Messages in this thread | | | Date | Mon, 3 Jan 2022 13:17:01 -0500 | Subject | Re: [PATCH] locking/lockdep: Avoid potential access of invalid memory in lock_class | From | Waiman Long <> |
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On 1/3/22 12:47, Bart Van Assche wrote: > On 1/2/22 18:35, Waiman Long wrote: >> - WARN_ON_ONCE(!found); >> - __lockdep_free_key_range(pf, key, 1); >> - call_rcu_zapped(pf); >> - graph_unlock(); >> -out_irq: >> + WARN_ON_ONCE(!found && debug_locks); > > lockdep_unregister_key() should only be called for a registered key so > I'd > like to keep the WARN_ON_ONCE(!found) here instead of changing it into > WARN_ON_ONCE(!found && debug_locks). Otherwise this patch looks good > to me.
The reason for this change is to handle the case that a lockdep_register_key()/lockdep_unregister_key() pair may be called after debug_locks is turned off. Without that change, we are going to get the warning in lockdep_unregister_key(). That is the motivation of your original commit 8b39adbee805 ("locking/lockdep: Make lockdep_unregister_key() honor 'debug_locks' again").
Cheers, Longman
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