Re: [PATCH 19/21] cpuidle: create list of registered drivers

[Viresh Kumar]

On 26 September 2013 04:00, Daniel Lezcano <daniel.lezcano@xxxxxxxxxx> wrote:
> If you introduce a list, you will have to introduce a lock to protect
> it.

I missed it, should have added that :)

> This lock will be in the fast path cpuidle_idle_call with the
> get_driver function and conforming to the comment: "NOTE: no locks or
> semaphores should be used here".
>
> A lock has been introduced in this function already and the system hangs
> with 1024 cpus.

Hmm... I see.. I didn't knew about this expectation.. What about a rcu
read/write lock? As far as I know its too lightweight... Can we have that
in fast path?
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