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dma-remap: support DMA_ATTR_NO_KERNEL_MAPPING

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Do not waste vmalloc space on allocations that do not require a mapping
into the kernel address space.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Robin Murphy <robin.murphy@arm.com>
This commit is contained in:
Christoph Hellwig 2018-11-04 17:51:50 +01:00
parent bfd56cd605
commit e440e26a02
1 changed files with 9 additions and 2 deletions
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11
kernel/dma/remap.c
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@ -200,7 +200,8 @@ void *arch_dma_alloc(struct device *dev, size_t size, dma_addr_t *dma_handle,
size = PAGE_ALIGN(size);
if (!gfpflags_allow_blocking(flags)) {
if (!gfpflags_allow_blocking(flags) &&
!(attrs & DMA_ATTR_NO_KERNEL_MAPPING)) {
ret = dma_alloc_from_pool(size, &page, flags);
if (!ret)
return NULL;
@ -215,6 +216,9 @@ void *arch_dma_alloc(struct device *dev, size_t size, dma_addr_t *dma_handle,
/* remove any dirty cache lines on the kernel alias */
arch_dma_prep_coherent(page, size);
if (attrs & DMA_ATTR_NO_KERNEL_MAPPING)
return page; /* opaque cookie */
/* create a coherent mapping */
ret = dma_common_contiguous_remap(page, size, VM_USERMAP,
arch_dma_mmap_pgprot(dev, PAGE_KERNEL, attrs),
@ -227,7 +231,10 @@ void *arch_dma_alloc(struct device *dev, size_t size, dma_addr_t *dma_handle,
void arch_dma_free(struct device *dev, size_t size, void *vaddr,
dma_addr_t dma_handle, unsigned long attrs)
{
if (!dma_free_from_pool(vaddr, PAGE_ALIGN(size))) {
if (attrs & DMA_ATTR_NO_KERNEL_MAPPING) {
/* vaddr is a struct page cookie, not a kernel address */
__dma_direct_free_pages(dev, size, vaddr);
} else if (!dma_free_from_pool(vaddr, PAGE_ALIGN(size))) {
phys_addr_t phys = dma_to_phys(dev, dma_handle);
struct page *page = pfn_to_page(__phys_to_pfn(phys));