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dma-mapping: reflow dma_supported

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dma_supported has become too much spaghetti for my taste.  Reflow it to
remove the duplicate use_dma_iommu condition and make the main path more
obvious.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Leon Romanovsky <leon@kernel.org>
This commit is contained in:
Christoph Hellwig 2024-09-12 09:21:18 +02:00
parent f45cfab28f
commit a5fb217f13
1 changed files with 14 additions and 11 deletions
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25
kernel/dma/mapping.c
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@ -841,20 +841,23 @@ static int dma_supported(struct device *dev, u64 mask)
{ {
const struct dma_map_ops *ops = get_dma_ops(dev); const struct dma_map_ops *ops = get_dma_ops(dev);
if (WARN_ON(ops && use_dma_iommu(dev))) if (use_dma_iommu(dev)) {
return false; if (WARN_ON(ops))
return false;
if (use_dma_iommu(dev))
return true; return true;
}
/* /*
* ->dma_supported sets the bypass flag, so we must always call * ->dma_supported sets and clears the bypass flag, so ignore it here
* into the method here unless the device is truly direct mapped. * and always call into the method if there is one.
*/ */
if (!ops) if (ops) {
return dma_direct_supported(dev, mask); if (!ops->dma_supported)
if (!ops->dma_supported) return true;
return 1; return ops->dma_supported(dev, mask);
return ops->dma_supported(dev, mask); }
return dma_direct_supported(dev, mask);
} }
bool dma_pci_p2pdma_supported(struct device *dev) bool dma_pci_p2pdma_supported(struct device *dev)