diff options
author | Nicolin Chen <nicoleotsuka@gmail.com> | 2019-05-23 21:06:32 -0700 |
---|---|---|
committer | Christoph Hellwig <hch@lst.de> | 2019-06-03 16:00:07 +0200 |
commit | b1d2dc009dece4cd7e629419b52266ba51960a6b (patch) | |
tree | a31a473e64a10c54420e767337fd288753b7d6e3 /kernel | |
parent | 1b961423158caaae49d3900b7c9c37477bbfa9b3 (diff) |
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>
Diffstat (limited to 'kernel')
-rw-r--r-- | kernel/dma/contiguous.c | 47 | ||||
-rw-r--r-- | kernel/dma/direct.c | 24 |
2 files changed, 51 insertions, 20 deletions
diff --git a/kernel/dma/contiguous.c b/kernel/dma/contiguous.c index b2a87905846d..637b120d647b 100644 --- a/kernel/dma/contiguous.c +++ b/kernel/dma/contiguous.c @@ -214,6 +214,53 @@ bool dma_release_from_contiguous(struct device *dev, struct page *pages, return cma_release(dev_get_cma_area(dev), pages, count); } +/** + * dma_alloc_contiguous() - allocate contiguous pages + * @dev: Pointer to device for which the allocation is performed. + * @size: Requested allocation size. + * @gfp: Allocation flags. + * + * This function allocates contiguous memory buffer for specified device. It + * first tries to use device specific contiguous memory area if available or + * the default global one, then tries a fallback allocation of normal pages. + */ +struct page *dma_alloc_contiguous(struct device *dev, size_t size, gfp_t gfp) +{ + int node = dev ? dev_to_node(dev) : NUMA_NO_NODE; + size_t count = PAGE_ALIGN(size) >> PAGE_SHIFT; + size_t align = get_order(PAGE_ALIGN(size)); + struct cma *cma = dev_get_cma_area(dev); + struct page *page = NULL; + + /* CMA can be used only in the context which permits sleeping */ + if (cma && gfpflags_allow_blocking(gfp)) { + align = min_t(size_t, align, CONFIG_CMA_ALIGNMENT); + page = cma_alloc(cma, count, align, gfp & __GFP_NOWARN); + } + + /* Fallback allocation of normal pages */ + if (!page) + page = alloc_pages_node(node, gfp, align); + return page; +} + +/** + * dma_free_contiguous() - release allocated pages + * @dev: Pointer to device for which the pages were allocated. + * @page: Pointer to the allocated pages. + * @size: Size of allocated pages. + * + * This function releases memory allocated by dma_alloc_contiguous(). As the + * cma_release returns false when provided pages do not belong to contiguous + * area and true otherwise, this function then does a fallback __free_pages() + * upon a false-return. + */ +void dma_free_contiguous(struct device *dev, struct page *page, size_t size) +{ + if (!cma_release(dev_get_cma_area(dev), page, size >> PAGE_SHIFT)) + __free_pages(page, get_order(size)); +} + /* * Support for reserved memory regions defined in device tree */ diff --git a/kernel/dma/direct.c b/kernel/dma/direct.c index 2c2772e9702a..0816c1e8b05a 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, |