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SubjectRe: [PATCH -rt] revert bh_lru_lock() to preempt_disable()
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On Wed, 2006-05-03 at 22:47 +0200, Ingo Molnar wrote:
> * Daniel Walker <dwalker@mvista.com> wrote:
>
> > The bh_lru_lock() was set to disable interrupt to protect from
> > IPI's, which are only on SMP . So I don't think it's needed in UP
> > PREEMPT_RT configs.
>
> i agree that this is a problem, but the fix is incorrect. What would be
> the right approach is to convert the PER_CPU bh_lrus to PER_CPU_LOCKED,
> and to use the appropriate primitives to use them. That automatically
> makes this code rt-safe. (it isnt right now)


Hmm, in UP it should be safe to access per cpu data under either a
preempt_disable or local_irq_disable . I'm not sure how RT changes
that .. Is there some other part of the code that isn't rt-safe, which
I've overlooked ?

Daniel

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