[PATCH 1/1] dma-mapping: to avoid exception when cpu_addr is NULL

[Zhen Lei]

Do this to keep consistent with kfree, which tolerate ptr is NULL.

Signed-off-by: Zhen Lei <thunder.leiz...@huawei.com>
---
 include/linux/dma-mapping.h | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/include/linux/dma-mapping.h b/include/linux/dma-mapping.h
index 75857cd..fdd4294 100644
--- a/include/linux/dma-mapping.h
+++ b/include/linux/dma-mapping.h
@@ -402,7 +402,10 @@ static inline void *dma_alloc_coherent(struct device *dev, 
size_t size,
 static inline void dma_free_coherent(struct device *dev, size_t size,
                void *cpu_addr, dma_addr_t dma_handle)
 {
-       return dma_free_attrs(dev, size, cpu_addr, dma_handle, NULL);
+       if (unlikely(!cpu_addr))
+               return;
+
+       dma_free_attrs(dev, size, cpu_addr, dma_handle, NULL);
 }

 static inline void *dma_alloc_noncoherent(struct device *dev, size_t size,
--
2.5.0