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 76BB2EB64DC for ; Thu, 6 Jul 2023 16:00:45 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232129AbjGFQAo (ORCPT ); Thu, 6 Jul 2023 12:00:44 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:56186 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229721AbjGFQAo (ORCPT ); Thu, 6 Jul 2023 12:00:44 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 872C09D; Thu, 6 Jul 2023 09:00:43 -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 2448660DD4; Thu, 6 Jul 2023 16:00:43 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id F2080C433C7; Thu, 6 Jul 2023 16:00:41 +0000 (UTC) Date: Thu, 6 Jul 2023 12:00:40 -0400 From: Steven Rostedt To: "Tzvetomir Stoyanov (VMware)" Cc: mhiramat@kernel.org, dan.carpenter@linaro.org, linux-trace-kernel@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v3] kernel/trace: Fix cleanup logic of enable_trace_eprobe Message-ID: <20230706120040.26a685cd@gandalf.local.home> In-Reply-To: <20230703042853.1427493-1-tz.stoyanov@gmail.com> References: <20230703042853.1427493-1-tz.stoyanov@gmail.com> X-Mailer: Claws Mail 3.17.8 (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 Mon, 3 Jul 2023 07:28:53 +0300 "Tzvetomir Stoyanov (VMware)" wrote: > The enable_trace_eprobe() function enables all event probes, attached > to given trace probe. If an error occurs in enabling one of the event > probes, all others should be roll backed. There is a bug in that roll > back logic - instead of all event probes, only the failed one is > disabled. > > Reported-by: Dan Carpenter > Fixes: 7491e2c44278 ("tracing: Add a probe that attaches to trace events") > Signed-off-by: Tzvetomir Stoyanov (VMware) Reviewed-by: Steven Rostedt (Google) Thanks Tzvetomir! -- Steve > --- > Changes since v1: https://lore.kernel.org/all/20230628121811.338655-1-tz.stoyanov@gmail.com/ > - Added one-time warning, suggested by Steven Rostedt. > Changed since v2: https://lore.kernel.org/lkml/20230630121627.833560-1-tz.stoyanov@gmail.com/ > - Added counter of successfully enabled eprobes, suggested by Steven Rostedt. > > kernel/trace/trace_eprobe.c | 18 ++++++++++++++++-- > 1 file changed, 16 insertions(+), 2 deletions(-) > > diff --git a/kernel/trace/trace_eprobe.c b/kernel/trace/trace_eprobe.c > index cb0077ba2b49..a0a704ba27db 100644 > --- a/kernel/trace/trace_eprobe.c > +++ b/kernel/trace/trace_eprobe.c > @@ -644,6 +644,7 @@ static int enable_trace_eprobe(struct trace_event_call *call, > struct trace_eprobe *ep; > bool enabled; > int ret = 0; > + int cnt = 0; > > tp = trace_probe_primary_from_call(call); > if (WARN_ON_ONCE(!tp)) > @@ -667,12 +668,25 @@ static int enable_trace_eprobe(struct trace_event_call *call, > if (ret) > break; > enabled = true; > + cnt++; > } > > if (ret) { > /* Failed to enable one of them. Roll back all */ > - if (enabled) > - disable_eprobe(ep, file->tr); > + if (enabled) { > + /* > + * It's a bug if one failed for something other than memory > + * not being available but another eprobe succeeded. > + */ > + WARN_ON_ONCE(ret != -ENOMEM); > + > + list_for_each_entry(pos, trace_probe_probe_list(tp), list) { > + ep = container_of(pos, struct trace_eprobe, tp); > + disable_eprobe(ep, file->tr); > + if (!--cnt) > + break; > + } > + } > if (file) > trace_probe_remove_file(tp, file); > else