[PATCH] mm/dmapool.c: avoid duplicate memset within dma_pool_alloc

[Liu Song <liusong@linux.alibaba.com>]

From: Liu Song <liusong@linux.alibaba.com>

In "dma_direct_alloc", the allocated memory is explicitly set to 0.
If use direct alloc, we need to avoid possible duplicate memset in
dma_pool_alloc.

Signed-off-by: Liu Song <liusong@linux.alibaba.com>
---
 mm/dmapool.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/mm/dmapool.c b/mm/dmapool.c
index a7eb5d0..94f4859 100644
--- a/mm/dmapool.c
+++ b/mm/dmapool.c
@@ -21,6 +21,7 @@
 
 #include <linux/device.h>
 #include <linux/dma-mapping.h>
+#include <linux/dma-map-ops.h>
 #include <linux/dmapool.h>
 #include <linux/kernel.h>
 #include <linux/list.h>
@@ -372,7 +373,7 @@ void *dma_pool_alloc(struct dma_pool *pool, gfp_t mem_flags,
 #endif
 	spin_unlock_irqrestore(&pool->lock, flags);
 
-	if (want_init_on_alloc(mem_flags))
+	if (want_init_on_alloc(mem_flags) && get_dma_ops(pool->dev))
 		memset(retval, 0, pool->size);
 
 	return retval;
-- 
1.8.3.1