[PATCH] mtd: partitions: fix of_node_get/put balance in parser

[Miquel Raynal <miquel.raynal@xxxxxxxxxxx>]

While at first mtd_part_of_parse() would just call
of_get_chil_by_name(), it has been edited to first try to get the OF
node thanks to mtd_get_of_node() and fallback on
of_get_child_by_name().

A of_node_put() was a bit below in the code, to balance the
of_get_child_by_name(). However, despite its name, mtd_get_of_node()
does not take a reference on the OF node. It is a simple helper hiding
some pointer logic to retrieve the OF node related to an MTD
device. People often used it this way:

    of_node_put(mtd_get_of_node(<mtd>)).

The direct effect of such unbalanced reference counting is visible by
rmmod'ing any module that would have added MTD partitions:

    OF: ERROR: Bad of_node_put() on <of_path_to_partition>

As it seems normal to get a reference on the OF node during the
of_property_for_each_string() that follows, add a call to
of_node_get() when relevant.

Fixes: 76a832254ab0 ("mtd: partitions: use DT info for parsing partitions with "compatible" prop")
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Miquel Raynal <miquel.raynal@xxxxxxxxxxx>
---
 drivers/mtd/mtdpart.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/mtd/mtdpart.c b/drivers/mtd/mtdpart.c
index 52e2cb35fc79..99c460facd5e 100644
--- a/drivers/mtd/mtdpart.c
+++ b/drivers/mtd/mtdpart.c
@@ -873,8 +873,11 @@ static int mtd_part_of_parse(struct mtd_info *master,
 	int ret, err = 0;
 
 	np = mtd_get_of_node(master);
-	if (!mtd_is_partition(master))
+	if (mtd_is_partition(master))
+		of_node_get(np);
+	else
 		np = of_get_child_by_name(np, "partitions");
+
 	of_property_for_each_string(np, "compatible", prop, compat) {
 		parser = mtd_part_get_compatible_parser(compat);
 		if (!parser)
-- 
2.17.1


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