linux-kernel - [PATCH 15/27] locking/lockdep: Make concurrent lockdep_reset

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Message-Id: <20181128234325.110011-16-bvanassche@acm.org>
Date:   Wed, 28 Nov 2018 15:43:13 -0800
From:   Bart Van Assche <bvanassche@....org>
To:     mingo@...hat.com
Cc:     peterz@...radead.org, tj@...nel.org, johannes.berg@...el.com,
        linux-kernel@...r.kernel.org, Bart Van Assche <bvanassche@....org>
Subject: [PATCH 15/27] locking/lockdep: Make concurrent lockdep_reset_lock() calls safe

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

Signed-off-by: Bart Van Assche <bvanassche@....org>
---
 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 83ffcc7f1ced..ab6abe52e974 100644
--- a/kernel/locking/lockdep.c
+++ b/kernel/locking/lockdep.c
@@ -4227,6 +4227,7 @@ 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:
@@ -4243,7 +4244,6 @@ 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.rc0.387.gc7a69e6b6c-goog