From: Christoph Hellwig <hch@lst.de> To: Ulf Hansson <ulf.hansson@linaro.org> Cc: Aaro Koskinen <aaro.koskinen@iki.fi>, Nicolas Pitre <nico@fluxnic.net>, linux-mmc@vger.kernel.org, Russell King <linux@armlinux.org.uk>, linux-kernel@vger.kernel.org, iommu@lists.linux-foundation.org, Ben Dooks <ben-linux@fluff.org>, linux-omap@vger.kernel.org, linux-arm-kernel@lists.infradead.org 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> (raw) In-Reply-To: <20190212072528.13167-1-hch@lst.de> 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 <hch@lst.de> --- 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 <linux/highmem.h> #include <linux/string.h> #include <linux/types.h> #include <linux/bug.h> @@ -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 -- 2.20.1 _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
next prev parent reply index Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top 2019-02-12 7:25 remove block layer bounce buffering for MMC v2 Christoph Hellwig 2019-02-12 7:25 ` Christoph Hellwig [this message] 2019-02-12 7:25 ` [PATCH 02/14] mmc: remove the unused use_blk_mq field from struct mmc_host Christoph Hellwig 2019-02-12 7:25 ` [PATCH 03/14] mmc: add a need_kmap flag to " Christoph Hellwig 2019-02-12 7:25 ` [PATCH 04/14] mmc: davinci: handle highmem pages Christoph Hellwig 2019-02-12 7:25 ` [PATCH 05/14] mmc: moxart: " Christoph Hellwig 2019-02-12 7:25 ` [PATCH 06/14] mmc: omap: " Christoph Hellwig 2019-02-12 18:39 ` Tony Lindgren 2019-02-12 7:25 ` [PATCH 07/14] mmc: omap: handle chained sglists Christoph Hellwig 2019-02-12 7:25 ` [PATCH 08/14] mmc: s3cmci: handle highmem pages Christoph Hellwig 2019-02-12 7:25 ` [PATCH 09/14] mmc: s3cmci: handle chained sglists Christoph Hellwig 2019-02-12 7:25 ` [PATCH 10/14] mmc: mvsdio: handle highmem pages Christoph Hellwig 2019-02-12 7:25 ` [PATCH 11/14] mmc: sh_mmcif: " Christoph Hellwig 2019-02-12 7:25 ` [PATCH 12/14] mmc: sh_mmcif: handle chained sglists Christoph Hellwig 2019-02-12 7:25 ` [PATCH 13/14] mmc: core: don't use block layer bounce buffers Christoph Hellwig 2019-02-12 7:25 ` [PATCH 14/14] dma-mapping: remove dma_max_pfn Christoph Hellwig 2019-02-25 13:54 ` remove block layer bounce buffering for MMC v2 Ulf Hansson 2019-03-08 9:18 ` Christoph Hellwig 2019-03-08 9:43 ` Ulf Hansson
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