From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S271750AbTHHTeo (ORCPT ); Fri, 8 Aug 2003 15:34:44 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S271812AbTHHTeo (ORCPT ); Fri, 8 Aug 2003 15:34:44 -0400 Received: from dp.samba.org ([66.70.73.150]:39632 "EHLO lists.samba.org") by vger.kernel.org with ESMTP id S271750AbTHHTel (ORCPT ); Fri, 8 Aug 2003 15:34:41 -0400 From: Rusty Russell To: Alan Cox Cc: Greg KH , Andrew Morton , dipankar@in.ibm.com, andrea@suse.de, Linux Kernel Mailing List , paulmck@us.ibm.com Subject: Re: [PATCH] RCU: Reduce size of rcu_head 1 of 2 In-reply-to: Your message of "02 Aug 2003 14:15:26 +0100." <1059830126.19819.8.camel@dhcp22.swansea.linux.org.uk> Date: Fri, 08 Aug 2003 12:21:04 +1000 Message-Id: <20030808193441.56F452C25E@lists.samba.org> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org In message <1059830126.19819.8.camel@dhcp22.swansea.linux.org.uk> you write: > On Sad, 2003-08-02 at 02:49, Rusty Russell wrote: > > Sure. But it's not neccessary. The replacement is cleaner and > > smaller, sure, but it's not worth changing once 2.6 is out. In 2.7, > > sure. > > > > I'm happy to accept "no" from Andrew, but not happy to accept "we'll > > just change the API midway through 2.6". > > Please distinguish API from ABI. There is no ABI, there is no need for > an ABI. You are confused, but it seems you are not alone. I don't understand where this talk of ABI came from. There are two patches. Both reduce the size of the "struct rcu_head". One simply changes the struct rcu_head from a double linked list to a single linked list. The other eliminates the "void *data" arg, and changes the prototype of the call_rcu() function to take a pointer to the struct rcu_head, rather than a user-defined data ptr. It is the latter that I am concerned about changing mid-stable-series. Hope that clarifies, Rusty. -- Anyone who quotes me in their sig is an idiot. -- Rusty Russell.