[PATCH 2/9] pci: mvebu: fix memory leaks and refcount leaks

[linux@arm.linux.org.uk (Russell King - ARM Linux)]

On Fri, Oct 09, 2015 at 05:14:42PM +0200, Thomas Petazzoni wrote:
> Julia: some of the Device Tree iterator functions have a somewhat
> "interesting" behavior in that they take the reference on the current
> child when entering the loop, and release it before entering the next
> iteration (which will also take a reference to the next child).
> 
> This means that if you have an exit point inside the loop (break or
> return), you are loosing a reference. For example,
> http://lxr.free-electrons.com/source/arch/arm/mach-shmobile/pm-rmobile.c#L367
> is wrong because there is a missing of_node_put(np) before the "return
> -ENOMEM".
> 
> So essentially, every exit point in such Device Tree iteration loops
> should make to call of_node_put() on the current element before exiting
> the loop unexpectedly.

There is an exception to that... if the loop is part of a DT node lookup
function, which would return a DT node based on some search criteria, it
would be valid to break out of the loop while holding a reference.

For example, of_get_child_by_name(), of_find_next_cache_node(),
of_graph_get_port_by_id(), are valid breaker-outer cases. ;)

However, of_platform_bus_probe(), of_platform_populate(),
of_overlay_apply_one(), overlay_subtree_check() are examples of
incorrect break-out cases.

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