Re: [PATCH] PCI: kirin: Fix of_node_put() issue in pcie-kirin

[Jiabing Wan]

On 2021/11/4 21:56, Rob Herring wrote:
> On Wed, Nov 3, 2021 at 9:31 AM Bjorn Helgaas <helgaas@xxxxxxxxxx> wrote:
> > [+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);
> Indeed. There should be a put on the parent.
OK, I'll fix in v2. Thanks.

Jiabing Wan