Commit 48b67038 authored by Nicolas Saenz Julienne's avatar Nicolas Saenz Julienne Committed by Christoph Hellwig
Browse files

dma-pool: introduce dma_guess_pool() 



dma-pool's dev_to_pool() creates the false impression that there is a
way to grantee a mapping between a device's DMA constraints and an
atomic pool. It tuns out it's just a guess, and the device might need to
use an atomic pool containing memory from a 'safer' (or lower) memory
zone.

To help mitigate this, introduce dma_guess_pool() which can be fed a
device's DMA constraints and atomic pools already known to be faulty, in
order for it to provide an better guess on which pool to use.

Signed-off-by: default avatarNicolas Saenz Julienne <nsaenzjulienne@suse.de>
Signed-off-by: default avatarChristoph Hellwig <hch@lst.de>
parent 23e469be

kernel/dma/pool.c

+23 −3
Original line number Diff line number Diff line
@@ -203,7 +203,7 @@ static int __init dma_atomic_pool_init(void) 
}

postcore_initcall(dma_atomic_pool_init);



static inline struct gen_pool *dev_to_pool(struct device *dev)

static inline struct gen_pool *dma_guess_pool_from_device(struct device *dev)

{

	u64 phys_mask;

	gfp_t gfp;
@@ -217,10 +217,30 @@ static inline struct gen_pool *dev_to_pool(struct device *dev) 
	return atomic_pool_kernel;

}



static inline struct gen_pool *dma_get_safer_pool(struct gen_pool *bad_pool)

{

	if (bad_pool == atomic_pool_kernel)

		return atomic_pool_dma32 ? : atomic_pool_dma;



	if (bad_pool == atomic_pool_dma32)

		return atomic_pool_dma;



	return NULL;

}



static inline struct gen_pool *dma_guess_pool(struct device *dev,

					      struct gen_pool *bad_pool)

{

	if (bad_pool)

		return dma_get_safer_pool(bad_pool);



	return dma_guess_pool_from_device(dev);

}



void *dma_alloc_from_pool(struct device *dev, size_t size,

			  struct page **ret_page, gfp_t flags)

{

	struct gen_pool *pool = dev_to_pool(dev);

	struct gen_pool *pool = dma_guess_pool(dev, NULL);

	unsigned long val;

	void *ptr = NULL;
@@ -249,7 +269,7 @@ void *dma_alloc_from_pool(struct device *dev, size_t size, 


bool dma_free_from_pool(struct device *dev, void *start, size_t size)

{

	struct gen_pool *pool = dev_to_pool(dev);

	struct gen_pool *pool = dma_guess_pool(dev, NULL);



	if (!pool || !gen_pool_has_addr(pool, (unsigned long)start, size))

		return false;

CRA Git | Maintained and supported by SUSTech CRA and CCSE