[PATCH 19/33] dma-mapping: warn when there is no coherent_dma_mask

Christoph Hellwig hch at lst.de
Wed Jan 10 00:00:13 PST 2018

These days all devices should have a DMA coherent mask, and most dma_ops
implementations rely on that fact.  But just to be sure add an assert to
ring the warning bell if that is not the case.

Signed-off-by: Christoph Hellwig <hch at lst.de>
 include/linux/dma-mapping.h | 1 +
 1 file changed, 1 insertion(+)

diff --git a/include/linux/dma-mapping.h b/include/linux/dma-mapping.h
index d84951865be7..9f28b2fa329e 100644
--- a/include/linux/dma-mapping.h
+++ b/include/linux/dma-mapping.h
@@ -513,6 +513,7 @@ static inline void *dma_alloc_attrs(struct device *dev, size_t size,
 	void *cpu_addr;
+	WARN_ON_ONCE(!dev->coherent_dma_mask);
 	if (dma_alloc_from_dev_coherent(dev, size, dma_handle, &cpu_addr))
 		return cpu_addr;

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