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Subject[PATCH] locking/lockdep: Make lockdep_unregister_key() honor 'debug_locks' again
Date
If lockdep_register_key() and lockdep_unregister_key() are called with
debug_locks == false then the following warning is reported:

WARNING: CPU: 2 PID: 15145 at kernel/locking/lockdep.c:4920 lockdep_unregister_key+0x1ad/0x240

That warning is reported because lockdep_unregister_key() ignores the
value of 'debug_locks' and because the behavior of lockdep_register_key()
depends on whether or not 'debug_locks' is set. Fix this inconsistency
by making lockdep_unregister_key() take 'debug_locks' again into
account.

Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Waiman Long <longman@redhat.com>
Cc: shenghui <shhuiw@foxmail.com>
Fixes: 90c1cba2b3b3 ("locking/lockdep: Zap lock classes even with lock debugging disabled")
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
---
kernel/locking/lockdep.c | 9 +++++----
1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c
index e16766ff184b..e221be724fe8 100644
--- a/kernel/locking/lockdep.c
+++ b/kernel/locking/lockdep.c
@@ -4907,8 +4907,9 @@ void lockdep_unregister_key(struct lock_class_key *key)
return;

raw_local_irq_save(flags);
- arch_spin_lock(&lockdep_lock);
- current->lockdep_recursion = 1;
+ if (!graph_lock())
+ goto out_irq;
+
pf = get_pending_free();
hlist_for_each_entry_rcu(k, hash_head, hash_entry) {
if (k == key) {
@@ -4920,8 +4921,8 @@ void lockdep_unregister_key(struct lock_class_key *key)
WARN_ON_ONCE(!found);
__lockdep_free_key_range(pf, key, 1);
call_rcu_zapped(pf);
- current->lockdep_recursion = 0;
- arch_spin_unlock(&lockdep_lock);
+ graph_unlock();
+out_irq:
raw_local_irq_restore(flags);

/* Wait until is_dynamic_key() has finished accessing k->hash_entry. */
--
2.21.0.196.g041f5ea1cf98
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