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dma-direct: fail allocations that can't be made coherent

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If the architecture can't remap or set an address uncached there is no way
to fullfill a request for a coherent allocation.  Return NULL in that case.
Note that this case currently does not happen, so this is a theoretical
fixup and/or a preparation for eventually supporting platforms that
can't support coherent allocations with the generic code.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Robin Murphy <robin.murphy@arm.com>
This commit is contained in:
Christoph Hellwig 2021-11-09 15:47:56 +01:00
parent a86d10942d
commit 955f58f740
1 changed files with 3 additions and 2 deletions
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5
kernel/dma/direct.c
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@ -233,8 +233,9 @@ void *dma_direct_alloc(struct device *dev, size_t size,
return dma_direct_alloc_from_pool(dev, size,
dma_handle, gfp);
} else {
if (IS_ENABLED(CONFIG_ARCH_HAS_DMA_SET_UNCACHED))
set_uncached = true;
if (!IS_ENABLED(CONFIG_ARCH_HAS_DMA_SET_UNCACHED))
return NULL;
set_uncached = true;
}
}