[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

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

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).


Julien Grall

Xen-devel mailing list



Lists.xenproject.org is hosted with RackSpace, monitoring our
servers 24x7x365 and backed by RackSpace's Fanatical Support®.