Hi!
2023-10-19 at 09:35, Herve Codina wrote:
> i2c-demux-pinctrl uses the pair of_find_i2c_adapter_by_node() /
> i2c_put_adapter(). These pair alone is not correct to properly lock the
> I2C parent adapter.
>
> Indeed, i2c_put_adapter() decrements the module refcount while
> of_find_i2c_adapter_by_node() does not increment it. This leads to an
> overflow over zero of the parent adapter user counter.
Perhaps "... underflow of the parent module refcount."?
>
> Use the dedicated function, of_get_i2c_adapter_by_node(), to handle
> correctly the module refcount.
>
> Signed-off-by: Herve Codina <herve.codina@xxxxxxxxxxx>
Good find!
Fixes: 50a5ba876908 ("i2c: mux: demux-pinctrl: add driver")
Acked-by: Peter Rosin <peda@xxxxxxxxxx>
Cheers,
Peter
> ---
> drivers/i2c/muxes/i2c-demux-pinctrl.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/i2c/muxes/i2c-demux-pinctrl.c b/drivers/i2c/muxes/i2c-demux-pinctrl.c
> index 22f2280eab7f..9f2e4aa28159 100644
> --- a/drivers/i2c/muxes/i2c-demux-pinctrl.c
> +++ b/drivers/i2c/muxes/i2c-demux-pinctrl.c
> @@ -61,7 +61,7 @@ static int i2c_demux_activate_master(struct i2c_demux_pinctrl_priv *priv, u32 ne
> if (ret)
> goto err;
>
> - adap = of_find_i2c_adapter_by_node(priv->chan[new_chan].parent_np);
> + adap = of_get_i2c_adapter_by_node(priv->chan[new_chan].parent_np);
> if (!adap) {
> ret = -ENODEV;
> goto err_with_revert;
