[tip: sched/core] rcu: Pull deferred rcuog wake up to rcu_eqs_enter() callers

["tip-bot2 for Frederic Weisbecker" <tip-bot2@linutronix.de>]

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

Commit-ID:     e4234f21d2ea7674bcc1aeaca9d382b50ca1efec
Gitweb:        https://git.kernel.org/tip/e4234f21d2ea7674bcc1aeaca9d382b50ca1efec
Author:        Frederic Weisbecker <frederic@kernel.org>
AuthorDate:    Mon, 01 Feb 2021 00:05:44 +01:00
Committer:     Peter Zijlstra <peterz@infradead.org>
CommitterDate: Wed, 10 Feb 2021 14:44:49 +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@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: stable@vger.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 */