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=0.9 required=3.0 tests=BODY_8BITS,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS,T_DKIM_INVALID 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 04AB4C5CFC1 for ; Tue, 19 Jun 2018 07:23:14 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id AA3F42083A for ; Tue, 19 Jun 2018 07:23:14 +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="M3iu43Ew" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org AA3F42083A Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.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 S1756206AbeFSHXM (ORCPT ); Tue, 19 Jun 2018 03:23:12 -0400 Received: from bombadil.infradead.org ([198.137.202.133]:44392 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755463AbeFSHXK (ORCPT ); Tue, 19 Jun 2018 03:23:10 -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-Transfer-Encoding :Content-Type:MIME-Version:References:Message-ID:Subject:Cc:To:From:Date: Sender:Reply-To: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=r82M0Nf+k4GMGFrElp0fUqvdbG8NbsQ0Xreisy+okG8=; b=M3iu43EwsnprKFN8+FnkQ3C/WV m4fwc6y37UrkZ4zD2jnM62LeOfYowtJ/mTrc3dScgmwLIJPwqKefw5z9r+pe7LKe39620ynspuqSy yVlHZywGRFeAqnyHJEZB4IL12Pmi4sUSRzlIWsQ/567bt8SYAYl5/qFrgh8SU13LYMcHPKc+jM+sd nIYM8OK+tYwIJkDRQD7lcurUwxpvXs1KbbrWb291ohsYYk6irwqEEnHwA4oB9UoRh8KLz08/oL+Mn Bo9G64DcErszTs7iu8lViuFa8/Z9Lfmd3LtuBCNsXm6ws5X9eGdMw4klY5GniZ6pTyCEPtXmw0XKm znufAlWQ==; 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 1fVAyT-000518-94; Tue, 19 Jun 2018 07:22:45 +0000 Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id D2AE120268507; Tue, 19 Jun 2018 09:22:42 +0200 (CEST) Date: Tue, 19 Jun 2018 09:22:42 +0200 From: Peter Zijlstra To: =?utf-8?B?6ZmI5Y2O5omN?= Cc: Paul Burton , Ralf Baechle , James Hogan , linux-mips , Fuxin Zhang , wuzhangjin , Huacai Chen , stable , Alan Stern , AndreaParri , Will Deacon , Boqun Feng , Nicholas Piggin , David Howells , Jade Alglave , Luc Maranget , "Paul E. McKenney" , Akira Yokosawa , linux-kernel Subject: Re: [PATCH] MIPS: implement smp_cond_load_acquire() for Loongson-3 Message-ID: <20180619072242.GC2494@hirez.programming.kicks-ass.net> References: <1529042858-9483-1-git-send-email-chenhc@lemote.com> <20180618185141.yvkrsbdi2gbxjxj7@pburton-laptop> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: User-Agent: Mutt/1.10.0 (2018-05-17) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Jun 19, 2018 at 02:40:14PM +0800, 陈华才 wrote: > Hi, Paul, > > First of all, could you please check why linux-mips reject e-mails > from lemote.com? Of course I can send e-mails by gmail, but my gmail > can't receive e-mails from linux-mips since March, 2018. Could you please learn to use email? No top posting and wrap lines at 78 chars. > I have already read Documentation/memory-barriers.txt, but I don't > think we should define a smp_read_barrier_depends() for Loongson-3. > Because Loongson-3's behavior isn't like Alpha, and in syntax, this is > not a data-dependent issue. Agreed, this is not a data-dependency issue. > There is no document about Loongson-3's SFB. In my opinion, SFB looks > like the L0 cache but sometimes it is out of cache-coherent machanism > (L1 cache's cross-core coherency is maintained by hardware, but not > always true for SFB). smp_mb() is needed for smp_cond_load_acquire(), > but not every READ_ONCE(). Linux does _NOT_ support non-coherent SMP. If your system is not fully coherent, you're out of luck. But please, explain in excruciating detail what exactly you need that smp_mb for. If, like I posited in my previous email, it is to ensure remote store buffer flushes, then your machine is terminally broken.