[RFC PATCH 0/8] workqueue: Fix for prematurely wakeups and cleanups

[Lai Jiangshan <jiangshanlai@gmail.com>]

From: Lai Jiangshan <jiangshan.ljs@antgroup.com>

Patch1-3 are fixes for prematurely wakeups and patch4-8 are cleanups.

Patch2 fixes when prematurely wakeup happens after kthread_bind_mask().
Patch3 fixes when prematurely wakeup happens before kthread_bind_mask().
Patch1 prepares for patch2-3.

Like Petr's patch[1], a completion is introduced to do the synchronization,
but the synchronization is done in a different direction which allows the
newly created worker itself do some initialization instead of the manager
and allows for a more simplified code.
(The changed synchronization direction is not necessarily better.)

And make workqueue code less dependence on the semantics that kthread
provides.


[1]: https://lore.kernel.org/all/20220622140853.31383-1-pmladek@suse.com/
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Tejun Heo <tj@kernel.org>,
Cc: Petr Mladek <pmladek@suse.com>
Cc: Michal Hocko <mhocko@suse.com>,
Cc: Peter Zijlstra <peterz@infradead.org>,
Cc: Wedson Almeida Filho <wedsonaf@google.com>

Lai Jiangshan (8):
  workqueue: Unconditionally set cpumask in worker_attach_to_pool()
  workqueue: Make create_worker() safe against prematurely wakeups
  workqueue: Set PF_NO_SETAFFINITY instead of kthread_bind_mask()
  workqueue: Set/Clear PF_WQ_WORKER while attaching/detaching
  workqueue: Use worker_set_flags() in worker_enter_idle()
  workqueue: Simplify the starting of the newly created worker
  workqueue: Remove the outer loop in maybe_create_worker()
  workqueue: Move the locking out of maybe_create_worker()

 kernel/workqueue.c          | 123 +++++++++++++++---------------------
 kernel/workqueue_internal.h |  11 +++-
 2 files changed, 60 insertions(+), 74 deletions(-)

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2.19.1.6.gb485710b