linux-kernel - [PATCH AUTOSEL 5.7 150/388] of: property: Do not link to disabled devices

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Date:   Wed, 17 Jun 2020 21:04:07 -0400
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Nicolas Saenz Julienne <nsaenzjulienne@...e.de>,
        Saravana Kannan <saravanak@...gle.com>,
        Rob Herring <robh@...nel.org>, Sasha Levin <sashal@...nel.org>,
        devicetree@...r.kernel.org
Subject: [PATCH AUTOSEL 5.7 150/388] of: property: Do not link to disabled devices

From: Nicolas Saenz Julienne <nsaenzjulienne@...e.de>

[ Upstream commit 7456427af9def0fec5508dd8b861556038ee96a8 ]

When creating a consumer/supplier relationship between two devices,
make sure the supplier node is actually active. Otherwise this will
create a link relationship that will never be fulfilled. This, in the
worst case scenario, will hang the system during boot.

Note that, in practice, the fact that a device-tree represented
consumer/supplier relationship isn't fulfilled will not prevent devices
from successfully probing.

Fixes: a3e1d1a7f5fc ("of: property: Add functional dependency link from DT bindings")
Signed-off-by: Nicolas Saenz Julienne <nsaenzjulienne@...e.de>
Reviewed-by: Saravana Kannan <saravanak@...gle.com>
Signed-off-by: Rob Herring <robh@...nel.org>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/of/property.c | 14 +++++++++++++-
 1 file changed, 13 insertions(+), 1 deletion(-)

diff --git a/drivers/of/property.c b/drivers/of/property.c
index a8c2b13521b2..6dc542af5a70 100644
--- a/drivers/of/property.c
+++ b/drivers/of/property.c
@@ -1045,8 +1045,20 @@ static int of_link_to_phandle(struct device *dev, struct device_node *sup_np,
 	 * Find the device node that contains the supplier phandle.  It may be
 	 * @sup_np or it may be an ancestor of @sup_np.
 	 */
-	while (sup_np && !of_find_property(sup_np, "compatible", NULL))
+	while (sup_np) {
+
+		/* Don't allow linking to a disabled supplier */
+		if (!of_device_is_available(sup_np)) {
+			of_node_put(sup_np);
+			sup_np = NULL;
+		}
+
+		if (of_find_property(sup_np, "compatible", NULL))
+			break;
+
 		sup_np = of_get_next_parent(sup_np);
+	}
+
 	if (!sup_np) {
 		dev_dbg(dev, "Not linking to %pOFP - No device\n", tmp_np);
 		return -ENODEV;
-- 
2.25.1