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 36ABDC43334 for ; Sun, 10 Jul 2022 15:42:52 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229568AbiGJPmv (ORCPT ); Sun, 10 Jul 2022 11:42:51 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:48178 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229479AbiGJPmt (ORCPT ); Sun, 10 Jul 2022 11:42:49 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [IPv6:2604:1380:4601:e00::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id C4C7412A82; Sun, 10 Jul 2022 08:42:48 -0700 (PDT) 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 66FD1B80AB1; Sun, 10 Jul 2022 15:42:47 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 0595EC3411E; Sun, 10 Jul 2022 15:42:43 +0000 (UTC) Date: Sun, 10 Jul 2022 11:42:42 -0400 From: Steven Rostedt To: Tao Zhou Cc: Daniel Bristot de Oliveira , Wim Van Sebroeck , Guenter Roeck , Jonathan Corbet , Ingo Molnar , Thomas Gleixner , Peter Zijlstra , Will Deacon , Catalin Marinas , Marco Elver , Dmitry Vyukov , "Paul E. McKenney" , Shuah Khan , Gabriele Paoloni , Juri Lelli , Clark Williams , linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-trace-devel@vger.kernel.org Subject: Re: [PATCH V4 01/20] rv: Add Runtime Verification (RV) interface Message-ID: <20220710114242.745d65b3@rorschach.local.home> In-Reply-To: References: <60548902dbccaa7ba420e40e46835693e27f643f.1655368610.git.bristot@kernel.org> 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 Sun, 10 Jul 2022 23:11:43 +0800 Tao Zhou wrote: > The @*pos of enable_monitors_start() can not be -1 or other negative value. > And I checked that the *pos is 0(right?). That is safe. Sorry for not being > that ture and maybe this is a notice here. Because if it is a negative value, > the returned m_def is a point to a data place 16 bytes before &rv_monitors_list. > That is a not ture rv_monitors_list stucture data. But it is not possiable now. > Maybe "inspired" from your question. Look it more, I image this simulation. > If the monitor(and all is enabled) is more enough to let the *pos to increase > to -1. And the returned m_def is last monitor that returned from enable_monitors_start(). > The enable_monitors_next() check from the last monitor and return NULL. > Only show the last monitor. This will not really happen I think. > But I am not focus enough to the seq file code or others now, so this may be > more possible to be not right. Late reply continued from me.. So basically you are saying we should have: > +static void *enabled_monitors_start(struct seq_file *m, loff_t *pos) > +{ > + struct rv_monitor_def *m_def; > + loff_t l; > + > + mutex_lock(&rv_interface_lock); if (list_empty(&rv_monitors_list->list)) return NULL; ? Probably safer to have that. -- Steve > + m_def = list_entry(&rv_monitors_list, struct rv_monitor_def, list); > + > + for (l = 0; l <= *pos; ) { > + m_def = enabled_monitors_next(m, m_def, &l); > + if (!m_def) > + break; > + } > + > + return m_def; > +}