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 816A3C433EF for ; Tue, 24 May 2022 14:32:41 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 0A3F08D0006; Tue, 24 May 2022 10:32:41 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 0564F8D0002; Tue, 24 May 2022 10:32:40 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id EAA458D0006; Tue, 24 May 2022 10:32:40 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0010.hostedemail.com [216.40.44.10]) by kanga.kvack.org (Postfix) with ESMTP id DD3618D0002 for ; Tue, 24 May 2022 10:32:40 -0400 (EDT) Received: from smtpin07.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay09.hostedemail.com (Postfix) with ESMTP id B14DB35761 for ; Tue, 24 May 2022 14:32:40 +0000 (UTC) X-FDA: 79500877680.07.43C4B09 Received: from szxga03-in.huawei.com (szxga03-in.huawei.com [45.249.212.189]) by imf11.hostedemail.com (Postfix) with ESMTP id C15B140036 for ; Tue, 24 May 2022 14:32:32 +0000 (UTC) Received: from dggpemm500022.china.huawei.com (unknown [172.30.72.55]) by szxga03-in.huawei.com (SkyGuard) with ESMTP id 4L6xVn01kZzDqKp; Tue, 24 May 2022 22:32:32 +0800 (CST) Received: from dggpemm500001.china.huawei.com (7.185.36.107) by dggpemm500022.china.huawei.com (7.185.36.162) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.24; Tue, 24 May 2022 22:32:35 +0800 Received: from [10.174.177.243] (10.174.177.243) by dggpemm500001.china.huawei.com (7.185.36.107) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.24; Tue, 24 May 2022 22:32:35 +0800 Message-ID: <4c848b48-6ddf-664a-6296-d85ab49a694d@huawei.com> Date: Tue, 24 May 2022 22:32:34 +0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:91.0) Gecko/20100101 Thunderbird/91.5.1 Subject: Re: [PATCH v3 4/6] mm: ioremap: Add arch_ioremap/iounmap() Content-Language: en-US To: Arnd Bergmann CC: Catalin Marinas , Will Deacon , Andrew Morton , Linux ARM , Linux Kernel Mailing List , Linux-MM , "Christoph Hellwig" , Anshuman Khandual References: <20220519082552.117736-1-wangkefeng.wang@huawei.com> <20220519082552.117736-5-wangkefeng.wang@huawei.com> From: Kefeng Wang In-Reply-To: Content-Type: text/plain; charset="UTF-8"; format=flowed Content-Transfer-Encoding: 8bit X-Originating-IP: [10.174.177.243] X-ClientProxiedBy: dggems701-chm.china.huawei.com (10.3.19.178) To dggpemm500001.china.huawei.com (7.185.36.107) X-CFilter-Loop: Reflected X-Rspamd-Server: rspam07 X-Rspamd-Queue-Id: C15B140036 X-Stat-Signature: gumzh9bqtwqr7xfqidyc7grc8gtdwzjy X-Rspam-User: Authentication-Results: imf11.hostedemail.com; dkim=none; spf=pass (imf11.hostedemail.com: domain of wangkefeng.wang@huawei.com designates 45.249.212.189 as permitted sender) smtp.mailfrom=wangkefeng.wang@huawei.com; dmarc=pass (policy=quarantine) header.from=huawei.com X-HE-Tag: 1653402752-617180 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 2022/5/24 20:37, Arnd Bergmann wrote: > On Thu, May 19, 2022 at 10:25 AM Kefeng Wang wrote: >> Add special hook for architecture to verify or setup addr, size >> or prot when ioremap() or iounmap(), which will make the generic >> ioremap more useful. >> >> arch_ioremap() return a pointer, >> - IS_ERR means return an error >> - NULL means continue to remap >> - a non-NULL, non-IS_ERR pointer is directly returned >> arch_iounmap() return a int value, >> - 0 means continue to vunmap >> - error code means skip vunmap and return directly >> >> Signed-off-by: Kefeng Wang > I don't really like interfaces that mix error pointers and NULL pointer > returns. > > Would it be possible to have a special error code other than NULL > for the fallback case? I don't find a good error code, maybe  ENOTSUPP, any better suggestion? > > arnd > > .