On Wed 2019-11-27 21:29:15, Greg Kroah-Hartman wrote:
> From: Christoph Hellwig <hch@xxxxxx>
>
> [ Upstream commit 8088546832aa2c0d8f99dd56edf6384f8a9b63b3 ]
>
> 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.
Umm. I trust you that is true in mainline, but is it also true for
-stable kernels?
Does this fix anything for -stable users?
Best regards,
Pavel
> +++ b/kernel/dma/swiotlb.c
> @@ -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);
>
> @@ -954,7 +924,6 @@ 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);
--
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
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