Re: [Xen-devel] [Patch] continue_hypercall_on_cpu rework using tasklets

[Juergen Gross <juergen.gross@xxxxxxxxxxxxxx>]

Keir Fraser wrote:
> On 14/04/2010 07:58, "Juergen Gross" <juergen.gross@xxxxxxxxxxxxxx> wrote:
> 
>>> The per-cpu area method should work fine, since Xen is non-preemptive? I
>>> don't think the concurrency you are concerned about can happen.
>> The tasklet knows only on which cpu it is running, so the data has to be
>> stored on the target cpu. And one pcpu can be the target of concurrent calls
>> from different calling cpus...
> 
> A tasklet also takes an arbitrary ulong parameter, which you can cast to a
> pointer to your informational structure. The parameter is specified via
> tasklet_init(). That should suffice.

I'm already using this. The problem is to find the original calling vcpu in
case of a nested call of continue_hypercall_on_cpu() while not conflicting
with concurrent calls from other vcpus which happen to address the same pcpu.


Juergen

-- 
Juergen Gross                 Principal Developer Operating Systems
TSP ES&S SWE OS6                       Telephone: +49 (0) 89 3222 2967
Fujitsu Technology Solutions              e-mail: juergen.gross@xxxxxxxxxxxxxx
Domagkstr. 28                           Internet: ts.fujitsu.com
D-80807 Muenchen                 Company details: ts.fujitsu.com/imprint.html

_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/xen-devel