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Re: [Xen-devel] [GIT PULL] for-2.6.32/bug-fixes

To: Jan Beulich <JBeulich@xxxxxxxxxx>
Subject: Re: [Xen-devel] [GIT PULL] for-2.6.32/bug-fixes
From: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
Date: Tue, 17 May 2011 11:57:46 -0400
Cc: Jeremy Fitzhardinge <jeremy@xxxxxxxx>, xen-devel@xxxxxxxxxxxxxxxxxxx
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> > No attaching of data to the barrier.
> Sure, this direction we agree about. But your change is enforcing
> it the other way around (if barrier then no data), which wasn't the
> case so far.

OK, even if the code that actually does the bio submission does
not attach any data to the bio? The end result is the same - no
data with barriers.

> >> Hence shouldn't you clear the sector number only when
> >> req->nr_segments is zero? Or alternatively, shouldn't
> > 
> > We could do that too.
> > 
> >> vbd_translate() simply not fail when req->nr_sects is zero?
> > 
> > It does not fail when req->nr_sects is zero. It fails when it is -1.
> >
> >> 
> >> Additionally, looking at the check in vbd_translate(), wouldn't you
> >> think there ought to be overflow checking for the addition, too?
> > 
> > Sure, could add that in. Albeit it seems incorrect to do it in that
> > function. It checks to see if the sector is correct, and -1 is definitly
> > wrong.
> Hmm, depends on your perspective - I'd say that any sector_number
> is valid when nr_sects is zero.

I concur. The value that is passed by the frontend is not zero. It is -1.

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