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 Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 774CDC433FE for ; Thu, 17 Feb 2022 10:44:11 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id E4CD56B0074; Thu, 17 Feb 2022 05:44:10 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id DFBB46B0075; Thu, 17 Feb 2022 05:44:10 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id CC4476B0078; Thu, 17 Feb 2022 05:44:10 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (relay.hostedemail.com [64.99.140.28]) by kanga.kvack.org (Postfix) with ESMTP id BD90A6B0074 for ; Thu, 17 Feb 2022 05:44:10 -0500 (EST) Received: from smtpin01.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay10.hostedemail.com (Postfix) with ESMTP id 8BD1585E for ; Thu, 17 Feb 2022 10:44:10 +0000 (UTC) X-FDA: 79151937060.01.80275D5 Received: from szxga08-in.huawei.com (szxga08-in.huawei.com [45.249.212.255]) by imf31.hostedemail.com (Postfix) with ESMTP id 1175E20002 for ; Thu, 17 Feb 2022 10:44:09 +0000 (UTC) Received: from canpemm500002.china.huawei.com (unknown [172.30.72.56]) by szxga08-in.huawei.com (SkyGuard) with ESMTP id 4JzrtR3XpPz1FDJ3; Thu, 17 Feb 2022 18:39:43 +0800 (CST) Received: from [10.174.177.76] (10.174.177.76) by canpemm500002.china.huawei.com (7.192.104.244) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2308.21; Thu, 17 Feb 2022 18:44:05 +0800 Subject: Re: [PATCH] mm/slab_common: use helper function is_power_of_2() To: Vlastimil Babka CC: , , Andrew Morton , Christoph Lameter , , , References: <20220217091609.8214-1-linmiaohe@huawei.com> <8f307e8a-5f97-cf5d-0a77-1c79b05abd60@suse.cz> From: Miaohe Lin Message-ID: <5d904bee-3faf-374a-090c-ce7c99c84ea9@huawei.com> Date: Thu, 17 Feb 2022 18:44:05 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Thunderbird/78.6.0 MIME-Version: 1.0 In-Reply-To: <8f307e8a-5f97-cf5d-0a77-1c79b05abd60@suse.cz> Content-Type: text/plain; charset="utf-8" Content-Language: en-US Content-Transfer-Encoding: 7bit X-Originating-IP: [10.174.177.76] X-ClientProxiedBy: dggems704-chm.china.huawei.com (10.3.19.181) To canpemm500002.china.huawei.com (7.192.104.244) X-CFilter-Loop: Reflected X-Rspam-User: X-Rspamd-Server: rspam08 X-Rspamd-Queue-Id: 1175E20002 X-Stat-Signature: 4pz6ewthj9x879pnz9bokbpr47tefoge Authentication-Results: imf31.hostedemail.com; dkim=none; spf=pass (imf31.hostedemail.com: domain of linmiaohe@huawei.com designates 45.249.212.255 as permitted sender) smtp.mailfrom=linmiaohe@huawei.com; dmarc=pass (policy=quarantine) header.from=huawei.com X-HE-Tag: 1645094649-208999 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On 2022/2/17 17:23, Vlastimil Babka wrote: > On 2/17/22 10:16, Miaohe Lin wrote: >> Use helper function is_power_of_2() to check if KMALLOC_MIN_SIZE is power >> of two. Minor readability improvement. >> >> Signed-off-by: Miaohe Lin > > We can try, but in case some compiler will no longer able to perform the > check at build-time (although is_power_of_2() looks sufficiently trivial > too), we'll have to revert it. I see. I checked the compiler in my env but there might be some compilers can't perform the check at build-time. Many thanks for your reply. > >> --- >> mm/slab_common.c | 2 +- >> 1 file changed, 1 insertion(+), 1 deletion(-) >> >> diff --git a/mm/slab_common.c b/mm/slab_common.c >> index 23f2ab0713b7..6ee64d6208b3 100644 >> --- a/mm/slab_common.c >> +++ b/mm/slab_common.c >> @@ -807,7 +807,7 @@ void __init setup_kmalloc_cache_index_table(void) >> unsigned int i; >> >> BUILD_BUG_ON(KMALLOC_MIN_SIZE > 256 || >> - (KMALLOC_MIN_SIZE & (KMALLOC_MIN_SIZE - 1))); >> + !is_power_of_2(KMALLOC_MIN_SIZE)); >> >> for (i = 8; i < KMALLOC_MIN_SIZE; i += 8) { >> unsigned int elem = size_index_elem(i); > > . >