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=-8.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_2 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 01021C0650F for ; Tue, 30 Jul 2019 16:15:31 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id B4D6D206E0 for ; Tue, 30 Jul 2019 16:15:30 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730919AbfG3QP3 (ORCPT ); Tue, 30 Jul 2019 12:15:29 -0400 Received: from mail.kernel.org ([198.145.29.99]:43990 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729025AbfG3QP3 (ORCPT ); Tue, 30 Jul 2019 12:15:29 -0400 Received: from gandalf.local.home (cpe-66-24-58-225.stny.res.rr.com [66.24.58.225]) (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 949F5206A2; Tue, 30 Jul 2019 16:15:28 +0000 (UTC) Date: Tue, 30 Jul 2019 12:15:27 -0400 From: Steven Rostedt To: Changbin Du Cc: Ingo Molnar , linux-kernel@vger.kernel.org Subject: Re: [PATCH] fgraph: Remove redundant ftrace_graph_notrace_addr() test Message-ID: <20190730121527.13f600f5@gandalf.local.home> In-Reply-To: <20190730140850.7927-1-changbin.du@gmail.com> References: <20190730140850.7927-1-changbin.du@gmail.com> X-Mailer: Claws Mail 3.17.3 (GTK+ 2.24.32; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 30 Jul 2019 22:08:50 +0800 Changbin Du wrote: > We already have tested it before. The second one should be removed. > With this change, the performance should have little improvement. > > Fixes: 9cd2992f2d6c ("fgraph: Have set_graph_notrace only affect function_graph tracer") Thanks! I think this should even be marked for stable. Not really a bad bug, but a bug none the less. -- Steve > Signed-off-by: Changbin Du > --- > kernel/trace/trace_functions_graph.c | 17 +++++++---------- > 1 file changed, 7 insertions(+), 10 deletions(-) > > diff --git a/kernel/trace/trace_functions_graph.c b/kernel/trace/trace_functions_graph.c > index 69ebf3c2f1b5..78af97163147 100644 > --- a/kernel/trace/trace_functions_graph.c > +++ b/kernel/trace/trace_functions_graph.c > @@ -137,6 +137,13 @@ int trace_graph_entry(struct ftrace_graph_ent *trace) > if (trace_recursion_test(TRACE_GRAPH_NOTRACE_BIT)) > return 0; > > + /* > + * Do not trace a function if it's filtered by set_graph_notrace. > + * Make the index of ret stack negative to indicate that it should > + * ignore further functions. But it needs its own ret stack entry > + * to recover the original index in order to continue tracing after > + * returning from the function. > + */ > if (ftrace_graph_notrace_addr(trace->func)) { > trace_recursion_set(TRACE_GRAPH_NOTRACE_BIT); > /* > @@ -155,16 +162,6 @@ int trace_graph_entry(struct ftrace_graph_ent *trace) > if (ftrace_graph_ignore_irqs()) > return 0; > > - /* > - * Do not trace a function if it's filtered by set_graph_notrace. > - * Make the index of ret stack negative to indicate that it should > - * ignore further functions. But it needs its own ret stack entry > - * to recover the original index in order to continue tracing after > - * returning from the function. > - */ > - if (ftrace_graph_notrace_addr(trace->func)) > - return 1; > - > /* > * Stop here if tracing_threshold is set. We only write function return > * events to the ring buffer.