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SubjectRe: Real-Time Preemption and RCU

* Ingo Molnar <mingo@elte.hu> wrote:

> [...] How about something like:
>
> void
> rcu_read_lock(void)
> {
> preempt_disable();
> if (current->rcu_read_lock_nesting++ == 0) {
> current->rcu_read_lock_ptr =
> &__get_cpu_var(rcu_data).lock;
> preempt_enable();
> read_lock(current->rcu_read_lock_ptr);
> } else
> preempt_enable();
> }
>
> this would still make it 'statistically scalable' - but is it correct?

thinking some more about it, i believe it's correct, because it picks
one particular CPU's lock and correctly releases that lock.

(read_unlock() is atomic even on PREEMPT_RT, so rcu_read_unlock() is
fine.)

Ingo
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