The series changes `wq_manager_wait' from waitqueues to simple waitqueues and its internal locking (pool::lock and wq_mayday_lock) to raw spinlocks so that workqueues can be used on PREEMPT_RT from truly atomic context.
v1…v2: Use rcuwait instead of swait. v1 can be found at https://lore.kernel.org/lkml/20200513162732.977489-1-bige...@linutronix.de/ Sebastian
