From patchwork Tue Jan 11 17:31:02 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Steven Rostedt X-Patchwork-Id: 531787 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 F3DE2C4332F for ; Tue, 11 Jan 2022 17:31:32 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1344544AbiAKRbb (ORCPT ); Tue, 11 Jan 2022 12:31:31 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:42874 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1344428AbiAKRbX (ORCPT ); Tue, 11 Jan 2022 12:31:23 -0500 Received: from ams.source.kernel.org (ams.source.kernel.org [IPv6:2604:1380:4601:e00::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 936F6C061201; Tue, 11 Jan 2022 09:31:20 -0800 (PST) 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 ams.source.kernel.org (Postfix) with ESMTPS id 36C62B81C3B; Tue, 11 Jan 2022 17:31:20 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id E789EC36AF3; Tue, 11 Jan 2022 17:31:19 +0000 (UTC) Received: from rostedt by gandalf.local.home with local (Exim 4.95) (envelope-from ) id 1n7KzP-0032Ln-47; Tue, 11 Jan 2022 12:31:19 -0500 Message-ID: <20220111173118.961361869@goodmis.org> User-Agent: quilt/0.66 Date: Tue, 11 Jan 2022 12:31:02 -0500 From: Steven Rostedt To: linux-kernel@vger.kernel.org Cc: Ingo Molnar , Andrew Morton , stable@vger.kernel.org, Daniel Bristot de Oliveira , Nikita Yushchenko Subject: [for-next][PATCH 31/31] tracing/osnoise: Properly unhook events if start_per_cpu_kthreads() fails References: <20220111173030.999527342@goodmis.org> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Nikita Yushchenko If start_per_cpu_kthreads() called from osnoise_workload_start() returns error, event hooks are left in broken state: unhook_irq_events() called but unhook_thread_events() and unhook_softirq_events() not called, and trace_osnoise_callback_enabled flag not cleared. On the next tracer enable, hooks get not installed due to trace_osnoise_callback_enabled flag. And on the further tracer disable an attempt to remove non-installed hooks happened, hitting a WARN_ON_ONCE() in tracepoint_remove_func(). Fix the error path by adding the missing part of cleanup. While at this, introduce osnoise_unhook_events() to avoid code duplication between this error path and normal tracer disable. Link: https://lkml.kernel.org/r/20220109153459.3701773-1-nikita.yushchenko@virtuozzo.com Cc: stable@vger.kernel.org Fixes: bce29ac9ce0b ("trace: Add osnoise tracer") Acked-by: Daniel Bristot de Oliveira Signed-off-by: Nikita Yushchenko Signed-off-by: Steven Rostedt --- kernel/trace/trace_osnoise.c | 20 ++++++++++++++++---- 1 file changed, 16 insertions(+), 4 deletions(-) diff --git a/kernel/trace/trace_osnoise.c b/kernel/trace/trace_osnoise.c index 4719a848bf17..36d9d5be08b4 100644 --- a/kernel/trace/trace_osnoise.c +++ b/kernel/trace/trace_osnoise.c @@ -2122,6 +2122,13 @@ static int osnoise_hook_events(void) return -EINVAL; } +static void osnoise_unhook_events(void) +{ + unhook_thread_events(); + unhook_softirq_events(); + unhook_irq_events(); +} + /* * osnoise_workload_start - start the workload and hook to events */ @@ -2154,7 +2161,14 @@ static int osnoise_workload_start(void) retval = start_per_cpu_kthreads(); if (retval) { - unhook_irq_events(); + trace_osnoise_callback_enabled = false; + /* + * Make sure that ftrace_nmi_enter/exit() see + * trace_osnoise_callback_enabled as false before continuing. + */ + barrier(); + + osnoise_unhook_events(); return retval; } @@ -2185,9 +2199,7 @@ static void osnoise_workload_stop(void) stop_per_cpu_kthreads(); - unhook_irq_events(); - unhook_softirq_events(); - unhook_thread_events(); + osnoise_unhook_events(); } static void osnoise_tracer_start(struct trace_array *tr)