From patchwork Thu Jul 25 06:33:58 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Christoph Hellwig X-Patchwork-Id: 11058027 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 27C0A17EF for ; Thu, 25 Jul 2019 06:34:39 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 17A151FE8B for ; Thu, 25 Jul 2019 06:34:39 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 0C37F2864E; Thu, 25 Jul 2019 06:34:39 +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=-7.7 required=2.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,MAILING_LIST_MULTI,RCVD_IN_DNSWL_HI autolearn=unavailable version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 5E4B5285F1 for ; Thu, 25 Jul 2019 06:34:38 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729221AbfGYGeR (ORCPT ); Thu, 25 Jul 2019 02:34:17 -0400 Received: from bombadil.infradead.org ([198.137.202.133]:60704 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727645AbfGYGeQ (ORCPT ); Thu, 25 Jul 2019 02:34:16 -0400 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20170209; h=Content-Transfer-Encoding: MIME-Version:References:In-Reply-To:Message-Id:Date:Subject:Cc:To:From:Sender :Reply-To:Content-Type:Content-ID:Content-Description:Resent-Date:Resent-From :Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id:List-Help: List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=k0Kys8RnDnHWhgPJ7TG+mio71r1htN8piJsJ6T2mgUo=; b=Vp6ECvLpQHalL67VGYOQ90nVqX +S5K1LPmpn1PwsPOajOnIxd1igwttTYuSaMTMg4o3BYZXDBY3BGafNdqp0jU0c9hLzIlIRQj06eiu gH+d/WwkpvOkVmeCho9ZBIC2MAm8/oAxz1YD2CMYT0oVK8btcwem2wLMh/i0k+CydJ0Quor4GIlSC JDf4pSmkl2O7RwQ+w5yLEtKB23S2dtb0T1Fcqa3HGL6pLMoQE/YpBfeWcvuxYitEyHiVz5sV1qMva RYsY+AM8kgXhiATsfnZL12OcgPOImxZu1ezixHGWBi3kJlUQXCiCm9Wy1egHY6JX46vuzx9pXRksa 5TE56QJg==; Received: from p57b3f613.dip0.t-ipconnect.de ([87.179.246.19] helo=localhost) by bombadil.infradead.org with esmtpsa (Exim 4.92 #3 (Red Hat Linux)) id 1hqXKM-0000GY-6y; Thu, 25 Jul 2019 06:34:10 +0000 From: Christoph Hellwig To: iommu@lists.linux-foundation.org, Marek Szyprowski Cc: Takashi Iwai , Robin Murphy , Michal Simek , linux-arm-kernel@lists.infradead.org, linux-m68k@lists.linux-m68k.org, linux-parisc@vger.kernel.org, linux-sh@vger.kernel.org, linux-xtensa@linux-xtensa.org, linuxppc-dev@lists.ozlabs.org, x86@kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH 2/5] dma-mapping: move the dma_get_sgtable API comments from arm to common code Date: Thu, 25 Jul 2019 08:33:58 +0200 Message-Id: <20190725063401.29904-3-hch@lst.de> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20190725063401.29904-1-hch@lst.de> References: <20190725063401.29904-1-hch@lst.de> MIME-Version: 1.0 X-SRS-Rewrite: SMTP reverse-path rewritten from by bombadil.infradead.org. See http://www.infradead.org/rpr.html Sender: linux-parisc-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-parisc@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP The comments are spot on and should be near the central API, not just near a single implementation. Signed-off-by: Christoph Hellwig --- arch/arm/mm/dma-mapping.c | 11 ----------- kernel/dma/mapping.c | 11 +++++++++++ 2 files changed, 11 insertions(+), 11 deletions(-) diff --git a/arch/arm/mm/dma-mapping.c b/arch/arm/mm/dma-mapping.c index 6774b03aa405..4410af33c5c4 100644 --- a/arch/arm/mm/dma-mapping.c +++ b/arch/arm/mm/dma-mapping.c @@ -877,17 +877,6 @@ static void arm_coherent_dma_free(struct device *dev, size_t size, void *cpu_add __arm_dma_free(dev, size, cpu_addr, handle, attrs, true); } -/* - * The whole dma_get_sgtable() idea is fundamentally unsafe - it seems - * that the intention is to allow exporting memory allocated via the - * coherent DMA APIs through the dma_buf API, which only accepts a - * scattertable. This presents a couple of problems: - * 1. Not all memory allocated via the coherent DMA APIs is backed by - * a struct page - * 2. Passing coherent DMA memory into the streaming APIs is not allowed - * as we will try to flush the memory through a different alias to that - * actually being used (and the flushes are redundant.) - */ int arm_dma_get_sgtable(struct device *dev, struct sg_table *sgt, void *cpu_addr, dma_addr_t handle, size_t size, unsigned long attrs) diff --git a/kernel/dma/mapping.c b/kernel/dma/mapping.c index b945239621d8..4ceb5b9016d8 100644 --- a/kernel/dma/mapping.c +++ b/kernel/dma/mapping.c @@ -136,6 +136,17 @@ int dma_common_get_sgtable(struct device *dev, struct sg_table *sgt, return ret; } +/* + * The whole dma_get_sgtable() idea is fundamentally unsafe - it seems + * that the intention is to allow exporting memory allocated via the + * coherent DMA APIs through the dma_buf API, which only accepts a + * scattertable. This presents a couple of problems: + * 1. Not all memory allocated via the coherent DMA APIs is backed by + * a struct page + * 2. Passing coherent DMA memory into the streaming APIs is not allowed + * as we will try to flush the memory through a different alias to that + * actually being used (and the flushes are redundant.) + */ int dma_get_sgtable_attrs(struct device *dev, struct sg_table *sgt, void *cpu_addr, dma_addr_t dma_addr, size_t size, unsigned long attrs)