From: Masahiro Yamada <yamada.masahiro@socionext.com>
To: devicetree@vger.kernel.org
Cc: Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
linux-arm-kernel <linux-arm-kernel@lists.infradead.org>,
Rob Herring <robh+dt@kernel.org>, Arnd Bergmann <arnd@arndb.de>,
Frank Rowand <frowand.list@gmail.com>
Subject: [Question] refcount of DT node
Date: Thu, 14 Apr 2016 16:47:57 +0900 [thread overview]
Message-ID: <CAK7LNATFUW2KXUpFas6C_SJ0C7Qb1DWU0njLg-FCYciK2U6Oag@mail.gmail.com> (raw)
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
next reply other threads:[~2016-04-14 7:48 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-04-14 7:47 Masahiro Yamada [this message]
2016-04-14 8:48 ` [Question] refcount of DT node Russell King - ARM Linux
2016-04-14 9:59 ` Mark Rutland
2016-04-14 10:02 ` Pantelis Antoniou
2016-04-14 16:10 ` Frank Rowand
2016-04-14 17:02 ` Rob Herring
2016-04-14 18:38 ` Russell King - ARM Linux
2016-04-16 15:02 ` Masahiro Yamada
2016-04-14 10:10 ` Mark Rutland
2016-04-14 10:40 ` Pantelis Antoniou
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