[PATCH] iommu/dma: Fix condition check in iommu_dma_unmap_sg

Nathan Chancellor
2019-05-29T08:16:05Z

Clang warns:

drivers/iommu/dma-iommu.c:897:6: warning: logical not is only applied to
the left hand side of this comparison [-Wlogical-not-parentheses]
if (!(attrs & DMA_ATTR_SKIP_CPU_SYNC) == 0)
^ ~~
drivers/iommu/dma-iommu.c:897:6: note: add parentheses after the '!' to
evaluate the comparison first
if (!(attrs & DMA_ATTR_SKIP_CPU_SYNC) == 0)
^
( )
drivers/iommu/dma-iommu.c:897:6: note: add parentheses around left hand
side expression to silence this warning
if (!(attrs & DMA_ATTR_SKIP_CPU_SYNC) == 0)
^
( )
1 warning generated.

Judging from the rest of the commit and the conditional in
iommu_dma_map_sg, either

if (!(attrs & DMA_ATTR_SKIP_CPU_SYNC))

or
if ((attrs & DMA_ATTR_SKIP_CPU_SYNC) == 0)

was intended, not a combination of the two.

I personally think that the former is easier to understand so use that.

Fixes: 06d60728ff5c ("iommu/dma: move the arm64 wrappers to common code")
Link: https://github.com/ClangBuiltLinux/linux/issues/497
Signed-off-by: Nathan Chancellor <natechancellor@gmail.com>
---
drivers/iommu/dma-iommu.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/iommu/dma-iommu.c b/drivers/iommu/dma-iommu.c
index 0cd49c2d3770..0dee374fc64a 100644
--- a/drivers/iommu/dma-iommu.c
+++ b/drivers/iommu/dma-iommu.c
@@ -894,7 +894,7 @@ static void iommu_dma_unmap_sg(struct device *dev, struct scatterlist *sg,
struct scatterlist *tmp;
int i;

- if (!(attrs & DMA_ATTR_SKIP_CPU_SYNC) == 0)
+ if (!(attrs & DMA_ATTR_SKIP_CPU_SYNC))
iommu_dma_sync_sg_for_cpu(dev, sg, nents, dir);

/*
--
2.22.0.rc1