Messages in this thread | | | Date | Wed, 3 Nov 2021 09:30:59 -0500 | From | Bjorn Helgaas <> | Subject | Re: [PATCH] PCI: kirin: Fix of_node_put() issue in pcie-kirin |
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[+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@vivo.com> > --- > 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
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