From: Christoph Hellwig Subject: [PATCH 01/23] dma-mapping: provide a generic DMA_MAPPING_ERROR Date: Fri, 30 Nov 2018 14:22:09 +0100 Message-ID: <20181130132231.16512-2-hch@lst.de> References: <20181130132231.16512-1-hch@lst.de> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: 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=uAVVZbZ4lOCyuUE6c3OSSVR5FUxUkQ0rwJ5NpEk5hIk=; b=n5su2fb/lbh7rccugjTnBESjHb e7pDDvbjoTtHRnlydrXmoI5jaYzjxZBFOuCtvxJbX/9KegeG+EnKnRqkMyevp5xgsaDDA1FIrLpi0 lp4IUVk7/x61NlgXS9bohj3BZNnuw97xkwasa0TZQgwlq0MnmGAdZmuNy4fJTyt8PoqnDgAd70zp2 3cvtJjYY+IP1mWWZhb0nzj2enVdGh171jyXEOzNDe6Bd1mO/JnljLRdsLhEgXWP0DNRO+Cue1aYya mYCeyTSv12WlmzG7orvm/usmsurjBbQ9ZpyqiJK8D/bJRfCf54Ns2CCHvbOwr8cySDck9RSfafNyX T9oDjsHg==; In-Reply-To: <20181130132231.16512-1-hch-jcswGhMUV9g@public.gmane.org> List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: iommu-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org Errors-To: iommu-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org To: iommu-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org Cc: linux-arch-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-alpha-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-ia64-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-parisc-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Linus Torvalds , x86-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org, Robin Murphy , linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, xen-devel-GuqFBffKawtpuQazS67q72D2FQJk+8+b@public.gmane.org, David Woodhouse , linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org Error handling of the dma_map_single and dma_map_page APIs is a little problematic at the moment, in that we use different encodings in the returned dma_addr_t to indicate an error. That means we require an additional indirect call to figure out if a dma mapping call returned an error, and a lot of boilerplate code to implement these semantics. Instead return the maximum addressable value as the error. As long as we don't allow mapping single-byte ranges with single-byte alignment this value can never be a valid return. Additionaly if drivers do not check the return value from the dma_map* routines this values means they will generally not be pointed to actual memory. Once the default value is added here we can start removing the various mapping_error methods and just rely on this generic check. Signed-off-by: Christoph Hellwig --- include/linux/dma-mapping.h | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/include/linux/dma-mapping.h b/include/linux/dma-mapping.h index 0f81c713f6e9..46bd612d929e 100644 --- a/include/linux/dma-mapping.h +++ b/include/linux/dma-mapping.h @@ -133,6 +133,8 @@ struct dma_map_ops { u64 (*get_required_mask)(struct device *dev); }; +#define DMA_MAPPING_ERROR (~(dma_addr_t)0) + extern const struct dma_map_ops dma_direct_ops; extern const struct dma_map_ops dma_virt_ops; @@ -576,6 +578,10 @@ static inline int dma_mapping_error(struct device *dev, dma_addr_t dma_addr) const struct dma_map_ops *ops = get_dma_ops(dev); debug_dma_mapping_error(dev, dma_addr); + + if (dma_addr == DMA_MAPPING_ERROR) + return 1; + if (ops->mapping_error) return ops->mapping_error(dev, dma_addr); return 0; -- 2.19.1