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

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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.

Signed-off-by: David Rientjes <rientjes@google.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
This commit is contained in:
David Rientjes 2020-04-14 17:04:55 -07:00 • committed by Christoph Hellwig
parent e860c299ac
commit c84dc6e68a
5 changed files with 91 additions and 54 deletions
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6
include/linux/dma-mapping.h
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@ -630,9 +630,9 @@ void *dma_common_pages_remap(struct page **pages, size_t size,
pgprot_t prot, const void *caller);
void dma_common_free_remap(void *cpu_addr, size_t size);
bool dma_in_atomic_pool(void *start, size_t size);
void *dma_alloc_from_pool(size_t size, struct page **ret_page, gfp_t flags);
bool dma_free_from_pool(void *start, size_t size);
void *dma_alloc_from_pool(struct device *dev, size_t size,
struct page **ret_page, gfp_t flags);
bool dma_free_from_pool(struct device *dev, void *start, size_t size);
int
dma_common_get_sgtable(struct device *dev, struct sg_table *sgt, void *cpu_addr,