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 F288CCA0FFB for ; Sat, 2 Sep 2023 01:26:00 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234584AbjIBB0C (ORCPT ); Fri, 1 Sep 2023 21:26:02 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:35828 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229489AbjIBB0B (ORCPT ); Fri, 1 Sep 2023 21:26:01 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 931BFA0; Fri, 1 Sep 2023 18:25:58 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 32AF160C0D; Sat, 2 Sep 2023 01:25:58 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id C8572C433C8; Sat, 2 Sep 2023 01:25:56 +0000 (UTC) Date: Fri, 1 Sep 2023 21:26:07 -0400 From: Steven Rostedt To: "Masami Hiramatsu (Google)" Cc: Chuang Wang , stable@vger.kernel.org, Zheng Yejian , linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org, Brian Foster Subject: Re: [PATCH] tracing: Fix the unusable problem caused by non-empty pipe_cpumask Message-ID: <20230901212607.1f8608de@gandalf.local.home> In-Reply-To: <20230901230206.9bf0250291acd7bfbde46b53@kernel.org> References: <20230901072626.278880-1-nashuiliang@gmail.com> <20230901230206.9bf0250291acd7bfbde46b53@kernel.org> X-Mailer: Claws Mail 3.19.1 (GTK+ 2.24.33; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-trace-kernel@vger.kernel.org On Fri, 1 Sep 2023 23:02:06 +0900 Masami Hiramatsu (Google) wrote: > On Fri, 1 Sep 2023 15:26:26 +0800 > Chuang Wang wrote: > > > There is a problem in the linux-6.5 when I execute the following > > command: > > > > $ perf ftrace -t irqsoff > > failed to open trace_pipe > > > > At the same time, when I open this file, the same error occurs. > > > > Therefore, after carefully looking at the code, the open function of > > 'trace_pipe' returns -EBUSY in open_pipe_on_cpu() because no clearing > > operation was performed when 'trace_array->pipe_cpumask' was allocated. > > > > With this patch, Use zalloc_cpumask_var() to ensure that > > 'trace_array->pipe_cpumask' is reset to 0 when allocated. Brian Foster beat you to it. https://lore.kernel.org/linux-trace-kernel/20230831125500.986862-1-bfoster@redhat.com > > Good catch. This looks good to me. > > Reviewed-by: Masami Hiramatsu (Google) > Masami, I'll add your Reviewed-by to that commit. Thanks! -- Steve > > > > Cc: stable@vger.kernel.org > > Fixes: c2489bb7e6be ("tracing: Introduce pipe_cpumask to avoid race on trace_pipes") > > Signed-off-by: Chuang Wang > > --- > > kernel/trace/trace.c | 4 ++-- > > 1 file changed, 2 insertions(+), 2 deletions(-) > > > > diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c > > index d8233d34b5a0..c0b8a72f3466 100644 > > --- a/kernel/trace/trace.c > > +++ b/kernel/trace/trace.c > > @@ -9461,7 +9461,7 @@ static struct trace_array *trace_array_create(const char *name) > > if (!alloc_cpumask_var(&tr->tracing_cpumask, GFP_KERNEL)) > > goto out_free_tr; > > > > - if (!alloc_cpumask_var(&tr->pipe_cpumask, GFP_KERNEL)) > > + if (!zalloc_cpumask_var(&tr->pipe_cpumask, GFP_KERNEL)) > > goto out_free_tr; > > > > tr->trace_flags = global_trace.trace_flags & ~ZEROED_TRACE_FLAGS; > > @@ -10406,7 +10406,7 @@ __init static int tracer_alloc_buffers(void) > > if (trace_create_savedcmd() < 0) > > goto out_free_temp_buffer; > > > > - if (!alloc_cpumask_var(&global_trace.pipe_cpumask, GFP_KERNEL)) > > + if (!zalloc_cpumask_var(&global_trace.pipe_cpumask, GFP_KERNEL)) > > goto out_free_savedcmd; > > > > /* TODO: make the number of buffers hot pluggable with CPUS */ > > -- > > 2.39.2 > > > >