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 C0135C433EF for ; Fri, 22 Apr 2022 22:40:33 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233479AbiDVWnZ (ORCPT ); Fri, 22 Apr 2022 18:43:25 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:43542 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234262AbiDVWnC (ORCPT ); Fri, 22 Apr 2022 18:43:02 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [IPv6:2604:1380:4601:e00::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 12ABA178F41 for ; Fri, 22 Apr 2022 14:43:04 -0700 (PDT) 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 C789CB8327E for ; Fri, 22 Apr 2022 21:43:02 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 78106C385AA; Fri, 22 Apr 2022 21:43:00 +0000 (UTC) Date: Fri, 22 Apr 2022 17:42:58 -0400 From: Steven Rostedt To: Mark-PK Tsai Cc: , , , , , Subject: Re: [PATCH v3 1/2] tracing: Avoid adding tracer option before update_tracer_options Message-ID: <20220422174258.1f41777a@gandalf.local.home> In-Reply-To: <20220323152257.7871-2-mark-pk.tsai@mediatek.com> References: <20220323152257.7871-1-mark-pk.tsai@mediatek.com> <20220323152257.7871-2-mark-pk.tsai@mediatek.com> X-Mailer: Claws Mail 3.17.8 (GTK+ 2.24.33; 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 Wed, 23 Mar 2022 23:22:56 +0800 Mark-PK Tsai wrote: > To prepare for support asynchronous tracer_init_tracefs initcall, > avoid calling create_trace_option_files before __update_tracer_options. > Otherwise, create_trace_option_files will show warning because > some tracers in trace_types list are already in tr->topts. > > For example, hwlat_tracer call register_tracer in late_initcall, > and global_trace.dir is already created in tracing_init_dentry, > hwlat_tracer will be put into tr->topts. > Then if the __update_tracer_options is executed after hwlat_tracer > registered, create_trace_option_files find that hwlat_tracer is > already in tr->topts. > > Link: https://lore.kernel.org/lkml/20220322133339.GA32582@xsang-OptiPlex-9020/ > Reported-by: kernel test robot > Signed-off-by: Mark-PK Tsai Before this patch: # ls /sys/kernel/tracing/options annotate funcgraph-duration hex stacktrace bin funcgraph-irqs irq-info sym-addr blk_cgname funcgraph-overhead latency-format sym-offset blk_cgroup funcgraph-overrun markers sym-userobj blk_classic funcgraph-proc overwrite test_nop_accept block funcgraph-tail pause-on-trace test_nop_refuse context-info func-no-repeats printk-msg-only trace_printk disable_on_free func_stack_trace print-parent userstacktrace display-graph function-fork raw verbose event-fork function-trace record-cmd funcgraph-abstime graph-time record-tgid funcgraph-cpu hash-ptr sleep-time After this patch: # ls /sys/kernel/tracing/options annotate disable_on_free irq-info raw trace_printk bin display-graph latency-format record-cmd userstacktrace blk_cgname event-fork markers record-tgid verbose blk_cgroup function-fork overwrite stacktrace blk_classic function-trace pause-on-trace sym-addr block hash-ptr printk-msg-only sym-offset context-info hex print-parent sym-userobj Not good. > --- > kernel/trace/trace.c | 7 +++++++ > 1 file changed, 7 insertions(+) > > diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c > index eb44418574f9..85ec758c4455 100644 > --- a/kernel/trace/trace.c > +++ b/kernel/trace/trace.c > @@ -6317,12 +6317,18 @@ static void tracing_set_nop(struct trace_array *tr) > tr->current_trace = &nop_trace; > } > > +static bool tracer_options_updated; > + > static void add_tracer_options(struct trace_array *tr, struct tracer *t) > { > /* Only enable if the directory has been created already. */ > if (!tr->dir) > return; > > + /* Only create trace option files after update_tracer_options finish */ > + if (!tracer_options_updated) > + return; > + > create_trace_option_files(tr, t); > } > > @@ -9133,6 +9139,7 @@ static void update_tracer_options(struct trace_array *tr) > { > mutex_lock(&trace_types_lock); > __update_tracer_options(tr); > + tracer_options_updated = true; I think you want to set this before the __update, as doing it after just makes the update a nop. -- Steve > mutex_unlock(&trace_types_lock); > } >