lkml.org 
[lkml]   [2016]   [Apr]   [14]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
Subject[Question] refcount of DT node
From
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

\
 
 \ /
  Last update: 2016-04-14 10:01    [W:0.473 / U:0.040 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site