From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-5.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_SANE_2 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id CCEA8C433DF for ; Fri, 16 Oct 2020 02:21:45 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 7E04020878 for ; Fri, 16 Oct 2020 02:21:45 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2393709AbgJPCVo (ORCPT ); Thu, 15 Oct 2020 22:21:44 -0400 Received: from mail.kernel.org ([198.145.29.99]:50886 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1732267AbgJPCVo (ORCPT ); Thu, 15 Oct 2020 22:21:44 -0400 Received: from gandalf.local.home (cpe-66-24-58-225.stny.res.rr.com [66.24.58.225]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id E371A20878; Fri, 16 Oct 2020 02:21:42 +0000 (UTC) Date: Thu, 15 Oct 2020 22:21:39 -0400 From: Steven Rostedt To: Linus Torvalds Cc: LKML , Ingo Molnar , Andrew Morton , Masami Hiramatsu , Tom Zanussi Subject: Re: [GIT PULL] tracing: Updates for 5.10 Message-ID: <20201015222139.1b92a3be@gandalf.local.home> In-Reply-To: References: <20201015135345.6b29e8c0@gandalf.local.home> X-Mailer: Claws Mail 3.17.3 (GTK+ 2.24.32; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 15 Oct 2020 18:54:34 -0700 Linus Torvalds wrote: > On Thu, Oct 15, 2020 at 10:53 AM Steven Rostedt wrote: > > > > Updates for tracing and bootconfig: > > Hmm. I haven't verified that this came from you, but it seems likely.. > Once again my clang build shows something that I don't see in my > allmodconfig gcc build: > > WARNING: modpost: vmlinux.o(.text+0x1e5b06): Section mismatch in > reference from the function __trace_early_add_events() to the function > .init.text:__trace_early_add_new_event() > The function __trace_early_add_events() references > the function __init __trace_early_add_new_event(). > This is often because __trace_early_add_events lacks a __init > annotation or the annotation of __trace_early_add_new_event is wrong. > > Hmm? > > Linus I see the issue, and I wonder if it has to do with optimization, for gcc not to warn. The issue is that we have: trace_array_create() that can be called at any time. And it has: if (trace_instance_dir) { ret = trace_array_create_dir(tr); if (ret) goto out_free_tr; } else __trace_early_add_events(tr); Where trace_instance_dir gets set at boot up, and thus the else statement will never get called after that. The __trace_early_add_events() then calls __trace_early_add_new_events() which is __init. I don't know how gcc didn't trigger this and clang does. I'll have to think about how to untangle this. Is there some kind of annotation that makes it show that a path can only be called at boot up and not later? -- Steve