linux-kernel - [PATCH 1/1] dma-mapping: to avoid exception when cpu

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Date:	Mon, 7 Mar 2016 17:21:25 +0800
From:	Zhen Lei <thunder.leizhen@...wei.com>
To:	Andrew Morton <akpm@...ux-foundation.org>,
	Marek Szyprowski <m.szyprowski@...sung.com>,
	Will Deacon <will.deacon@....com>,
	linux-kernel <linux-kernel@...r.kernel.org>
CC:	Zefan Li <lizefan@...wei.com>, Xinwei Hu <huxinwei@...wei.com>,
	"Tianhong Ding" <dingtianhong@...wei.com>,
	Hanjun Guo <guohanjun@...wei.com>,
	Zhen Lei <thunder.leizhen@...wei.com>
Subject: [PATCH 1/1] dma-mapping: to avoid exception when cpu_addr is NULL

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

Signed-off-by: Zhen Lei <thunder.leizhen@...wei.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