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 36589C10F12 for ; Wed, 17 Apr 2019 10:19:41 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 05DC320872 for ; Wed, 17 Apr 2019 10:19:41 +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="BVS/84be" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731753AbfDQKTk (ORCPT ); Wed, 17 Apr 2019 06:19:40 -0400 Received: from merlin.infradead.org ([205.233.59.134]:55428 "EHLO merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726695AbfDQKTj (ORCPT ); Wed, 17 Apr 2019 06:19:39 -0400 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: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=PtxPNhcPSDEVq3vvBY5zgEd48XRH8i7KjKjRALWKodY=; b=BVS/84be1IE7J0Q6Y+M+/S4xw iQsZsRWvQzaKLZdOOuynb10Y0bR1guVMd1Rqs3j8hgQ2x0YPWB6C6lkIstUtjJLG0Fzlh+0cbL3El 9McolpLLOiuxJUipQzdzxNRYvyduRzyW+Wa4fQY61Qp2lZ69mTSRySoTHDKuBqdgaP6FBJAzdpAXn lSsjBM4wlBOUab/rX3cjRjmzJ5d6wzqZuxG9usezNk8WI0t2++cVpVIeuRJJROz3EK0ZtgvrHPz5m HNjDSmXBR6nbDlTODmBPjDKTDPeF8sWMdwavtJmhSI8qdRE5vOgxQ+SkRmbEtbfZ+CdZwF9Iu0PPZ let3TKMag==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=hirez.programming.kicks-ass.net) by merlin.infradead.org with esmtpsa (Exim 4.90_1 #2 (Red Hat Linux)) id 1hGhek-00080P-4c; Wed, 17 Apr 2019 10:19:07 +0000 Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 9592529B53433; Wed, 17 Apr 2019 12:19:03 +0200 (CEST) Date: Wed, 17 Apr 2019 12:19:03 +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 08/16] locking/rwsem: Make rwsem_spin_on_owner() return owner state Message-ID: <20190417101903.GD4038@hirez.programming.kicks-ass.net> References: <20190413172259.2740-1-longman@redhat.com> <20190413172259.2740-9-longman@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190413172259.2740-9-longman@redhat.com> 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 Sat, Apr 13, 2019 at 01:22:51PM -0400, Waiman Long wrote: > In the special case that there is no active lock and the handoff bit > is set, optimistic spinning has to be stopped. This makes me think this should've been _before_ you added the handoff bit. So that when you introduce the handoff, everything is solid.