[PATCH 02/10] workqueue: remove unneeded check

Since we always pass flush responsibility to next, we will not deprive it, now the ->first_flusher can only be changed by the first_flusher, no one can change it, no race as 4ce48b37 said. Remove the check introduced by 4ce48b37, use BUG_ON() instead. Also move "wq->first_flusher = NULL;" later.

[PATCH 02/10] workqueue: remove unneeded check

Since we always pass flush responsibility to next, we will not deprive it, now the -first_flusher can only be changed by the first_flusher, no one can change it, no race as 4ce48b37 said. Remove the check introduced by 4ce48b37, use BUG_ON() instead. Also move wq-first_flusher = NULL; later.