Messages in this thread | | | Date | Tue, 11 Feb 2020 16:31:24 +0100 | From | Peter Zijlstra <> | Subject | Re: [PATCH] tracing/perf: Move rcu_irq_enter/exit_irqson() to perf trace point hook |
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On Tue, Feb 11, 2020 at 07:06:15AM -0800, Paul E. McKenney wrote: > And I have to ask... What happens if we are very early in from-idle > NMI entry (or very late in NMI exit), such that both in_nmi() and > rcu_is_watching() are returning false? Or did I miss a turn somewhere?
We must, by very careful inspection, ensure that doesn't happen.
No tracing must happen before preempt_count increment / after preempt_count decrement. Otherwise we can no longer recover.
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