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Subject[PATCH v12 1/3] lockdep: use this_cpu_ptr instead of get_cpu_var stats
Date
From: "Joel Fernandes (Google)" <joel@joelfernandes.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.

Suggested-by: Peter Zijlstra <peterz@infradead.org>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.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;
--
2.18.0.345.g5c9ce644c3-goog
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