[PATCH v2 12/24] locking/lockdep: Make concurrent lockdep_reset_lock() calls safe

From: Bart Van Assche
Date: Mon Dec 03 2018 - 19:30:32 EST


Since zap_class() removes items from the all_lock_classes list and the
classhash_table, protect all zap_class() calls with the graph lock.

Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Waiman Long <longman@xxxxxxxxxx>
Cc: Johannes Berg <johannes@xxxxxxxxxxxxxxxx>
Signed-off-by: Bart Van Assche <bvanassche@xxxxxxx>
---
kernel/locking/lockdep.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c
index 346b5a1fd062..e78623819184 100644
--- a/kernel/locking/lockdep.c
+++ b/kernel/locking/lockdep.c
@@ -4229,6 +4229,7 @@ void lockdep_reset_lock(struct lockdep_map *lock)
int j, locked;

raw_local_irq_save(flags);
+ locked = graph_lock();

/*
* Remove all classes this lock might have:
@@ -4245,7 +4246,6 @@ void lockdep_reset_lock(struct lockdep_map *lock)
* Debug check: in the end all mapped classes should
* be gone.
*/
- locked = graph_lock();
if (unlikely(lock_class_cache_is_registered(lock))) {
if (debug_locks_off_graph_unlock()) {
/*
--
2.20.0.rc1.387.gf8505762e3-goog