linux-kernel - [PATCH v2 11/45] migration: Use raw_spin_lock/unlock since interrupts are already disabled

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Message-ID: <20130625202717.16593.55189.stgit@srivatsabhat.in.ibm.com>
Date:	Wed, 26 Jun 2013 01:57:17 +0530
From:	"Srivatsa S. Bhat" <srivatsa.bhat@...ux.vnet.ibm.com>
To:	tglx@...utronix.de, peterz@...radead.org, tj@...nel.org,
	oleg@...hat.com, paulmck@...ux.vnet.ibm.com, rusty@...tcorp.com.au,
	mingo@...nel.org, akpm@...ux-foundation.org, namhyung@...nel.org,
	walken@...gle.com, vincent.guittot@...aro.org, laijs@...fujitsu.com
Cc:	rostedt@...dmis.org, wangyun@...ux.vnet.ibm.com,
	xiaoguangrong@...ux.vnet.ibm.com, sbw@....edu, fweisbec@...il.com,
	zhong@...ux.vnet.ibm.com, nikunj@...ux.vnet.ibm.com,
	srivatsa.bhat@...ux.vnet.ibm.com, linux-pm@...r.kernel.org,
	linux-arch@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org,
	netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
	Ingo Molnar <mingo@...hat.com>,
	Peter Zijlstra <peterz@...radead.org>,
	"Srivatsa S. Bhat" <srivatsa.bhat@...ux.vnet.ibm.com>
Subject: [PATCH v2 11/45] migration: Use raw_spin_lock/unlock since interrupts
 are already disabled

We need not use the raw_spin_lock_irqsave/restore primitives because
all CPU_DYING notifiers run with interrupts disabled. So just use
raw_spin_lock/unlock.

Cc: Ingo Molnar <mingo@...hat.com>
Cc: Peter Zijlstra <peterz@...radead.org>
Signed-off-by: Srivatsa S. Bhat <srivatsa.bhat@...ux.vnet.ibm.com>
---

 kernel/sched/core.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index accd550..ff26f54 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -4682,14 +4682,14 @@ migration_call(struct notifier_block *nfb, unsigned long action, void *hcpu)
 	case CPU_DYING:
 		sched_ttwu_pending();
 		/* Update our root-domain */
-		raw_spin_lock_irqsave(&rq->lock, flags);
+		raw_spin_lock(&rq->lock); /* IRQs already disabled */
 		if (rq->rd) {
 			BUG_ON(!cpumask_test_cpu(cpu, rq->rd->span));
 			set_rq_offline(rq);
 		}
 		migrate_tasks(cpu);
 		BUG_ON(rq->nr_running != 1); /* the migration thread */
-		raw_spin_unlock_irqrestore(&rq->lock, flags);
+		raw_spin_unlock(&rq->lock);
 		break;
 
 	case CPU_DEAD:

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