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 X-Spam-Level: X-Spam-Status: No, score=-10.2 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,USER_AGENT_SANE_2 autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id EEAEFC63697 for ; Tue, 17 Nov 2020 19:22:09 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B37252463D for ; Tue, 17 Nov 2020 19:22:09 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730165AbgKQTVt (ORCPT ); Tue, 17 Nov 2020 14:21:49 -0500 Received: from mail.kernel.org ([198.145.29.99]:35682 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726817AbgKQTVs (ORCPT ); Tue, 17 Nov 2020 14:21:48 -0500 Received: from gandalf.local.home (cpe-66-24-58-225.stny.res.rr.com [66.24.58.225]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 92242221FC; Tue, 17 Nov 2020 19:21:46 +0000 (UTC) Date: Tue, 17 Nov 2020 14:21:45 -0500 From: Steven Rostedt To: Mathieu Desnoyers Cc: linux-kernel , Matt Mullins , Ingo Molnar , Alexei Starovoitov , Daniel Borkmann , Dmitry Vyukov , Martin KaFai Lau , Song Liu , Yonghong Song , Andrii Nakryiko , John Fastabend , KP Singh , netdev , bpf , Kees Cook Subject: Re: [PATCH] tracepoint: Do not fail unregistering a probe due to memory allocation Message-ID: <20201117142145.43194f1a@gandalf.local.home> In-Reply-To: <47463878.48157.1605640510560.JavaMail.zimbra@efficios.com> References: <20201116175107.02db396d@gandalf.local.home> <47463878.48157.1605640510560.JavaMail.zimbra@efficios.com> X-Mailer: Claws Mail 3.17.3 (GTK+ 2.24.32; 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-kernel@vger.kernel.org On Tue, 17 Nov 2020 14:15:10 -0500 (EST) Mathieu Desnoyers wrote: > diff --git a/include/linux/tracepoint-defs.h b/include/linux/tracepoint-defs.h > index e7c2276be33e..e0351bb0b140 100644 > --- a/include/linux/tracepoint-defs.h > +++ b/include/linux/tracepoint-defs.h > @@ -38,6 +38,7 @@ struct tracepoint { > int (*regfunc)(void); > void (*unregfunc)(void); > struct tracepoint_func __rcu *funcs; > + void *stub_func; > }; > > #ifdef CONFIG_HAVE_ARCH_PREL32_RELOCATIONS > diff --git a/include/linux/tracepoint.h b/include/linux/tracepoint.h > index 0f21617f1a66..b0b805de3779 100644 > --- a/include/linux/tracepoint.h > +++ b/include/linux/tracepoint.h > @@ -287,6 +287,9 @@ static inline struct tracepoint *tracepoint_ptr_deref(tracepoint_ptr_t *p) > #define DEFINE_TRACE_FN(_name, _reg, _unreg, proto, args) \ > static const char __tpstrtab_##_name[] \ > __section("__tracepoints_strings") = #_name; \ > + static void __cold __tracepoint_stub_func_##_name(void *__data, proto) \ > + { \ > + } \ The thing is, tracepoints are already bloated. I do not want to add something like this that will unnecessarily add more text. Since all tracepoints callbacks have at least one parameter (__data), we could declare tp_stub_func as: static void tp_stub_func(void *data, ...) { return; } And now C knows that tp_stub_func() can be called with one or more parameters, and had better be able to deal with it! -- Steve > extern struct static_call_key STATIC_CALL_KEY(tp_func_##_name); \ > int __traceiter_##_name(void *__data, proto); \ > struct tracepoint __tracepoint_##_name __used \ > @@ -298,7 +301,8 @@ static inline struct tracepoint *tracepoint_ptr_deref(tracepoint_ptr_t *p) > .iterator = &__traceiter_##_name, \ > .regfunc = _reg, \ > .unregfunc = _unreg, \ > - .funcs = NULL }; \ > + .funcs = NULL, \ > + .stub_func = __tracepoint_stub_func_##_name, }; \ > __TRACEPOINT_ENTRY(_name); \ > int __traceiter_##_name(void *__data, proto) \ > { \ > > Thanks, > > Mathieu >