Re: [Patch] continue_hypercall_on_cpu rework using tasklets

[Juergen Gross <juergen.gross@ts.fujitsu.com>]

Keir Fraser wrote:
> On 14/04/2010 07:58, "Juergen Gross" <juergen.gross@ts.fujitsu.com> 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

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