From: Marek Szyprowski <m.szyprowski@samsung.com>
To: dri-devel@lists.freedesktop.org,
iommu@lists.linux-foundation.org, linaro-mm-sig@lists.linaro.org,
linux-kernel@vger.kernel.org
Cc: Marek Szyprowski <m.szyprowski@samsung.com>,
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>,
Sumit Semwal <sumit.semwal@linaro.org>,
Gerd Hoffmann <kraxel@redhat.com>,
linux-media@vger.kernel.org
Subject: [PATCH v5 30/38] dmabuf: fix common struct sg_table related issues
Date: Wed, 13 May 2020 15:32:37 +0200 [thread overview]
Message-ID: <20200513133245.6408-30-m.szyprowski@samsung.com> (raw)
In-Reply-To: <20200513133245.6408-1-m.szyprowski@samsung.com>
The Documentation/DMA-API-HOWTO.txt states that the dma_map_sg() function
returns the number of the created entries in the DMA address space.
However the subsequent calls to the dma_sync_sg_for_{device,cpu}() and
dma_unmap_sg must be called with the original number of the entries
passed to the dma_map_sg().
struct sg_table is a common structure used for describing a non-contiguous
memory buffer, used commonly in the DRM and graphics subsystems. 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 DMA-mapping functions with a wrong number of entries or
ignoring the number of mapped entries returned by the dma_map_sg()
function.
To avoid such issues, lets use a common dma-mapping wrappers operating
directly on the struct sg_table objects and use scatterlist page
iterators where possible. This, almost always, hides references to the
nents and orig_nents entries, making the code robust, easier to follow
and copy/paste safe.
Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
---
For more information, see '[PATCH v5 00/38] DRM: fix struct sg_table nents
vs. orig_nents misuse' thread:
https://lore.kernel.org/linux-iommu/20200513132114.6046-1-m.szyprowski@samsung.com/T/
---
drivers/dma-buf/heaps/heap-helpers.c | 13 ++++++-------
drivers/dma-buf/udmabuf.c | 7 +++----
2 files changed, 9 insertions(+), 11 deletions(-)
diff --git a/drivers/dma-buf/heaps/heap-helpers.c b/drivers/dma-buf/heaps/heap-helpers.c
index 9f964ca..d0696cf 100644
--- a/drivers/dma-buf/heaps/heap-helpers.c
+++ b/drivers/dma-buf/heaps/heap-helpers.c
@@ -140,13 +140,12 @@ struct sg_table *dma_heap_map_dma_buf(struct dma_buf_attachment *attachment,
enum dma_data_direction direction)
{
struct dma_heaps_attachment *a = attachment->priv;
- struct sg_table *table;
-
- table = &a->table;
+ struct sg_table *table = &a->table;
+ int ret;
- if (!dma_map_sg(attachment->dev, table->sgl, table->nents,
- direction))
- table = ERR_PTR(-ENOMEM);
+ ret = dma_map_sgtable(attachment->dev, table, direction, 0);
+ if (ret)
+ table = ERR_PTR(ret);
return table;
}
@@ -154,7 +153,7 @@ static void dma_heap_unmap_dma_buf(struct dma_buf_attachment *attachment,
struct sg_table *table,
enum dma_data_direction direction)
{
- dma_unmap_sg(attachment->dev, table->sgl, table->nents, direction);
+ dma_unmap_sgtable(attachment->dev, table, direction, 0);
}
static vm_fault_t dma_heap_vm_fault(struct vm_fault *vmf)
diff --git a/drivers/dma-buf/udmabuf.c b/drivers/dma-buf/udmabuf.c
index acb26c6..89e293b 100644
--- a/drivers/dma-buf/udmabuf.c
+++ b/drivers/dma-buf/udmabuf.c
@@ -63,10 +63,9 @@ static struct sg_table *get_sg_table(struct device *dev, struct dma_buf *buf,
GFP_KERNEL);
if (ret < 0)
goto err;
- if (!dma_map_sg(dev, sg->sgl, sg->nents, direction)) {
- ret = -EINVAL;
+ ret = dma_map_sgtable(dev, sg, direction, 0);
+ if (ret < 0)
goto err;
- }
return sg;
err:
@@ -78,7 +77,7 @@ static struct sg_table *get_sg_table(struct device *dev, struct dma_buf *buf,
static void put_sg_table(struct device *dev, struct sg_table *sg,
enum dma_data_direction direction)
{
- dma_unmap_sg(dev, sg->sgl, sg->nents, direction);
+ dma_unmap_sgtable(dev, sg, direction, 0);
sg_free_table(sg);
kfree(sg);
}
--
1.9.1
next prev parent reply other threads:[~2020-05-13 13:34 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20200513132114.6046-1-m.szyprowski@samsung.com>
[not found] ` <20200513133245.6408-1-m.szyprowski@samsung.com>
[not found] ` <CGME20200513133317eucas1p27aead4025db2da13e5b7c3e14a7cd79d@eucas1p2.samsung.com>
2020-05-13 13:32 ` [PATCH v5 29/38] drm: rcar-du: fix common struct sg_table related issues Marek Szyprowski
2020-05-13 14:23 ` Laurent Pinchart
[not found] ` <CGME20200513133318eucas1p1dd6c1ac6a777874c115070d8b5197f34@eucas1p1.samsung.com>
2020-05-13 13:32 ` Marek Szyprowski [this message]
2020-05-15 10:13 ` [PATCH v5 30/38] dmabuf: " Gerd Hoffmann
[not found] ` <CGME20200513133321eucas1p13acea3aa6219ce5f7076c7677ef9eae3@eucas1p1.samsung.com>
2020-05-13 13:32 ` [PATCH v5 33/38] staging: tegra-vde: " Marek Szyprowski
2020-05-14 20:07 ` Dmitry Osipenko
[not found] ` <CGME20200513133324eucas1p25dc380046c516ca8f07677ed14f93e63@eucas1p2.samsung.com>
2020-05-13 13:32 ` [PATCH v5 37/38] media: pci: fix common ALSA DMA-mapping related codes Marek Szyprowski
[not found] ` <CGME20200513133325eucas1p1c8faf557b23b5d171b7c328eca5f6482@eucas1p1.samsung.com>
2020-05-13 13:32 ` [PATCH v5 38/38] videobuf2: use sgtable-based scatterlist wrappers Marek Szyprowski
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