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    SubjectRe: [PATCH v2] tracing/perf: Move rcu_irq_enter/exit_irqson() to perf trace point hook
    On Tue, 11 Feb 2020 16:34:52 +0100
    Peter Zijlstra <peterz@infradead.org> wrote:

    > > + if (unlikely(in_nmi()))
    > > + goto out;
    >
    > unless I'm mistaken, we can simply do rcu_nmi_enter() in this case, and
    > rcu_nmi_exit() on the other end.
    >
    > > + rcu_irq_enter_irqson();

    The thing is, I don't think this can ever happen. We've had in the
    tracepoint.h:

    /* srcu can't be used from NMI */ \
    WARN_ON_ONCE(rcuidle && in_nmi()); \

    And this has yet to trigger.

    -- Steve

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