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

[Michael Ellerman]

Frank Rowand <frowand.list@xxxxxxxxx> writes:
> On 12/11/18 8:07 AM, Rob Herring wrote:
>> 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;
>
> The bug you found exposes a couple of different issues, a little bit
> deeper than the proposed fix.  I'll work on a fuller fix tonight or
> tomorrow.

OK thanks.

>> 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. Or maybe we need both?
>
> Yes, it should be explicitly removed.  I may also add in a paranoia check in
> of_find_node_by_phandle().

That seems best to me.

cheers