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 20AF7C77B75 for ; Tue, 9 May 2023 16:46:08 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233293AbjEIQqH convert rfc822-to-8bit (ORCPT ); Tue, 9 May 2023 12:46:07 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:58576 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229489AbjEIQqG (ORCPT ); Tue, 9 May 2023 12:46:06 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 26B0740C2; Tue, 9 May 2023 09:46:03 -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 dfw.source.kernel.org (Postfix) with ESMTPS id A910862CFC; Tue, 9 May 2023 16:46:02 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 8B120C433D2; Tue, 9 May 2023 16:46:01 +0000 (UTC) Date: Tue, 9 May 2023 12:45:59 -0400 From: Steven Rostedt To: Ajay Kaher Cc: kernel test robot , "mhiramat@kernel.org" , "shuah@kernel.org" , "llvm@lists.linux.dev" , "oe-kbuild-all@lists.linux.dev" , "linux-kernel@vger.kernel.org" , "linux-trace-kernel@vger.kernel.org" , "linux-kselftest@vger.kernel.org" , "chinglinyu@google.com" , Nadav Amit , Srivatsa Bhat , "srivatsa@csail.mit.edu" , Alexey Makhalov , Vasavi Sirnapalli , Tapas Kundu , "er.ajay.kaher@gmail.com" Subject: Re: [PATCH v2 8/9] eventfs: moving tracing/events to eventfs Message-ID: <20230509124559.0d5557ad@rorschach.local.home> In-Reply-To: <1CAC8265-A4F3-4AF6-80E4-8F264ED670A9@vmware.com> References: <1683026600-13485-9-git-send-email-akaher@vmware.com> <202305030116.Gu6yyvKj-lkp@intel.com> <1CAC8265-A4F3-4AF6-80E4-8F264ED670A9@vmware.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=UTF-8 Content-Transfer-Encoding: 8BIT Precedence: bulk List-ID: X-Mailing-List: linux-trace-kernel@vger.kernel.org On Tue, 9 May 2023 12:29:23 +0000 Ajay Kaher wrote: > > On 02/05/23, 11:42 PM, "kernel test robot" wrote: > > >> kernel/trace/trace_events.c:2424:17: warning: variable 'd_events' set but not used [-Wunused-but-set-variable] > > struct dentry *d_events; > > ^ > > 1 warning generated. > > > > Steve, with-in event_create_dir(), do we have any scenario when file->event_call->class->system > doesn't have TRACE_SYSTEM? And need to execute following: > > ae63b31e4d0e2e Steven Rostedt 2012-05-03 2437 d_events = parent; > > looking for your input if we could remove d_events from event_create_dir(). > I have hit this in the beginning, but I don't think it's an issue anymore. Perhaps just have it be: if (WARN_ON_ONCE(strcmp(call->class->system, TRACE_SYSTEM) == 0)) return -ENODEV; ef_subsystem = event_subsystem_dir(tr, call->class->system, file, parent); Hmm, how about just add this patch before your patch set: -- Steve From: "Steven Rostedt (Google)" Subject: [PATCH] tracing: Require all trace events to have a TRACE_SYSTEM The creation of the trace event directory requires that a TRACE_SYSTEM is defined that the trace event directory is added within the system it was defined in. The code handled the case where a TRACE_SYSTEM was not added, and would then add the event at the events directory. But nothing should be doing this. This code also prevents the implementation of creating dynamic dentrys for the eventfs system. As this path has never been hit on correct code, remove it. If it does get hit, issues a WARN_ON_ONCE() and return ENODEV. Signed-off-by: Steven Rostedt (Google) --- (lightly tested) kernel/trace/trace_events.c | 15 ++++++++------- 1 file changed, 8 insertions(+), 7 deletions(-) diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c index 654ffa40457a..16bc5ba45507 100644 --- a/kernel/trace/trace_events.c +++ b/kernel/trace/trace_events.c @@ -2424,14 +2424,15 @@ event_create_dir(struct dentry *parent, struct trace_event_file *file) /* * If the trace point header did not define TRACE_SYSTEM - * then the system would be called "TRACE_SYSTEM". + * then the system would be called "TRACE_SYSTEM". This should + * never happen. */ - if (strcmp(call->class->system, TRACE_SYSTEM) != 0) { - d_events = event_subsystem_dir(tr, call->class->system, file, parent); - if (!d_events) - return -ENOMEM; - } else - d_events = parent; + if (WARN_ON_ONCE(strcmp(call->class->system, TRACE_SYSTEM) == 0)) + return -ENODEV; + + d_events = event_subsystem_dir(tr, call->class->system, file, parent); + if (!d_events) + return -ENOMEM; name = trace_event_name(call); file->dir = tracefs_create_dir(name, d_events); -- 2.39.2