linux-kernel - [for-next][PATCH 14/34] lockdep: Use this_cpu_ptr instead of get_cpu

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Date:   Sat, 11 Aug 2018 09:49:42 -0400
From:   Steven Rostedt <rostedt@...dmis.org>
To:     linux-kernel@...r.kernel.org
Cc:     Ingo Molnar <mingo@...nel.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Peter Zijlstra <peterz@...radead.org>,
        "Joel Fernandes (Google)" <joel@...lfernandes.org>
Subject: [for-next][PATCH 14/34] lockdep: Use this_cpu_ptr instead of get_cpu_var stats

From: "Joel Fernandes (Google)" <joel@...lfernandes.org>

get_cpu_var disables preemption which has the potential to call into the
preemption disable trace points causing some complications. There's also
no need to disable preemption in uses of get_lock_stats anyway since
preempt is already disabled. So lets simplify the code.

Link: http://lkml.kernel.org/r/20180730222423.196630-2-joel@joelfernandes.org

Suggested-by: Peter Zijlstra <peterz@...radead.org>
Acked-by: Peter Zijlstra <peterz@...radead.org>
Signed-off-by: Joel Fernandes (Google) <joel@...lfernandes.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@...dmis.org>
---
 kernel/locking/lockdep.c | 10 +---------
 1 file changed, 1 insertion(+), 9 deletions(-)

diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c
index 5fa4d3138bf1..fbbb79d5cfa0 100644
--- a/kernel/locking/lockdep.c
+++ b/kernel/locking/lockdep.c
@@ -248,12 +248,7 @@ void clear_lock_stats(struct lock_class *class)
 
 static struct lock_class_stats *get_lock_stats(struct lock_class *class)
 {
-	return &get_cpu_var(cpu_lock_stats)[class - lock_classes];
-}
-
-static void put_lock_stats(struct lock_class_stats *stats)
-{
-	put_cpu_var(cpu_lock_stats);
+	return &this_cpu_ptr(cpu_lock_stats)[class - lock_classes];
 }
 
 static void lock_release_holdtime(struct held_lock *hlock)
@@ -271,7 +266,6 @@ static void lock_release_holdtime(struct held_lock *hlock)
 		lock_time_inc(&stats->read_holdtime, holdtime);
 	else
 		lock_time_inc(&stats->write_holdtime, holdtime);
-	put_lock_stats(stats);
 }
 #else
 static inline void lock_release_holdtime(struct held_lock *hlock)
@@ -4090,7 +4084,6 @@ __lock_contended(struct lockdep_map *lock, unsigned long ip)
 		stats->contending_point[contending_point]++;
 	if (lock->cpu != smp_processor_id())
 		stats->bounces[bounce_contended + !!hlock->read]++;
-	put_lock_stats(stats);
 }
 
 static void
@@ -4138,7 +4131,6 @@ __lock_acquired(struct lockdep_map *lock, unsigned long ip)
 	}
 	if (lock->cpu != cpu)
 		stats->bounces[bounce_acquired + !!hlock->read]++;
-	put_lock_stats(stats);
 
 	lock->cpu = cpu;
 	lock->ip = ip;
-- 
2.18.0