From a5fb217f13f74b2af2ab366ffad522bae717f93c Mon Sep 17 00:00:00 2001
From: Christoph Hellwig <hch@lst.de>
Date: Thu, 12 Sep 2024 09:21:18 +0200
Subject: [PATCH] dma-mapping: reflow dma_supported
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>
---
kernel/dma/mapping.c | 25 ++++++++++++++-----------
1 file changed, 14 insertions(+), 11 deletions(-)
diff --git a/kernel/dma/mapping.c b/kernel/dma/mapping.c
index 022d670f8cad..b839683da0ba 100644
--- a/kernel/dma/mapping.c
+++ b/kernel/dma/mapping.c
@@ -841,20 +841,23 @@ static int dma_supported(struct device *dev, u64 mask)
{
const struct dma_map_ops *ops = get_dma_ops(dev);
- if (WARN_ON(ops && use_dma_iommu(dev)))
- return false;
-
- if (use_dma_iommu(dev))
+ if (use_dma_iommu(dev)) {
+ if (WARN_ON(ops))
+ return false;
return true;
+ }
+
/*
- * ->dma_supported sets the bypass flag, so we must always call
- * into the method here unless the device is truly direct mapped.
+ * ->dma_supported sets and clears the bypass flag, so ignore it here
+ * and always call into the method if there is one.
*/
- if (!ops)
- return dma_direct_supported(dev, mask);
- if (!ops->dma_supported)
- return 1;
- return ops->dma_supported(dev, mask);
+ if (ops) {
+ if (!ops->dma_supported)
+ return true;
+ return ops->dma_supported(dev, mask);
+ }
+
+ return dma_direct_supported(dev, mask);
}
bool dma_pci_p2pdma_supported(struct device *dev)
--
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