diff mbox series

[v2,3/3] i2c: muxes: i2c-mux-gpmux: Use of_get_i2c_adapter_by_node()

Message ID 20231019101017.425284-4-herve.codina@bootlin.com
State New
Headers
Series Fix i2c mux module refcount issues |

Commit Message

Herve Codina Oct. 19, 2023, 10:10 a.m. UTC 
  i2c-mux-gpmux 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: ac8498f0ce53 ("i2c: i2c-mux-gpmux: new driver")
Signed-off-by: Herve Codina <herve.codina@bootlin.com>
Acked-by: Peter Rosin <peda@axentia.se>
---
 drivers/i2c/muxes/i2c-mux-gpmux.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

Comments

Greg KH Oct. 19, 2023, 6 p.m. UTC | #1 
On Thu, Oct 19, 2023 at 12:10:16PM +0200, Herve Codina wrote:
> i2c-mux-gpmux 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: ac8498f0ce53 ("i2c: i2c-mux-gpmux: new driver")
> Signed-off-by: Herve Codina <herve.codina@bootlin.com>
> Acked-by: Peter Rosin <peda@axentia.se>
> ---
>  drivers/i2c/muxes/i2c-mux-gpmux.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)

Hi,

This is the friendly patch-bot of Greg Kroah-Hartman.  You have sent him
a patch that has triggered this response.  He used to manually respond
to these common problems, but in order to save his sanity (he kept
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created.  Hopefully you will not take offence and will fix the problem
in your patch and resubmit it so that it can be accepted into the Linux
kernel tree.

You are receiving this message because of the following common error(s)
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  Documentation/process/stable-kernel-rules.rst file for how to resolve
  this.

If you wish to discuss this problem further, or you have questions about
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Greg will reply once he has dug out from the pending patches received
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thanks,

greg k-h's patch email bot
Jonathan Cameron Oct. 20, 2023, 7:37 a.m. UTC | #2 
On Thu, 19 Oct 2023 12:10:16 +0200
Herve Codina <herve.codina@bootlin.com> wrote:

> i2c-mux-gpmux 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: ac8498f0ce53 ("i2c: i2c-mux-gpmux: new driver")
> Signed-off-by: Herve Codina <herve.codina@bootlin.com>
> Acked-by: Peter Rosin <peda@axentia.se>

Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

> ---
>  drivers/i2c/muxes/i2c-mux-gpmux.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/i2c/muxes/i2c-mux-gpmux.c b/drivers/i2c/muxes/i2c-mux-gpmux.c
> index baccf4bfaf02..8305661e1253 100644
> --- a/drivers/i2c/muxes/i2c-mux-gpmux.c
> +++ b/drivers/i2c/muxes/i2c-mux-gpmux.c
> @@ -52,7 +52,7 @@ static struct i2c_adapter *mux_parent_adapter(struct device *dev)
>  		dev_err(dev, "Cannot parse i2c-parent\n");
>  		return ERR_PTR(-ENODEV);
>  	}
> -	parent = of_find_i2c_adapter_by_node(parent_np);
> +	parent = of_get_i2c_adapter_by_node(parent_np);
>  	of_node_put(parent_np);
>  	if (!parent)
>  		return ERR_PTR(-EPROBE_DEFER);
diff mbox series

Patch

diff --git a/drivers/i2c/muxes/i2c-mux-gpmux.c b/drivers/i2c/muxes/i2c-mux-gpmux.c
index baccf4bfaf02..8305661e1253 100644
--- a/drivers/i2c/muxes/i2c-mux-gpmux.c
+++ b/drivers/i2c/muxes/i2c-mux-gpmux.c
@@ -52,7 +52,7 @@  static struct i2c_adapter *mux_parent_adapter(struct device *dev)
 		dev_err(dev, "Cannot parse i2c-parent\n");
 		return ERR_PTR(-ENODEV);
 	}
-	parent = of_find_i2c_adapter_by_node(parent_np);
+	parent = of_get_i2c_adapter_by_node(parent_np);
 	of_node_put(parent_np);
 	if (!parent)
 		return ERR_PTR(-EPROBE_DEFER);