From: Nicolas Saenz Julienne nsaenzjulienne@suse.de
upstream 48b6703858dd5526c82d8ff2dbac59acab3a9dda commit.
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 Signed-off-by: Peter Gonda pgonda@google.com --- kernel/dma/pool.c | 26 +++++++++++++++++++++++--- 1 file changed, 23 insertions(+), 3 deletions(-)
diff --git a/kernel/dma/pool.c b/kernel/dma/pool.c index 318035e093fb..5b9eaa2b498d 100644 --- a/kernel/dma/pool.c +++ b/kernel/dma/pool.c @@ -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;