[PATCH 3/7] i3c: master: Prevent reuse of dynamic address on device add failure

[Adrian Hunter]

i3c_master_add_i3c_dev_locked() is called after a device has already
been assigned a dynamic address.  If the function fails, the address
remains marked as free and may be reallocated to another device,
leading to address conflicts on the bus.

Mark the address as in use even on failure by updating the address slot
state to prevent the address from being re-used.

Emit an error message to inform of the failure.

Signed-off-by: Adrian Hunter <adrian.hunter@xxxxxxxxx>
---
 drivers/i3c/master.c | 13 +++++++++----
 1 file changed, 9 insertions(+), 4 deletions(-)

diff --git a/drivers/i3c/master.c b/drivers/i3c/master.c
index f87bf0099d3c..7820f58ab4aa 100644
--- a/drivers/i3c/master.c
+++ b/drivers/i3c/master.c
@@ -2345,12 +2345,9 @@ int i3c_master_add_i3c_dev_locked(struct i3c_master_controller *master,
 	bool enable_ibi = false;
 	int ret;
 
-	if (!master)
-		return -EINVAL;
-
 	newdev = i3c_master_alloc_i3c_dev(master, &info);
 	if (IS_ERR(newdev))
-		return PTR_ERR(newdev);
+		goto err_prevent_addr_reuse;
 
 	ret = i3c_master_attach_i3c_dev(master, newdev);
 	if (ret)
@@ -2472,6 +2469,14 @@ int i3c_master_add_i3c_dev_locked(struct i3c_master_controller *master,
 err_free_dev:
 	i3c_master_free_i3c_dev(newdev);
 
+err_prevent_addr_reuse:
+	/*
+	 * Although the device has not been added, the address has been
+	 * assigned. Prevent the address from being used again.
+	 */
+	i3c_bus_set_addr_slot_status(&master->bus, addr, I3C_ADDR_SLOT_I3C_DEV);
+	dev_err(&master->dev, "Failed to add I3C device at address %u, error %d\n", addr, ret);
+
 	return ret;
 }
 EXPORT_SYMBOL_GPL(i3c_master_add_i3c_dev_locked);
-- 
2.51.0