Merge branch 'for-5.17' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq

Merge branch 'for-5.17' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq

Pull workqueue updates from Tejun Heo:

 - The code around workqueue scheduler hooks got reorganized early 2019
   which unfortuately introdued a couple subtle and rare race conditions
   where preemption can mangle internal workqueue state triggering a
   WARN and possibly causing a stall or at least delay in execution.

   Frederic fixed both early December and the fixes were sitting in
   for-5.16-fixes which I forgot to push. They are here now. I'll
   forward them to stable after they land.

 - The scheduler hook reorganization has more implicatoins for workqueue
   code in that the hooks are now more strictly synchronized and thus
   the interacting operations can become more straight-forward.

   Lai is in the process of simplifying workqueue code and this pull
   request contains some of the patches.

* 'for-5.17' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq:
  workqueue: Remove the cacheline_aligned for nr_running
  workqueue: Move the code of waking a worker up in unbind_workers()
  workqueue: Remove schedule() in unbind_workers()
  workqueue: Remove outdated comment about exceptional workers in unbind_workers()
  workqueue: Remove the advanced kicking of the idle workers in rebind_workers()
  workqueue: Remove the outdated comment before wq_worker_sleeping()
  workqueue: Fix unbind_workers() VS wq_worker_sleeping() race
  workqueue: Fix unbind_workers() VS wq_worker_running() race
  workqueue: Upgrade queue_work_on() comment