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dma-pool: introduce dma_guess_pool()

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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: Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
Signed-off-by: Christoph Hellwig <hch@lst.de>
This commit is contained in:
Nicolas Saenz Julienne 2020-07-14 14:39:27 +02:00 committed by Christoph Hellwig
parent 23e469be62
commit 48b6703858
1 changed files with 23 additions and 3 deletions
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26
kernel/dma/pool.c
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@ -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;