From: Muchun Song <songmuchun@bytedance.com>
Date: Mon, 27 Apr 2020 10:08:41 +0100
Subject: [PATCH] sched/cpuacct: Use __this_cpu_add() instead of this_cpu_ptr()

References: bnc#1155798 (CPU scheduler functional and performance backports)
Patch-mainline: v5.8-rc1
Git-commit: 12aa2587388de6697fd2e585ae6a90f70249540b

The cpuacct_charge() and cpuacct_account_field() are called with
rq->lock held, and this means preemption(and IRQs) are indeed
disabled, so it is safe to use __this_cpu_*() to allow for better
code-generation.

Signed-off-by: Muchun Song <songmuchun@bytedance.com>
Signed-off-by: Mel Gorman <mgorman@suse.de>
---
 kernel/sched/cpuacct.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/kernel/sched/cpuacct.c b/kernel/sched/cpuacct.c
index 9fbb10383434..6448b0438ffb 100644
--- a/kernel/sched/cpuacct.c
+++ b/kernel/sched/cpuacct.c
@@ -347,7 +347,7 @@ void cpuacct_charge(struct task_struct *tsk, u64 cputime)
 	rcu_read_lock();
 
 	for (ca = task_ca(tsk); ca; ca = parent_ca(ca))
-		this_cpu_ptr(ca->cpuusage)->usages[index] += cputime;
+		__this_cpu_add(ca->cpuusage->usages[index], cputime);
 
 	rcu_read_unlock();
 }
@@ -363,7 +363,7 @@ void cpuacct_account_field(struct task_struct *tsk, int index, u64 val)
 
 	rcu_read_lock();
 	for (ca = task_ca(tsk); ca != &root_cpuacct; ca = parent_ca(ca))
-		this_cpu_ptr(ca->cpustat)->cpustat[index] += val;
+		__this_cpu_add(ca->cpustat->cpustat[index], val);
 	rcu_read_unlock();
 }