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    SubjectRe: [RFC] Make need_resched() return true when rcu_urgent_qs requested
    On Fri, Jul 06, 2018 at 03:53:30PM +0100, David Woodhouse wrote:
    > diff --git a/include/linux/sched.h b/include/linux/sched.h
    > index e4d4e60..89f5814 100644
    > --- a/include/linux/sched.h
    > +++ b/include/linux/sched.h
    > @@ -1616,7 +1616,8 @@ static inline int spin_needbreak(spinlock_t *lock)
    >
    > static __always_inline bool need_resched(void)
    > {
    > - return unlikely(tif_need_resched());
    > + return unlikely(tif_need_resched()) ||
    > + rcu_urgent_qs_requested();
    > }

    Instead of making need_resched() touch two cachelines, I think I would
    prefer adding resched_cpu() to rcu_request_urgent_qs_task().

    The preempt state is alread a bit complicated and shadowed in the
    preempt_count (on some architectures) adding additional bits to it like
    this is just asking for trouble.


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