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

From: Waiman Long <longman@redhat.com>
To: Peter Zijlstra <peterz@infradead.org>,
	Ingo Molnar <mingo@redhat.com>, Will Deacon <will.deacon@arm.com>,
	Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org, kasan-dev@googlegroups.com,
	linux-mm@kvack.org, Petr Mladek <pmladek@suse.com>,
	Sergey Senozhatsky <sergey.senozhatsky@gmail.com>,
	Andrey Ryabinin <aryabinin@virtuozzo.com>,
	Tejun Heo <tj@kernel.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	Waiman Long <longman@redhat.com>
Subject: [RFC PATCH 11/12] cgroup: Mark the rstat percpu lock as terminal
Date: Thu,  8 Nov 2018 15:34:27 -0500	[thread overview]
Message-ID: <1541709268-3766-12-git-send-email-longman@redhat.com> (raw)
In-Reply-To: <1541709268-3766-1-git-send-email-longman@redhat.com>

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@redhat.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

