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=-2.3 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS,USER_AGENT_MUTT 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 8F87BC282E3 for ; Fri, 19 Apr 2019 22:54:28 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 53B54217F9 for ; Fri, 19 Apr 2019 22:54:28 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="QQ2igCFD" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726961AbfDSWyX (ORCPT ); Fri, 19 Apr 2019 18:54:23 -0400 Received: from bombadil.infradead.org ([198.137.202.133]:49702 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726485AbfDSWyX (ORCPT ); Fri, 19 Apr 2019 18:54:23 -0400 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.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:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=0Pkxu52DB5IBr5OGBbKFzngS+GfS86DjCSgv6kVsApo=; b=QQ2igCFDXgmj80eLgbpIoDtQg dkebKQqI8jLRgRv//u3TXClaiTuNktF467S0Ik47hrX+T/f7Eqoc3Zl1dz0ctEZ9Me3euzXbXtUor Tl/0mHmz/cAjNv7xxReKyedEAH8ZBFWdwvsFsk+QfWiMts0yBrLBEteTUT4nss7mMqPoCqT8mbe2p STPVmp9iAb9tTbpxWtWPq0zKruhKjTooxvPl6llRedgXGe7z8Weh8vaKNUVJVxQEGkG3YwkKZoII3 +p6q+xFHxWCkac9ZhRIVdJ+g07a7rxa+HqDEru6XXvxfZ0gKQ0KjWnXg/VTYOpOIjudIf/nOTJU9k Xw30PjVAg==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=hirez.programming.kicks-ass.net) by bombadil.infradead.org with esmtpsa (Exim 4.90_1 #2 (Red Hat Linux)) id 1hHSDZ-0001Nn-Th; Fri, 19 Apr 2019 12:02:10 +0000 Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 71B5C29BB5803; Fri, 19 Apr 2019 14:02:07 +0200 (CEST) Date: Fri, 19 Apr 2019 14:02:07 +0200 From: Peter Zijlstra To: Waiman Long Cc: Ingo Molnar , Will Deacon , Thomas Gleixner , linux-kernel@vger.kernel.org, x86@kernel.org, Davidlohr Bueso , Linus Torvalds , Tim Chen , huang ying Subject: Re: [PATCH v4 14/16] locking/rwsem: Guard against making count negative Message-ID: <20190419120207.GO4038@hirez.programming.kicks-ass.net> References: <20190413172259.2740-1-longman@redhat.com> <20190413172259.2740-15-longman@redhat.com> <20190418135151.GB12232@hirez.programming.kicks-ass.net> <20190418144036.GE12232@hirez.programming.kicks-ass.net> <4cbd3c18-c9c0-56eb-4e01-ee355a69057a@redhat.com> <20190419102647.GP7905@worktop.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190419102647.GP7905@worktop.programming.kicks-ass.net> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Apr 19, 2019 at 12:26:47PM +0200, Peter Zijlstra wrote: > I thought of a horrible horrible alternative: Hurm, that's broken as heck. Let me try again.