On 2021-10-21 10:06, Christoph Hellwig wrote:
Split the code for DMA_ATTR_NO_KERNEL_MAPPING allocations into a separate
helper to make dma_direct_alloc a little more readable.
Signed-off-by: Christoph Hellwig <[email protected]>
Acked-by: David Rientjes <[email protected]>
---
kernel/dma/direct.c | 31 ++++++++++++++++++++-----------
1 file changed, 20 insertions(+), 11 deletions(-)
diff --git a/kernel/dma/direct.c b/kernel/dma/direct.c
index a6b6fe72af4d1..4ffdb524942a1 100644
--- a/kernel/dma/direct.c
+++ b/kernel/dma/direct.c
@@ -163,6 +163,24 @@ static void *dma_direct_alloc_from_pool(struct device
*dev, size_t size,
return ret;
}
+static void *dma_direct_alloc_no_mapping(struct device *dev, size_t size,
+ dma_addr_t *dma_handle, gfp_t gfp)
+{
+ struct page *page;
+
+ page = __dma_direct_alloc_pages(dev, size, gfp & ~__GFP_ZERO);
+ if (!page)
+ return NULL;
+
+ /* remove any dirty cache lines on the kernel alias */
+ if (!PageHighMem(page))
+ arch_dma_prep_coherent(page, size);
+
+ /* return the page pointer as the opaque cookie */
+ *dma_handle = phys_to_dma_direct(dev, page_to_phys(page));
+ return page;
+}
+
void *dma_direct_alloc(struct device *dev, size_t size,
dma_addr_t *dma_handle, gfp_t gfp, unsigned long attrs)
{
@@ -175,17 +193,8 @@ void *dma_direct_alloc(struct device *dev, size_t size,
gfp |= __GFP_NOWARN;
if ((attrs & DMA_ATTR_NO_KERNEL_MAPPING) &&
- !force_dma_unencrypted(dev) && !is_swiotlb_for_alloc(dev)) {
- page = __dma_direct_alloc_pages(dev, size, gfp & ~__GFP_ZERO);
- if (!page)
- return NULL;
- /* remove any dirty cache lines on the kernel alias */
- if (!PageHighMem(page))
- arch_dma_prep_coherent(page, size);
- *dma_handle = phys_to_dma_direct(dev, page_to_phys(page));
- /* return the page pointer as the opaque cookie */
- return page;
- }
+ !force_dma_unencrypted(dev) && !is_swiotlb_for_alloc(dev))
Hmm, does force_dma_unencrypted() actually matter if the caller doesn't
want to access the buffer itself? Presumably any subsequent mmap() to
userspace would still do the right thing?
Robin.
+ return dma_direct_alloc_no_mapping(dev, size, dma_handle, gfp);
if (!IS_ENABLED(CONFIG_ARCH_HAS_DMA_SET_UNCACHED) &&
!IS_ENABLED(CONFIG_DMA_DIRECT_REMAP) &&
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