linux-kernel - [PATCH 5/5] time: Drop local_irq_save/restore from irqtime_account

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Date:	Wed, 13 Jul 2016 16:50:05 +0200
From:	Frederic Weisbecker <fweisbec@...il.com>
To:	Ingo Molnar <mingo@...nel.org>
Cc:	LKML <linux-kernel@...r.kernel.org>,
	Rik van Riel <riel@...hat.com>,
	Paolo Bonzini <pbonzini@...hat.com>,
	Peter Zijlstra <peterz@...radead.org>,
	Wanpeng Li <wanpeng.li@...mail.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Radim Krcmar <rkrcmar@...hat.com>,
	Frederic Weisbecker <fweisbec@...il.com>,
	Mike Galbraith <efault@....de>
Subject: [PATCH 5/5] time: Drop local_irq_save/restore from irqtime_account_irq

From: Rik van Riel <riel@...hat.com>

Paolo pointed out that irqs are already blocked when irqtime_account_irq
is called. That means there is no reason to call local_irq_save/restore
again.

Suggested-by: Paolo Bonzini <pbonzini@...hat.com>
Reviewed-by: Paolo Bonzini <pbonzini@...hat.com>
Signed-off-by: Rik van Riel <riel@...hat.com>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Ingo Molnar <mingo@...nel.org>
Cc: Paolo Bonzini <pbonzini@...hat.com>
Cc: Wanpeng Li <wanpeng.li@...mail.com>
Cc: Mike Galbraith <efault@....de>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: Radim Krcmar <rkrcmar@...hat.com>
Signed-off-by: Frederic Weisbecker <fweisbec@...il.com>
---
 kernel/sched/cputime.c | 4 ----
 1 file changed, 4 deletions(-)

diff --git a/kernel/sched/cputime.c b/kernel/sched/cputime.c
index 16a873c..ea0f6f3 100644
--- a/kernel/sched/cputime.c
+++ b/kernel/sched/cputime.c
@@ -49,15 +49,12 @@ DEFINE_PER_CPU(seqcount_t, irq_time_seq);
  */
 void irqtime_account_irq(struct task_struct *curr)
 {
-	unsigned long flags;
 	s64 delta;
 	int cpu;
 
 	if (!sched_clock_irqtime)
 		return;
 
-	local_irq_save(flags);
-
 	cpu = smp_processor_id();
 	delta = sched_clock_cpu(cpu) - __this_cpu_read(irq_start_time);
 	__this_cpu_add(irq_start_time, delta);
@@ -75,7 +72,6 @@ void irqtime_account_irq(struct task_struct *curr)
 		__this_cpu_add(cpu_softirq_time, delta);
 
 	irq_time_write_end();
-	local_irq_restore(flags);
 }
 EXPORT_SYMBOL_GPL(irqtime_account_irq);
 
-- 
2.7.0