From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1760899AbZCPMg2 (ORCPT ); Mon, 16 Mar 2009 08:36:28 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751101AbZCPMgS (ORCPT ); Mon, 16 Mar 2009 08:36:18 -0400 Received: from an-out-0708.google.com ([209.85.132.242]:27780 "EHLO an-out-0708.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752094AbZCPMgR (ORCPT ); Mon, 16 Mar 2009 08:36:17 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=date:from:to:cc:subject:message-id:references:mime-version :content-type:content-disposition:in-reply-to:user-agent; b=CBkjSX2AKgOZVYxYDDYn1XTwHsU2RAsAQkfMxtEw5UUTqkpVFoae9tHulgpYnTAcxi RUHNRuvc0h9zU5wcCznsvFL/QNDNLUZCLWIhq1gyIeN/o/ZU9PzjvrncTPHT52fd4Te4 6vX4GBQ5CLAaRNP8j38Iw/YwumjGqfbsuCF0g= Date: Mon, 16 Mar 2009 13:36:09 +0100 From: Frederic Weisbecker To: mingo@redhat.com, hpa@zytor.com, linux-kernel@vger.kernel.org, srostedt@redhat.com, tglx@linutronix.de, laijs@cn.fujitsu.com, mingo@elte.hu Cc: linux-tip-commits@vger.kernel.org Subject: Re: [tip:tracing/ftrace] ftrace: remove struct list_head from struct dyn_ftrace Message-ID: <20090316123607.GA5096@nowhere> References: <49BA2C9F.8020009@cn.fujitsu.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.18 (2008-05-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Mar 13, 2009 at 10:39:36AM +0000, Lai Jiangshan wrote: > Commit-ID: e94142a67f8bad494c593f0a07c9fc2fbec98c0e > Gitweb: http://git.kernel.org/tip/e94142a67f8bad494c593f0a07c9fc2fbec98c0e > Author: Lai Jiangshan > AuthorDate: Fri, 13 Mar 2009 17:51:27 +0800 > Commit: Ingo Molnar > CommitDate: Fri, 13 Mar 2009 11:36:20 +0100 > > ftrace: remove struct list_head from struct dyn_ftrace > > Impact: save memory > > The struct dyn_ftrace table is very large, this patch will save > about 50%. > > Signed-off-by: Lai Jiangshan > Cc: Steven Rostedt > LKML-Reference: <49BA2C9F.8020009@cn.fujitsu.com> > Signed-off-by: Ingo Molnar > > > --- > include/linux/ftrace.h | 1 - > kernel/trace/ftrace.c | 14 ++++++++------ > 2 files changed, 8 insertions(+), 7 deletions(-) > > diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h > index c146c10..9d598bb 100644 > --- a/include/linux/ftrace.h > +++ b/include/linux/ftrace.h > @@ -145,7 +145,6 @@ enum { > }; > > struct dyn_ftrace { > - struct list_head list; > unsigned long ip; /* address of mcount call-site */ > unsigned long flags; > struct dyn_arch_ftrace arch; > diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c > index bf78a4c..90d5729 100644 > --- a/kernel/trace/ftrace.c > +++ b/kernel/trace/ftrace.c > @@ -272,7 +272,7 @@ enum { > > static int ftrace_filtered; > > -static LIST_HEAD(ftrace_new_addrs); > +static struct dyn_ftrace *ftrace_new_addrs; > > static DEFINE_MUTEX(ftrace_regex_lock); > > @@ -409,8 +409,8 @@ ftrace_record_ip(unsigned long ip) > return NULL; > > rec->ip = ip; > - > - list_add(&rec->list, &ftrace_new_addrs); > + rec->flags = (unsigned long)ftrace_new_addrs; > + ftrace_new_addrs = rec; But... you are overwritting all the ftrace flags infrastructure by using it as a list pointer. This is breaking dynamic tracing. > > return rec; > } > @@ -716,19 +716,21 @@ unsigned long ftrace_update_tot_cnt; > > static int ftrace_update_code(struct module *mod) > { > - struct dyn_ftrace *p, *t; > + struct dyn_ftrace *p; > cycle_t start, stop; > > start = ftrace_now(raw_smp_processor_id()); > ftrace_update_cnt = 0; > > - list_for_each_entry_safe(p, t, &ftrace_new_addrs, list) { > + while (ftrace_new_addrs) { > > /* If something went wrong, bail without enabling anything */ > if (unlikely(ftrace_disabled)) > return -1; > > - list_del_init(&p->list); > + p = ftrace_new_addrs; > + ftrace_new_addrs = (struct dyn_ftrace *)p->flags; > + p->flags = 0L; > > /* convert record (i.e, patch mcount-call with NOP) */ > if (ftrace_code_disable(mod, p)) { > -- > To unsubscribe from this list: send the line "unsubscribe linux-tip-commits" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html