linux-kernel - [PATCH 2/5] irqtime: Remove needless IRQs disablement on kcpustat update

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Date:   Mon, 26 Sep 2016 02:29:18 +0200
From:   Frederic Weisbecker <fweisbec@...il.com>
To:     LKML <linux-kernel@...r.kernel.org>
Cc:     Frederic Weisbecker <fweisbec@...il.com>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Wanpeng Li <wanpeng.li@...mail.com>,
        Eric Dumazet <eric.dumazet@...il.com>,
        Ingo Molnar <mingo@...nel.org>, Mike Galbraith <efault@....de>,
        Rik van Riel <riel@...hat.com>
Subject: [PATCH 2/5] irqtime: Remove needless IRQs disablement on kcpustat update

The callers of the functions performing irqtime kcpustat updates have
IRQS disabled, no need to disable them again.

Reviewed-by: Rik van Riel <riel@...hat.com>
Cc: Paolo Bonzini <pbonzini@...hat.com>
Cc: Wanpeng Li <wanpeng.li@...mail.com>
Cc: Mike Galbraith <efault@....de>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Ingo Molnar <mingo@...nel.org>
Cc: Eric Dumazet <eric.dumazet@...il.com>
Cc: Rik van Riel <riel@...hat.com>
Signed-off-by: Frederic Weisbecker <fweisbec@...il.com>
---
 kernel/sched/cputime.c | 11 +++++------
 1 file changed, 5 insertions(+), 6 deletions(-)

diff --git a/kernel/sched/cputime.c b/kernel/sched/cputime.c
index f111076..94b1a72 100644
--- a/kernel/sched/cputime.c
+++ b/kernel/sched/cputime.c
@@ -78,30 +78,26 @@ EXPORT_SYMBOL_GPL(irqtime_account_irq);
 static cputime_t irqtime_account_hi_update(cputime_t maxtime)
 {
 	u64 *cpustat = kcpustat_this_cpu->cpustat;
-	unsigned long flags;
 	cputime_t irq_cputime;
 
-	local_irq_save(flags);
 	irq_cputime = nsecs_to_cputime64(__this_cpu_read(cpu_hardirq_time)) -
 		      cpustat[CPUTIME_IRQ];
 	irq_cputime = min(irq_cputime, maxtime);
 	cpustat[CPUTIME_IRQ] += irq_cputime;
-	local_irq_restore(flags);
+
 	return irq_cputime;
 }
 
 static cputime_t irqtime_account_si_update(cputime_t maxtime)
 {
 	u64 *cpustat = kcpustat_this_cpu->cpustat;
-	unsigned long flags;
 	cputime_t softirq_cputime;
 
-	local_irq_save(flags);
 	softirq_cputime = nsecs_to_cputime64(__this_cpu_read(cpu_softirq_time)) -
 			  cpustat[CPUTIME_SOFTIRQ];
 	softirq_cputime = min(softirq_cputime, maxtime);
 	cpustat[CPUTIME_SOFTIRQ] += softirq_cputime;
-	local_irq_restore(flags);
+
 	return softirq_cputime;
 }
 
@@ -295,6 +291,9 @@ static inline cputime_t account_other_time(cputime_t max)
 {
 	cputime_t accounted;
 
+	/* Shall be converted to a lockdep-enabled lightweight check */
+	WARN_ON_ONCE(!irqs_disabled());
+
 	accounted = steal_account_process_time(max);
 
 	if (accounted < max)
-- 
2.7.4