Locking Between User Context and Tasklets/Soft IRQs

This is exactly the same as above, because local_bh_disable() actually disables all softirqs and tasklets on that CPU as well. It should really be called `local_softirq_disable()', but the name has been preserved for historical reasons. Similarly, spin_lock_bh() would now be called spin_lock_softirq() in a perfect world.