From: Frederic Weisbecker frederic@kernel.org
commit 54b7429efffc99e845ba9381bee3244f012a06c2 upstream.
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 Signed-off-by: Ingo Molnar mingo@kernel.org Cc: stable@vger.kernel.org Link: https://lkml.kernel.org/r/20210131230548.32970-2-frederic@kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- kernel/rcu/tree.c | 11 ++++++++++- 1 file changed, 10 insertions(+), 1 deletion(-)
--- a/kernel/rcu/tree.c +++ b/kernel/rcu/tree.c @@ -579,7 +579,6 @@ static 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); WRITE_ONCE(rdp->dynticks_nesting, 0); /* Avoid irq-access tearing. */ @@ -600,7 +599,10 @@ static 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); }
@@ -618,7 +620,14 @@ void rcu_idle_enter(void) */ 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 */