linux-kernel - Re: [PATCH] return hidden bug

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Message-ID: <20071021214209.1a7567d7@bree.surriel.com>
Date:	Sun, 21 Oct 2007 21:42:09 -0400
From:	Rik van Riel <riel@...hat.com>
To:	Roel Kluin <12o3l@...cali.nl>
Cc:	lkml <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] return hidden bug

On Mon, 22 Oct 2007 03:05:05 +0200
Roel Kluin <12o3l@...cali.nl> wrote:

>     return hidden bug
>     
>     Signed-off-by: Roel Kluin <12o3l@...cali.nl>
> 
> diff --git a/arch/alpha/kernel/pci_iommu.c
> b/arch/alpha/kernel/pci_iommu.c index e1c4707..6a69425 100644
> --- a/arch/alpha/kernel/pci_iommu.c
> +++ b/arch/alpha/kernel/pci_iommu.c
> @@ -365,8 +365,8 @@ pci_unmap_single(struct pci_dev *pdev, dma_addr_t
> dma_addr, size_t size, printk(KERN_ERR "Bogus pci_unmap_single:
> dma_addr %lx " " base %lx size %x\n", dma_addr, arena->dma_base,
>  		       arena->size);
> -		return;
>  		BUG();
> +		return;
>  	}
>  
>  	npages = calc_npages((dma_addr & ~PAGE_MASK) + size);

BUG() will terminate the process that runs into it, so you can
just remove the return alltogether.  If BUG() is hit, the return
will never be reached.

-- 
"Debugging is twice as hard as writing the code in the first place.
Therefore, if you write the code as cleverly as possible, you are,
by definition, not smart enough to debug it." - Brian W. Kernighan
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