From 4f02ac237813a31d4fcb4c9eb9b699b15956b53b Mon Sep 17 00:00:00 2001 From: Zqiang Date: Fri, 3 Feb 2023 14:40:54 +0800 Subject: [PATCH] rcutorture: Create nocb kthreads only when testing rcu in CONFIG_RCU_NOCB_CPU=y kernels Given a non-zero rcutorture.nocbs_nthreads module parameter, the specified number of nocb kthreads will be created, regardless of whether or not the RCU implementation under test is capable of offloading callbacks. Please note that even vanilla RCU is incapable of offloading in kernels built with CONFIG_RCU_NOCB_CPU=n. And when the RCU implementation is incapable of offloading callbacks, there is no point in creating those kthreads. This commit therefore checks the cur_ops.torture_type module parameter and CONFIG_RCU_NOCB_CPU Kconfig option in order to avoid creating unnecessary nocb tasks. Signed-off-by: Zqiang Reviewed-by: Joel Fernandes (Google) Signed-off-by: Paul E. McKenney [ boqun: Fix checkpatch warning ] Signed-off-by: Boqun Feng --- kernel/rcu/rcutorture.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/kernel/rcu/rcutorture.c b/kernel/rcu/rcutorture.c index c0b2fd687bbb5..e046d2c6fe105 100644 --- a/kernel/rcu/rcutorture.c +++ b/kernel/rcu/rcutorture.c @@ -3525,6 +3525,12 @@ 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(); -- 2.30.2