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=-11.5 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_2 autolearn=unavailable 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 2FEDDC433E3 for ; Mon, 27 Jul 2020 15:42:58 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 16AE921744 for ; Mon, 27 Jul 2020 15:42:58 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730965AbgG0Pm4 (ORCPT ); Mon, 27 Jul 2020 11:42:56 -0400 Received: from mail.kernel.org ([198.145.29.99]:37890 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729699AbgG0Pm4 (ORCPT ); Mon, 27 Jul 2020 11:42:56 -0400 Received: from oasis.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 AF03B206E7; Mon, 27 Jul 2020 15:42:55 +0000 (UTC) Date: Mon, 27 Jul 2020 11:42:54 -0400 From: Steven Rostedt To: Josef Bacik Cc: kernel-team@fb.com, linux-kernel@vger.kernel.org, mingo@redhat.com Subject: Re: [PATCH] ftrace: fix ftrace_trace_task return value Message-ID: <20200727114254.3086b8b9@oasis.local.home> In-Reply-To: <20200725005048.1790-1-josef@toxicpanda.com> References: <20200725005048.1790-1-josef@toxicpanda.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 Fri, 24 Jul 2020 20:50:48 -0400 Josef Bacik wrote: > I was attempting to use pid filtering with function_graph, but it wasn't > allowing anything to make it through. Turns out ftrace_trace_task > returns false if ftrace_ignore_pid is not-empty, which isn't correct > anymore. We're now setting it to FTRACE_PID_IGNORE if we need to ignore > that pid, otherwise it's set to the pid (which is weird considering the > name) or to FTRACE_PID_TRACE. Fix the check to check for != > FTRACE_PID_IGNORE. With this we can now use function_graph with pid > filtering. > I just ran into this myself! And was about to go look at why function graph pid filtering wasn't working. Thanks for the patch! I'll start testing it this week. -- Steve > Fixes: 717e3f5ebc82 ("ftrace: Make function trace pid filtering a bit more exact") > Signed-off-by: Josef Bacik > --- > kernel/trace/ftrace.c | 3 --- > kernel/trace/trace.h | 7 ++++++- > 2 files changed, 6 insertions(+), 4 deletions(-) > > diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c > index 1903b80db6eb..7d879fae3777 100644 > --- a/kernel/trace/ftrace.c > +++ b/kernel/trace/ftrace.c > @@ -139,9 +139,6 @@ static inline void ftrace_ops_init(struct ftrace_ops *ops) > #endif > } > > -#define FTRACE_PID_IGNORE -1 > -#define FTRACE_PID_TRACE -2 > - > static void ftrace_pid_func(unsigned long ip, unsigned long parent_ip, > struct ftrace_ops *op, struct pt_regs *regs) > { > diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h > index 13db4000af3f..1531ec565cb5 100644 > --- a/kernel/trace/trace.h > +++ b/kernel/trace/trace.h > @@ -1103,6 +1103,10 @@ print_graph_function_flags(struct trace_iterator *iter, u32 flags) > extern struct list_head ftrace_pids; > > #ifdef CONFIG_FUNCTION_TRACER > + > +#define FTRACE_PID_IGNORE -1 > +#define FTRACE_PID_TRACE -2 > + > struct ftrace_func_command { > struct list_head list; > char *name; > @@ -1114,7 +1118,8 @@ struct ftrace_func_command { > extern bool ftrace_filter_param __initdata; > static inline int ftrace_trace_task(struct trace_array *tr) > { > - return !this_cpu_read(tr->array_buffer.data->ftrace_ignore_pid); > + return this_cpu_read(tr->array_buffer.data->ftrace_ignore_pid) != > + FTRACE_PID_IGNORE; > } > extern int ftrace_is_dead(void); > int ftrace_create_function_files(struct trace_array *tr,