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SubjectRe: [RFC PATCH] OF: fix of_find_node_by_path() assumption that of_allnodes is root
On Fri, Jun 13, 2014 at 4:06 PM, Grant Likely <grant.likely@linaro.org> wrote:
> On Fri, Jun 13, 2014 at 2:52 PM, Rob Herring <robherring2@gmail.com> wrote:
>> On Fri, Jun 13, 2014 at 12:53 AM, Frank Rowand <frowand.list@gmail.com> wrote:
>>> From: Frank Rowand <frank.rowand@sonymobile.com>
>>>
>>> Pantelis Antoniou reports that of_find_node_by_path() is borked because
>>> of_allnodes is not guaranteed to contain the root of the tree after using
>>> any of the dynamic update functions because some other nodes ends up as
>>> of_allnodes.
>>>
>>> Fixes: c22e650e66b8 of: Make of_find_node_by_path() handle /aliases
>>
>> Is it not possible to do a fix in of_find_node_by_path instead? I just
>> wonder if this could have any other unintended side-effects on
>> of_attach_node's behavior.
>
> Given that I'm going to replace the custom list with list_head which
> makes this problem go away, I think this solution is fine.
>
> Acked-by: Grant Likely <grant.likely@linaro.org>

That said, the following might be better because it would guarantee
that children always appear after parents...

>> Rob
>>
>>>
>>> Signed-off-by: Frank Rowand <frank.rowand@sonymobile.com>
>>> ---
>>>
>>>
>>> Pantelis,
>>>
>>> Can you test whether the problem you reported in irc?
>>>
>>> This patch has not been tested, not even compile tested.
>>>
>>>
>>> drivers/of/base.c | 8 6 + 2 - 0 !
>>> 1 file changed, 6 insertions(+), 2 deletions(-)
>>>
>>> Index: b/drivers/of/base.c
>>> ===================================================================
>>> --- a/drivers/of/base.c
>>> +++ b/drivers/of/base.c
>>> @@ -1948,6 +1948,9 @@ int of_reconfig_notify(unsigned long act
>>>
>>> /**
>>> * of_attach_node - Plug a device node into the tree and global list.
>>> + *
>>> + * Put the device node after of_allnodes in the global list so that
>>> + * of_allnodes remains the root.
>>> */
>>> int of_attach_node(struct device_node *np)
>>> {
>>> @@ -1958,11 +1961,12 @@ int of_attach_node(struct device_node *n
>>> if (rc)
>>> return rc;
>>>
>>> + BUG_ON(!of_allnodes);
>>> raw_spin_lock_irqsave(&devtree_lock, flags);
>>> np->sibling = np->parent->child;
>>> - np->allnext = of_allnodes;
>>> + np->allnext = of_allnodes->allnext;

np->allnext = np->parent->allnext;
np->parent->allnext = np;

>>> np->parent->child = np;
>>> - of_allnodes = np;
>>> + of_allnodes->allnext = np;
>>> of_node_clear_flag(np, OF_DETACHED);
>>> raw_spin_unlock_irqrestore(&devtree_lock, flags);
>>>


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