linux-kernel - [PATCH tip/core/rcu 13/15] rcu: Make rcu_idle

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Message-Id: <1500932684-10469-13-git-send-email-paulmck@linux.vnet.ibm.com>
Date:   Mon, 24 Jul 2017 14:44:42 -0700
From:   "Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>
To:     linux-kernel@...r.kernel.org
Cc:     mingo@...nel.org, jiangshanlai@...il.com, dipankar@...ibm.com,
        akpm@...ux-foundation.org, mathieu.desnoyers@...icios.com,
        josh@...htriplett.org, tglx@...utronix.de, peterz@...radead.org,
        rostedt@...dmis.org, dhowells@...hat.com, edumazet@...gle.com,
        fweisbec@...il.com, oleg@...hat.com,
        "Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>
Subject: [PATCH tip/core/rcu 13/15] rcu: Make rcu_idle_enter() rely on callers disabling irqs

From: "Peter Zijlstra (Intel)" <peterz@...radead.org>

All callers to rcu_idle_enter() have irqs disabled, so there is no
point in rcu_idle_enter disabling them again.  This commit therefore
replaces the irq disabling with a RCU_LOCKDEP_WARN().

Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
Signed-off-by: Paul E. McKenney <paulmck@...ux.vnet.ibm.com>
---
 kernel/rcu/tree.c | 5 +----
 1 file changed, 1 insertion(+), 4 deletions(-)

diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index c028eb254704..64b2cb9a8830 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -843,11 +843,8 @@ static void rcu_eqs_enter(bool user)
  */
 void rcu_idle_enter(void)
 {
-	unsigned long flags;
-
-	local_irq_save(flags);
+	RCU_LOCKDEP_WARN(!irqs_disabled(), "rcu_idle_enter() invoked with irqs enabled!!!");
 	rcu_eqs_enter(false);
-	local_irq_restore(flags);
 }
 EXPORT_SYMBOL_GPL(rcu_idle_enter);
 
-- 
2.5.2