dma-contiguous: add dma_{alloc,free}_contiguous() helpers
Both dma_alloc_from_contiguous() and dma_release_from_contiguous() are
very simply implemented, but requiring callers to pass certain
parameters like count and align, and taking a boolean parameter to check
__GFP_NOWARN in the allocation flags. So every function call duplicates
similar work:
unsigned long order = get_order(size);
size_t count = size >> PAGE_SHIFT;
page = dma_alloc_from_contiguous(dev, count, order,
gfp & __GFP_NOWARN);
[...]
dma_release_from_contiguous(dev, page, size >> PAGE_SHIFT);
Additionally, as CMA can be used only in the context which permits
sleeping, most of callers do a gfpflags_allow_blocking() check and a
corresponding fallback allocation of normal pages upon any false result:
if (gfpflags_allow_blocking(flag))
page = dma_alloc_from_contiguous();
if (!page)
page = alloc_pages();
[...]
if (!dma_release_from_contiguous(dev, page, count))
__free_pages(page, get_order(size));
So this patch simplifies those function calls by abstracting these
operations into the two new functions: dma_{alloc,free}_contiguous.
As some callers of dma_{alloc,release}_from_contiguous() might be
complicated, this patch just implements these two new functions to
kernel/dma/direct.c only as an initial step.
Suggested-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Nicolin Chen <nicoleotsuka@gmail.com>
Tested-by: dann frazier <dann.frazier@canonical.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
diff --git a/kernel/dma/direct.c b/kernel/dma/direct.c
index 2c2772e..0816c1e 100644
--- a/kernel/dma/direct.c
+++ b/kernel/dma/direct.c
@@ -96,8 +96,6 @@ static bool dma_coherent_ok(struct device *dev, phys_addr_t phys, size_t size)
struct page *__dma_direct_alloc_pages(struct device *dev, size_t size,
dma_addr_t *dma_handle, gfp_t gfp, unsigned long attrs)
{
- unsigned int count = PAGE_ALIGN(size) >> PAGE_SHIFT;
- int page_order = get_order(size);
struct page *page = NULL;
u64 phys_mask;
@@ -109,20 +107,9 @@ struct page *__dma_direct_alloc_pages(struct device *dev, size_t size,
gfp |= __dma_direct_optimal_gfp_mask(dev, dev->coherent_dma_mask,
&phys_mask);
again:
- /* CMA can be used only in the context which permits sleeping */
- if (gfpflags_allow_blocking(gfp)) {
- page = dma_alloc_from_contiguous(dev, count, page_order,
- gfp & __GFP_NOWARN);
- if (page && !dma_coherent_ok(dev, page_to_phys(page), size)) {
- dma_release_from_contiguous(dev, page, count);
- page = NULL;
- }
- }
- if (!page)
- page = alloc_pages_node(dev_to_node(dev), gfp, page_order);
-
+ page = dma_alloc_contiguous(dev, size, gfp);
if (page && !dma_coherent_ok(dev, page_to_phys(page), size)) {
- __free_pages(page, page_order);
+ dma_free_contiguous(dev, page, size);
page = NULL;
if (IS_ENABLED(CONFIG_ZONE_DMA32) &&
@@ -154,7 +141,7 @@ void *dma_direct_alloc_pages(struct device *dev, size_t size,
if (PageHighMem(page)) {
/*
* Depending on the cma= arguments and per-arch setup
- * dma_alloc_from_contiguous could return highmem pages.
+ * dma_alloc_contiguous could return highmem pages.
* Without remapping there is no way to return them here,
* so log an error and fail.
*/
@@ -176,10 +163,7 @@ void *dma_direct_alloc_pages(struct device *dev, size_t size,
void __dma_direct_free_pages(struct device *dev, size_t size, struct page *page)
{
- unsigned int count = PAGE_ALIGN(size) >> PAGE_SHIFT;
-
- if (!dma_release_from_contiguous(dev, page, count))
- __free_pages(page, get_order(size));
+ dma_free_contiguous(dev, page, size);
}
void dma_direct_free_pages(struct device *dev, size_t size, void *cpu_addr,