[PATCH 5.15 0/1] rcutorture: Add missing return and use __func__ in warning

[Daniil Dulov <d.dulov@xxxxxxxxxx>]

Svacer reports a potential division by zero at rcu_torture_writer() in
5.15 stable release. The problem has been fixed by the following patch
that can be cleanly applied to 5.15 branch.