rcu-tasks: Use rcuwait for the rcu_tasks_kthread()

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The waitqueue used by rcu_tasks_kthread() has always only one waiter.
With a guaranteed only one waiter, this can be replaced with rcuwait
which is smaller and simpler. With rcuwait based wake counterpart, the
irqwork function (call_rcu_tasks_iw_wakeup()) can be invoked hardirq
context because it is only a wake up and no sleeping locks are involved
(unlike the wait_queue_head).
As a side effect, this is also one piece of the puzzle to pass the RCU
selftest at early boot on PREEMPT_RT.

Replace wait_queue_head with rcuwait and let the irqwork run in hardirq
context on PREEMPT_RT.

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>

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Sebastian Andrzej Siewior 2022-03-04 12:07:25 +01:00 • committed by Paul E. McKenney

parent f25390033f

commit 88db792bbe

1 changed files with 8 additions and 6 deletions

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kernel/rcu/tasks.h

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