[PATCH] PCI: keystone: Fix host bridge device leak in ks_pcie_quirk()

[Wentao Liang <vulab@iscas.ac.cn>]

ks_pcie_quirk() obtains a reference to the host bridge device with
pci_get_host_bridge_device() but never releases it.  Every early exit
from the AM654 PG1.0 workaround leaks the reference: when the bridge
device or its parent is missing, when the parent has no driver data,
and when the RTL revision is not AM6_PCI_PG1_RTL_VER.  The quirk runs
for every downstream PCI device, so the reference count grows without
bound.

Add a common out label that drops the reference with
pci_put_host_bridge_device() before returning.

Fixes: 86f271f22bbb ("PCI: keystone: Add workaround for Errata #i2037 (AM65x SR 1.0)")
Cc: stable@vger.kernel.org
Signed-off-by: Wentao Liang <vulab@iscas.ac.cn>
---
 drivers/pci/controller/dwc/pci-keystone.c | 12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/drivers/pci/controller/dwc/pci-keystone.c b/drivers/pci/controller/dwc/pci-keystone.c
index 278d2dba1db0..cc6739edd434 100644
--- a/drivers/pci/controller/dwc/pci-keystone.c
+++ b/drivers/pci/controller/dwc/pci-keystone.c
@@ -528,7 +528,7 @@ static void ks_pcie_quirk(struct pci_dev *dev)
 {
 	struct pci_bus *bus = dev->bus;
 	struct keystone_pcie *ks_pcie;
-	struct device *bridge_dev;
+	struct device *bridge_dev = NULL;
 	struct pci_dev *bridge;
 	u32 val;
 
@@ -582,23 +582,27 @@ static void ks_pcie_quirk(struct pci_dev *dev)
 	if (pci_match_id(am6_pci_devids, bridge)) {
 		bridge_dev = pci_get_host_bridge_device(dev);
 		if (!bridge_dev || !bridge_dev->parent)
-			return;
+			goto out;
 
 		ks_pcie = dev_get_drvdata(bridge_dev->parent);
 		if (!ks_pcie)
-			return;
+			goto out;
 
 		val = ks_pcie_app_readl(ks_pcie, PID);
 		val &= RTL;
 		val >>= RTL_SHIFT;
 		if (val != AM6_PCI_PG1_RTL_VER)
-			return;
+			goto out;
 
 		if (pcie_get_readrq(dev) > 128) {
 			dev_info(&dev->dev, "limiting MRRS to 128 bytes\n");
 			pcie_set_readrq(dev, 128);
 		}
 	}
+
+out:
+	if (bridge_dev)
+		pci_put_host_bridge_device(bridge_dev);
 }
 DECLARE_PCI_FIXUP_ENABLE(PCI_ANY_ID, PCI_ANY_ID, ks_pcie_quirk);
 
-- 
2.34.1