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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id C8451C63797 for ; Fri, 3 Feb 2023 10:29:17 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233665AbjBCK3R (ORCPT ); Fri, 3 Feb 2023 05:29:17 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:51312 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233645AbjBCK2v (ORCPT ); Fri, 3 Feb 2023 05:28:51 -0500 Received: from ams.source.kernel.org (ams.source.kernel.org [IPv6:2604:1380:4601:e00::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 96B4E1D92A for ; Fri, 3 Feb 2023 02:28:06 -0800 (PST) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id 244CCB82A68 for ; Fri, 3 Feb 2023 10:28:05 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 4E8E1C433D2; Fri, 3 Feb 2023 10:28:03 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1675420083; bh=yU/KHOVoY3cgHVv7ftkC4XUH3Cf97dmamGzRt85zphM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Y9nU3l8H9V+aF0Gdi4JxfupM+PhwCmiP61wTgZ7PcgpL4NOG8HIG8qP6oqwCELUY6 m55dPYq+/kICx2P53GENhFzwThsh/7Wo/oqOqsBiUMR2sbNXavJPZoIn89wFz3eRtS ewRvmTUGfqU4fNtXskQiodGHi5JQ4cYFX8PhDvYg= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Masami Hiramatsu , "Joel Fernandes (Google)" , "Steven Rostedt (Google)" Subject: [PATCH 5.4 075/134] tracing: Make sure trace_printk() can output as soon as it can be used Date: Fri, 3 Feb 2023 11:13:00 +0100 Message-Id: <20230203101027.229420105@linuxfoundation.org> X-Mailer: git-send-email 2.39.1 In-Reply-To: <20230203101023.832083974@linuxfoundation.org> References: <20230203101023.832083974@linuxfoundation.org> User-Agent: quilt/0.67 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Steven Rostedt (Google) commit 3bb06eb6e9acf7c4a3e1b5bc87aed398ff8e2253 upstream. Currently trace_printk() can be used as soon as early_trace_init() is called from start_kernel(). But if a crash happens, and "ftrace_dump_on_oops" is set on the kernel command line, all you get will be: [ 0.456075] -0 0dN.2. 347519us : Unknown type 6 [ 0.456075] -0 0dN.2. 353141us : Unknown type 6 [ 0.456075] -0 0dN.2. 358684us : Unknown type 6 This is because the trace_printk() event (type 6) hasn't been registered yet. That gets done via an early_initcall(), which may be early, but not early enough. Instead of registering the trace_printk() event (and other ftrace events, which are not trace events) via an early_initcall(), have them registered at the same time that trace_printk() can be used. This way, if there is a crash before early_initcall(), then the trace_printk()s will actually be useful. Link: https://lkml.kernel.org/r/20230104161412.019f6c55@gandalf.local.home Cc: stable@vger.kernel.org Cc: Masami Hiramatsu Fixes: e725c731e3bb1 ("tracing: Split tracing initialization into two for early initialization") Reported-by: "Joel Fernandes (Google)" Tested-by: Joel Fernandes (Google) Signed-off-by: Steven Rostedt (Google) Signed-off-by: Greg Kroah-Hartman --- kernel/trace/trace.c | 2 ++ kernel/trace/trace.h | 1 + kernel/trace/trace_output.c | 3 +-- 3 files changed, 4 insertions(+), 2 deletions(-) --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -9317,6 +9317,8 @@ void __init early_trace_init(void) static_key_enable(&tracepoint_printk_key.key); } tracer_alloc_buffers(); + + init_events(); } void __init trace_init(void) --- a/kernel/trace/trace.h +++ b/kernel/trace/trace.h @@ -1590,6 +1590,7 @@ extern void trace_event_enable_cmd_recor extern void trace_event_enable_tgid_record(bool enable); extern int event_trace_init(void); +extern int init_events(void); extern int event_trace_add_tracer(struct dentry *parent, struct trace_array *tr); extern int event_trace_del_tracer(struct trace_array *tr); --- a/kernel/trace/trace_output.c +++ b/kernel/trace/trace_output.c @@ -1366,7 +1366,7 @@ static struct trace_event *events[] __in NULL }; -__init static int init_events(void) +__init int init_events(void) { struct trace_event *event; int i, ret; @@ -1384,4 +1384,3 @@ __init static int init_events(void) return 0; } -early_initcall(init_events);