[GIT PULL] workqueue changes for v5.17-rc1

[Tejun Heo]

Hello, Linus.

* 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. Merged into this pull request. 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.

Thanks.

The following changes since commit c741e49150dbb0c0aebe234389f4aa8b47958fa8:

  Merge tag 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/rdma/rdma (2021-12-09 13:20:59 -0800)

are available in the Git repository at:

  git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq.git for-5.17

for you to fetch changes up to 2a8ab0fbd110dec25795a98aaa232ede36f6c855:

  Merge branch 'workqueue/for-5.16-fixes' into workqueue/for-5.17 (2022-01-10 07:54:04 -1000)

----------------------------------------------------------------
Frederic Weisbecker (2):
      workqueue: Fix unbind_workers() VS wq_worker_running() race
      workqueue: Fix unbind_workers() VS wq_worker_sleeping() race

Lai Jiangshan (6):
      workqueue: Remove the outdated comment before wq_worker_sleeping()
      workqueue: Remove the advanced kicking of the idle workers in rebind_workers()
      workqueue: Remove outdated comment about exceptional workers in unbind_workers()
      workqueue: Remove schedule() in unbind_workers()
      workqueue: Move the code of waking a worker up in unbind_workers()
      workqueue: Remove the cacheline_aligned for nr_running

Paul E. McKenney (1):
      workqueue: Upgrade queue_work_on() comment

Tejun Heo (1):
      Merge branch 'workqueue/for-5.16-fixes' into workqueue/for-5.17

 kernel/workqueue.c | 101 ++++++++++++++++++++++++-----------------------------
 1 file changed, 45 insertions(+), 56 deletions(-)

-- 
tejun