From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757125AbZCRCvi (ORCPT ); Tue, 17 Mar 2009 22:51:38 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754388AbZCRCva (ORCPT ); Tue, 17 Mar 2009 22:51:30 -0400 Received: from cn.fujitsu.com ([222.73.24.84]:57169 "EHLO song.cn.fujitsu.com" rhost-flags-OK-FAIL-OK-OK) by vger.kernel.org with ESMTP id S1753884AbZCRCv3 (ORCPT ); Tue, 17 Mar 2009 22:51:29 -0400 Message-ID: <49C06159.9010704@cn.fujitsu.com> Date: Wed, 18 Mar 2009 10:50:01 +0800 From: Lai Jiangshan User-Agent: Thunderbird 2.0.0.6 (Windows/20070728) MIME-Version: 1.0 To: Frederic Weisbecker CC: mingo@redhat.com, hpa@zytor.com, linux-kernel@vger.kernel.org, srostedt@redhat.com, tglx@linutronix.de, mingo@elte.hu, linux-tip-commits@vger.kernel.org Subject: Re: [tip:tracing/ftrace] ftrace: remove struct list_head from struct dyn_ftrace References: <49BA2C9F.8020009@cn.fujitsu.com> <20090316123607.GA5096@nowhere> <20090316124229.GB5096@nowhere> In-Reply-To: <20090316124229.GB5096@nowhere> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Frederic Weisbecker wrote: > > > May be I'm wrong. May be I misunderstood this patch. > But I don't understand how flags can be used at the same time as a pointer > and as a flag value. > When a new dyn_ftrace is added to ftrace_new_addrs list, the flag is 0, it's always 0 until this dyn_ftrace is removed from the list, so we can reuse the flag field. As Steven's suggest, using an union is better. ftrace_convert_nops() ftrace_record_ip() // allocate dyn_ftrace, and add it // to ftrace_new_addrs list ftrace_update_code() // remove it from ftrace_new_addrs. Lai.