[PATCH v2 2/4] PCI: mvebu: Keep child node refcnt for probe duration

[Krzysztof Kozlowski]

Driver in probe() first iterates over child device nodes, storing the OF
node pointer but does not take the reference to it for the remaining
part of the probe where it is used.

The pointer thus could become invalid if children OF nodes are being
removed from the Devicetree, e.g. by removing OF overlay, while the
probe is being executed.  That's is highly theoretical issue, thus it
does not look like bug with any effect.

Nevertheless, make the code logically correct, so acquire the OF node
refcnt for entire lifetime of the device, since the pointer is stored in
each port state container structure.

Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski at oss.qualcomm.com>

---

Changes in v2:
1. New patch

Note: Not a fix, because practical impact is absolutely zero since
of_node_get is a noop.
---
 drivers/pci/controller/pci-mvebu.c | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/drivers/pci/controller/pci-mvebu.c b/drivers/pci/controller/pci-mvebu.c
index 4d3c97b62fe0..7fb9c7393588 100644
--- a/drivers/pci/controller/pci-mvebu.c
+++ b/drivers/pci/controller/pci-mvebu.c
@@ -1236,6 +1236,11 @@ static void mvebu_pcie_port_clk_put(void *data)
 	clk_put(port->clk);
 }
 
+static void mvebu_pcie_port_of_node_put(void *data)
+{
+	of_node_put(data);
+}
+
 static int mvebu_pcie_parse_port(struct mvebu_pcie *pcie,
 	struct mvebu_pcie_port *port, struct device_node *child)
 {
@@ -1482,7 +1487,11 @@ static int mvebu_pcie_probe(struct platform_device *pdev)
 		else if (ret == 0)
 			continue;
 
-		port->dn = child;
+		port->dn = of_node_get(child);
+		ret = devm_add_action_or_reset(dev, mvebu_pcie_port_of_node_put,
+					       child);
+		if (ret)
+			return ret;
 		i++;
 	}
 	pcie->nports = i;
-- 
2.51.0