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Commit 95f18391 authored by Christoph Hellwig's avatar Christoph Hellwig
Browse files

dma-direct: retry allocations using GFP_DMA for small masks 



If an attempt to allocate memory succeeded, but isn't inside the
supported DMA mask, retry the allocation with GFP_DMA set as a
last resort.

Based on the x86 code, but an off by one error in what is now
dma_coherent_ok has been fixed vs the x86 code.

Signed-off-by: default avatarChristoph Hellwig <hch@lst.de>
parent c61e9637

lib/dma-direct.c

+24 −1
Original line number Diff line number Diff line
@@ -35,6 +35,11 @@ check_addr(struct device *dev, dma_addr_t dma_addr, size_t size, 
	return true;

}



static bool dma_coherent_ok(struct device *dev, phys_addr_t phys, size_t size)

{

	return phys_to_dma(dev, phys) + size - 1 <= dev->coherent_dma_mask;

}



static void *dma_direct_alloc(struct device *dev, size_t size,

		dma_addr_t *dma_handle, gfp_t gfp, unsigned long attrs)

{
@@ -48,11 +53,29 @@ static void *dma_direct_alloc(struct device *dev, size_t size, 
	if (dev->coherent_dma_mask <= DMA_BIT_MASK(32) && !(gfp & GFP_DMA))

		gfp |= GFP_DMA32;



again:

	/* CMA can be used only in the context which permits sleeping */

	if (gfpflags_allow_blocking(gfp))

	if (gfpflags_allow_blocking(gfp)) {

		page = dma_alloc_from_contiguous(dev, count, page_order, gfp);

		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);



	if (page && !dma_coherent_ok(dev, page_to_phys(page), size)) {

		__free_pages(page, page_order);

		page = NULL;



		if (dev->coherent_dma_mask < DMA_BIT_MASK(32) &&

		    !(gfp & GFP_DMA)) {

			gfp = (gfp & ~GFP_DMA32) | GFP_DMA;

			goto again;

		}

	}



	if (!page)

		return NULL;