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Date:   Tue, 12 May 2020 14:18:49 +0200
From:   Christoph Hellwig <hch@lst.de>
To:     Marek Szyprowski <m.szyprowski@samsung.com>
Cc:     dri-devel@lists.freedesktop.org, iommu@lists.linux-foundation.org,
        linaro-mm-sig@lists.linaro.org, linux-kernel@vger.kernel.org,
        Christoph Hellwig <hch@lst.de>,
        Robin Murphy <robin.murphy@arm.com>,
        Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>,
        linux-arm-kernel@lists.infradead.org,
        David Airlie <airlied@linux.ie>,
        Daniel Vetter <daniel@ffwll.ch>, Joerg Roedel <joro@8bytes.org>
Subject: Re: [PATCH v4 03/38] iommu: add generic helper for mapping sgtable
 objects
Message-ID: <20200512121849.GC20393@lst.de>
References: <20200512085710.14688-1-m.szyprowski@samsung.com> <20200512090058.14910-1-m.szyprowski@samsung.com> <CGME20200512090108eucas1p2168167ab5e1de09df0d5def83f64dbfe@eucas1p2.samsung.com> <20200512090058.14910-3-m.szyprowski@samsung.com>
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On Tue, May 12, 2020 at 11:00:23AM +0200, Marek Szyprowski wrote:
> struct sg_table is a common structure used for describing a memory
> buffer. It consists of a scatterlist with memory pages and DMA addresses
> (sgl entry), as well as the number of scatterlist entries: CPU pages
> (orig_nents entry) and DMA mapped pages (nents entry).
> 
> It turned out that it was a common mistake to misuse nents and orig_nents
> entries, calling mapping functions with a wrong number of entries.
> 
> To avoid such issues, lets introduce a common wrapper operating directly
> on the struct sg_table objects, which take care of the proper use of
> the nents and orig_nents entries.
> 
> Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>

Looks good,

Reviewed-by: Christoph Hellwig <hch@lst.de>