From: Paul E. McKenney <paulmck@kernel.org>
Date: Wed, 11 May 2022 18:49:35 +0000 (-0700)
Subject: Merge branch 'exp.2022.05.11a' into HEAD
X-Git-Url: https://repo.jachan.dev/J-linux.git/commitdiff_plain/ce13389053a347aa9f8ffbfda2238352536e15c9

Merge branch 'exp.2022.05.11a' into HEAD

exp.2022.05.11a: Expedited-grace-period latency-reduction updates.
---

ce13389053a347aa9f8ffbfda2238352536e15c9
diff --cc kernel/rcu/rcu.h
index a985dfc2ce26,e27bf7d1e3a4..152492d52715
--- a/kernel/rcu/rcu.h
+++ b/kernel/rcu/rcu.h
@@@ -536,9 -536,12 +538,14 @@@ int rcu_get_gp_kthreads_prio(void)
  void rcu_fwd_progress_check(unsigned long j);
  void rcu_force_quiescent_state(void);
  extern struct workqueue_struct *rcu_gp_wq;
+ #ifdef CONFIG_RCU_EXP_KTHREAD
+ extern struct kthread_worker *rcu_exp_gp_kworker;
+ extern struct kthread_worker *rcu_exp_par_gp_kworker;
+ #else /* !CONFIG_RCU_EXP_KTHREAD */
  extern struct workqueue_struct *rcu_par_gp_wq;
+ #endif /* CONFIG_RCU_EXP_KTHREAD */
 +void rcu_gp_slow_register(atomic_t *rgssp);
 +void rcu_gp_slow_unregister(atomic_t *rgssp);
  #endif /* #else #ifdef CONFIG_TINY_RCU */
  
  #ifdef CONFIG_RCU_NOCB_CPU
diff --cc kernel/rcu/tree.c
index 75a35b7adbfa,763e45fdf49b..c25ba442044a
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@@ -4553,15 -4542,11 +4598,17 @@@ static int __init rcu_spawn_gp_kthread(
  	smp_store_release(&rcu_state.gp_kthread, t);  /* ^^^ */
  	raw_spin_unlock_irqrestore_rcu_node(rnp, flags);
  	wake_up_process(t);
 -	rcu_spawn_nocb_kthreads();
 -	rcu_spawn_boost_kthreads();
 +	/* This is a pre-SMP initcall, we expect a single CPU */
 +	WARN_ON(num_online_cpus() > 1);
 +	/*
 +	 * Those kthreads couldn't be created on rcu_init() -> rcutree_prepare_cpu()
 +	 * due to rcu_scheduler_fully_active.
 +	 */
 +	rcu_spawn_cpu_nocb_kthread(smp_processor_id());
 +	rcu_spawn_one_boost_kthread(rdp->mynode);
  	rcu_spawn_core_kthreads();
+ 	/* Create kthread worker for expedited GPs */
+ 	rcu_start_exp_gp_kworkers();
  	return 0;
  }
  early_initcall(rcu_spawn_gp_kthread);