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From:   Sebastian Andrzej Siewior <bigeasy@linutronix.de>
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To:     linux-kernel@vger.kernel.org
Cc:     Peter Zijlstra <peterz@infradead.org>,
        Thomas Gleixner <tglx@linutronix.de>
Subject: [PATCH v2 0/4] irq_work: PREEMPT_RT bits
Date:   Wed,  6 Oct 2021 13:18:48 +0200
Message-Id: <20211006111852.1514359-1-bigeasy@linutronix.de>
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This is v2 of the series. v1 can be found at
   https://lkml.kernel.org/20210927211919.310855-1-bigeasy@linutronix.de

Changelog:
v1=E2=80=A6v2:
  - Drop "irq_work: Ensure that irq_work runs in in-IRQ context". This
    triggers if a CPU goes down.

  - #3 now uses per-CPU threads with the lowest RT priority instead of
    the timer softirq.

This are the PREEMPT_RT bits for irq_work. The annotation for
IRQ_WORK_HARD_IRQ was already merged except for one missed annotation.
Patch #3 introduces the required processing split of callbacks with are
really invoked from hard-irq context and those which are processed in a
per-CPU thread. Unless "LAZY" the thread is woken from the irq_work
hardirq.

This has been done as quite a few them acquire locks which need to sleep
on PREEMPT_RT and must not be invoked in hardirq context. We can not
delay all of them since a few need to be invoked hardirq context in
order to work properly (NOHZ, scheduler, =E2=80=A6).

Sebastian