Re: [PATCH V2 3/7] i3c: master: Prevent reuse of dynamic address on device add failure

[Frank Li]

On Mon, Jun 08, 2026 at 10:57:56AM +0300, Adrian Hunter wrote:
> 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.

There are other error patch, which also free dynamic address. And if add
dev failure, should it send CCC command to clean device dymatic address?

Frank
>
> Ensure the address is not marked as free 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.
>
> Opportunistically remove the !master check because it is impossible.
>
> Fixes: 3a379bbcea0af ("i3c: Add core I3C infrastructure")
> Signed-off-by: Adrian Hunter <adrian.hunter@xxxxxxxxx>
> ---
>
>
> Changes in V2:
>
> 	Fix 'if (IS_ERR(newdev)' error path.
> 	Be defensive and do not change the addr_slot_status if it is not
> 	free, and update commit message accordingly.
> 	Amend commit message to note removal of unnecesary 'if (!master)'
> 	check.
> 	Add Fixes tag.
>
>
>  drivers/i3c/master.c | 19 ++++++++++++++-----
>  1 file changed, 14 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/i3c/master.c b/drivers/i3c/master.c
> index f87bf0099d3c..7b60b0c7f646 100644
> --- a/drivers/i3c/master.c
> +++ b/drivers/i3c/master.c
> @@ -2345,12 +2345,11 @@ 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);
> +	if (IS_ERR(newdev)) {
> +		ret = PTR_ERR(newdev);
> +		goto err_prevent_addr_reuse;
> +	}
>
>  	ret = i3c_master_attach_i3c_dev(master, newdev);
>  	if (ret)
> @@ -2472,6 +2471,16 @@ 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.
> +	 */
> +	if (i3c_bus_get_addr_slot_status(&master->bus, addr) == I3C_ADDR_SLOT_FREE)
> +		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
>