Re: [PATCH -rt] revert bh_lru_lock() to preempt_disable()

[Daniel Walker]

On Wed, 2006-05-03 at 22:47 +0200, Ingo Molnar wrote:
> * Daniel Walker <dwalker@xxxxxxxxxx> 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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