linux-kernel - [PATCH] dma_declare_coherent

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Message-ID: <Pine.LNX.4.60.0704132000030.5919@poirot.grange>
Date:	Fri, 13 Apr 2007 20:08:28 +0200 (CEST)
From:	Guennadi Liakhovetski <g.liakhovetski@....de>
To:	James Bottomley <James.Bottomley@...elEye.com>
cc:	linux-kernel@...r.kernel.org
Subject: [PATCH] dma_declare_coherent_memory wrong allocation

Hi

Either I've finally gone blind on this Friday 13th or... Looks like this 
almost 3 year old function has a bug. Patch below compile-tested... in a 
way.

Thanks
Guennadi
---
Guennadi Liakhovetski

dma_declare_coherent_memory() allocates a bitmap 1 bit per page, it 
calculates the bitmap size based on size of long, but allocates bytes...

Signed-off-by: G. Liakhovetski <g.liakhovetski@....de>

diff --git a/arch/i386/kernel/pci-dma.c b/arch/i386/kernel/pci-dma.c
index 3ebcea0..3d55226 100644
--- a/arch/i386/kernel/pci-dma.c
+++ b/arch/i386/kernel/pci-dma.c
@@ -77,7 +77,7 @@ int dma_declare_coherent_memory(struct device *dev, dma_addr_t bus_addr,
 {
 	void __iomem *mem_base = NULL;
 	int pages = size >> PAGE_SHIFT;
-	int bitmap_size = (pages + 31)/32;
+	int bitmap_size = DIV_ROUND_UP(pages, 8);
 
 	if ((flags & (DMA_MEMORY_MAP | DMA_MEMORY_IO)) == 0)
 		goto out;
-
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