Commit e440e26a authored by Christoph Hellwig's avatar Christoph Hellwig
Browse files

dma-remap: support DMA_ATTR_NO_KERNEL_MAPPING 



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

Signed-off-by: default avatarChristoph Hellwig <hch@lst.de>
Reviewed-by: default avatarRobin Murphy <robin.murphy@arm.com>
parent bfd56cd6

kernel/dma/remap.c

+9 −2
Original line number Diff line number Diff line
@@ -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));