linux-kernel - [RFC PATCH 11/12] cgroup: Mark the rstat percpu lock as terminal

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Message-Id: <1541709268-3766-12-git-send-email-longman@redhat.com>
Date:   Thu,  8 Nov 2018 15:34:27 -0500
From:   Waiman Long <longman@...hat.com>
To:     Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...hat.com>,
        Will Deacon <will.deacon@....com>,
        Thomas Gleixner <tglx@...utronix.de>
Cc:     linux-kernel@...r.kernel.org, kasan-dev@...glegroups.com,
        linux-mm@...ck.org, Petr Mladek <pmladek@...e.com>,
        Sergey Senozhatsky <sergey.senozhatsky@...il.com>,
        Andrey Ryabinin <aryabinin@...tuozzo.com>,
        Tejun Heo <tj@...nel.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Waiman Long <longman@...hat.com>
Subject: [RFC PATCH 11/12] cgroup: Mark the rstat percpu lock as terminal

By classifying the cgroup rstat percpu locks as terminal locks, it
reduces the lockdep overhead when these locks are being used.

Signed-off-by: Waiman Long <longman@...hat.com>
---
 kernel/cgroup/rstat.c | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/kernel/cgroup/rstat.c b/kernel/cgroup/rstat.c
index d503d1a..47f7ffb 100644
--- a/kernel/cgroup/rstat.c
+++ b/kernel/cgroup/rstat.c
@@ -291,8 +291,13 @@ void __init cgroup_rstat_boot(void)
 {
 	int cpu;
 
-	for_each_possible_cpu(cpu)
-		raw_spin_lock_init(per_cpu_ptr(&cgroup_rstat_cpu_lock, cpu));
+	for_each_possible_cpu(cpu) {
+		raw_spinlock_t *cgroup_rstat_percpu_lock =
+				per_cpu_ptr(&cgroup_rstat_cpu_lock, cpu);
+
+		raw_spin_lock_init(cgroup_rstat_percpu_lock);
+		lockdep_set_terminal_class(cgroup_rstat_percpu_lock);
+	}
 
 	BUG_ON(cgroup_rstat_init(&cgrp_dfl_root.cgrp));
 }
-- 
1.8.3.1