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Commit 80885468 authored by Christoph Hellwig's avatar Christoph Hellwig
Browse files

swiotlb: do not panic on mapping failures 



All properly written drivers now have error handling in the
dma_map_single / dma_map_page callers.  As swiotlb_tbl_map_single already
prints a useful warning when running out of swiotlb pool space we can
also remove swiotlb_full entirely as it serves no purpose now.

Signed-off-by: default avatarChristoph Hellwig <hch@lst.de>
Reviewed-by: default avatarRobin Murphy <robin.murphy@arm.com>
parent b65125c6

kernel/dma/swiotlb.c

+1 −32
Original line number Diff line number Diff line
@@ -761,34 +761,6 @@ static bool swiotlb_free_buffer(struct device *dev, size_t size, 
	return true;

}



static void

swiotlb_full(struct device *dev, size_t size, enum dma_data_direction dir,

	     int do_panic)

{

	if (swiotlb_force == SWIOTLB_NO_FORCE)

		return;



	/*

	 * Ran out of IOMMU space for this operation. This is very bad.

	 * Unfortunately the drivers cannot handle this operation properly.

	 * unless they check for dma_mapping_error (most don't)

	 * When the mapping is small enough return a static buffer to limit

	 * the damage, or panic when the transfer is too big.

	 */

	dev_err_ratelimited(dev, "DMA: Out of SW-IOMMU space for %zu bytes\n",

			    size);



	if (size <= io_tlb_overflow || !do_panic)

		return;



	if (dir == DMA_BIDIRECTIONAL)

		panic("DMA: Random memory could be DMA accessed\n");

	if (dir == DMA_FROM_DEVICE)

		panic("DMA: Random memory could be DMA written\n");

	if (dir == DMA_TO_DEVICE)

		panic("DMA: Random memory could be DMA read\n");

}



/*

 * Map a single buffer of the indicated size for DMA in streaming mode.  The

 * physical address to use is returned.
@@ -817,10 +789,8 @@ dma_addr_t swiotlb_map_page(struct device *dev, struct page *page, 


	/* Oh well, have to allocate and map a bounce buffer. */

	map = map_single(dev, phys, size, dir, attrs);

	if (map == SWIOTLB_MAP_ERROR) {

		swiotlb_full(dev, size, dir, 1);

	if (map == SWIOTLB_MAP_ERROR)

		return __phys_to_dma(dev, io_tlb_overflow_buffer);

	}



	dev_addr = __phys_to_dma(dev, map);
@@ -948,7 +918,6 @@ swiotlb_map_sg_attrs(struct device *hwdev, struct scatterlist *sgl, int nelems, 
			if (map == SWIOTLB_MAP_ERROR) {

				/* Don't panic here, we expect map_sg users

				   to do proper error handling. */

				swiotlb_full(hwdev, sg->length, dir, 0);

				attrs |= DMA_ATTR_SKIP_CPU_SYNC;

				swiotlb_unmap_sg_attrs(hwdev, sgl, i, dir,

						       attrs);