[v3,2/3] i2c: muxes: i2c-demux-pinctrl: Use of_get_i2c_adapter_by_node()

Message ID 20231020153017.759926-3-herve.codina@bootlin.com
State New
Headers
Series Fix i2c mux module refcount issues |

Commit Message

Herve Codina Oct. 20, 2023, 3:30 p.m. UTC
  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
underflow of the parent module refcount.

Use the	dedicated function, of_get_i2c_adapter_by_node(), to handle
correctly the module refcount.

Fixes: 50a5ba876908 ("i2c: mux: demux-pinctrl: add driver")
Signed-off-by: Herve Codina <herve.codina@bootlin.com>
Cc: stable@vger.kernel.org
Acked-by: Peter Rosin <peda@axentia.se>
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
---
 drivers/i2c/muxes/i2c-demux-pinctrl.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
  

Comments

Wolfram Sang Oct. 21, 2023, 5:57 p.m. UTC | #1
On Fri, Oct 20, 2023 at 05:30:12PM +0200, 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
> underflow of the parent module refcount.
> 
> Use the	dedicated function, of_get_i2c_adapter_by_node(), to handle
> correctly the module refcount.
> 
> Fixes: 50a5ba876908 ("i2c: mux: demux-pinctrl: add driver")
> Signed-off-by: Herve Codina <herve.codina@bootlin.com>
> Cc: stable@vger.kernel.org
> Acked-by: Peter Rosin <peda@axentia.se>
> Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

Applied to for-current, thanks!
  

Patch

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;