From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S264372AbTLPXXj (ORCPT ); Tue, 16 Dec 2003 18:23:39 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S264373AbTLPXXj (ORCPT ); Tue, 16 Dec 2003 18:23:39 -0500 Received: from ausmtp01.au.ibm.com ([202.81.18.186]:22153 "EHLO ausmtp01.au.ibm.com") by vger.kernel.org with ESMTP id S264372AbTLPXXh (ORCPT ); Tue, 16 Dec 2003 18:23:37 -0500 From: Rusty Russell To: paulmck@us.ibm.com Cc: linux-kernel@vger.kernel.org Subject: Re: [DOCUMENTATION] Revised Unreliable Kernel Locking Guide In-reply-to: Your message of "Mon, 15 Dec 2003 14:22:14 -0800." <20031215222213.GA1270@us.ibm.com> Date: Tue, 16 Dec 2003 17:32:37 +1100 Message-Id: <20031216232331.8A111189E1@ozlabs.au.ibm.com> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org In message <20031215222213.GA1270@us.ibm.com> you write: > > How do we get rid of read locks? Getting rid of read locks > > means that writers may be changing the list underneath the readers. > > That is actually quite simple: > > Looks good! Upon rereading... Does "wmb()" want to be "smp_wmb()"? Yes, but I didn't want to turn this into a document on memory barriers: you'll note that I almost avoided it entirely. > Again, upon rereading, "read Read Copy Update code" probably wants to > be "real Read Copy Update code". I moused it this time, given > my past record with eyeballing. ;-) Fixed. > > Now, because the 'read lock' in RCU is simply disabling preemption, a > > caller which always preemption disabled between calling > disables preemption Ah, I inserted a 'has' as well (a caller which always has preemption disabled...). The implication that the caller probably has preempt disabled as a side effect of being in an interrupt or holding a spinlock. > > I've uploaded a new draft with these and other fixes... > > Good stuff, thank you!!! Hey, thanks for the review! Cheers, Rusty. -- Anyone who quotes me in their sig is an idiot. -- Rusty Russell.