From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <linux-kernel-owner@vger.kernel.org>
Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand
	id S1753844AbcHRJ3D (ORCPT <rfc822;w@1wt.eu>);
	Thu, 18 Aug 2016 05:29:03 -0400
Received: from bombadil.infradead.org ([198.137.202.9]:40567 "EHLO
	bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org
	with ESMTP id S1752965AbcHRJ3C (ORCPT
	<rfc822;linux-kernel@vger.kernel.org>);
	Thu, 18 Aug 2016 05:29:02 -0400
Date: Thu, 18 Aug 2016 11:01:16 +0200
From: Peter Zijlstra <peterz@infradead.org>
To: zijun_hu <zijun_hu@zoho.com>
Cc: Andrew Morton <akpm@linux-foundation.org>, dhowells@redhat.com,
        linux-kernel@vger.kernel.org, zijun_hu@htc.com
Subject: Re: [PATCH 1/1] rbtree: correct mask for extracting node's parent
Message-ID: <20160818090116.GA25687@twins.programming.kicks-ass.net>
References: <57B56F7E.7090608@zoho.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <57B56F7E.7090608@zoho.com>
User-Agent: Mutt/1.5.23.1 (2014-03-12)
Sender: linux-kernel-owner@vger.kernel.org
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

On Thu, Aug 18, 2016 at 04:19:10PM +0800, zijun_hu wrote:
> From: zijun_hu <zijun_hu@htc.com>
> 
> for LP64 ABI, struct rb_node aligns at 8 bytes boundary due to
> sizeof(long) == 8 normally, so 0x07 should be used to extract
> node's parent rather than 0x03

Doesn't matter though, in practise. The remaining bits are always 0.