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cb739d3ce5
commit 9448e55d032d99af8e23487f51a542d51b2f1a48 upstream.
The recent addition of scope based cleanup support to the kernel
provides a convenient tool to reduce the chances of leaking reference
counts where of_node_put() should have been called in an error path.
This enables
struct device_node *child __free(device_node) = NULL;
for_each_child_of_node(np, child) {
if (test)
return test;
}
with no need for a manual call of of_node_put().
A following patch will reduce the scope of the child variable to the
for loop, to avoid an issues with ordering of autocleanup, and make it
obvious when this assigned a non NULL value.
In this simple example the gains are small but there are some very
complex error handling cases buried in these loops that will be
greatly simplified by enabling early returns with out the need
for this manual of_node_put() call.
Note that there are coccinelle checks in
scripts/coccinelle/iterators/for_each_child.cocci to detect a failure
to call of_node_put(). This new approach does not cause false positives.
Longer term we may want to add scripting to check this new approach is
done correctly with no double of_node_put() calls being introduced due
to the auto cleanup. It may also be useful to script finding places
this new approach is useful.
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20240225142714.286440-2-jic23@kernel.org
Signed-off-by: Rob Herring <robh@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.