swiotlb: Return consistent SWIOTLB segments/nr_tbl

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With a specifically contrived memory layout where there is no physical
memory available to the kernel below the 4GB boundary, we will fail to
perform the initial swiotlb_init() call and set no_iotlb_memory to true.

There are drivers out there that call into swiotlb_nr_tbl() to determine
whether they can use the SWIOTLB. With the right DMA_BIT_MASK() value
for these drivers (say 64-bit), they won't ever need to hit
swiotlb_tbl_map_single() so this can go unoticed and we would be
possibly lying about those drivers.

Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>

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Florian Fainelli 2019-06-11 10:58:25 -07:00 • committed by Konrad Rzeszutek Wilk

parent 0bfaffbf4c

commit 4aa095ea32

1 changed files with 4 additions and 4 deletions

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kernel/dma/swiotlb.c

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