linux-kernel - [PATCH 3.16 038/254] mfd: twl6040: Fix child-node lookup

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Message-ID: <lsq.1519831218.742866676@decadent.org.uk>
Date:   Wed, 28 Feb 2018 15:20:18 +0000
From:   Ben Hutchings <ben@...adent.org.uk>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:     akpm@...ux-foundation.org, "Johan Hovold" <johan@...nel.org>,
        "Peter Ujfalusi" <peter.ujfalusi@...com>,
        "Lee Jones" <lee.jones@...aro.org>
Subject: [PATCH 3.16 038/254] mfd: twl6040: Fix child-node lookup

3.16.55-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Johan Hovold <johan@...nel.org>

commit 85e9b13cbb130a3209f21bd7933933399c389ffe upstream.

Fix child-node lookup during probe, which ended up searching the whole
device tree depth-first starting at the parent rather than just matching
on its children.

To make things worse, the parent node was prematurely freed, while the
child node was leaked.

Note that the CONFIG_OF compile guard can be removed as
of_get_child_by_name() provides a !CONFIG_OF implementation which always
fails.

Fixes: 37e13cecaa14 ("mfd: Add support for Device Tree to twl6040")
Fixes: ca2cad6ae38e ("mfd: Fix twl6040 build failure")
Signed-off-by: Johan Hovold <johan@...nel.org>
Acked-by: Peter Ujfalusi <peter.ujfalusi@...com>
Signed-off-by: Lee Jones <lee.jones@...aro.org>
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 drivers/mfd/twl6040.c | 12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

--- a/drivers/mfd/twl6040.c
+++ b/drivers/mfd/twl6040.c
@@ -97,12 +97,16 @@ static struct reg_default twl6040_patch[
 };
 
 
-static bool twl6040_has_vibra(struct device_node *node)
+static bool twl6040_has_vibra(struct device_node *parent)
 {
-#ifdef CONFIG_OF
-	if (of_find_node_by_name(node, "vibra"))
+	struct device_node *node;
+
+	node = of_get_child_by_name(parent, "vibra");
+	if (node) {
+		of_node_put(node);
 		return true;
-#endif
+	}
+
 	return false;
 }