OF_DYNAMIC node lifecycle

[Grant Likely]

On Thu, 26 Jun 2014 15:01:49 -0500, Nathan Fontenot <nfont at austin.ibm.com> wrote:
> On 06/25/2014 03:24 PM, Grant Likely wrote:
> > On Tue, 24 Jun 2014 15:10:55 -0500, Nathan Fontenot <nfont at austin.ibm.com> wrote:
> >>>> heh! I have often thought about adding reference counting to device tree
> >>>> properties.
> >>>
> >>> You horrible, horrible man.
> >>
> >> Yes. I are evil :)
> >>
> >> After looking again the work needed to add reference counts to properties
> >> would be huge. The few properties I am concerned with are specific to powerpc
> >> so perhaps just adding an arch specific lock around updating those
> >> properties would work.
> > 
> > Which code/properties? I'd like to have a look myself.
> 
> /ibm,dynamic-reconfiguration-memory/ibm,dynamic-memory
> 
> The property is updated in 
> arch/powerpc/platforms/pseries/hotplug-memory.c:pseries_update_drconf_memory()

Specifically, what do you need for the locking? Are you wanting to hold
off additional changes while that function is executing? Pantelis is
adding a mutex for device tree writers. Holding that mutex would prevent
any changes from happening in the tree without affecting readers. Would
that be sufficient?

g.