lockdep: Use this_cpu_ptr instead of get_cpu_var stats

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@infradead.org>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c
index 5fa4d31..fbbb79d 100644 (file)
--- 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;