linux-kernel - [PATCH v2 -next] rcu: rcu_qs -- Use raise_softirq

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Message-ID: <20190124181437.GE2332@uranus.lan>
Date:   Thu, 24 Jan 2019 21:14:37 +0300
From:   Cyrill Gorcunov <gorcunov@...il.com>
To:     LKML <linux-kernel@...r.kernel.org>
Cc:     "Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>
Subject: [PATCH v2 -next] rcu: rcu_qs -- Use raise_softirq_irqoff to not save
 irqs twice

The rcu_qs is disabling IRQs by self so no need to do the same in raise_softirq
but instead we can save some cycles using raise_softirq_irqoff directly.

CC: Paul E. McKenney <paulmck@...ux.ibm.com>
Signed-off-by: Cyrill Gorcunov <gorcunov@...il.com>
---
The prev patch body has been screwed, sorry.

 kernel/rcu/tiny.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

Index: linux-next.git/kernel/rcu/tiny.c
===================================================================
--- linux-next.git.orig/kernel/rcu/tiny.c
+++ linux-next.git/kernel/rcu/tiny.c
@@ -65,7 +65,7 @@ void rcu_qs(void)
 	local_irq_save(flags);
 	if (rcu_ctrlblk.donetail != rcu_ctrlblk.curtail) {
 		rcu_ctrlblk.donetail = rcu_ctrlblk.curtail;
-		raise_softirq(RCU_SOFTIRQ);
+		raise_softirq_irqoff(RCU_SOFTIRQ);
 	}
 	local_irq_restore(flags);
 }