Re: [Qemu-devel] fw cfg files cross-version migration races

[Gabriel L. Somlo]

On Mon, Jun 08, 2015 at 02:33:45PM +0200, Gerd Hoffmann wrote:
>  Hi,
> 
> > I'm wonderingjust when exactly to start sorting items in fw_cfg ? 
> 
> I'd suggest to sort as entries are added, i.e. just insert the new entry
> at the correct place instead of tacking it to the end.  So the list is
> always sorted.

I was thinking that too, but since these are all arrays (not linked
lists), I'm a bit put off by the idea of having to shift everything
that's already in there by one position upon each "sorted insert".
Not to mention updating the "select" field of each FWCfgFile entry in
the directory (and maybe sorting/shifting the FWCfgFiles directory
itself) :(

Combined with "only do this on machine versions 2.4 or later", maybe
just sorting everything during the machine_ready callback would be
less hairy ?

I'll be on vacation for one week, so meditating on this in the back
of my mind might help come up with something... :)

Thanks,
--Gabriel