[PATCH 2/2] dma-mapping: deprecate dma_zalloc_coherent

Christoph Hellwig
2018-12-14T08:25:27Z

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>
---
Documentation/DMA-API.txt | 9 ---------
include/linux/dma-mapping.h | 7 ++++---
2 files changed, 4 insertions(+), 12 deletions(-)

diff --git a/Documentation/DMA-API.txt b/Documentation/DMA-API.txt
index 016eb6909b8a..e133ccd60228 100644
--- a/Documentation/DMA-API.txt
+++ b/Documentation/DMA-API.txt
@@ -58,15 +58,6 @@ specify the ``GFP_`` flags (see kmalloc()) for the allocation (the
implementation may choose to ignore flags that affect the location of
the returned memory, like GFP_DMA).

-::
-
- void *
- dma_zalloc_coherent(struct device *dev, size_t size,
- dma_addr_t *dma_handle, gfp_t flag)
-
-Wraps dma_alloc_coherent() and also zeroes the returned memory if the
-allocation attempt succeeded.
-
::

void
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)
--
2.19.2