linux-kernel - [tip: sched/core] rcu: Pull deferred rcuog wake up to rcu_eqs

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Date:   Wed, 17 Feb 2021 13:17:31 -0000
From:   "tip-bot2 for Frederic Weisbecker" <tip-bot2@...utronix.de>
To:     linux-tip-commits@...r.kernel.org
Cc:     Frederic Weisbecker <frederic@...nel.org>,
        "Peter Zijlstra (Intel)" <peterz@...radead.org>,
        Ingo Molnar <mingo@...nel.org>, stable@...r.kernel.org,
        x86@...nel.org, linux-kernel@...r.kernel.org
Subject: [tip: sched/core] rcu: Pull deferred rcuog wake up to rcu_eqs_enter() callers

The following commit has been merged into the sched/core branch of tip:

Commit-ID:     54b7429efffc99e845ba9381bee3244f012a06c2
Gitweb:        https://git.kernel.org/tip/54b7429efffc99e845ba9381bee3244f012a06c2
Author:        Frederic Weisbecker <frederic@...nel.org>
AuthorDate:    Mon, 01 Feb 2021 00:05:44 +01:00
Committer:     Ingo Molnar <mingo@...nel.org>
CommitterDate: Wed, 17 Feb 2021 14:12:42 +01:00

rcu: Pull deferred rcuog wake up to rcu_eqs_enter() callers

Deferred wakeup of rcuog kthreads upon RCU idle mode entry is going to
be handled differently whether initiated by idle, user or guest. Prepare
with pulling that control up to rcu_eqs_enter() callers.

Signed-off-by: Frederic Weisbecker <frederic@...nel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
Signed-off-by: Ingo Molnar <mingo@...nel.org>
Cc: stable@...r.kernel.org
Link: https://lkml.kernel.org/r/20210131230548.32970-2-frederic@kernel.org
---
 kernel/rcu/tree.c | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index 40e5e3d..63032e5 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -644,7 +644,6 @@ static noinstr void rcu_eqs_enter(bool user)
 	trace_rcu_dyntick(TPS("Start"), rdp->dynticks_nesting, 0, atomic_read(&rdp->dynticks));
 	WARN_ON_ONCE(IS_ENABLED(CONFIG_RCU_EQS_DEBUG) && !user && !is_idle_task(current));
 	rdp = this_cpu_ptr(&rcu_data);
-	do_nocb_deferred_wakeup(rdp);
 	rcu_prepare_for_idle();
 	rcu_preempt_deferred_qs(current);
 
@@ -672,7 +671,10 @@ static noinstr void rcu_eqs_enter(bool user)
  */
 void rcu_idle_enter(void)
 {
+	struct rcu_data *rdp = this_cpu_ptr(&rcu_data);
+
 	lockdep_assert_irqs_disabled();
+	do_nocb_deferred_wakeup(rdp);
 	rcu_eqs_enter(false);
 }
 EXPORT_SYMBOL_GPL(rcu_idle_enter);
@@ -691,7 +693,14 @@ EXPORT_SYMBOL_GPL(rcu_idle_enter);
  */
 noinstr void rcu_user_enter(void)
 {
+	struct rcu_data *rdp = this_cpu_ptr(&rcu_data);
+
 	lockdep_assert_irqs_disabled();
+
+	instrumentation_begin();
+	do_nocb_deferred_wakeup(rdp);
+	instrumentation_end();
+
 	rcu_eqs_enter(true);
 }
 #endif /* CONFIG_NO_HZ_FULL */