[+to Mauro, author of code being changed,
Rob for "of_pci_get_devfn()" naming question]
On Wed, Nov 03, 2021 at 02:25:18AM -0400, Wan Jiabing wrote:
> Fix following coccicheck warning:
> ./drivers/pci/controller/dwc/pcie-kirin.c:414:2-34: WARNING: Function
> for_each_available_child_of_node should have of_node_put() before return.
>
> Early exits from for_each_available_child_of_node should decrement the
> node reference counter. Replace return by goto here.
>
> Signed-off-by: Wan Jiabing <wanjiabing@xxxxxxxx>
> ---
> drivers/pci/controller/dwc/pcie-kirin.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/pci/controller/dwc/pcie-kirin.c b/drivers/pci/controller/dwc/pcie-kirin.c
> index 06017e826832..23a2c076ce53 100644
> --- a/drivers/pci/controller/dwc/pcie-kirin.c
> +++ b/drivers/pci/controller/dwc/pcie-kirin.c
> @@ -422,7 +422,8 @@ static int kirin_pcie_parse_port(struct kirin_pcie *pcie,
> pcie->num_slots++;
> if (pcie->num_slots > MAX_PCI_SLOTS) {
> dev_err(dev, "Too many PCI slots!\n");
> - return -EINVAL;
> + ret = -EINVAL;
> + goto put_node;
> }
>
> ret = of_pci_get_devfn(child);
This is a change to the code added here:
https://git.kernel.org/pub/scm/linux/kernel/git/helgaas/pci.git/commit/?id=31bd24f0cfe0
This fix looks right to me; all the other early exits from the inner
loop drop the "child" reference.
But this is a nested loop and the *outer* loop also increments
refcounts, and I don't see that outer loop reference on "parent" being
dropped at all:
for_each_available_child_of_node(node, parent) {
for_each_available_child_of_node(parent, child) {
...
if (error)
goto put_node;
}
}
put_node:
of_node_put(child);
The "of_pci_get_devfn()" immediately after is unrelated, but possibly
a confusing name. "Get" often suggests a reference count being
increased, but that's not the case with of_pci_get_devfn().
I want to fix this before sending a pull request to Linus, and I can
easily squash it into a local branch, but I need an ack from Mauro
that this patch is correct and also a fix or explanation for the outer
loop reference situation.
Bjorn
