linux-kernel - [PATCH 24/33] powerpc/dma: fix an off-by-one in dma

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Date:   Tue,  9 Oct 2018 15:24:51 +0200
From:   Christoph Hellwig <hch@....de>
To:     Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Paul Mackerras <paulus@...ba.org>,
        Michael Ellerman <mpe@...erman.id.au>
Cc:     linuxppc-dev@...ts.ozlabs.org, iommu@...ts.linux-foundation.org,
        linux-mm@...ck.org, linux-arch@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH 24/33] powerpc/dma: fix an off-by-one in dma_capable

We need to compare the last byte in the dma range and not the one after it
for the bus_dma_mask, just like we do for the regular dma_mask.  Fix this
cleanly by merging the two comparisms into one.

Signed-off-by: Christoph Hellwig <hch@....de>
---
 arch/powerpc/include/asm/dma-direct.h | 8 ++------
 1 file changed, 2 insertions(+), 6 deletions(-)

diff --git a/arch/powerpc/include/asm/dma-direct.h b/arch/powerpc/include/asm/dma-direct.h
index e00ab5d0612d..92d8aed86422 100644
--- a/arch/powerpc/include/asm/dma-direct.h
+++ b/arch/powerpc/include/asm/dma-direct.h
@@ -4,15 +4,11 @@
 
 static inline bool dma_capable(struct device *dev, dma_addr_t addr, size_t size)
 {
-#ifdef CONFIG_SWIOTLB
-	if (dev->bus_dma_mask && addr + size > dev->bus_dma_mask)
-		return false;
-#endif
-
 	if (!dev->dma_mask)
 		return false;
 
-	return addr + size - 1 <= *dev->dma_mask;
+	return addr + size - 1 <=
+		min_not_zero(*dev->dma_mask, dev->bus_dma_mask);
 }
 
 static inline dma_addr_t __phys_to_dma(struct device *dev, phys_addr_t paddr)
-- 
2.19.0