Re: [PATCH v03] powerpc/mobility: Fix node detach/rename problem

[Michael Ellerman]

Rob Herring <robh+dt@xxxxxxxxxx> writes:
> On Tue, Dec 11, 2018 at 7:29 AM Michael Ellerman <mpe@xxxxxxxxxxxxxx> wrote:
...
>> diff --git a/drivers/of/base.c b/drivers/of/base.c
>> index 09692c9b32a7..d8e4534c0686 100644
>> --- a/drivers/of/base.c
>> +++ b/drivers/of/base.c
>> @@ -1190,6 +1190,10 @@ struct device_node *of_find_node_by_phandle(phandle handle)
>>                 if (phandle_cache[masked_handle] &&
>>                     handle == phandle_cache[masked_handle]->phandle)
>>                         np = phandle_cache[masked_handle];
>> +
>> +               /* If we find a detached node, remove it */
>> +               if (of_node_check_flag(np, OF_DETACHED))
>> +                       np = phandle_cache[masked_handle] = NULL;
>
> I'm wondering if we should explicitly remove the node from the cache
> when we set OF_DETACHED. Otherwise, it could be possible that the node
> pointer has been freed already.

Yeah good point.

> Or maybe we need both?

That's probably best, it could even be a WARN_ON() if we find one in
of_find_node_by_phandle().

cheers