From patchwork Fri Jun 16 18:10:41 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Christoph Hellwig X-Patchwork-Id: 777017 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by ozlabs.org (Postfix) with ESMTP id 3wq7vY1dlsz9s8Y for ; Sat, 17 Jun 2017 04:20:09 +1000 (AEST) Authentication-Results: ozlabs.org; dkim=fail reason="signature verification failed" (2048-bit key; unprotected) header.d=infradead.org header.i=@infradead.org header.b="PwEKiz1/"; dkim-atps=neutral Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753185AbdFPSMr (ORCPT ); Fri, 16 Jun 2017 14:12:47 -0400 Received: from bombadil.infradead.org ([65.50.211.133]:56257 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753146AbdFPSMm (ORCPT ); Fri, 16 Jun 2017 14:12:42 -0400 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20170209; h=References:In-Reply-To:Message-Id: Date:Subject:Cc:To:From:Sender:Reply-To:MIME-Version:Content-Type: Content-Transfer-Encoding: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=Er/PBxW/tOtoCNR0FHj1VvmeiHjF/tVFU+Dqgf9uoBM=; b=PwEKiz1/d+5GHhFW25SuPn11O UmiPFDoaBCV7iC0XQ/rSy00j5UCqTaCTIHCKQ5aQ84Xmy3IkKuKpWplOD331aKXGmHjkEHmng8nnT EVQCSuBCAWONfNBQO0dKx6VhVHgnET64G2sbrfLzQVW6wiqkCPoGJn9gHmo506zMr7mYmMXHNXH3w h7OLb2+njOZrkwePaLqnzDC+xdJBIi7fEgCew7binew41+vZ2j+2JDMfUUyvmZBnPDbs+Bxn3l7lX /o8KjHUEwC0HsuNdnqQ9nyJCKf2d6pQuYMTbTxbZZEKWIt9fYwcMqITju7V0aZjSSVTfHjVuF1+tu lnSmA+Bqw==; Received: from clnet-p099-196.ikbnet.co.at ([83.175.99.196] helo=localhost) by bombadil.infradead.org with esmtpsa (Exim 4.87 #1 (Red Hat Linux)) id 1dLvja-00060v-0U; Fri, 16 Jun 2017 18:12:38 +0000 From: Christoph Hellwig To: x86@kernel.org, linux-arm-kernel@lists.infradead.org, xen-devel@lists.xenproject.org, linux-c6x-dev@linux-c6x.org, linux-hexagon@vger.kernel.org, linux-ia64@vger.kernel.org, linux-mips@linux-mips.org, openrisc@lists.librecores.org, linuxppc-dev@lists.ozlabs.org, linux-s390@vger.kernel.org, linux-sh@vger.kernel.org, sparclinux@vger.kernel.org, linux-xtensa@linux-xtensa.org, dmaengine@vger.kernel.org, linux-tegra@vger.kernel.org, dri-devel@lists.freedesktop.org, linux-samsung-soc@vger.kernel.org, iommu@lists.linux-foundation.org, netdev@vger.kernel.org Cc: linux-kernel@vger.kernel.org Subject: [PATCH 26/44] dma-mapping: remove DMA_ERROR_CODE Date: Fri, 16 Jun 2017 20:10:41 +0200 Message-Id: <20170616181059.19206-27-hch@lst.de> X-Mailer: git-send-email 2.11.0 In-Reply-To: <20170616181059.19206-1-hch@lst.de> References: <20170616181059.19206-1-hch@lst.de> X-SRS-Rewrite: SMTP reverse-path rewritten from by bombadil.infradead.org. See http://www.infradead.org/rpr.html Sender: linux-tegra-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-tegra@vger.kernel.org And update the documentation - dma_mapping_error has been supported everywhere for a long time. Signed-off-by: Christoph Hellwig --- Documentation/DMA-API-HOWTO.txt | 31 +++++-------------------------- include/linux/dma-mapping.h | 5 ----- 2 files changed, 5 insertions(+), 31 deletions(-) diff --git a/Documentation/DMA-API-HOWTO.txt b/Documentation/DMA-API-HOWTO.txt index 979228bc9035..4ed388356898 100644 --- a/Documentation/DMA-API-HOWTO.txt +++ b/Documentation/DMA-API-HOWTO.txt @@ -550,32 +550,11 @@ and to unmap it: dma_unmap_single(dev, dma_handle, size, direction); You should call dma_mapping_error() as dma_map_single() could fail and return -error. Not all DMA implementations support the dma_mapping_error() interface. -However, it is a good practice to call dma_mapping_error() interface, which -will invoke the generic mapping error check interface. Doing so will ensure -that the mapping code will work correctly on all DMA implementations without -any dependency on the specifics of the underlying implementation. Using the -returned address without checking for errors could result in failures ranging -from panics to silent data corruption. A couple of examples of incorrect ways -to check for errors that make assumptions about the underlying DMA -implementation are as follows and these are applicable to dma_map_page() as -well. - -Incorrect example 1: - dma_addr_t dma_handle; - - dma_handle = dma_map_single(dev, addr, size, direction); - if ((dma_handle & 0xffff != 0) || (dma_handle >= 0x1000000)) { - goto map_error; - } - -Incorrect example 2: - dma_addr_t dma_handle; - - dma_handle = dma_map_single(dev, addr, size, direction); - if (dma_handle == DMA_ERROR_CODE) { - goto map_error; - } +error. Doing so will ensure that the mapping code will work correctly on all +DMA implementations without any dependency on the specifics of the underlying +implementation. Using the returned address without checking for errors could +result in failures ranging from panics to silent data corruption. The same +applies to dma_map_page() as well. You should call dma_unmap_single() when the DMA activity is finished, e.g., from the interrupt which told you that the DMA transfer is done. diff --git a/include/linux/dma-mapping.h b/include/linux/dma-mapping.h index 4f3eecedca2d..a57875309bfd 100644 --- a/include/linux/dma-mapping.h +++ b/include/linux/dma-mapping.h @@ -546,12 +546,7 @@ static inline int dma_mapping_error(struct device *dev, dma_addr_t dma_addr) if (get_dma_ops(dev)->mapping_error) return get_dma_ops(dev)->mapping_error(dev, dma_addr); - -#ifdef DMA_ERROR_CODE - return dma_addr == DMA_ERROR_CODE; -#else return 0; -#endif } #ifndef HAVE_ARCH_DMA_SUPPORTED