dma-pool: add additional coherent pools to map to gfp mask

The single atomic pool is allocated from the lowest zone possible since it is guaranteed to be applicable for any DMA allocation. Devices may allocate through the DMA API but not have a strict reliance on GFP_DMA memory. Since the atomic pool will be used for all non-blockable allocations, returning all memory from ZONE_DMA may unnecessarily deplete the zone. Provision for multiple atomic pools that will map to the optimal gfp mask of the device. When allocating non-blockable memory, determine the optimal gfp mask of the device and use the appropriate atomic pool. The coherent DMA mask will remain the same between allocation and free and, thus, memory will be freed to the same atomic pool it was allocated from. __dma_atomic_pool_init() will be changed to return struct gen_pool * later once dynamic expansion is added.

David Rientjes committed 6 years ago

Commit c84dc6e1 parent e860c295 files · +91 −54Browse files

Showing the changes to include/linux (2 of 5 files). Show all

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2 files

include/linux/dma-direct.h +2 −0
include/linux/dma-mapping.h +3 −3

include/linux/dma-direct.h+2−0

@@ -67,6 +67,8 @@ static inline bool dma_capable(struct device *dev, dma_addr_t addr, size_t size, · 66 unmodified lines
67	67	}
68	68
69	69	u64 dma_direct_get_required_mask(struct device *dev);
	70	+gfp_t dma_direct_optimal_gfp_mask(struct device *dev, u64 dma_mask,
	71	+ u64 *phys_mask);
70	72	void dma_direct_alloc(struct device dev, size_t size, dma_addr_t *dma_handle,
71	73	gfp_t gfp, unsigned long attrs);
72	74	void dma_direct_free(struct device dev, size_t size, void cpu_addr,

include/linux/dma-mapping.h+3−3

@@ -630,9 +630,9 @@ void dma_common_pages_remap(struct page *pages, size_t size, · 629 unmodified lines
630	630	pgprot_t prot, const void *caller);
631	631	void dma_common_free_remap(void *cpu_addr, size_t size);
632	632
633		−bool dma_in_atomic_pool(void *start, size_t size);
634		−void dma_alloc_from_pool(size_t size, struct page *ret_page, gfp_t flags);
635		−bool dma_free_from_pool(void *start, size_t size);
	633	+void dma_alloc_from_pool(struct device dev, size_t size,
	634	+ struct page **ret_page, gfp_t flags);
	635	+bool dma_free_from_pool(struct device dev, void start, size_t size);
636	636
637	637	int
638	638	dma_common_get_sgtable(struct device dev, struct sg_table sgt, void *cpu_addr,