Re: [PATCH] adjust root-domain->online span in response to hotplug event

[Suresh Siddha <suresh.b.siddha@intel.com>]

On Sat, Mar 08, 2008 at 12:10:15AM -0500, Gregory Haskins wrote:
> Suresh Siddha wrote:
>  >
>  > -	cpus_and(*lowest_mask, task_rq(task)->rd->online, task->cpus_allowed);
>  > +	cpus_and(*lowest_mask, task->cpus_allowed, cpu_online_map);
> 
> Hi Suresh,
>    Unfortunately, this patch will introduce its own set of bugs. 

Is that because of the missing get/put_online_cpus() ?

> However, your analysis was spot-on.  I think I see the problem now.  It 
> was introduced when I put a hack in to "fix" s2ram problems in -mm as a 
> result of the new root-domain logic.  I think the following patch will 
> fix both issues:

BTW, what is use of per root domains online map, when we have global
cpu_online_map() ? Each domains span & cpu_online_map should give
domain_online_map anyhow.

And is n't it buggy if someone accesses rd->online with out get/put_online_map()

thanks,
suresh