ARM: 8404/1: dma-mapping: fix off-by-one error in bitmap size check

commit 462859aa upstream.

nr_bitmaps member of mapping structure stores the number of already
allocated bitmaps and it is interpreted as loop iterator (it starts from
0 not from 1), so a comparison against number of possible bitmap
extensions should include this fact. This patch fixes this by changing
the extension failure condition. This issue has been introduced by
commit 4d852ef8 ("arm: dma-mapping: Add
support to extend DMA IOMMU mappings").
Reported-by: Hyungwon Hwang <human.hwang@samsung.com>
Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Reviewed-by: Hyungwon Hwang <human.hwang@samsung.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Signed-off-by: Luis Henriques <luis.henriques@canonical.com>

arch/arm/mm/dma-mapping.c

@@ -2013,7 +2013,7 @@ static int extend_iommu_mapping(struct dma_iommu_mapping *mapping)
 {
 	int next_bitmap;
 
-	if (mapping->nr_bitmaps > mapping->extensions)
+	if (mapping->nr_bitmaps >= mapping->extensions)
 		return -EINVAL;
 
 	next_bitmap = mapping->nr_bitmaps;