From patchwork Thu Aug 8 15:59:59 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Christoph Hellwig X-Patchwork-Id: 11084461 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 9BB38912 for ; Thu, 8 Aug 2019 16:00:49 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 8CB05287C9 for ; Thu, 8 Aug 2019 16:00:49 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 8A7F12884B; Thu, 8 Aug 2019 16:00:49 +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 B5650287C9 for ; Thu, 8 Aug 2019 16:00:44 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2404076AbfHHQAk (ORCPT ); Thu, 8 Aug 2019 12:00:40 -0400 Received: from bombadil.infradead.org ([198.137.202.133]:56230 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1732698AbfHHQAj (ORCPT ); Thu, 8 Aug 2019 12:00:39 -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=UT0QGbnuDq6FC5quPJwbHVX/HquOJ1BwL51+Ue/v5rM=; b=oB8ZxGlIlwRJNgwFDQdUUkWsQb qbprHg7MnM6taXhqWRfmtOy5rLOIII99AfBkndza0anhdbffJkSVyC7NlcnGkNkGnyBndCvb6ECEv QYUclIgK+vSmzCgT9MVkSi/BtMMFOF49LKuhnxcR5TR3FNb5y5JDPVbABkEU++TyMm3LPKxuJ3QWe 5rgAC9N0ohJ1lgGrGn7IYFKXVYjjaxzh10Xr8sgWJSmN8uFBBaP0RLwhiB+CPuzWNgFDDDSsZ9Qvy 9QhoJ9XfKVcnYo5QxEPfQ76L9tFEzk1DvoMiWF84lBFIynkGWu0pXuiXoUMip0t5tGw1Lc1Wt4tty luPQpL1g==; Received: from [195.167.85.94] (helo=localhost) by bombadil.infradead.org with esmtpsa (Exim 4.92 #3 (Red Hat Linux)) id 1hvkq9-0006ZA-DB; Thu, 08 Aug 2019 16:00:34 +0000 From: Christoph Hellwig To: iommu@lists.linux-foundation.org, Marek Szyprowski Cc: Vladimir Murzin , Takashi Iwai , Helge Deller , 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 2/8] dma-mapping: move the dma_get_sgtable API comments from arm to common code Date: Thu, 8 Aug 2019 18:59:59 +0300 Message-Id: <20190808160005.10325-3-hch@lst.de> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20190808160005.10325-1-hch@lst.de> References: <20190808160005.10325-1-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 ad64d32fb39a..b4d65da76393 100644 --- a/arch/arm/mm/dma-mapping.c +++ b/arch/arm/mm/dma-mapping.c @@ -880,17 +880,6 @@ 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 9c0f6a8eb5cb..41590d003465 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)