Re: [PATCH] can: c_can: Use platform id data when OF data is absent

[Vincent Mailhol <mailhol@kernel.org>]

On 24/06/2026 at 07:49, Pengpeng Hou wrote:
> The platform driver keeps controller metadata in both the OF match table
> and the platform id table.  Probe reads the metadata with
> device_get_match_data(), which does not fall back to platform id-table
> driver_data.
> 
> When the device is matched through the platform id table, drvdata can
> therefore be NULL before it is dereferenced for msg_obj_num and the
> controller type.  Fall back to platform_get_device_id() when firmware
> match data is not available.

So, you are telling me that this patch fixes a NULL pointer
dereference? In that case, it needs to be backported. Please add a
Fixes: tag.

Fixes: 5e6c3454b405 ("net: can: Use device_get_match_data()")

> Signed-off-by: Pengpeng Hou <pengpeng@iscas.ac.cn>
> ---
>  drivers/net/can/c_can/c_can_platform.c | 8 ++++++++
>  1 file changed, 8 insertions(+)
> 
> diff --git a/drivers/net/can/c_can/c_can_platform.c b/drivers/net/can/c_can/c_can_platform.c
> index 19c86b94a40e..564c9e5b4c2c 100644
> --- a/drivers/net/can/c_can/c_can_platform.c
> +++ b/drivers/net/can/c_can/c_can_platform.c
> @@ -263,9 +263,17 @@ static int c_can_plat_probe(struct platform_device *pdev)
>  	int irq;
>  	struct clk *clk;
>  	const struct c_can_driver_data *drvdata;
> +	const struct platform_device_id *id;
>  	struct device_node *np = pdev->dev.of_node;
>  
>  	drvdata = device_get_match_data(&pdev->dev);
> +	if (!drvdata) {
> +		id = platform_get_device_id(pdev);
> +		if (!id)
> +			return -ENODEV;
> +
> +		drvdata = (const struct c_can_driver_data *)id->driver_data;
> +	}

Reduce the visibility of id:

	if (!drvdata) {
		const struct platform_device_id *id;

		id = platform_get_device_id(pdev);
		if (!id)
			return -ENODEV;

		drvdata = (const struct c_can_driver_data *)id->driver_data;
	}

>  
>  	/* get the appropriate clk */
>  	clk = devm_clk_get(&pdev->dev, NULL);

With the Fixes: tag added and above nitpick addressed:

Reviewed-by: Vincent Mailhol <mailhol@kernel.org>


Yours sincerely,
Vincent Mailhol