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=-3.8 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 DE8F9C4346A for ; Fri, 18 Sep 2020 10:13:17 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A4B60208C3 for ; Fri, 18 Sep 2020 10:13:17 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="jUzYMtaK" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726456AbgIRKMw (ORCPT ); Fri, 18 Sep 2020 06:12:52 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:44406 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726718AbgIRKM3 (ORCPT ); Fri, 18 Sep 2020 06:12:29 -0400 Received: from merlin.infradead.org (merlin.infradead.org [IPv6:2001:8b0:10b:1231::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 2F7EBC06174A; Fri, 18 Sep 2020 03:12:29 -0700 (PDT) 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=2l+gXFpnZHzuk7NSeFYdJJ/yNRYkbW64rAwKN3DxjKA=; b=jUzYMtaK5+GrJ9HNVahLDOhK/8 Rrp7tSho8cuH9+dL3+KG/BYAl3UEvh6zbmhgpfWUWJqgMoLZdCejGZMhcaWVEkgCzQy52+tQpgF+0 HAd7wLoDUcxYCh+l6m0pKFFbXd4jL8vfddR20nDQUYsM3e2wA0rj3ryFrcO3jvLbMg0/VTEprwSIh hJGsxZvM6rQStB8BJjTVWtlUc1GCADL1m7F5dhpn89M2DZ+oMQLCfl0RXq9uPu8dPwT0c1bLv+cs4 NAmRB8kMfsQO6U80S19CDuzvl+Baa9GL2prfUPen9nU76dGRwFurDanmpGwyHQJvnE7V41r4Pk4Tq QSCX+uhg==; 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 1kJDNL-0004Cy-Ki; Fri, 18 Sep 2020 10:12:19 +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 6C846303A02; Fri, 18 Sep 2020 12:12:16 +0200 (CEST) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id CD69620D4DC9F; Fri, 18 Sep 2020 12:12:16 +0200 (CEST) Date: Fri, 18 Sep 2020 12:12:16 +0200 From: peterz@infradead.org To: Jan Kara Cc: Oleg Nesterov , Boaz Harrosh , Hou Tao , Ingo Molnar , Will Deacon , Dennis Zhou , Tejun Heo , Christoph Lameter , linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org Subject: Re: [RFC PATCH] locking/percpu-rwsem: use this_cpu_{inc|dec}() for read_count Message-ID: <20200918101216.GL35926@hirez.programming.kicks-ass.net> References: <20200915140750.137881-1-houtao1@huawei.com> <20200915150610.GC2674@hirez.programming.kicks-ass.net> <20200915153113.GA6881@redhat.com> <20200915155150.GD2674@hirez.programming.kicks-ass.net> <20200915160344.GH35926@hirez.programming.kicks-ass.net> <20200917120132.GA5602@redhat.com> <20200918090702.GB18920@quack2.suse.cz> <20200918100112.GN1362448@hirez.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200918100112.GN1362448@hirez.programming.kicks-ass.net> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Sep 18, 2020 at 12:01:12PM +0200, peterz@infradead.org wrote: > + u64 sum = per_cpu_sum(*(u64 *)sem->read_count); Moo, that doesn't work, we have to do two separate sums. I shouldn't try to be clever on a Friday I suppose :-(