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 8D630EB64DD for ; Sat, 1 Jul 2023 13:03:04 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229701AbjGANDD (ORCPT ); Sat, 1 Jul 2023 09:03:03 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:43158 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229480AbjGANDC (ORCPT ); Sat, 1 Jul 2023 09:03:02 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id D9290135; Sat, 1 Jul 2023 06:03:01 -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) server-digest SHA256) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 6479560B6D; Sat, 1 Jul 2023 13:03:01 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 6777CC433C8; Sat, 1 Jul 2023 13:02:59 +0000 (UTC) Date: Sat, 1 Jul 2023 09:02:54 -0400 From: Steven Rostedt To: "Tzvetomir Stoyanov (VMware)" Cc: mhiramat@kernel.org, dan.carpenter@linaro.org, linux-trace-devel@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v2] kernel/trace: Fix cleanup logic of enable_trace_eprobe Message-ID: <20230701090254.72323659@rorschach.local.home> In-Reply-To: <20230630121627.833560-1-tz.stoyanov@gmail.com> References: <20230630121627.833560-1-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-devel@vger.kernel.org On Fri, 30 Jun 2023 15:16:27 +0300 "Tzvetomir Stoyanov (VMware)" wrote: Hi Tzvetomir, FYI, linux-trace-devel is for the tracing user space code, please Cc to linux-trace-kernel for kernel patches. That makes it fall into the proper patchwork. I noticed this because I couldn't find your patch in: https://patchwork.kernel.org/project/linux-trace-kernel/list/ Also, the Subject should just start with "tracing:". > 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) > --- > v2: Added one-time warning, as suggested by Steven Rostedt. It's always a nice touch (optional, but something I always do) to add a link to the previous version: Changes since v2: https://lore.kernel.org/all/20230628121811.338655-1-tz.stoyanov@gmail.com/ - Added one-time warning (Steven Rostedt) > > kernel/trace/trace_eprobe.c | 14 ++++++++++++-- > 1 file changed, 12 insertions(+), 2 deletions(-) > > diff --git a/kernel/trace/trace_eprobe.c b/kernel/trace/trace_eprobe.c > index 67e854979d53..6629fa217c99 100644 > --- a/kernel/trace/trace_eprobe.c > +++ b/kernel/trace/trace_eprobe.c > @@ -702,8 +702,18 @@ static int enable_trace_eprobe(struct trace_event_call *call, > > 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); > + } I think we may need the counter again ;-) But for another reason. We only want to call disable for what we enabled, to avoid any unforeseen side effects. cnt = 0; list_for_each_entry(pos, trace_probe_probe_list(tp), list) { ep = container_of(pos, struct trace_eprobe, tp); ret = enable_eprobe(ep, file); if (ret) break; enabled = true; cnt++; } if (ret) { /* Failed to enable one of them. Roll back all */ if (enabled) { 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; } } Thoughts? -- Steve > + } > if (file) > trace_probe_remove_file(tp, file); > else