Re: [PATCH v4 2/2] net: qcom/emac: Find sgmii_ops by device_for_each_child()

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

On Thu, Sep 05, 2024 at 07:29:10AM +0200, Greg Kroah-Hartman wrote:
> On Thu, Sep 05, 2024 at 08:36:10AM +0800, Zijun Hu wrote:
> > From: Zijun Hu <quic_zijuhu@quicinc.com>
> > 
> > To prepare for constifying the following old driver core API:
> > 
> > struct device *device_find_child(struct device *dev, void *data,
> > 		int (*match)(struct device *dev, void *data));
> > to new:
> > struct device *device_find_child(struct device *dev, const void *data,
> > 		int (*match)(struct device *dev, const void *data));
> > 
> > The new API does not allow its match function (*match)() to modify
> > caller's match data @*data, but emac_sgmii_acpi_match() as the old
> > API's match function indeed modifies relevant match data, so it is not
> > suitable for the new API any more, solved by using device_for_each_child()
> > to implement relevant finding sgmii_ops function.
> > 
> > By the way, this commit does not change any existing logic.
> > 
> > Signed-off-by: Zijun Hu <quic_zijuhu@quicinc.com>
> > ---
> >  drivers/net/ethernet/qualcomm/emac/emac-sgmii.c | 22 +++++++++++++++++-----
> >  1 file changed, 17 insertions(+), 5 deletions(-)
> > 
> > diff --git a/drivers/net/ethernet/qualcomm/emac/emac-sgmii.c b/drivers/net/ethernet/qualcomm/emac/emac-sgmii.c
> > index e4bc18009d08..29392c63d115 100644
> > --- a/drivers/net/ethernet/qualcomm/emac/emac-sgmii.c
> > +++ b/drivers/net/ethernet/qualcomm/emac/emac-sgmii.c
> > @@ -293,6 +293,11 @@ static struct sgmii_ops qdf2400_ops = {
> >  };
> >  #endif
> >  
> > +struct emac_match_data {
> > +	struct sgmii_ops **sgmii_ops;
> > +	struct device *target_device;
> > +};
> > +
> >  static int emac_sgmii_acpi_match(struct device *dev, void *data)
> >  {
> >  #ifdef CONFIG_ACPI
> > @@ -303,7 +308,7 @@ static int emac_sgmii_acpi_match(struct device *dev, void *data)
> >  		{}
> >  	};
> >  	const struct acpi_device_id *id = acpi_match_device(match_table, dev);
> > -	struct sgmii_ops **ops = data;
> > +	struct emac_match_data *match_data = data;
> >  
> >  	if (id) {
> >  		acpi_handle handle = ACPI_HANDLE(dev);
> > @@ -324,10 +329,12 @@ static int emac_sgmii_acpi_match(struct device *dev, void *data)
> >  
> >  		switch (hrv) {
> >  		case 1:
> > -			*ops = &qdf2432_ops;
> > +			*match_data->sgmii_ops = &qdf2432_ops;
> > +			match_data->target_device = get_device(dev);
> >  			return 1;
> >  		case 2:
> > -			*ops = &qdf2400_ops;
> > +			*match_data->sgmii_ops = &qdf2400_ops;
> > +			match_data->target_device = get_device(dev);
> 
> Where is put_device() now called?

Nevermind, I see it now.

That being said, this feels wrong still, why not just do this "set up
the ops" logic _after_ you find the device and not here in the match
function?

thanks,

greg k-h