Re: [PATCH v5 8/9] driver core: Replace dev->of_node_reused with dev_of_node_reused()

[Johan Hovold]

On Mon, Apr 06, 2026 at 04:23:01PM -0700, Doug Anderson wrote:
> In C, bitfields are not necessarily safe to modify from multiple
> threads without locking. Switch "of_node_reused" over to the "flags"
> field so modifications are safe.

This flag is only set before registering a device with driver core so
there is no issue using the existing bitfield here (with the caveat that
PCI pwrctrl may have gotten that wrong). I haven't checked the other
flags, but I assume most of them work the same way.

But apart from the commit message being misleading, switching to using
atomic ops and accessors for consistency is fine.

> Cc: Johan Hovold <johan@xxxxxxxxxx>
> Acked-by: Mark Brown <broonie@xxxxxxxxxx>
> Reviewed-by: Rafael J. Wysocki (Intel) <rafael@xxxxxxxxxx>
> Reviewed-by: Danilo Krummrich <dakr@xxxxxxxxxx>
> Signed-off-by: Douglas Anderson <dianders@xxxxxxxxxxxx>
> ---
> Not fixing any known bugs; problem is theoretical and found by code
> inspection. Change is done somewhat manually and only lightly tested
> (mostly compile-time tested).
 
> diff --git a/drivers/regulator/bq257xx-regulator.c b/drivers/regulator/bq257xx-regulator.c
> index dab8f1ab4450..40e0f1a7ae81 100644
> --- a/drivers/regulator/bq257xx-regulator.c
> +++ b/drivers/regulator/bq257xx-regulator.c
> @@ -143,7 +143,7 @@ static int bq257xx_regulator_probe(struct platform_device *pdev)
>  	struct regulator_config cfg = {};
>  
>  	pdev->dev.of_node = pdev->dev.parent->of_node;
> -	pdev->dev.of_node_reused = true;
> +	dev_set_of_node_reused(&pdev->dev);
>  
>  	pdata = devm_kzalloc(&pdev->dev, sizeof(struct bq257xx_reg_data), GFP_KERNEL);
>  	if (!pdata)
> diff --git a/drivers/regulator/rk808-regulator.c b/drivers/regulator/rk808-regulator.c
> index e66408f23bb6..8297d31cde9f 100644
> --- a/drivers/regulator/rk808-regulator.c
> +++ b/drivers/regulator/rk808-regulator.c
> @@ -2115,7 +2115,7 @@ static int rk808_regulator_probe(struct platform_device *pdev)
>  	int ret, i, nregulators;
>  
>  	pdev->dev.of_node = pdev->dev.parent->of_node;
> -	pdev->dev.of_node_reused = true;
> +	dev_set_of_node_reused(&pdev->dev);
>  
>  	regmap = dev_get_regmap(pdev->dev.parent, NULL);
>  	if (!regmap)

These two uses are broken currently though and should be using
device_set_of_node_from_dev() so that an extra reference is taken to
balance the one dropped by the platform bus code.

I'll send two fixes to Mark, any merge conflict should be trivial to
fixup.

Reviewed-by: Johan Hovold <johan@xxxxxxxxxx>

Johan