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=-2.0 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 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 B6A3CC33CA9 for ; Mon, 13 Jan 2020 15:51:40 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 865D221569 for ; Mon, 13 Jan 2020 15:51:40 +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="Uh+G5lpZ" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728778AbgAMPvj (ORCPT ); Mon, 13 Jan 2020 10:51:39 -0500 Received: from merlin.infradead.org ([205.233.59.134]:35194 "EHLO merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726567AbgAMPvj (ORCPT ); Mon, 13 Jan 2020 10:51:39 -0500 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=YnZsglYJ3u81cdSyEaSN9mPuuxqI7Jwbrr370DvLj7w=; b=Uh+G5lpZ3vHiXznUv+6uORZU0 edqX1ot3Xedws/WEVHaRIpUozKfzgI+qyHbkwhHTL3cf+MOnh7PgKhXflNQrlQi7uZViJhOzNS3bn k4ZZgG74MMimomwiKuYsNwAKfkBPyCsa14MoeJlahSVJnYi0NYjklLarE+er8UEFvRFnk4vlQ6oRg oGRvWAB93uLZuXskXAuaUvusTwAGd5BcvM5w2DRuRU7Hc+cbFZLSOZa1rbPKKC/J1VSwFmi4SBV8X zxPoiBLcc32WnyY/ZEes/n+XiF+4mRWOKySuH7yMeh3ODpBM+hH1wMlbSQEgOEOHeh5NFXjIHpVr4 Q9RTfM1KA==; 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 1ir203-0008Tf-AB; Mon, 13 Jan 2020 15:51:31 +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 5F2DC3042BC; Mon, 13 Jan 2020 16:49:53 +0100 (CET) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id C1A0720427392; Mon, 13 Jan 2020 16:51:28 +0100 (CET) Date: Mon, 13 Jan 2020 16:51:28 +0100 From: Peter Zijlstra To: Waiman Long Cc: Ingo Molnar , Will Deacon , linux-kernel@vger.kernel.org, Bart Van Assche Subject: Re: [PATCH v2 4/6] locking/lockdep: Reuse freed chain_hlocks entries Message-ID: <20200113155128.GX2844@hirez.programming.kicks-ass.net> References: <20191216151517.7060-1-longman@redhat.com> <20191216151517.7060-5-longman@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20191216151517.7060-5-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 Mon, Dec 16, 2019 at 10:15:15AM -0500, Waiman Long wrote: > +#define CHAIN_HLOCKS_MASK 0xffff > +static inline void set_chain_block(int offset, int size, int next) > +{ > + if (unlikely(offset < 0)) { > + chain_block_buckets[0] = next; > + return; > + } > + chain_hlocks[offset] = (next >> 16) | CHAIN_BLK_FLAG; > + chain_hlocks[offset + 1] = next & CHAIN_HLOCKS_MASK; > + if (size > MAX_CHAIN_BUCKETS) { > + chain_hlocks[offset + 2] = size >> 16; > + chain_hlocks[offset + 3] = size & CHAIN_HLOCKS_MASK; > + } > +} AFAICT HLOCKS_MASK is superfluous. That is, you're assigning to a u16, it will truncate automagically. But if you want to make it more explicit, something like: chain_hlocks[offset + 1] = (u16)next; might be easier to read still.