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=-3.9 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 E511BC4363A for ; Mon, 26 Oct 2020 17:48:39 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 699F922265 for ; Mon, 26 Oct 2020 17:48:39 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="BQxuNr6v" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1788380AbgJZRsj (ORCPT ); Mon, 26 Oct 2020 13:48:39 -0400 Received: from merlin.infradead.org ([205.233.59.134]:35270 "EHLO merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1775447AbgJZRsi (ORCPT ); Mon, 26 Oct 2020 13:48:38 -0400 X-Greylist: delayed 2257 seconds by postgrey-1.27 at vger.kernel.org; Mon, 26 Oct 2020 13:48:38 EDT DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=merlin.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=3A9q2IhbrbbgCoZBVLOX5wUlF9BQu6Y6eHOrbw86Mcc=; b=BQxuNr6voGvi5oh8K7c+jdPvn8 fwncWQ5lOSomWpTsu15ATlZGZcMmGBNaB5gElLpMYM/f26jqlVqG5WRsEFBh///pMNMn9h0KfCbnW p4G6OZ8XMtmxt07GK7Lz/xAjUJ3cIU4bSK51WVepY3p3q+rPnUUXkXtfEp53J6qph+vFCP4oRkc73 Tatb6wD665L3jvldjF+3xO1zGzeJwqCMT5pxrEk8h5ABUbn9DD+dsfl4g3rDP+kZslOuk2zUXgciX o8jsaonQ1WFVIQWD9NS9GiAttlt5LTWbDUjkBBlE4/tXfrv14MQSlghB17MNU61G+O9tNN+GqLadJ UP+marPw==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=noisy.programming.kicks-ass.net) by merlin.infradead.org with esmtpsa (Exim 4.92.3 #3 (Red Hat Linux)) id 1kX61A-0000AK-NS; Mon, 26 Oct 2020 17:10:48 +0000 Received: from hirez.programming.kicks-ass.net (hirez.programming.kicks-ass.net [192.168.1.225]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by noisy.programming.kicks-ass.net (Postfix) with ESMTPS id 34608301179; Mon, 26 Oct 2020 18:10:46 +0100 (CET) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id EEAC8203BE3CA; Mon, 26 Oct 2020 18:10:45 +0100 (CET) Date: Mon, 26 Oct 2020 18:10:45 +0100 From: Peter Zijlstra To: Arnd Bergmann Cc: Arnd Bergmann , Matthew Wilcox , Ingo Molnar , Will Deacon , Will Deacon , Thomas Gleixner , Waiman Long , Nicholas Piggin , Michael Ellerman , Herbert Xu , linux-arch@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] qspinlock: use signed temporaries for cmpxchg Message-ID: <20201026171045.GU2611@hirez.programming.kicks-ass.net> References: <20201026165807.3724647-1-arnd@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20201026165807.3724647-1-arnd@kernel.org> Precedence: bulk List-ID: X-Mailing-List: linux-arch@vger.kernel.org On Mon, Oct 26, 2020 at 05:57:51PM +0100, Arnd Bergmann wrote: > From: Arnd Bergmann > > When building with W=2, the build log is flooded with > > include/asm-generic/qrwlock.h:65:56: warning: pointer targets in passing argument 2 of 'atomic_try_cmpxchg_acquire' differ in signedness [-Wpointer-sign] > include/asm-generic/qrwlock.h:92:53: warning: pointer targets in passing argument 2 of 'atomic_try_cmpxchg_acquire' differ in signedness [-Wpointer-sign] > include/asm-generic/qspinlock.h:68:55: warning: pointer targets in passing argument 2 of 'atomic_try_cmpxchg_acquire' differ in signedness [-Wpointer-sign] > include/asm-generic/qspinlock.h:82:52: warning: pointer targets in passing argument 2 of 'atomic_try_cmpxchg_acquire' differ in signedness [-Wpointer-sign] > > The atomics are built on top of signed integers, but the caller > doesn't actually care. Just use signed types as well. > Yuck, no. This is actively wrong. All that code very much wants u32.