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 7C982C433EF for ; Tue, 26 Apr 2022 08:17:38 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1344412AbiDZIUn (ORCPT ); Tue, 26 Apr 2022 04:20:43 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:39276 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1344562AbiDZIUb (ORCPT ); Tue, 26 Apr 2022 04:20:31 -0400 Received: from mailgw01.mediatek.com (unknown [60.244.123.138]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 4A6A34D9DC for ; Tue, 26 Apr 2022 01:17:14 -0700 (PDT) X-UUID: ea449387750345078522c858417b48e9-20220426 X-CID-P-RULE: Release_Ham X-CID-O-INFO: VERSION:1.1.4,REQID:40a5b8ef-fb72-49dc-a62d-9043f4f2051c,OB:0,LO B:0,IP:0,URL:0,TC:0,Content:0,EDM:0,RT:0,SF:50,FILE:0,RULE:Release_Ham,ACT ION:release,TS:50 X-CID-INFO: VERSION:1.1.4,REQID:40a5b8ef-fb72-49dc-a62d-9043f4f2051c,OB:0,LOB: 0,IP:0,URL:0,TC:0,Content:0,EDM:0,RT:0,SF:50,FILE:0,RULE:Release_Ham,ACTIO N:release,TS:50 X-CID-META: VersionHash:faefae9,CLOUDID:9a6483c6-85ee-4ac1-ac05-bd3f1e72e732,C OID:IGNORED,Recheck:0,SF:13|15|28|17|19|48,TC:nil,Content:-5,EDM:-3,File:n il,QS:0,BEC:nil X-UUID: ea449387750345078522c858417b48e9-20220426 Received: from mtkmbs10n2.mediatek.inc [(172.21.101.183)] by mailgw01.mediatek.com (envelope-from ) (Generic MTA with TLSv1.2 ECDHE-RSA-AES256-GCM-SHA384 256/256) with ESMTP id 810141183; Tue, 26 Apr 2022 16:17:09 +0800 Received: from mtkexhb02.mediatek.inc (172.21.101.103) by mtkmbs07n1.mediatek.inc (172.21.101.16) with Microsoft SMTP Server (TLS) id 15.0.1497.2; Tue, 26 Apr 2022 16:17:07 +0800 Received: from mtkcas11.mediatek.inc (172.21.101.40) by mtkexhb02.mediatek.inc (172.21.101.103) with Microsoft SMTP Server (TLS) id 15.0.1497.2; Tue, 26 Apr 2022 16:17:06 +0800 Received: from mtksdccf07.mediatek.inc (172.21.84.99) by mtkcas11.mediatek.inc (172.21.101.73) with Microsoft SMTP Server id 15.0.1497.2 via Frontend Transport; Tue, 26 Apr 2022 16:17:06 +0800 From: Mark-PK Tsai To: CC: , , , , , , Subject: Re: [PATCH v3 1/2] tracing: Avoid adding tracer option before update_tracer_options Date: Tue, 26 Apr 2022 16:17:06 +0800 Message-ID: <20220426081706.13274-1-mark-pk.tsai@mediatek.com> X-Mailer: git-send-email 2.18.0 In-Reply-To: <20220422174258.1f41777a@gandalf.local.home> References: <20220422174258.1f41777a@gandalf.local.home> MIME-Version: 1.0 Content-Type: text/plain X-MTK: N Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org > > 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. Calling __update_tracer_options() when tracer_options_updated=false have no effect because it return directly in add_tracer_options(). I will fix it in v4 as you suggest in the below comment. > > > --- > > 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. You are right. I will update in v4, thanks! > > -- Steve > > > > mutex_unlock(&trace_types_lock); > > } > >