[PATCH 2/5] i3c: master: Fix refcount of i3c fwnode

[Akhil R]

i3c_master_add_i3c_boardinfo() takes a reference on the firmware node of
every i3c child described for the bus and never drops it, while
i3c_device_release() drops one that the device never took, as
i3c_master_register_new_i3c_devs() assigns the node of the boardinfo as
is.

The two mistakes cancel out for a device that is registered exactly once,
which is why the imbalance goes unnoticed. Register it again, as happens
when the bus is re-initialised, and the count underflows, so the node may
be freed while the boardinfo still refers to it. A child that never joins
the bus leaks its reference instead.

Take a reference where the node is handed to the device, so that the one
the release callback drops is balanced, and drop the reference of the
boardinfo with a device managed action, as it is done for the i2c
boardinfo.

Fixes: 3a379bbcea0a ("i3c: Add core I3C infrastructure")
Reported-by: Adrian Hunter <adrian.hunter at intel.com>
Closes: https://lore.kernel.org/all/97465893-3650-4f37-98b7-1db76fc6fd03@intel.com/
Assisted-by: Cursor:claude-opus-5
Signed-off-by: Akhil R <akhilrajeev at nvidia.com>
---
 drivers/i3c/master.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/i3c/master.c b/drivers/i3c/master.c
index 08dc10f172aa..568788e4cdb5 100644
--- a/drivers/i3c/master.c
+++ b/drivers/i3c/master.c
@@ -2102,7 +2102,8 @@ i3c_master_register_new_i3c_devs(struct i3c_master_controller *master)
 				     desc->info.static_addr);
 
 		if (desc->boardinfo)
-			device_set_node(&desc->dev->dev, desc->boardinfo->fwnode);
+			device_set_node(&desc->dev->dev,
+					fwnode_handle_get(desc->boardinfo->fwnode));
 
 		ret = device_register(&desc->dev->dev);
 		if (ret) {
@@ -2994,7 +2995,8 @@ i3c_master_add_i3c_boardinfo(struct i3c_master_controller *master,
 	boardinfo->fwnode = fwnode_handle_get(fwnode);
 	list_add_tail(&boardinfo->node, &master->boardinfo.i3c);
 
-	return 0;
+	return devm_add_action_or_reset(dev, i3c_master_put_boardinfo_fwnode,
+					fwnode);
 }
 
 static int i3c_master_add_of_dev(struct i3c_master_controller *master,
-- 
2.43.0