On Thu, Jun 27, 2019 at 04:07:46PM +0900, Byungchul Park wrote: > Hello, > > I tested if the WARN_ON_ONCE() is fired with my box and it was ok.
Looks pretty safe to me and nice clean up! Acked-by: Joel Fernandes (Google) <[email protected]> - Joel > > Thanks, > Byungchul > > Changes from v1 > -. WARN_ON_ONCE() on failing to create rcu_boost_kthread. > -. Changed title and commit message a bit. > > ---8<--- > From 7100fcf82202f063f70f45def208ea5198412f5a Mon Sep 17 00:00:00 2001 > From: Byungchul Park <[email protected]> > Date: Thu, 27 Jun 2019 15:58:10 +0900 > Subject: [PATCH v2] rcu: Change return type of rcu_spawn_one_boost_kthread() > > The return value of rcu_spawn_one_boost_kthread() is not used any > longer. Change return type of that function from int to void. > > Signed-off-by: Byungchul Park <[email protected]> > --- > kernel/rcu/tree_plugin.h | 17 ++++++++--------- > 1 file changed, 8 insertions(+), 9 deletions(-) > > diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h > index 1102765..3c8444e 100644 > --- a/kernel/rcu/tree_plugin.h > +++ b/kernel/rcu/tree_plugin.h > @@ -1131,7 +1131,7 @@ static void rcu_preempt_boost_start_gp(struct rcu_node > *rnp) > * already exist. We only create this kthread for preemptible RCU. > * Returns zero if all is well, a negated errno otherwise. > */ > -static int rcu_spawn_one_boost_kthread(struct rcu_node *rnp) > +static void rcu_spawn_one_boost_kthread(struct rcu_node *rnp) > { > int rnp_index = rnp - rcu_get_root(); > unsigned long flags; > @@ -1139,25 +1139,24 @@ static int rcu_spawn_one_boost_kthread(struct > rcu_node *rnp) > struct task_struct *t; > > if (!IS_ENABLED(CONFIG_PREEMPT_RCU)) > - return 0; > + return; > > if (!rcu_scheduler_fully_active || rcu_rnp_online_cpus(rnp) == 0) > - return 0; > + return; > > rcu_state.boost = 1; > if (rnp->boost_kthread_task != NULL) > - return 0; > + return; > t = kthread_create(rcu_boost_kthread, (void *)rnp, > "rcub/%d", rnp_index); > - if (IS_ERR(t)) > - return PTR_ERR(t); > + if (WARN_ON_ONCE(IS_ERR(t))) > + return; > raw_spin_lock_irqsave_rcu_node(rnp, flags); > rnp->boost_kthread_task = t; > raw_spin_unlock_irqrestore_rcu_node(rnp, flags); > sp.sched_priority = kthread_prio; > sched_setscheduler_nocheck(t, SCHED_FIFO, &sp); > wake_up_process(t); /* get to TASK_INTERRUPTIBLE quickly. */ > - return 0; > } > > static void rcu_cpu_kthread_setup(unsigned int cpu) > @@ -1265,7 +1264,7 @@ static void __init rcu_spawn_boost_kthreads(void) > if (WARN_ONCE(smpboot_register_percpu_thread(&rcu_cpu_thread_spec), > "%s: Could not start rcub kthread, OOM is now expected behavior\n", __func__)) > return; > rcu_for_each_leaf_node(rnp) > - (void)rcu_spawn_one_boost_kthread(rnp); > + rcu_spawn_one_boost_kthread(rnp); > } > > static void rcu_prepare_kthreads(int cpu) > @@ -1275,7 +1274,7 @@ static void rcu_prepare_kthreads(int cpu) > > /* Fire up the incoming CPU's kthread and leaf rcu_node kthread. */ > if (rcu_scheduler_fully_active) > - (void)rcu_spawn_one_boost_kthread(rnp); > + rcu_spawn_one_boost_kthread(rnp); > } > > #else /* #ifdef CONFIG_RCU_BOOST */ > -- > 1.9.1 >
