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dma-direct: retry allocations using GFP_DMA for small masks

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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: Christoph Hellwig <hch@lst.de>
This commit is contained in:
Christoph Hellwig 2018-01-09 23:40:57 +01:00
parent c61e963734
commit 95f183916d
1 changed files with 24 additions and 1 deletions
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25
lib/dma-direct.c
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@ -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;