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swiotlb: fix phys_addr_t overflow warning 

On architectures that have a larger dma_addr_t than phys_addr_t,
the swiotlb_tbl_map_single() function truncates its return code
in the failure path, making it impossible to identify the error
later, as we compare to the original value:

kernel/dma/swiotlb.c:551:9: error: implicit conversion from 'dma_addr_t' (aka 'unsigned long long') to 'phys_addr_t' (aka 'unsigned int') changes value from 18446744073709551615 to 4294967295 [-Werror,-Wconstant-conversion]
        return DMA_MAPPING_ERROR;

Use an explicit typecast here to convert it to the narrower type,
and use the same expression in the error handling later.

Fixes: b907e20508 ("swiotlb: remove SWIOTLB_MAP_ERROR")
Acked-by: Stefano Stabellini <sstabellini@kernel.org>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
This commit is contained in:
Arnd Bergmann 2019-06-17 15:28:43 +02:00 committed by Konrad Rzeszutek Wilk
parent 4e7372e0dc
commit 9c106119f6
2 changed files with 3 additions and 3 deletions
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2
drivers/xen/swiotlb-xen.c
View File

@ -408,7 +408,7 @@ static dma_addr_t xen_swiotlb_map_page(struct device *dev, struct page *page,
map = swiotlb_tbl_map_single(dev, start_dma_addr, phys, size, dir,
attrs);
if (map == DMA_MAPPING_ERROR)
if (map == (phys_addr_t)DMA_MAPPING_ERROR)
return DMA_MAPPING_ERROR;
dev_addr = xen_phys_to_bus(map);

4
kernel/dma/swiotlb.c
View File

@ -538,7 +538,7 @@ not_found:
if (!(attrs & DMA_ATTR_NO_WARN) && printk_ratelimit())
dev_warn(hwdev, "swiotlb buffer is full (sz: %zd bytes), total %lu (slots), used %lu (slots)\n",
size, io_tlb_nslabs, tmp_io_tlb_used);
return DMA_MAPPING_ERROR;
return (phys_addr_t)DMA_MAPPING_ERROR;
found:
io_tlb_used += nslots;
spin_unlock_irqrestore(&io_tlb_lock, flags);
@ -656,7 +656,7 @@ bool swiotlb_map(struct device *dev, phys_addr_t *phys, dma_addr_t *dma_addr,
/* Oh well, have to allocate and map a bounce buffer. */
*phys = swiotlb_tbl_map_single(dev, __phys_to_dma(dev, io_tlb_start),
*phys, size, dir, attrs);
if (*phys == DMA_MAPPING_ERROR)
if (*phys == (phys_addr_t)DMA_MAPPING_ERROR)
return false;
/* Ensure that the address returned is DMA'ble */