On Fri, May 24, 2019 at 11:15:09PM +0300, Imre Deak wrote:
> diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c
> index 967352d32af1..9e2a4ab6c731 100644
> --- a/kernel/locking/lockdep.c
> +++ b/kernel/locking/lockdep.c
> @@ -3637,6 +3637,11 @@ print_lock_nested_lock_not_held(struct task_struct
> *curr,
>
> static int __lock_is_held(const struct lockdep_map *lock, int read);
>
> +static int hlock_reference(int reference)
> +{
> + return reference ? : 1;
> +}
> +
> /*
> * This gets called for every mutex_lock*()/spin_lock*() operation.
> * We maintain the dependency maps and validate the locking attempt:
> @@ -3702,17 +3707,15 @@ static int __lock_acquire(struct lockdep_map *lock,
> unsigned int subclass,
> if (depth) {
> hlock = curr->held_locks + depth - 1;
> if (hlock->class_idx == class_idx && nest_lock) {
> - if (hlock->references) {
> - /*
> - * Check: unsigned int references overflow.
> - */
> - if (DEBUG_LOCKS_WARN_ON(hlock->references ==
> UINT_MAX))
What tree is this against? Afaict this is still 12 bits ?!
> - return 0;
> + /*
> + * Check: unsigned int references overflow.
> + */
> + if
> (DEBUG_LOCKS_WARN_ON(hlock_reference(hlock->references) >
> + UINT_MAX -
> hlock_reference(references)))
Idem. Also very weird overflow check..
> + return 0;
>
> - hlock->references++;
> - } else {
> - hlock->references = 2;
> - }
> + hlock->references = hlock_reference(hlock->references) +
> + hlock_reference(references);
>
> return 2;
> }
> --
> 2.17.1
>
