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Subject[PATCH] locking/lockdep: Make lockdep_register_key() ignore 'debug_locks'
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_register_key() unconditionally register lock keys.

Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Waiman Long <longman@redhat.com>
Cc: shenghui <shhuiw@foxmail.com>
Reported-by: shenghui <shhuiw@foxmail.com>
Fixes: a0b0fd53e1e6 ("locking/lockdep: Free lock classes that are no longer in use") # v5.1-rc1.
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
---
kernel/locking/lockdep.c | 7 ++++---
1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c
index d2d65bbfae01..a228509b62f1 100644
--- a/kernel/locking/lockdep.c
+++ b/kernel/locking/lockdep.c
@@ -1027,15 +1027,16 @@ void lockdep_register_key(struct lock_class_key *key)
hash_head = keyhashentry(key);

raw_local_irq_save(flags);
- if (!graph_lock())
- goto restore_irqs;
+ arch_spin_lock(&lockdep_lock);
+ current->lockdep_recursion = 1;
hlist_for_each_entry_rcu(k, hash_head, hash_entry) {
if (WARN_ON_ONCE(k == key))
goto out_unlock;
}
hlist_add_head_rcu(&key->hash_entry, hash_head);
out_unlock:
- graph_unlock();
+ current->lockdep_recursion = 0;
+ arch_spin_unlock(&lockdep_lock);
restore_irqs:
raw_local_irq_restore(flags);
}
--
2.21.0.196.g041f5ea1cf98
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