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From:   Ben Hutchings <ben@decadent.org.uk>
To:     linux-kernel@vger.kernel.org, stable@vger.kernel.org
CC:     akpm@linux-foundation.org, "Johan Hovold" <johan@kernel.org>,
        "Lee Jones" <lee.jones@linaro.org>,
        "Daniel Thompson" <daniel.thompson@linaro.org>
Date:   Sun, 11 Nov 2018 19:49:05 +0000
Message-ID: <lsq.1541965745.641036678@decadent.org.uk>
Subject: [PATCH 3.16 131/366] backlight: max8925_bl: Fix Device Tree node
 lookup
In-Reply-To: <lsq.1541965744.387173642@decadent.org.uk>
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

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

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

From: Johan Hovold <johan@kernel.org>

commit d1cc0ec3da23e44c23712579515494b374f111c9 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 mfd node was also prematurely freed,
while the child backlight node was leaked.

Fixes: 47ec340cb8e2 ("mfd: max8925: Support dt for backlight")
Signed-off-by: Johan Hovold <johan@kernel.org>
Acked-by: Daniel Thompson <daniel.thompson@linaro.org>
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
 drivers/video/backlight/max8925_bl.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

--- a/drivers/video/backlight/max8925_bl.c
+++ b/drivers/video/backlight/max8925_bl.c
@@ -116,7 +116,7 @@ static void max8925_backlight_dt_init(st
 	if (!pdata)
 		return;
 
-	np = of_find_node_by_name(nproot, "backlight");
+	np = of_get_child_by_name(nproot, "backlight");
 	if (!np) {
 		dev_err(&pdev->dev, "failed to find backlight node\n");
 		return;
@@ -125,6 +125,8 @@ static void max8925_backlight_dt_init(st
 	if (!of_property_read_u32(np, "maxim,max8925-dual-string", &val))
 		pdata->dual_string = val;
 
+	of_node_put(np);
+
 	pdev->dev.platform_data = pdata;
 }