swiotlb: do not panic on mapping failures

BugLink: https://bugs.launchpad.net/bugs/1854975
[ 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.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Robin Murphy <robin.murphy@arm.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
Signed-off-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>

diff --git a/lib/swiotlb.c b/lib/swiotlb.c
index b632c6e060bc983cbc394b5b4fd17524759592d2..2fab4208728f95ad4506bf5015744718fca19882 100644 (file)
--- a/lib/swiotlb.c
+++ b/lib/swiotlb.c
@@ -797,34 +797,6 @@ swiotlb_free_coherent(struct device *hwdev, size_t size, void *vaddr,
 }
 EXPORT_SYMBOL(swiotlb_free_coherent);
 
-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.
@@ -853,10 +825,8 @@ 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 swiotlb_phys_to_dma(dev, io_tlb_overflow_buffer);
-       }
 
        dev_addr = swiotlb_phys_to_dma(dev, map);
 
@@ -994,7 +964,6 @@ 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);