Re: [PATCH] PCI/hotplug: Remove unneeded of_node_put() in pnv_php

[Nathan Lynch]

Wan Jiabing <wanjiabing@xxxxxxxx> writes:
> Fix following coccicheck warning:
> ./drivers/pci/hotplug/pnv_php.c:161:2-13: ERROR: probable double put.
>
> Device node iterators put the previous value of the index variable, so
> an explicit put causes a double put.

I suppose Coccinelle doesn't take into account that this code is
detaching and freeing the nodes.


> diff --git a/drivers/pci/hotplug/pnv_php.c b/drivers/pci/hotplug/pnv_php.c
> index f4c2e6e01be0..f3da4f95d73f 100644
> --- a/drivers/pci/hotplug/pnv_php.c
> +++ b/drivers/pci/hotplug/pnv_php.c
> @@ -158,7 +158,6 @@ static void pnv_php_detach_device_nodes(struct device_node *parent)
>  	for_each_child_of_node(parent, dn) {
>  		pnv_php_detach_device_nodes(dn);
>  
> -		of_node_put(dn);
>  		of_detach_node(dn);
>  	}

The code might be improved by comments explaining how the bare
of_node_put() corresponds to a "get" somewhere else in the driver, and
how it doesn't render the ongoing traversal unsafe. It looks suspicious
on first review, but I believe it's intentional and probably correct as
written.