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From: Gerd Hoffmann <kraxel@redhat.com>
Date: Tue, 13 May 2014 10:44:45 +0200
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Subject: Re: [Qemu-devel] [PATCH] usb: fix up post load checks
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To: "Michael S. Tsirkin" <mst@redhat.com>
Cc: qemu-devel@nongnu.org, dgilbert@redhat.com

On Di, 2014-05-13 at 11:32 +0300, Michael S. Tsirkin wrote:
> On Tue, May 13, 2014 at 09:50:09AM +0200, Gerd Hoffmann wrote:
> >   Hi,
> > 
> > > +        (dev->setup_state == SETUP_STATE_DATA &&
> > 
> > Fails to build, SETUP_STATE_DATA is not defined here.
> > 
> > I think we can simply drop that check, index should never ever be larger
> > than len, no matter what the state is.
> > 
> > cheers,
> >   Gerd
> 
> I'm confused by usb_generic_async_ctrl_complete which can modify len
> without touching index.

only in setup state, before any data from/to the buffer is transfered,
so index is still zero at that point.

flow is this:

state_setup: len = $buflen, index = 0
state_data:  xfer %buf data, increase index up to len while doing so.
state_ack:   index == len
state_idle:  likewise.

cheers,
  Gerd