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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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2
include/linux/dma-direct.h
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@@ -67,6 +67,8 @@ static inline bool dma_capable(struct device *dev, dma_addr_t addr, size_t size,
}
u64 dma_direct_get_required_mask(struct device *dev);
gfp_t dma_direct_optimal_gfp_mask(struct device *dev, u64 dma_mask,
u64 *phys_mask);
void *dma_direct_alloc(struct device *dev, size_t size, dma_addr_t *dma_handle,
gfp_t gfp, unsigned long attrs);
void dma_direct_free(struct device *dev, size_t size, void *cpu_addr,