[PATCH v2 19/21] dmabuf: fix sg_table nents vs. orig_nents misuse
From: Marek Szyprowski <m.szyprowski@samsung.com>
Date: 2020-05-04 12:54:52
Also in:
dri-devel, linux-iommu, lkml
Subsystem:
dma buffer sharing framework, dma-buf heaps framework, the rest, userspace dma buffer driver · Maintainers:
Sumit Semwal, Christian König, Linus Torvalds, Gerd Hoffmann, Vivek Kasireddy
The Documentation/DMA-API-HOWTO.txt states that dma_map_sg returns the
numer of the created entries in the DMA address space. However the
subsequent calls to dma_sync_sg_for_{device,cpu} and dma_unmap_sg must be
called with the original number of entries passed to dma_map_sg. The
sg_table->nents in turn holds the result of the dma_map_sg call as stated
in include/linux/scatterlist.h. Adapt the code to obey those rules.
Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
---
For more information, see '[PATCH v2 00/21] DRM: fix struct sg_table nents
vs. orig_nents misuse' thread: https://lkml.org/lkml/2020/5/4/373
---
drivers/dma-buf/heaps/heap-helpers.c | 7 ++++---
drivers/dma-buf/udmabuf.c | 5 +++--
2 files changed, 7 insertions(+), 5 deletions(-)
diff --git a/drivers/dma-buf/heaps/heap-helpers.c b/drivers/dma-buf/heaps/heap-helpers.c
index 9f964ca..b923863 100644
--- a/drivers/dma-buf/heaps/heap-helpers.c
+++ b/drivers/dma-buf/heaps/heap-helpers.c@@ -144,8 +144,9 @@ struct sg_table *dma_heap_map_dma_buf(struct dma_buf_attachment *attachment, table = &a->table; - if (!dma_map_sg(attachment->dev, table->sgl, table->nents, - direction)) + table->nents = dma_map_sg(attachment->dev, table->sgl, + table->orig_nents, direction); + if (!table->nents) table = ERR_PTR(-ENOMEM); return table; }
@@ -154,7 +155,7 @@ 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_sg(attachment->dev, table->sgl, table->orig_nents, direction); } 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..ea0cf71 100644
--- a/drivers/dma-buf/udmabuf.c
+++ b/drivers/dma-buf/udmabuf.c@@ -63,7 +63,8 @@ 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)) { + sg->nents = dma_map_sg(dev, sg->sgl, sg->orig_nents, direction); + if (!sg->nents) { ret = -EINVAL; goto err; }
@@ -78,7 +79,7 @@ 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_sg(dev, sg->sgl, sg->orig_nents, direction); sg_free_table(sg); kfree(sg); }
--
1.9.1
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