Re: [PATCH 1/3] libxl: In domain death search, start search at first domid we want

[Ian Campbell <ian.campbell@citrix.com>]

On Tue, 2015-03-17 at 09:30 -0600, Jim Fehlig wrote:
> From: Ian Jackson <Ian.Jackson@eu.citrix.com>
> 
> From: Ian Jackson <Ian.Jackson@eu.citrix.com>
> 
> When domain_death_xswatch_callback needed a further call to
> xc_domain_getinfolist it would restart it with the last domain it
> found rather than the first one it wants.
> 
> If it only wants one it will also only ask for one domain.  The result
> would then be that it gets the previous domain again (ie, the previous
> one to the one it wants), which still doesn't reveal the answer to the
> question, and it would therefore loop again.
> 
> It's completely unclear to me why I thought it was a good idea to
> start the xc_domain_getinfolist with the last domain previously found
> rather than the first one left un-confirmed.  The code has been that
> way since it was introduced.

Is it because the xc_domain_getinfolist will fetch at most:
        int nentries = LIBXL_TAILQ_NEXT(evg, entry) ? 200 : 1;
entries?

After your change then if the domid we are looking for is the 201st
domain then won't we just keep going round looking at the first 200
(undying) domains?

Ian.