[PATCH 1/3] PCI: pci-host-generic: Fix lookup of linux, pci-probe-only property

[Marc Zyngier <marc.zyngier@arm.com>]

When pci-host-generic looks for the probe-only property, it seems
to trust the DT to be correctly written, and assumes that there
is a parameter to the property.

Unfortunately, this is not always the case, and some firmware expose
this property naked. The driver ends up making a decision based on
whatever the property pointer points to, which is likely to be junk.

Instead, let's check for the validity of the property, and ignore
it if the firmware couldn't make up its mind.

Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
---
 drivers/pci/host/pci-host-generic.c | 15 ++++++++++-----
 1 file changed, 10 insertions(+), 5 deletions(-)

diff --git a/drivers/pci/host/pci-host-generic.c b/drivers/pci/host/pci-host-generic.c
index 265dd25..2b2e2ff 100644
--- a/drivers/pci/host/pci-host-generic.c
+++ b/drivers/pci/host/pci-host-generic.c
@@ -211,6 +211,7 @@ static int gen_pci_probe(struct platform_device *pdev)
 	const char *type;
 	const struct of_device_id *of_id;
 	const int *prop;
+	int len;
 	struct device *dev = &pdev->dev;
 	struct device_node *np = dev->of_node;
 	struct gen_pci *pci = devm_kzalloc(dev, sizeof(*pci), GFP_KERNEL);
@@ -225,12 +226,16 @@ static int gen_pci_probe(struct platform_device *pdev)
 		return -EINVAL;
 	}
 
-	prop = of_get_property(of_chosen, "linux,pci-probe-only", NULL);
+	prop = of_get_property(of_chosen, "linux,pci-probe-only", &len);
 	if (prop) {
-		if (*prop)
-			pci_add_flags(PCI_PROBE_ONLY);
-		else
-			pci_clear_flags(PCI_PROBE_ONLY);
+		if (len) {
+			if (be32_to_cpup(prop))
+				pci_add_flags(PCI_PROBE_ONLY);
+			else
+				pci_clear_flags(PCI_PROBE_ONLY);
+		} else {
+			dev_warn(&pdev->dev, "linux,pci-probe-only set without value, ignoring\n");
+		}
 	}
 
 	of_id = of_match_node(gen_pci_of_match, np);
-- 
2.1.4