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    SubjectRe: [patch V6 12/37] x86/entry: Provide idtentry_entry/exit_cond_rcu()
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    "Paul E. McKenney" <paulmck@kernel.org> writes:
    > On Wed, May 20, 2020 at 09:51:17AM -0700, Andy Lutomirski wrote:
    >> Paul, the major change here is that if an IRQ hits normal kernel code
    >> (i.e. code where RCU is watching and we're not in an EQS), the IRQ
    >> won't call rcu_irq_enter() and rcu_irq_exit(). Instead it will call
    >> rcu_tickle() on entry and nothing on exit. Does that cover all the
    >> bases?
    >
    > From an RCU viewpoint, yes, give or take my concerns about someone
    > putting rcu_tickle() on entry and rcu_irq_exit() on exit. Perhaps
    > I can bring some lockdep trickery to bear.

    An surplus rcu_irq_exit() should already trigger alarms today.

    > But I must defer to Thomas and Peter on the non-RCU/non-NO_HZ_FULL
    > portions of this.

    I don't see a problem. Let me write that into actual testable patch
    form.

    Thanks,

    tglx

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