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=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS autolearn=ham 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 06983C6787C for ; Fri, 12 Oct 2018 23:57:14 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id B1C462087F for ; Fri, 12 Oct 2018 23:57:13 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org B1C462087F Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=linux-foundation.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726077AbeJMHbp (ORCPT ); Sat, 13 Oct 2018 03:31:45 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:45630 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725931AbeJMHbp (ORCPT ); Sat, 13 Oct 2018 03:31:45 -0400 Received: from localhost.localdomain (c-24-4-154-175.hsd1.ca.comcast.net [24.4.154.175]) by mail.linuxfoundation.org (Postfix) with ESMTPSA id D7127F7F; Fri, 12 Oct 2018 23:56:56 +0000 (UTC) Date: Fri, 12 Oct 2018 16:56:55 -0700 From: Andrew Morton To: Sebastian Andrzej Siewior Cc: Dmitry Vyukov , Clark Williams , Alexander Potapenko , kasan-dev , Linux-MM , LKML , linux-rt-users@vger.kernel.org, Peter Zijlstra , Thomas Gleixner Subject: Re: [PATCH] mm/kasan: make quarantine_lock a raw_spinlock_t Message-Id: <20181012165655.f067886428a394dc7fbae7af@linux-foundation.org> In-Reply-To: <20181010214945.5owshc3mlrh74z4b@linutronix.de> References: <20180918152931.17322-1-williams@redhat.com> <20181005163018.icbknlzymwjhdehi@linutronix.de> <20181005163320.zkacovxvlih6blpp@linutronix.de> <20181009142742.ikh7xv2dn5skjjbe@linutronix.de> <20181010092929.a5gd3fkkw6swco4c@linutronix.de> <20181010095343.6qxved3owi6yokoa@linutronix.de> <20181010214945.5owshc3mlrh74z4b@linutronix.de> X-Mailer: Sylpheed 3.5.1 (GTK+ 2.24.31; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 10 Oct 2018 23:49:45 +0200 Sebastian Andrzej Siewior wrote: > On 2018-10-10 11:57:41 [+0200], Dmitry Vyukov wrote: > > Yes. Clark's patch looks good to me. Probably would be useful to add a > > comment as to why raw spinlock is used (otherwise somebody may > > refactor it back later). > > If you really insist, I could add something but this didn't happen so > far. git's changelog should provide enough information why to why it was > changed. Requiring code readers to look up changelogs in git is rather user-hostile. There are several reasons for using raw_*, so an explanatory comment at each site is called for. However it would be smarter to stop "using raw_* for several reasons". Instead, create a differently named variant for each such reason. ie, do /* * Nice comment goes here. It explains all the possible reasons why -rt * might use a raw_spin_lock when a spin_lock could otherwise be used. */ #define raw_spin_lock_for_rt raw_spinlock Then use raw_spin_lock_for_rt() at all such sites.