Re: [PATCH can 2/4] can: flexcan: flexcan_probe(): fix probing for m68k/coldfire and reject devices without match data

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found no new issues
in this patch, but noticed 1 related pre-existing issue it does not
introduce:
- [Medium] can: flexcan: PM runtime double put in flexcan_probe() [1]
--

commit 358ff5ffd9961920463407d0074c445e652d7609
Author: Marc Kleine-Budde <mkl@pengutronix.de>

can: flexcan: flexcan_probe(): fix probing for m68k/coldfire and reject devices without match data

This commit restores falling back to platform_get_device_id() in
flexcan_probe() for non-OF devices and returns -ENODEV when no match data
is found.

> diff --git a/drivers/net/can/flexcan/flexcan-core.c b/drivers/net/can/flexcan/flexcan-core.c
> index 86b40abe9e767..2bb9e4184eb57 100644
> --- a/drivers/net/can/flexcan/flexcan-core.c
> +++ b/drivers/net/can/flexcan/flexcan-core.c
> @@ -2148,6 +2148,11 @@ static int flexcan_probe(struct platform_device *pdev)
>  		return PTR_ERR(regs);
>  
>  	devtype_data = device_get_match_data(&pdev->dev);
> +	if (!devtype_data && platform_get_device_id(pdev))
> +		devtype_data = (struct flexcan_devtype_data *)
> +			platform_get_device_id(pdev)->driver_data;
> +	if (!devtype_data)
> +		return -ENODEV;
>  
>  	if ((devtype_data->quirks & FLEXCAN_QUIRK_SUPPORT_FD) &&
>  	    !((devtype_data->quirks &

[Severity: Medium]
This problem wasn't introduced by this patch, but does flexcan_probe() drop
the PM runtime reference twice [1] when flexcan_setup_stop_mode()
fails?

flexcan_probe() acquires a reference with pm_runtime_get_noresume(), and
register_flexcandev() drops it with pm_runtime_put() before returning 0.  If
flexcan_setup_stop_mode() then fails, the error path falls through from
failed_setup_stop_mode to failed_register and calls pm_runtime_put_noidle()
a second time, underflowing the usage counter:

drivers/net/can/flexcan/flexcan-core.c:flexcan_probe() {
	...
	err = register_flexcandev(dev);
	if (err) {
		dev_err(&pdev->dev, "registering netdev failed\n");
		goto failed_register;
	}

	err = flexcan_setup_stop_mode(pdev);
	if (err < 0) {
		dev_err_probe(&pdev->dev, err, "setup stop mode failed\n");
		goto failed_setup_stop_mode;
	}
	...
 failed_setup_stop_mode:
	unregister_flexcandev(dev);
 failed_register:
	pm_runtime_put_noidle(&pdev->dev);
	pm_runtime_disable(&pdev->dev);
}

[1] https://sashiko.dev/#/bug/linux-34c83ee1-4b00-422c-b485-f3256591cdcf

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20261114-fix-device_get_match_data-v1-0-2d82025e9646@pengutronix.de?part=2