From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751103AbWECU4b (ORCPT ); Wed, 3 May 2006 16:56:31 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751119AbWECU4a (ORCPT ); Wed, 3 May 2006 16:56:30 -0400 Received: from mx2.mail.elte.hu ([157.181.151.9]:60388 "EHLO mx2.mail.elte.hu") by vger.kernel.org with ESMTP id S1751103AbWECU4a (ORCPT ); Wed, 3 May 2006 16:56:30 -0400 Date: Wed, 3 May 2006 23:01:25 +0200 From: Ingo Molnar To: Daniel Walker Cc: linux-kernel@vger.kernel.org Subject: Re: [PATCH -rt] revert bh_lru_lock() to preempt_disable() Message-ID: <20060503210125.GB16696@elte.hu> References: <200604221505.k3MF5mql022083@dwalker1.mvista.com> <20060503204747.GC15965@elte.hu> <1146689257.3363.13.camel@localhost.localdomain> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1146689257.3363.13.camel@localhost.localdomain> User-Agent: Mutt/1.4.2.1i X-ELTE-SpamScore: -2.8 X-ELTE-SpamLevel: X-ELTE-SpamCheck: no X-ELTE-SpamVersion: ELTE 2.0 X-ELTE-SpamCheck-Details: score=-2.8 required=5.9 tests=ALL_TRUSTED,AWL autolearn=no SpamAssassin version=3.0.3 -2.8 ALL_TRUSTED Did not pass through any untrusted hosts 0.0 AWL AWL: From: address is in the auto white-list X-ELTE-VirusStatus: clean Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org * Daniel Walker wrote: > > 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 ? hm, you are right - that code can be in a preempt-off section. I've applied your patch. Ingo