[PATCH 2/5] i2c: cpm: fix device_node refcount leak in cpm_i2c_probe()/cpm_i2c_remove()

[Liu Zhenlong <dragonliu2018@gmail.com>]

cpm_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 paths nor cpm_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 the probe error cleanup (out_free, which
covers both the cpm_i2c_setup() and i2c_add_numbered_adapter() failure
paths, neither of which runs i2c_del_adapter()) and to cpm_i2c_remove().

In cpm_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.
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 tqm8xx defconfig; no
hardware available for runtime testing.

Fixes: 9fd049927ccb ("of/i2c: Generalize OF support")
Cc: stable@vger.kernel.org
Assisted-by: Claude:claude-opus-5
Signed-off-by: Liu Zhenlong <dragonliu2018@gmail.com>
---
 drivers/i2c/busses/i2c-cpm.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/i2c/busses/i2c-cpm.c b/drivers/i2c/busses/i2c-cpm.c
index 2cb6a233d313..08e33db32f14 100644
--- a/drivers/i2c/busses/i2c-cpm.c
+++ b/drivers/i2c/busses/i2c-cpm.c
@@ -671,6 +671,7 @@ static int cpm_i2c_probe(struct platform_device *ofdev)
 out_shut:
 	cpm_i2c_shutdown(cpm);
 out_free:
+	of_node_put(cpm->adap.dev.of_node);
 	kfree(cpm);
 
 	return result;
@@ -679,9 +680,11 @@ static int cpm_i2c_probe(struct platform_device *ofdev)
 static void cpm_i2c_remove(struct platform_device *ofdev)
 {
 	struct cpm_i2c *cpm = platform_get_drvdata(ofdev);
+	struct device_node *node = cpm->adap.dev.of_node;
 
 	i2c_del_adapter(&cpm->adap);
 
+	of_node_put(node);
 	cpm_i2c_shutdown(cpm);
 
 	kfree(cpm);
-- 
2.55.0