[PATCH] net: stmmac: fix device node reference leaks in stmmac_mtl_setup()

[Md Rabbani]

In stmmac_mtl_setup(), q_node is shared across the RX and TX queue
parsing loops. When the RX queue loop breaks early because the number
of parsed queues reaches plat->rx_queues_to_use, q_node retains an
acquired reference count. If the error check passes
(queue == plat->rx_queues_to_use), execution proceeds directly to the
TX queue loop, where of_get_next_child() immediately overwrites q_node
with the first TX child, permanently leaking the retained RX child
device node reference.

Switch both loops to for_each_child_of_node_scoped() so child node
references are automatically dropped upon loop exit or early break,
and remove the now-unnecessary function-scoped q_node variable and
its manual of_node_put() at the exit label.

Signed-off-by: Md Rabbani <rabbanyhmm at gmail.com>
---
 drivers/net/ethernet/stmicro/stmmac/stmmac_platform.c | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_platform.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_platform.c
index dc5f951a31..6128ed1bd5 100644
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac_platform.c
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_platform.c
@@ -130,7 +130,6 @@ static struct stmmac_axi *stmmac_axi_setup(struct platform_device *pdev)
 static int stmmac_mtl_setup(struct platform_device *pdev,
 			    struct plat_stmmacenet_data *plat)
 {
-	struct device_node *q_node;
 	struct device_node *rx_node;
 	struct device_node *tx_node;
 	u8 queue = 0;
@@ -169,7 +168,7 @@ static int stmmac_mtl_setup(struct platform_device *pdev,
 		plat->rx_sched_algorithm = MTL_RX_ALGORITHM_SP;
 
 	/* Processing individual RX queue config */
-	for_each_child_of_node(rx_node, q_node) {
+	for_each_child_of_node_scoped(rx_node, q_node) {
 		if (queue >= plat->rx_queues_to_use)
 			break;
 
@@ -227,7 +226,7 @@ static int stmmac_mtl_setup(struct platform_device *pdev,
 	queue = 0;
 
 	/* Processing individual TX queue config */
-	for_each_child_of_node(tx_node, q_node) {
+	for_each_child_of_node_scoped(tx_node, q_node) {
 		if (queue >= plat->tx_queues_to_use)
 			break;
 
@@ -276,7 +275,6 @@ static int stmmac_mtl_setup(struct platform_device *pdev,
 out:
 	of_node_put(rx_node);
 	of_node_put(tx_node);
-	of_node_put(q_node);
 
 	return ret;
 }
-- 
2.55.0.windows.3