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 CCCDCC433F5 for ; Mon, 24 Jan 2022 23:54:20 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2365102AbiAXXuP (ORCPT ); Mon, 24 Jan 2022 18:50:15 -0500 Received: from ams.source.kernel.org ([145.40.68.75]:47772 "EHLO ams.source.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1455590AbiAXVfm (ORCPT ); Mon, 24 Jan 2022 16:35:42 -0500 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 0F85FB81057; Mon, 24 Jan 2022 21:35:41 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 28AA6C340E4; Mon, 24 Jan 2022 21:35:38 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1643060139; bh=28iv+IlR6fG6foqJ96vlzt15jft0kK5kKyy556Qfa+s=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=z6CmdiCUHFs85Zu9DIQ6UumaurjpZL4aSIYS3dZNusQhE+6Yiwp66S0XmrMNby3b6 pnF4EwBC8TjsbMI/Ne47mZUDRqne0Llsq2SXpj0dcwHMcBrnZfrgdld4Tag6dkGFxe KeeCQb1uYE10zR2Rl02dsFZrji5YE/seYYxPOh0Y= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Daniel Bristot de Oliveira , Nikita Yushchenko , Steven Rostedt Subject: [PATCH 5.16 0852/1039] tracing/osnoise: Properly unhook events if start_per_cpu_kthreads() fails Date: Mon, 24 Jan 2022 19:44:01 +0100 Message-Id: <20220124184153.916097176@linuxfoundation.org> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20220124184125.121143506@linuxfoundation.org> References: <20220124184125.121143506@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Nikita Yushchenko commit 0878355b51f5f26632e652c848a8e174bb02d22d upstream. 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 Signed-off-by: Greg Kroah-Hartman --- kernel/trace/trace_osnoise.c | 20 ++++++++++++++++---- 1 file changed, 16 insertions(+), 4 deletions(-) --- a/kernel/trace/trace_osnoise.c +++ b/kernel/trace/trace_osnoise.c @@ -2123,6 +2123,13 @@ out_unhook_irq: 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 */ @@ -2155,7 +2162,14 @@ 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; } @@ -2186,9 +2200,7 @@ 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)