[PATCH 1/5] i2c: mpc: fix device_node refcount leak in fsl_i2c_probe()/fsl_i2c_remove()

fsl_i2c_probe() calls of_node_get() to take an extra reference on the
platform device's of_node when assigning it to the adapter device, but
neither the probe error path nor fsl_i2c_remove() drops it.

device_release() does not call of_node_put() and i2c_adapter_dev_release()
only completes a struct, so the extra reference is never released, leaking
the device_node on every probe failure and every adapter removal.

Add the matching of_node_put() to both paths.

In the probe error path, i2c_add_numbered_adapter() failure does not run
i2c_del_adapter(), so of_node_put(i2c->adap.dev.of_node) is safe.

In fsl_i2c_remove(), i2c_del_adapter() clears adap->dev with memset() at
the end (commit bd4bc3dbded9 ("i2c: Clear i2c_adapter.dev on adapter
removal")), which zeroes adap->dev.of_node before of_node_put() runs,
turning it into a no-op.  Cache the pointer before calling
i2c_del_adapter(), the same approach used in i2c-mux
(i2c_mux_del_adapters) and mtd (commit 56570bdad5e3 ("mtd: core: Fix
refcount error in del_mtd_device()")).

Compile-tested with gcc-powerpc-linux-gnu on pmac32 defconfig; no
hardware available for runtime testing.

Fixes: 9fd049927ccb ("of/i2c: Generalize OF support")
Cc: [email protected]
Assisted-by: Claude:claude-opus-5
Signed-off-by: Liu Zhenlong <[email protected]>
---
 drivers/i2c/busses/i2c-mpc.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/drivers/i2c/busses/i2c-mpc.c b/drivers/i2c/busses/i2c-mpc.c
index a21fa45bd64c..8182f7dc3d0f 100644
--- a/drivers/i2c/busses/i2c-mpc.c
+++ b/drivers/i2c/busses/i2c-mpc.c
@@ -867,8 +867,10 @@ static int fsl_i2c_probe(struct platform_device *op)
 	i2c_set_adapdata(&i2c->adap, i2c);
 
 	result = i2c_add_numbered_adapter(&i2c->adap);
-	if (result)
+	if (result) {
+		of_node_put(i2c->adap.dev.of_node);
 		return result;
+	}
 
 	return 0;
 };
@@ -876,8 +878,10 @@ static int fsl_i2c_probe(struct platform_device *op)
 static void fsl_i2c_remove(struct platform_device *op)
 {
 	struct mpc_i2c *i2c = platform_get_drvdata(op);
+	struct device_node *node = i2c->adap.dev.of_node;
 
 	i2c_del_adapter(&i2c->adap);
+	of_node_put(node);
 };
 
 static int __maybe_unused mpc_i2c_suspend(struct device *dev)
-- 
2.55.0