linux-kernel - [PATCH] of: Check 'of_node_reused' flag on of_match

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Date:   Tue, 18 Jan 2022 11:34:04 -0600
From:   Rob Herring <robh@...nel.org>
To:     Frank Rowand <frowand.list@...il.com>,
        Peter Chen <peter.chen@...nel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:     Charles Keepax <ckeepax@...nsource.cirrus.com>,
        Arnd Bergmann <arnd@...db.de>,
        Tony Lindgren <tony@...mide.com>,
        Peter Chen <peter.chen@....com>, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH] of: Check 'of_node_reused' flag on of_match_device()

Commit 0f153a1b8193 ("usb: chipidea: Set the DT node on the child
device") caused the child device to match on the parent driver
instead of the child's driver since the child's DT node pointer matched.
The worst case result is a loop of the parent driver probing another
instance and creating yet another child device eventually exhausting the
stack. If the child driver happens to match first, then everything works
fine.

A device sharing the DT node should never do DT based driver matching,
so let's simply check of_node_reused in of_match_device() to prevent
that.

Fixes: 0f153a1b8193 ("usb: chipidea: Set the DT node on the child device")
Link: https://lore.kernel.org/all/20220114105620.GK18506@ediswmail.ad.cirrus.com/
Reported-by: Charles Keepax <ckeepax@...nsource.cirrus.com>
Cc: Frank Rowand <frowand.list@...il.com>
Cc: Arnd Bergmann <arnd@...db.de>
Cc: Tony Lindgren <tony@...mide.com>
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc: Peter Chen <peter.chen@....com>
Tested-by: Charles Keepax <ckeepax@...nsource.cirrus.com>
Signed-off-by: Rob Herring <robh@...nel.org>
---
 drivers/of/device.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/of/device.c b/drivers/of/device.c
index b0800c260f64..874f031442dc 100644
--- a/drivers/of/device.c
+++ b/drivers/of/device.c
@@ -28,7 +28,7 @@
 const struct of_device_id *of_match_device(const struct of_device_id *matches,
 					   const struct device *dev)
 {
-	if ((!matches) || (!dev->of_node))
+	if (!matches || !dev->of_node || dev->of_node_reused)
 		return NULL;
 	return of_match_node(matches, dev->of_node);
 }
-- 
2.32.0