.
>
>Signed-off-by: Zqiang <qiang1.zhang@xxxxxxxxx>
>---
> kernel/rcu/rcutorture.c | 10 ++++++++--
> 1 file changed, 8 insertions(+), 2 deletions(-)
>
>diff --git a/kernel/rcu/rcutorture.c b/kernel/rcu/rcutorture.c
>index 297da28ce92d..27becacbe3b2 100644
>--- a/kernel/rcu/rcutorture.c
>+++ b/kernel/rcu/rcutorture.c
>@@ -383,6 +383,7 @@ struct rcu_torture_ops {
> long cbflood_max;
> int irq_capable;
> int can_boost;
>+ int can_nocbs_toggle;
> int extendables;
> int slow_gps;
> int no_pi_lock;
>@@ -569,6 +570,7 @@ static struct rcu_torture_ops rcu_ops = {
> .stall_dur = rcu_jiffies_till_stall_check,
> .irq_capable = 1,
> .can_boost = IS_ENABLED(CONFIG_RCU_BOOST),
>+ .can_nocbs_toggle = IS_ENABLED(CONFIG_RCU_NOCB_CPU),
> .extendables = RCUTORTURE_MAX_EXTEND,
> .name = "rcu"
> };
>@@ -2356,7 +2358,7 @@ rcu_torture_print_module_parms(struct rcu_torture_ops *cur_ops, const char *tag)
> "n_barrier_cbs=%d "
> "onoff_interval=%d onoff_holdoff=%d "
> "read_exit_delay=%d read_exit_burst=%d "
>- "nocbs_nthreads=%d nocbs_toggle=%d "
>+ "nocbs_nthreads=%d/%d nocbs_toggle=%d "
> "test_nmis=%d\n",
> torture_type, tag, nrealreaders, nfakewriters,
> stat_interval, verbose, test_no_idle_hz, shuffle_interval,
>@@ -2368,7 +2370,7 @@ rcu_torture_print_module_parms(struct rcu_torture_ops *cur_ops, const char *tag)
> n_barrier_cbs,
> onoff_interval, onoff_holdoff,
> read_exit_delay, read_exit_burst,
>- nocbs_nthreads, nocbs_toggle,
>+ nocbs_nthreads, cur_ops->can_nocbs_toggle, nocbs_toggle,
> test_nmis);
> }
>
>@@ -3708,6 +3710,10 @@ rcu_torture_init(void)
> pr_alert("rcu-torture: ->fqs NULL and non-zero fqs_duration, fqs disabled.\n");
> fqs_duration = 0;
> }
>+ if (!cur_ops->can_nocbs_toggle && nocbs_nthreads > 0) {
>+ pr_alert("rcu-torture: ->can_nocbs_toggle false and non-zero nocbs_nthreads, nocbs_toggle disabled.\n");
>+ nocbs_nthreads = 0;
>+ }
Sorry, I ignored the case where the nocbs_nthreads is set to a negative value, will resend.
> if (cur_ops->init)
> cur_ops->init();
>
>--
2.25.1
