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| author |   Marek Szyprowski <m.szyprowski@samsung.com> | 2020-08-26 08:33:12 +0200 |
|---|---|---|
| committer |   Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2020-08-28 12:10:04 +0200 |
| commit | 7cd7edb89437457ec36ffdbb970cc314d00c4aba (patch) | |
| tree | 13e5160986c31b27f867c69dcfc4c07d74716070 /drivers/misc/fastrpc.c | |
| parent | char: mspec: Use kvzalloc() in mspec_mmap() (diff) | |
| download | linux-dev-7cd7edb89437457ec36ffdbb970cc314d00c4aba.tar.xz linux-dev-7cd7edb89437457ec36ffdbb970cc314d00c4aba.zip | |
misc: fastrpc: fix common struct sg_table related issues
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>
Link: https://lore.kernel.org/r/20200826063316.23486-29-m.szyprowski@samsung.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/misc/fastrpc.c')
| -rw-r--r-- | drivers/misc/fastrpc.c | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/drivers/misc/fastrpc.c b/drivers/misc/fastrpc.c index 7939c55daceb..9d6867749316 100644 --- a/drivers/misc/fastrpc.c +++ b/drivers/misc/fastrpc.c @@ -518,7 +518,7 @@ fastrpc_map_dma_buf(struct dma_buf_attachment *attachment, table = &a->sgt; - if (!dma_map_sg(attachment->dev, table->sgl, table->nents, dir)) + if (!dma_map_sgtable(attachment->dev, table, dir, 0)) return ERR_PTR(-ENOMEM); return table; @@ -528,7 +528,7 @@ static void fastrpc_unmap_dma_buf(struct dma_buf_attachment *attach, struct sg_table *table, enum dma_data_direction dir) { - dma_unmap_sg(attach->dev, table->sgl, table->nents, dir); + dma_unmap_sgtable(attach->dev, table, dir, 0); } static void fastrpc_release(struct dma_buf *dmabuf) |