Re: [PATCH v2] lockdep: Let lock_is_held_type() detect recursive read as read

[Waiman Long <llong@redhat.com>]

On 9/3/21 4:40 AM, Sebastian Andrzej Siewior wrote:
> lock_is_held_type(, 1) detects acquired read locks. It only recognized
> locks acquired with lock_acquire_shared(). Read locks acquired with
> lock_acquire_shared_recursive() are not recognized because a `2' is
> stored as the read value.
>
> Rework the check to additionally recognise lock's read value one and two
> as a read held lock.
>
> Fixes: e918188611f07 ("locking: More accurate annotations for read_lock()")
> Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
> ---
> v1…v2:
>    - simplify the read check to !!read as suggested by Waiman Long.
>
>   kernel/locking/lockdep.c |    2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
>
> --- a/kernel/locking/lockdep.c
> +++ b/kernel/locking/lockdep.c
> @@ -5366,7 +5366,7 @@ int __lock_is_held(const struct lockdep_
>   		struct held_lock *hlock = curr->held_locks + i;
>   
>   		if (match_held_lock(hlock, lock)) {
> -			if (read == -1 || hlock->read == read)
> +			if (read == -1 || hlock->read == !!read)
>   				return LOCK_STATE_HELD;
>   
>   			return LOCK_STATE_NOT_HELD;
>
Thanks for accepting my suggestion.

Acked-by: Waiman Long <longman@redhat.com>