[PATCH] i2c: prevent new device registration during adapter removal

[Yun Zhou]

Remove new_device and delete_device sysfs attributes early in
i2c_del_adapter() to prevent concurrent client registrations during
adapter teardown. Without this, a racing new_device_store() can
register a client that will never be cleaned up, causing
wait_for_completion() to block indefinitely.

Fixes: 99cd8e25875a ("i2c: Add a sysfs interface to instantiate devices")
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Yun Zhou <yun.zhou@xxxxxxxxxxxxx>
---
 drivers/i2c/i2c-core-base.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/drivers/i2c/i2c-core-base.c b/drivers/i2c/i2c-core-base.c
index 3ec04787a737..0f207520d6f9 100644
--- a/drivers/i2c/i2c-core-base.c
+++ b/drivers/i2c/i2c-core-base.c
@@ -1817,6 +1817,14 @@ void i2c_del_adapter(struct i2c_adapter *adap)
 
 	i2c_acpi_remove_space_handler(adap);
 
+	/*
+	 * Remove new_device/delete_device sysfs attrs early to prevent
+	 * new client registrations via userspace while we're tearing down.
+	 * kernfs will wait for any in-flight writes to complete.
+	 */
+	device_remove_file(&adap->dev, &dev_attr_new_device);
+	device_remove_file(&adap->dev, &dev_attr_delete_device);
+
 	i2c_deregister_clients(adap);
 
 	/* device name is gone after device_unregister */
-- 
2.43.0