From: Daniel Walker <dwalker@mvista.com>
To: Ingo Molnar <mingo@elte.hu>
Cc: linux-kernel@vger.kernel.org
Subject: Re: [PATCH -rt] revert bh_lru_lock() to preempt_disable()
Date: Wed, 03 May 2006 13:47:37 -0700 [thread overview]
Message-ID: <1146689257.3363.13.camel@localhost.localdomain> (raw)
In-Reply-To: <20060503204747.GC15965@elte.hu>
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
next prev parent reply other threads:[~2006-05-03 20:47 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-04-22 15:05 [PATCH -rt] revert bh_lru_lock() to preempt_disable() Daniel Walker
2006-05-03 20:47 ` Ingo Molnar
2006-05-03 20:47 ` Daniel Walker [this message]
2006-05-03 21:01 ` Ingo Molnar
2006-05-03 21:01 ` Daniel Walker
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