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Mon, 22 Aug 2022 20:20:27 -0400 X-MC-Unique: POZqojPkPHyzqJX0OrHRVw-1 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.rdu2.redhat.com [10.11.54.2]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id EDC0B1C19762; Tue, 23 Aug 2022 00:20:26 +0000 (UTC) Received: from localhost (ovpn-12-31.pek2.redhat.com [10.72.12.31]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 27F45401B54F; Tue, 23 Aug 2022 00:20:25 +0000 (UTC) Date: Tue, 23 Aug 2022 08:20:22 +0800 From: Baoquan He To: Christophe Leroy Cc: "linux-kernel@vger.kernel.org" , "linux-mm@kvack.org" , "akpm@linux-foundation.org" , "hch@infradead.org" , "agordeev@linux.ibm.com" , "wangkefeng.wang@huawei.com" , "linux-arm-kernel@lists.infradead.org" Subject: Re: [PATCH v2 01/11] mm/ioremap: change the return value of io[re|un]map_allowed and rename Message-ID: References: <20220820003125.353570-1-bhe@redhat.com> <20220820003125.353570-2-bhe@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: X-Scanned-By: MIMEDefang 2.84 on 10.11.54.2 ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1661214033; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=Ard+XQ2JmpaoV1Zy66Z597OHMvsCkwrAtFiswd3hAns=; b=TZ9aPAjSjk+9+ZvFQ9HR5uKlg6yFyVCCA4VecilXfeHZzZ+BOh9ixgcZZIpTMffkpEjEFx wrIUtIb+86O04BqVPx8HULARJfvGIDH95QkR62m5YNAJ6UGYMOkZUpxSKY3CNvfoFDO77r gMwn2my8zcB+yuEU1N61/kMXWcy/DjU= ARC-Authentication-Results: i=1; imf27.hostedemail.com; dkim=pass header.d=redhat.com header.s=mimecast20190719 header.b=IgFiuzyu; spf=pass (imf27.hostedemail.com: domain of bhe@redhat.com designates 170.10.129.124 as permitted sender) smtp.mailfrom=bhe@redhat.com; dmarc=pass (policy=none) header.from=redhat.com ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1661214033; a=rsa-sha256; cv=none; b=pqA/VIED5PmEzkzynJSTiybgBY66V6dsfmtZKfbZY4nxd+SUV/w+Enc6O9L47jCJVUaQc6 LGmwphsVqD4754l9FYvTXIiYSyrgFFpLrgq1SnUfQLgtWKGkugVhNKWnXX+vx2DF1fUfG9 WErtRiLRO+KzJvxaaXk8hs1TMJBQ5zU= X-Rspam-User: Authentication-Results: imf27.hostedemail.com; dkim=pass header.d=redhat.com header.s=mimecast20190719 header.b=IgFiuzyu; spf=pass (imf27.hostedemail.com: domain of bhe@redhat.com designates 170.10.129.124 as permitted sender) smtp.mailfrom=bhe@redhat.com; dmarc=pass (policy=none) header.from=redhat.com X-Stat-Signature: xjxec6dffxn66rt7w9c5fwysrfik4xme X-Rspamd-Queue-Id: 66EC44001A X-Rspamd-Server: rspam08 X-HE-Tag: 1661214033-811984 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 08/22/22 at 06:25am, Christophe Leroy wrote: > > > Le 20/08/2022 à 02:31, Baoquan He a écrit : > > In some architectures, there are ARCH specifici io address mapping > > handling when calling ioremap() or ioremap_prot(), e.g, arc, ia64, > > openrisc, s390, sh. > > > > In oder to convert them to take GENERIC_IOREMAP method, we need change > > the return value of hook ioremap_allowed() and iounmap_allowed(). > > Meanwhile, rename them to arch_ioremap() and arch_iounmap() to reflect > > their current behaviour. Thanks for reviewing. > > Please don't just say you need to change the return value. Explain why. The 1st paragraph and the sentence 'In oder to convert them to take GENERIC_IOREMAP method' tell the reason, no? > > And why does it need a name change ? The new name suggests that what was > simply a check function becomes now a function doing the job. Is that > the intention ? Yes, it's not a simple checking any more. It could do io address mapping inside arch_ioremap(), and could modify the passed in 'phys_addr' and 'prot' in patch 2. The ioremap_allowed() isn't appropriate to reflect those. > > > > > > === > > arch_ioremap() return a bool, > > It is not a bool. A bool is either true or false. Thanks, I forgot to update this accordingly. > > > - IS_ERR means return an error > > - NULL means continue to remap > > - a non-NULL, non-IS_ERR pointer is returned directly > > arch_iounmap() return a bool, > > Same here, not a bool either. And this place. > > > - 0 means continue to vunmap > > - error code means skip vunmap and return directly > > > > This is taken from Kefeng's below old patch. Christoph suggested the > > return value because he foresaw the doablity of converting to take > > GENERIC_IOREMAP on more architectures. > > - [PATCH v3 4/6] mm: ioremap: Add arch_ioremap/iounmap() > > - https://lore.kernel.org/all/20220519082552.117736-5-wangkefeng.wang@huawei.com/T/#u > > > > While at it, the invocation of arch_ioremap() need be moved to the > > beginning of ioremap_prot() because architectures like sh, openrisc, > > ia64, need do the ARCH specific io address mapping on the original > > physical address. And in the later patch, the address fix up code > > in arch_ioremap() also need be done on the original addre on some > > architectures. > > > > This is preparation for later patch, no functionality change. > > No functionnal change, really ? You mean the new arch_ioremap() owning different definition or the invocation of arch_ioremap() moved up is functional change? Now I am not sure about the latter one, may need update my knowledge base. Thanks Baoquan