[PATCH] ALSA: aoa: i2sbus: fix OF node lifetime handling

["Cássio Gabriel" <cassiogabrielcontato@gmail.com>]

i2sbus_add_dev() keeps the matched "sound" child pointer after
for_each_child_of_node() has dropped the iterator reference. Take an
extra reference before saving that node and drop it after the
layout-id/device-id lookup is complete.

The function also stores np in dev->sound.ofdev.dev.of_node without
taking a reference for the embedded soundbus device. Since i2sbus
overrides the embedded platform device release callback, balance that
reference explicitly in the local error path and in i2sbus_release_dev().

Fixes: f3d9478b2ce4 ("[ALSA] snd-aoa: add snd-aoa")
Cc: stable@vger.kernel.org
Signed-off-by: Cássio Gabriel <cassiogabrielcontato@gmail.com>
---
 sound/aoa/soundbus/i2sbus/core.c | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/sound/aoa/soundbus/i2sbus/core.c b/sound/aoa/soundbus/i2sbus/core.c
index 22c956267f4e..833c44c0a950 100644
--- a/sound/aoa/soundbus/i2sbus/core.c
+++ b/sound/aoa/soundbus/i2sbus/core.c
@@ -84,6 +84,7 @@ static void i2sbus_release_dev(struct device *dev)
 	for (i = aoa_resource_i2smmio; i <= aoa_resource_rxdbdma; i++)
 		free_irq(i2sdev->interrupts[i], i2sdev);
 	i2sbus_control_remove_dev(i2sdev->control, i2sdev);
+	of_node_put(i2sdev->sound.ofdev.dev.of_node);
 	mutex_destroy(&i2sdev->lock);
 	kfree(i2sdev);
 }
@@ -147,7 +148,6 @@ static int i2sbus_get_and_fixup_rsrc(struct device_node *np, int index,
 }
 
 /* Returns 1 if added, 0 for otherwise; don't return a negative value! */
-/* FIXME: look at device node refcounting */
 static int i2sbus_add_dev(struct macio_dev *macio,
 			  struct i2sbus_control *control,
 			  struct device_node *np)
@@ -178,8 +178,9 @@ static int i2sbus_add_dev(struct macio_dev *macio,
 	i = 0;
 	for_each_child_of_node(np, child) {
 		if (of_node_name_eq(child, "sound")) {
+			of_node_put(sound);
 			i++;
-			sound = child;
+			sound = of_node_get(child);
 		}
 	}
 	if (i == 1) {
@@ -205,6 +206,7 @@ static int i2sbus_add_dev(struct macio_dev *macio,
 			}
 		}
 	}
+	of_node_put(sound);
 	/* for the time being, until we can handle non-layout-id
 	 * things in some fabric, refuse to attach if there is no
 	 * layout-id property or we haven't been forced to attach.
@@ -219,7 +221,7 @@ static int i2sbus_add_dev(struct macio_dev *macio,
 	mutex_init(&dev->lock);
 	spin_lock_init(&dev->low_lock);
 	dev->sound.ofdev.archdata.dma_mask = macio->ofdev.archdata.dma_mask;
-	dev->sound.ofdev.dev.of_node = np;
+	dev->sound.ofdev.dev.of_node = of_node_get(np);
 	dev->sound.ofdev.dev.dma_mask = &dev->sound.ofdev.archdata.dma_mask;
 	dev->sound.ofdev.dev.parent = &macio->ofdev.dev;
 	dev->sound.ofdev.dev.release = i2sbus_release_dev;
@@ -327,6 +329,7 @@ static int i2sbus_add_dev(struct macio_dev *macio,
 	for (i=0;i<3;i++)
 		release_and_free_resource(dev->allocated_resource[i]);
 	mutex_destroy(&dev->lock);
+	of_node_put(dev->sound.ofdev.dev.of_node);
 	kfree(dev);
 	return 0;
 }

---
base-commit: bea8d9e445caf009ccadc17c353cc82f07885dd6
change-id: 20260329-aoa-i2sbus-ofnode-lifetime-572d49ce3ce3

Best regards,
--  
Cássio Gabriel <cassiogabrielcontato@gmail.com>