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=-5.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_2 autolearn=no 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 5165AC11F69 for ; Thu, 1 Jul 2021 18:08:01 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 35658611F1 for ; Thu, 1 Jul 2021 18:08:01 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233932AbhGASKa (ORCPT ); Thu, 1 Jul 2021 14:10:30 -0400 Received: from mail.kernel.org ([198.145.29.99]:35866 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233305AbhGASK1 (ORCPT ); Thu, 1 Jul 2021 14:10:27 -0400 Received: from oasis.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 A22E6611F1; Thu, 1 Jul 2021 18:07:56 +0000 (UTC) Date: Thu, 1 Jul 2021 14:07:54 -0400 From: Steven Rostedt To: Paul Burton Cc: Joel Fernandes , linux-kernel@vger.kernel.org, Ingo Molnar , stable@vger.kernel.org Subject: Re: [PATCH 1/2] tracing: Simplify & fix saved_tgids logic Message-ID: <20210701140754.5847a50f@oasis.local.home> In-Reply-To: References: <20210630003406.4013668-1-paulburton@google.com> X-Mailer: Claws Mail 3.17.3 (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-kernel@vger.kernel.org On Thu, 1 Jul 2021 10:31:59 -0700 Paul Burton wrote: > I was tempted to just add the redundant checks anyway (pick your battles > and all) but for show() in particular it wound up making things seem > non-sensical to me ("display the value describing this non-NULL pointer > into tgid_map only if tgid_map is not NULL?"). I agree with your assessment, and will actually take your first patch, as I don't think the comment is that helpful, not to mention, we don't use '//' comments in the kernel, so that would have to be changed. But for cases like this, I usually have something like: if (WARN_ON_ONCE(!tgid_map)) return -1; Because the logic is what makes tgid_map not being NULL, but as experience has taught me, the logic can sometimes be mistaken, at least as time goes by. And things that are protected by logic, deserve a WARN*() when it doesn't go as planned. We can always add that later, if needed. -- Steve