[RFC PATCH 2/4] dma/pool: Add an API to check if DMA allocation is from pool

[Samiullah Khawaja <skhawaja@google.com>]

DMA allocations can be done through DMA pools, add an API that can be
used to check if an allocation is done from a pool. This will be used in
the later commit during preservation of DMA allocation.

Signed-off-by: Samiullah Khawaja <skhawaja@google.com>
---
 include/linux/dma-map-ops.h |  1 +
 kernel/dma/pool.c           | 13 +++++++++++++
 2 files changed, 14 insertions(+)

diff --git a/include/linux/dma-map-ops.h b/include/linux/dma-map-ops.h
index 6a1832a73cad..6a0bc4ea2467 100644
--- a/include/linux/dma-map-ops.h
+++ b/include/linux/dma-map-ops.h
@@ -216,6 +216,7 @@ struct page *dma_alloc_from_pool(struct device *dev, size_t size,
 		bool (*phys_addr_ok)(struct device *, phys_addr_t, size_t));
 bool dma_free_from_pool(struct device *dev, void *start, size_t size);
 
+bool dma_is_from_pool(struct device *dev, void *start, size_t size);
 int dma_direct_set_offset(struct device *dev, phys_addr_t cpu_start,
 		dma_addr_t dma_start, u64 size);
 
diff --git a/kernel/dma/pool.c b/kernel/dma/pool.c
index 2b2fbb709242..32ce4d6d7683 100644
--- a/kernel/dma/pool.c
+++ b/kernel/dma/pool.c
@@ -307,3 +307,16 @@ bool dma_free_from_pool(struct device *dev, void *start, size_t size)
 
 	return false;
 }
+
+bool dma_is_from_pool(struct device *dev, void *start, size_t size)
+{
+	struct gen_pool *pool = NULL;
+
+	while ((pool = dma_guess_pool(pool, 0))) {
+		if (!gen_pool_has_addr(pool, (unsigned long)start, size))
+			continue;
+		return true;
+	}
+
+	return false;
+}
-- 
2.54.0.545.g6539524ca2-goog