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=-0.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS 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 8501EC433DF for ; Wed, 27 May 2020 23:05:11 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 54992207BC for ; Wed, 27 May 2020 23:05:11 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1590620711; bh=+OCiFvqapFwho37Ni+WlLY1vTVuWc8/yy5EEM83gbnM=; h=Date:From:To:Cc:Subject:In-Reply-To:References:List-ID:From; b=E+gXxXvBBUdnB6iLRBlo2NNVp0epZSesORNxZfdDXA4qvz943JpShMiWwgGywtij+ k5qldJOjDqkfs3waMjct1Nb3syoZ7XDYyAfeDrpaKpVs0XxA5uxix2DifB3rX7gMw3 XLP8WVForRyIFiuSpXiwGhnjyQD6GGSrszzKH0JQ= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726337AbgE0XFK (ORCPT ); Wed, 27 May 2020 19:05:10 -0400 Received: from mail.kernel.org ([198.145.29.99]:38668 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725795AbgE0XFK (ORCPT ); Wed, 27 May 2020 19:05:10 -0400 Received: from localhost.localdomain (c-73-231-172-41.hsd1.ca.comcast.net [73.231.172.41]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 8B36C207BC; Wed, 27 May 2020 23:05:08 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1590620708; bh=+OCiFvqapFwho37Ni+WlLY1vTVuWc8/yy5EEM83gbnM=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=X4cefrp3c3fJivmkV69IA2bJcizzHytTU73I4j30H3cDKndZSfY2hZOFg9mFhEhzX xH3U4jr6nh7Pjh72BWvOt3jNN0mXVJr/51BU5Y2BOqp8ikAYT7M+hriOi4UdM9C0Lp fzLJAnP0CWyORRU8CVAhHwnhquU6RjYh0xNvkP5A= Date: Wed, 27 May 2020 16:05:08 -0700 From: Andrew Morton To: Wei Yang Cc: Andy Shevchenko , Jesse Brandeburg , christian.brauner@ubuntu.com, linux-kernel@vger.kernel.org Subject: Re: [PATCH] bitops: simplify get_count_order_long() Message-Id: <20200527160508.2ef29d6904c07ca6c650638c@linux-foundation.org> In-Reply-To: <20200527224542.yx45druzqtlaxrl7@master> References: <20200524123551.9469-1-richard.weiyang@gmail.com> <20200525091458.GK1634618@smile.fi.intel.com> <20200525144312.mbw2z3ydncyasvss@master> <20200525153216.GD1634618@smile.fi.intel.com> <20200525134110.5737dd603d5fa1230e2f7ece@linux-foundation.org> <20200525215741.zd3gry4yyqqplix6@master> <20200525153146.c1337b1ca7af386ac30e5702@linux-foundation.org> <20200527224542.yx45druzqtlaxrl7@master> X-Mailer: Sylpheed 3.5.1 (GTK+ 2.24.31; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 27 May 2020 22:45:42 +0000 Wei Yang wrote: > /* a tiny module only meant to test get_count_order/long */ > unsigned int order_comb[][2] = { > {0x00000003, 2}, > {0x00000004, 2}, > {0x00001fff, 13}, > {0x00002000, 13}, > {0x50000000, 32}, > {0x80000000, 32}, > }; > > static int __init test_getorder_startup(void) > { > int i; > > for (i = 0; i < ARRAY_SIZE(order_comb); i++) { > if (order_comb[i][1] != get_count_order(order_comb[i][0])) > pr_warn("get_count_order wrong for %lx\n", > order_comb[i][0]); > } > > return 0; > } > > Since I don't get a way to iterate all the possibilities, some random > combination is chosen. Is this one looks good? Looks good. You might want to add a less-negative number as well? 0x80030000. Something that won't turn positive if it has 1 subtracted from it.