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    SubjectRe: [tip: timers/core] hrtimer: Annotate lockless access to timer->state
    On Thu, Nov 7, 2019 at 8:11 AM Paul E. McKenney <paulmck@kernel.org> wrote:
    >
    > OK, so this is due to timer_pending() lockless access to ->entry.pprev
    > to determine whether or not the timer is on the list. New one on me!
    >
    > Given that use case, I don't have an objection to your patch to list.h.
    >
    > Except...
    >
    > Would it make sense to add a READ_ONCE() to hlist_unhashed()
    > and to then make timer_pending() invoke hlist_unhashed()? That
    > would better confine the needed uses of READ_ONCE().

    Sounds good to me, I had the same idea but was too lazy to look at the
    history of timer_pending()
    to check if the pprev pointer check was really the same underlying idea.

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