[PATCH 02/12] cgroup: rstat: Make cgroup_rstat_cpu_lock name readable

[Namhyung Kim <namhyung-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>]

The raw_spin_lock_init() uses the argument to name its lockdep map.
But passing per_cpu_ptr() macro directly makes it a very very long
name as it expanded like below:

  ({ do { const void *__vpp_verify = (typeof((&cgroup_rstat_cpu_lock) ...

Let's fix it by passing a local variable instead.  With this change,
the name now looks like:

  cgrp_rstat_cpu_lock

Cc: Zefan Li <lizefan.x-EC8Uxl6Npydl57MIdRCFDg@public.gmane.org>
Cc: Johannes Weiner <hannes-druUgvl0LCNAfugRpC6u6w@public.gmane.org>
Cc: cgroups-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
Acked-by: Tejun Heo <tj-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
Signed-off-by: Namhyung Kim <namhyung-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
---
 kernel/cgroup/rstat.c | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/kernel/cgroup/rstat.c b/kernel/cgroup/rstat.c
index 9d331ba44870..371f54a59c38 100644
--- a/kernel/cgroup/rstat.c
+++ b/kernel/cgroup/rstat.c
@@ -286,9 +286,17 @@ void cgroup_rstat_exit(struct cgroup *cgrp)
 void __init cgroup_rstat_boot(void)
 {
 	int cpu;
+	raw_spinlock_t *cgrp_rstat_cpu_lock;
 
-	for_each_possible_cpu(cpu)
-		raw_spin_lock_init(per_cpu_ptr(&cgroup_rstat_cpu_lock, cpu));
+	for_each_possible_cpu(cpu) {
+		/*
+		 * raw_spin_lock_init() uses the argument to name the lock in
+		 * lockdep results.  Passing per_cpu_ptr() directly created a
+		 * cryptic name as the macro was expanded before stringified.
+		 */
+		cgrp_rstat_cpu_lock = per_cpu_ptr(&cgroup_rstat_cpu_lock, cpu);
+		raw_spin_lock_init(cgrp_rstat_cpu_lock);
+	}
 }
 
 /*
-- 
2.35.0.263.gb82422642f-goog