Re: [PATCH net-next v2 7/7] net: dsa: mv88e6xxx: Add per port devlink regions

[Vladimir Oltean <olteanv@gmail.com>]

On Sat, Sep 26, 2020 at 11:06:32PM +0200, Andrew Lunn wrote:
> Add a devlink region to return the per port registers.
> 
> Signed-off-by: Andrew Lunn <andrew@lunn.ch>
> ---
>  drivers/net/dsa/mv88e6xxx/devlink.c | 109 +++++++++++++++++++++++++++-
>  1 file changed, 105 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/net/dsa/mv88e6xxx/devlink.c b/drivers/net/dsa/mv88e6xxx/devlink.c
> index 81e1560db206..ed74b075de84 100644
> --- a/drivers/net/dsa/mv88e6xxx/devlink.c
> +++ b/drivers/net/dsa/mv88e6xxx/devlink.c
> @@ -415,6 +415,36 @@ static int mv88e6xxx_region_atu_snapshot(struct devlink *dl,
>  	return err;
>  }
>  
> +static int mv88e6xxx_region_port_snapshot(struct devlink_port *devlink_port,
> +					  const struct devlink_port_region_ops *ops,
> +					  struct netlink_ext_ack *extack,
> +					  u8 **data)
> +{
> +	struct dsa_switch *ds = dsa_devlink_port_to_ds(devlink_port);
> +	int port = dsa_devlink_port_to_port(devlink_port);
> +	struct mv88e6xxx_chip *chip = ds->priv;

> +	u16 *registers;

I was meaning to ask this since the global regions patchset, but I
forgot.

Do we not expect to see, under the same circumstances, the same region
snapshot on a big endian and on a little endian system?

> +	int i, err;
> +
> +	registers = kmalloc_array(32, sizeof(u16), GFP_KERNEL);
> +	if (!registers)
> +		return -ENOMEM;
> +
> +	mv88e6xxx_reg_lock(chip);
> +	for (i = 0; i < 32; i++) {
> +		err = mv88e6xxx_port_read(chip, port, i, &registers[i]);
> +		if (err) {
> +			kfree(registers);
> +			goto out;
> +		}
> +	}
> +	*data = (u8 *)registers;
> +out:
> +	mv88e6xxx_reg_unlock(chip);
> +
> +	return err;
> +}
> +
>  static struct mv88e6xxx_region_priv mv88e6xxx_region_global1_priv = {
>  	.id = MV88E6XXX_REGION_GLOBAL1,
>  };
> @@ -443,6 +473,12 @@ static struct devlink_region_ops mv88e6xxx_region_atu_ops = {
>  	.destructor = kfree,
>  };
>  
> +static const struct devlink_port_region_ops mv88e6xxx_region_port_ops = {
> +	.name = "port",
> +	.snapshot = mv88e6xxx_region_port_snapshot,
> +	.destructor = kfree,
> +};
> +
>  struct mv88e6xxx_region {
>  	struct devlink_region_ops *ops;
>  	u64 size;
> @@ -471,11 +507,59 @@ mv88e6xxx_teardown_devlink_regions_global(struct mv88e6xxx_chip *chip)
>  		dsa_devlink_region_destroy(chip->regions[i]);
>  }
>  
> -void mv88e6xxx_teardown_devlink_regions(struct dsa_switch *ds)
> +static void
> +mv88e6xxx_teardown_devlink_regions_port(struct mv88e6xxx_chip *chip,
> +					int port)
>  {
> -	struct mv88e6xxx_chip *chip = ds->priv;
> +	dsa_devlink_region_destroy(chip->ports[port].region);
> +}
>  
> -	mv88e6xxx_teardown_devlink_regions_global(chip);
> +static int mv88e6xxx_setup_devlink_regions_port(struct dsa_switch *ds,
> +						struct mv88e6xxx_chip *chip,
> +						int port)
> +{
> +	struct devlink_region *region;
> +
> +	region = dsa_devlink_port_region_create(ds,
> +						port,
> +						&mv88e6xxx_region_port_ops, 1,
> +						32 * sizeof(u16));
> +	if (IS_ERR(region))
> +		return PTR_ERR(region);
> +
> +	chip->ports[port].region = region;
> +
> +	return 0;
> +}
> +
> +static void
> +mv88e6xxx_teardown_devlink_regions_ports(struct mv88e6xxx_chip *chip)
> +{
> +	int port;
> +
> +	for (port = 0; port < mv88e6xxx_num_ports(chip); port++)
> +		mv88e6xxx_teardown_devlink_regions_port(chip, port);
> +}
> +
> +static int mv88e6xxx_setup_devlink_regions_ports(struct dsa_switch *ds,
> +						 struct mv88e6xxx_chip *chip)
> +{
> +	int port, port_err;
> +	int err;
> +
> +	for (port = 0; port < mv88e6xxx_num_ports(chip); port++) {
> +		err = mv88e6xxx_setup_devlink_regions_port(ds, chip, port);
> +		if (err)
> +			goto out;
> +	}
> +
> +	return 0;
> +
> +out:
> +	for (port_err = 0; port_err < port; port_err++)

"while (port-- >= 0)" should do the trick. Also, maybe it would be
overall more aesthetic if you wouldn't use the goto and have 2 exit
points in such a small function, but a simple break here. Like this:

	int err;

	for (port = 0; port < mv88e6xxx_num_ports(chip); port++) {
		err = mv88e6xxx_setup_devlink_regions_port(ds, chip, port);
		if (err) {
			while (port-- >= 0)
				mv88e6xxx_teardown_devlink_regions_port(chip,
									port);
			break;
		}
	}

	return err;

> +		mv88e6xxx_teardown_devlink_regions_port(chip, port_err);
> +
> +	return err;
>  }
>  
>  static int mv88e6xxx_setup_devlink_regions_global(struct dsa_switch *ds,
> @@ -511,8 +595,25 @@ static int mv88e6xxx_setup_devlink_regions_global(struct dsa_switch *ds,
>  int mv88e6xxx_setup_devlink_regions(struct dsa_switch *ds)
>  {
>  	struct mv88e6xxx_chip *chip = ds->priv;
> +	int err;
> +
> +	err = mv88e6xxx_setup_devlink_regions_global(ds, chip);
> +	if (err)
> +		return err;
> +
> +	err = mv88e6xxx_setup_devlink_regions_ports(ds, chip);
> +	if (err)
> +		mv88e6xxx_teardown_devlink_regions_global(chip);
>  
> -	return mv88e6xxx_setup_devlink_regions_global(ds, chip);
> +	return err;
> +}
> +
> +void mv88e6xxx_teardown_devlink_regions(struct dsa_switch *ds)
> +{
> +	struct mv88e6xxx_chip *chip = ds->priv;
> +
> +	mv88e6xxx_teardown_devlink_regions_ports(chip);
> +	mv88e6xxx_teardown_devlink_regions_global(chip);
>  }
>  
>  int mv88e6xxx_devlink_info_get(struct dsa_switch *ds,
> -- 
> 2.28.0
>