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[Question] refcount of DT node

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Hi experts.

My understanding of refcount of DT node is poor.
Please help me understand it correctly.

Sorry if I am asking stupid questions.


[1] Does this reference count exist for Overlay?
    Is a node freed when its refcount becomes zero?


[2] When of_node_put() should be called,
     or should not be called?


Shouldn't of_node_put() be called
when we are still referencing to any of its properties?

For example,  cpu_read_enable_method()
in arch/arm64/kernel/cpu_ops.c
returns a pointer to the property value
instead of creating a copy of it.

In this case, of_node_put() should not be called
because we are still referencing the DT property
(in other words, referencing to the DT node indirectly).

Am I right?


[3] Is the following code correct?

   np = of_find_compatible_node(NULL, NULL,"foo-node");
   of_node_put(np);
   ret = of_address_to_resource(np, 0, &res);
   if (ret) {
            pr_err("failed to get resource\n");
            return ret;
   }

Actually I wrote the code above, and it was applied.

But, the node is still referenced while of_address_to_resource() is being run.

So the correct code should be as follows?

   np = of_find_compatible_node(NULL, NULL,"foo-node");
   ret = of_address_to_resource(np, 0, &res);
   of_node_put(np);
   if (ret) {
            pr_err("failed to get resource\n");
            return ret;
   }



-- 
Best Regards
Masahiro Yamada

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[Question] refcount of DT node Masahiro Yamada <yamada.masahiro@socionext.com> - 2016-04-14 09:50 +0200
  Re: [Question] refcount of DT node Russell King - ARM Linux <linux@arm.linux.org.uk> - 2016-04-14 10:50 +0200
    Re: [Question] refcount of DT node Mark Rutland <mark.rutland@arm.com> - 2016-04-14 12:10 +0200
      Re: [Question] refcount of DT node Pantelis Antoniou <pantelis.antoniou@konsulko.com> - 2016-04-14 12:10 +0200
        Re: [Question] refcount of DT node Frank Rowand <frowand.list@gmail.com> - 2016-04-14 18:20 +0200
        Re: [Question] refcount of DT node Rob Herring <robh@kernel.org> - 2016-04-14 19:10 +0200
      Re: [Question] refcount of DT node Russell King - ARM Linux <linux@arm.linux.org.uk> - 2016-04-14 20:40 +0200
  Re: [Question] refcount of DT node Mark Rutland <mark.rutland@arm.com> - 2016-04-14 12:20 +0200
    Re: [Question] refcount of DT node Pantelis Antoniou <pantelis.antoniou@konsulko.com> - 2016-04-14 12:50 +0200

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