Commit 3aa91625 authored by Christoph Hellwig's avatar Christoph Hellwig Committed by Daniel Borkmann
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dma-mapping: Add a new dma_need_sync API 



Add a new API to check if calls to dma_sync_single_for_{device,cpu} are
required for a given DMA streaming mapping.

Signed-off-by: default avatarChristoph Hellwig <hch@lst.de>
Signed-off-by: default avatarDaniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20200629130359.2690853-2-hch@lst.de
parent 2bdeb3ed

Documentation/core-api/dma-api.rst

+8 −0
Original line number Diff line number Diff line
@@ -204,6 +204,14 @@ Returns the maximum size of a mapping for the device. The size parameter 
of the mapping functions like dma_map_single(), dma_map_page() and

others should not be larger than the returned value.



::



	bool

	dma_need_sync(struct device *dev, dma_addr_t dma_addr);



Returns %true if dma_sync_single_for_{device,cpu} calls are required to

transfer memory ownership.  Returns %false if those calls can be skipped.



::



	unsigned long

include/linux/dma-direct.h

+1 −0
Original line number Diff line number Diff line
@@ -87,4 +87,5 @@ int dma_direct_mmap(struct device *dev, struct vm_area_struct *vma, 
		void *cpu_addr, dma_addr_t dma_addr, size_t size,

		unsigned long attrs);

int dma_direct_supported(struct device *dev, u64 mask);

bool dma_direct_need_sync(struct device *dev, dma_addr_t dma_addr);

#endif /* _LINUX_DMA_DIRECT_H */

include/linux/dma-mapping.h

+5 −0
Original line number Diff line number Diff line
@@ -461,6 +461,7 @@ int dma_set_mask(struct device *dev, u64 mask); 
int dma_set_coherent_mask(struct device *dev, u64 mask);

u64 dma_get_required_mask(struct device *dev);

size_t dma_max_mapping_size(struct device *dev);

bool dma_need_sync(struct device *dev, dma_addr_t dma_addr);

unsigned long dma_get_merge_boundary(struct device *dev);

#else /* CONFIG_HAS_DMA */

static inline dma_addr_t dma_map_page_attrs(struct device *dev,
@@ -571,6 +572,10 @@ static inline size_t dma_max_mapping_size(struct device *dev) 
{

	return 0;

}

static inline bool dma_need_sync(struct device *dev, dma_addr_t dma_addr)

{

	return false;

}

static inline unsigned long dma_get_merge_boundary(struct device *dev)

{

	return 0;

kernel/dma/direct.c

+6 −0
Original line number Diff line number Diff line
@@ -530,3 +530,9 @@ size_t dma_direct_max_mapping_size(struct device *dev) 
		return swiotlb_max_mapping_size(dev);

	return SIZE_MAX;

}



bool dma_direct_need_sync(struct device *dev, dma_addr_t dma_addr)

{

	return !dev_is_dma_coherent(dev) ||

		is_swiotlb_buffer(dma_to_phys(dev, dma_addr));

}

kernel/dma/mapping.c

+10 −0
Original line number Diff line number Diff line
@@ -397,6 +397,16 @@ size_t dma_max_mapping_size(struct device *dev) 
}

EXPORT_SYMBOL_GPL(dma_max_mapping_size);



bool dma_need_sync(struct device *dev, dma_addr_t dma_addr)

{

	const struct dma_map_ops *ops = get_dma_ops(dev);



	if (dma_is_direct(ops))

		return dma_direct_need_sync(dev, dma_addr);

	return ops->sync_single_for_cpu || ops->sync_single_for_device;

}

EXPORT_SYMBOL_GPL(dma_need_sync);



unsigned long dma_get_merge_boundary(struct device *dev)

{

	const struct dma_map_ops *ops = get_dma_ops(dev);

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