Re: [Xen-devel] [PATCH 4/7] xen/arm: When CPU dies, free percpu area immediatelly

[Julien Grall <julien.grall@xxxxxxx>]

On 16/04/18 14:41, Mirela Simonovic wrote:
> On Mon, Apr 16, 2018 at 3:14 PM, Julien Grall <julien.grall@xxxxxxx> wrote:
> > On 12/04/18 22:31, Stefano Stabellini wrote:
> > > On Thu, 12 Apr 2018, Julien Grall wrote:
> > > > On 12/04/18 00:46, Stefano Stabellini wrote:
> > > > > On Wed, 11 Apr 2018, Julien Grall wrote:
> > > > > > On 11/04/18 14:19, Mirela Simonovic wrote:
> > I guess the rcu_barrier() in the function handling suspend/resume works. But
> > that doesn't cover the hotplug case. Looking at x86, suspend/resume case.
> > For the hotplug case, there are an rcu_barrier in cpu_{up,down}_helper but
> > they are only present in the case of cpu_{up,down} failed. I am not entirely
> > sure how this is handled in x86
> >
> > Andrew, Jan, do you know when the percpu will be free on hotplug? It is call
> > to call_rcu(...) but I am not sure when this is going to be executed.
> AFAIK disable/enable_nonboot_cpus() is the only way to do the hotplug
> and rcu_barrier() is not included in the flow.
That's not the only way. I clearly specified one in my previous answer 
(see cpu_{up,down}_helper) and there are other place (look for cpu_up).
Cheers,

--
Julien Grall

_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxxx
https://lists.xenproject.org/mailman/listinfo/xen-devel