dma-mapping: deprecate dma_zalloc_coherent

We now always return zeroed memory from dma_alloc_coherent.  Note that
simply passing GFP_ZERO to dma_alloc_coherent wasn't always doing the
right thing to start with given that various allocators are not backed
by the page allocator and thus would ignore GFP_ZERO.

Signed-off-by: Christoph Hellwig <hch@lst.de>

1 files changed, 4 insertions, 3 deletions

diff --git a/include/linux/dma-mapping.h b/include/linux/dma-mapping.h
index f422aec0f53c..a52c6409bdc2 100644
--- a/include/linux/dma-mapping.h
+++ b/include/linux/dma-mapping.h
@@ -644,12 +644,13 @@ static inline unsigned long dma_max_pfn(struct device *dev)
 }
 #endif
 
+/*
+ * Please always use dma_alloc_coherent instead as it already zeroes the memory!
+ */
 static inline void *dma_zalloc_coherent(struct device *dev, size_t size,
                                         dma_addr_t *dma_handle, gfp_t flag)
 {
-        void *ret = dma_alloc_coherent(dev, size, dma_handle,
-                                       flag | __GFP_ZERO);
-        return ret;
+        return dma_alloc_coherent(dev, size, dma_handle, flag);
 }
 
 static inline int dma_get_cache_alignment(void)