From patchwork Tue Feb 12 07:25:15 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Christoph Hellwig X-Patchwork-Id: 10807419 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 2925214E1 for ; Tue, 12 Feb 2019 07:25:40 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 02B142915C for ; Tue, 12 Feb 2019 07:25:40 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id E84D52A3CA; Tue, 12 Feb 2019 07:25:39 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-5.2 required=2.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,MAILING_LIST_MULTI,RCVD_IN_DNSWL_MED autolearn=ham version=3.3.1 Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.wl.linuxfoundation.org (Postfix) with ESMTPS id 7AEAA2915C for ; Tue, 12 Feb 2019 07:25:39 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20170209; h=Sender: Content-Transfer-Encoding:Content-Type:Cc:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:MIME-Version:References:In-Reply-To: Message-Id:Date:Subject:To:From:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=46h17l3MuyYGD+SO/v9Te+uPPHFqxBzhXM9Kz28bYhI=; b=Dvzp4DbXVsdZd6 dxbUThlLhasd6eOtLkQ4MghzL3p+w3lCwK3z3kCPXN/L0GObMi4d1wAozza7AA5tE4PHKSUexfx3H iM8aPSFDfAP4PA1G18TUrZp4O912W9qDRBCwNfI/JXLQlG1DrsdDi7vJFikt11wx1DwEMqgRpqhmz eIWbCWNIHerRScEZs55I0S45XXo2vLwAsYuHkUOW5uf37RpLsRggd2aSXAB6b9313o9WW/5GvH8lm 7byUaVtNYPuViLm5i+F3aoN24kFpKKH78RIicQ5oPvPUAizwBo8gneZdMcE2cdiceDyu1vV1nsp3T XPceLLRwJuGOJzY/IjCw==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.90_1 #2 (Red Hat Linux)) id 1gtSRk-0002OV-8b; Tue, 12 Feb 2019 07:25:36 +0000 Received: from 089144210182.atnat0019.highway.a1.net ([89.144.210.182] helo=localhost) by bombadil.infradead.org with esmtpsa (Exim 4.90_1 #2 (Red Hat Linux)) id 1gtSRh-0002OC-IA; Tue, 12 Feb 2019 07:25:33 +0000 From: Christoph Hellwig To: Ulf Hansson Subject: [PATCH 01/14] scatterlist: add sg_kmap_atomic / sg_kunmap_atomic helpers Date: Tue, 12 Feb 2019 08:25:15 +0100 Message-Id: <20190212072528.13167-2-hch@lst.de> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20190212072528.13167-1-hch@lst.de> References: <20190212072528.13167-1-hch@lst.de> MIME-Version: 1.0 X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Aaro Koskinen , Nicolas Pitre , linux-mmc@vger.kernel.org, Russell King , linux-kernel@vger.kernel.org, iommu@lists.linux-foundation.org, Ben Dooks , linux-omap@vger.kernel.org, linux-arm-kernel@lists.infradead.org Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org X-Virus-Scanned: ClamAV using ClamSMTP This avoids bug prone open coding of the sg offset handling and also helps to document the limitations of mapping scatterlist entries. Signed-off-by: Christoph Hellwig --- include/linux/scatterlist.h | 26 ++++++++++++++++++++++++++ 1 file changed, 26 insertions(+) diff --git a/include/linux/scatterlist.h b/include/linux/scatterlist.h index b96f0d0b5b8f..524cd8448a48 100644 --- a/include/linux/scatterlist.h +++ b/include/linux/scatterlist.h @@ -2,6 +2,7 @@ #ifndef _LINUX_SCATTERLIST_H #define _LINUX_SCATTERLIST_H +#include #include #include #include @@ -239,6 +240,31 @@ static inline void *sg_virt(struct scatterlist *sg) return page_address(sg_page(sg)) + sg->offset; } +/** + * sg_kmap_atomic - map a S/G list entry to a kernel address + * @sg: scatterlist entry + * + * Return a kernel address for scatterlist entry by kmapping it. Note that + * this function must only be called on scatterlist entries that do not span + * multiple pages. + */ +static inline void *sg_kmap_atomic(struct scatterlist *sg) +{ + if (WARN_ON_ONCE(sg->offset + sg->length > PAGE_SIZE)) + return NULL; + return kmap_atomic(sg_page(sg)) + sg->offset; +} + +/** + * sg_kunmap_atomic - unmap a S/G list entry to a kernel address + * @sg: scatterlist entry + * @ptr: address returned from sg_kmap_atomic + */ +static inline void sg_kunmap_atomic(struct scatterlist *sg, void *ptr) +{ + kunmap_atomic(ptr - sg->offset); +} + /** * sg_init_marker - Initialize markers in sg table * @sgl: The SG table