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Re: [Xen-devel] Re: [PATCH] sysfs attributes for xen

To: "Mike D. Day" <ncmike@xxxxxxxxxx>
Subject: Re: [Xen-devel] Re: [PATCH] sysfs attributes for xen
From: Dave Hansen <haveblue@xxxxxxxxxx>
Date: Mon, 30 Jan 2006 09:04:25 -0800
Cc: Greg KH <greg@xxxxxxxxx>, xen-devel@xxxxxxxxxxxxxxxxxxx, lkml <linux-kernel@xxxxxxxxxxxxxxx>
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On Mon, 2006-01-30 at 11:58 -0500, Mike D. Day wrote:
> Dave Hansen wrote:
> > Where does that 1024 come from?  Is it a guarantee from Xen that it will
> > never fill more than 1k?  I know it is a long shot, but what if the page
> > size is less than 1k?  Would this function have strange results?
> Per the xen headers, this particular hcall option returns a typedef
> char[1024] thingy_t (which is simply a char [1024] in the patch). Yes,
> if the page size is < 1024 there is a problem. So a check against
> PAGE_SIZE may be prudent. 

I was just looking, and noticed that there is a check in the sysfs
->show() code that checks for return values greater than PAGE_SIZE and
BUG()s, so you at least won't get silent corruption.  That is probably
good enough to not worry about it.

In the final version, there will be available Xen headers, and the patch
won't need the open-coded 1024?

-- Dave

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