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=-10.3 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI, NICE_REPLY_A,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS autolearn=ham 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 4D996C433DF for ; Sat, 10 Oct 2020 23:03:59 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 243AD2067C for ; Sat, 10 Oct 2020 23:03:59 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1602371039; bh=xGydme+UTV4NKZi6UvEPEeCFfn0iIC8Oj9EpAiXdy5Q=; h=Date:From:To:Cc:Subject:In-Reply-To:References:List-ID:From; b=mwyIpWVhZNSkIj/9FP65Z4CfiGDt/0unbNQV36M2hNhKV8ilxbkIZXv29H/HZXFZ/ FgGRUuyTdZ4O/+P3MJtXKK1f1zPkHnUfVe5oFYSMBQX/P4TAwiOpj7BqKxXBK02FGI DIDZitQ5YuT2M9agl17Hhb8Q6BAGTz0wyyckP0qE= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732117AbgJJW7Q (ORCPT ); Sat, 10 Oct 2020 18:59:16 -0400 Received: from mail.kernel.org ([198.145.29.99]:57032 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731620AbgJJTyL (ORCPT ); Sat, 10 Oct 2020 15:54:11 -0400 Received: from devnote2 (NE2965lan1.rev.em-net.ne.jp [210.141.244.193]) (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 5926720776; Sat, 10 Oct 2020 15:03:47 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1602342228; bh=xGydme+UTV4NKZi6UvEPEeCFfn0iIC8Oj9EpAiXdy5Q=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=EezBVq+qYtujYEV7awQcPBPp7Se6Ebzh9AuAq56e5AOD3lzLp6VlNBENcOjxOl6PD UUouMBBQqZ3ZAUi52rzSHqc5/DyvlNQuxwkezscH1M+7RweUdByJjjr3XZZrx8qDHm sz26hp80dilYI+0HsuV5v5TkCBaACy1B7N//qluA= Date: Sun, 11 Oct 2020 00:03:44 +0900 From: Masami Hiramatsu To: Tom Zanussi Cc: rostedt@goodmis.org, axelrasmussen@google.com, mhiramat@kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 1/5] tracing: Don't show dynamic string internals in synthetic event description Message-Id: <20201011000344.4056fd1b0e8a7e48f2677ac0@kernel.org> In-Reply-To: References: X-Mailer: Sylpheed 3.7.0 (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 Hi Tom, On Fri, 9 Oct 2020 10:17:07 -0500 Tom Zanussi wrote: > For synthetic event dynamic fields, the type contains "__data_loc", > which is basically an internal part of the type which is only meant to > be displayed in the format, not in the event description itself, which > is confusing to users since they can't use __data_loc on the > command-line to define an event field, which printing it would lead > them to believe. > > So filter it out from the description, while leaving it in the type. > OK, I confirmed this removes __data_loc from synth_events interface. However, I also found another issue. /sys/kernel/debug/tracing # echo "myevent char str[]; int v" >> synthetic_events /sys/kernel/debug/tracing # cat synthetic_events myevent char[]; str; int v It seems that the type "char[]" includes ";" as a type, this results /sys/kernel/debug/tracing # cat events/synthetic/myevent/format name: myevent ID: 1220 format: field:unsigned short common_type; offset:0; size:2; signed:0; field:unsigned char common_flags; offset:2; size:1; signed:0; field:unsigned char common_preempt_count; offset:3; size:1; signed:0; field:int common_pid; offset:4; size:4; signed:1; field:__data_loc char[]; str; offset:8; size:8; signed:1; field:int v; offset:16; size:4; signed:1; print fmt: "str=%.*s, v=%d", __get_str(str), REC->v As you can see, the field type has ";" in format file too. This will prevent parsing event information correctly. I also try to remove ";" as below, it seems to work correctly. /sys/kernel/debug/tracing # echo "myevent char[] str; int v" >> synthetic_events /sys/kernel/debug/tracing # cat events/synthetic/myevent/format name: myevent ID: 1221 format: field:unsigned short common_type; offset:0; size:2; signed:0; field:unsigned char common_flags; offset:2; size:1; signed:0; field:unsigned char common_preempt_count; offset:3; size:1; signed:0; field:int common_pid; offset:4; size:4; signed:1; field:__data_loc char[] str; offset:8; size:8; signed:1; field:int v; offset:16; size:4; signed:1; print fmt: "str=%.*s, v=%d", __get_str(str), REC->v Thank you, > Reported-by: Masami Hiramatsu > Signed-off-by: Tom Zanussi > --- > kernel/trace/trace_events_synth.c | 10 +++++++++- > 1 file changed, 9 insertions(+), 1 deletion(-) > > diff --git a/kernel/trace/trace_events_synth.c b/kernel/trace/trace_events_synth.c > index 3b2dcc42b8ee..b19e2f4159ab 100644 > --- a/kernel/trace/trace_events_synth.c > +++ b/kernel/trace/trace_events_synth.c > @@ -1867,14 +1867,22 @@ static int __synth_event_show(struct seq_file *m, struct synth_event *event) > { > struct synth_field *field; > unsigned int i; > + char *type, *t; > > seq_printf(m, "%s\t", event->name); > > for (i = 0; i < event->n_fields; i++) { > field = event->fields[i]; > > + type = field->type; > + t = strstr(type, "__data_loc"); > + if (t) { /* __data_loc belongs in format but not event desc */ > + t += sizeof("__data_loc"); > + type = t; > + } > + > /* parameter values */ > - seq_printf(m, "%s %s%s", field->type, field->name, > + seq_printf(m, "%s %s%s", type, field->name, > i == event->n_fields - 1 ? "" : "; "); > } > > -- > 2.17.1 > -- Masami Hiramatsu