From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Date: Fri, 16 Aug 2019 12:49:36 +0200
Subject: [PATCH 4/4] cgroup: Acquire cgroup_rstat_lock with enabled interrupts
Git-repo: git://git.kernel.org/pub/scm/linux/kernel/git/rt/linux-rt-devel.git
Git-commit: da77ceac3d20f27310a07a7c346a4ee6b40d6c28
Patch-mainline: Queued in subsystem maintainer repository
References: SLE Realtime Extensio

There is no need to disable interrupts while cgroup_rstat_lock is
acquired. The lock is never used in-IRQ context so a simple spin_lock()
is enough for synchronisation purpose.

Acquire cgroup_rstat_lock without disabling interrupts and ensure that
cgroup_rstat_cpu_lock is acquired with disabled interrupts (this one is
acquired in-IRQ context).

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Daniel Wagner <dwagner@suse.de>
---
 kernel/cgroup/rstat.c |   16 ++++++++--------
 1 file changed, 8 insertions(+), 8 deletions(-)

--- a/kernel/cgroup/rstat.c
+++ b/kernel/cgroup/rstat.c
@@ -161,17 +161,17 @@ static void cgroup_rstat_flush_locked(st
 						       cpu);
 		struct cgroup *pos = NULL;
 
-		raw_spin_lock(cpu_lock);
+		raw_spin_lock_irq(cpu_lock);
 		while ((pos = cgroup_rstat_cpu_pop_updated(pos, cgrp, cpu)))
 			cgroup_base_stat_flush(pos, cpu);
 
-		raw_spin_unlock(cpu_lock);
+		raw_spin_unlock_irq(cpu_lock);
 
 		if (need_resched() || spin_needbreak(&cgroup_rstat_lock)) {
-			spin_unlock_irq(&cgroup_rstat_lock);
+			spin_unlock(&cgroup_rstat_lock);
 			if (!cond_resched())
 				cpu_relax();
-			spin_lock_irq(&cgroup_rstat_lock);
+			spin_lock(&cgroup_rstat_lock);
 		}
 	}
 }
@@ -193,9 +193,9 @@ void cgroup_rstat_flush(struct cgroup *c
 {
 	might_sleep();
 
-	spin_lock_irq(&cgroup_rstat_lock);
+	spin_lock(&cgroup_rstat_lock);
 	cgroup_rstat_flush_locked(cgrp);
-	spin_unlock_irq(&cgroup_rstat_lock);
+	spin_unlock(&cgroup_rstat_lock);
 }
 
 /**
@@ -211,7 +211,7 @@ static void cgroup_rstat_flush_hold(stru
 	__acquires(&cgroup_rstat_lock)
 {
 	might_sleep();
-	spin_lock_irq(&cgroup_rstat_lock);
+	spin_lock(&cgroup_rstat_lock);
 	cgroup_rstat_flush_locked(cgrp);
 }
 
@@ -221,7 +221,7 @@ static void cgroup_rstat_flush_hold(stru
 static void cgroup_rstat_flush_release(void)
 	__releases(&cgroup_rstat_lock)
 {
-	spin_unlock_irq(&cgroup_rstat_lock);
+	spin_unlock(&cgroup_rstat_lock);
 }
 
 int cgroup_rstat_init(struct cgroup *cgrp)