[Lguest] [PATCH 4/5] lguest: use KVM hypercalls

Herbert Xu herbert at gondor.apana.org.au
Wed Apr 15 23:46:10 EST 2009


On Wed, Apr 15, 2009 at 06:35:58AM -0700, Eric W. Biederman wrote:
> 
> Because as far as I can tell we would just leak that refcount.
> 
> The poll code does not appear to call back into any of the file
> methods when it frees itself from the wait queue.

OK my suggestion was stupid.

But I still don't see how this race is possible at all.

So process A has a tun fd open and is spinning in poll(2).  Now
process B comes along and deletes that tun device.  Process A's
fd should have a netdev reference that keeps the device and
associated structures alive.

Oh I see what's going on.  We're automatically detaching the
device in uninit.  This is just wrong.  Just because process B
deleted the netdev, process A should not be involutarily detached.

Does anything actually rely on this behaviour?

If not we should just change it to not do that.

Cheers,
-- 
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Email: Herbert Xu ~{PmV>HI~} <herbert at gondor.apana.org.au>
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