Re: [PATCH net v3] net: ethernet: ti: am65-cpsw: Fix devlink port register sequence

[Paolo Abeni <pabeni@redhat.com>]

On Wed, 2022-07-06 at 12:32 +0530, Siddharth Vadapalli wrote:
> Renaming interfaces using udevd depends on the interface being registered
> before its netdev is registered. Otherwise, udevd reads an empty
> phys_port_name value, resulting in the interface not being renamed.
> 
> Fix this by registering the interface before registering its netdev
> by invoking am65_cpsw_nuss_register_devlink() before invoking
> register_netdev() for the interface.
> 
> Move the function call to devlink_port_type_eth_set(), invoking it after
> register_netdev() is invoked, to ensure that netlink notification for the
> port state change is generated after the netdev is completely initialized.
> 
> Fixes: 58356eb31d60 ("net: ti: am65-cpsw-nuss: Add devlink support")
> Signed-off-by: Siddharth Vadapalli <s-vadapalli@ti.com>
> ---
> Changelog:
> v2 -> v3:
> 1. Add error handling to unregister devlink.
> 
> v1-> v2:
> 1. Add Fixes tag in commit message.
> 2. Update patch subject to include "net".
> 3. Invoke devlink_port_type_eth_set() after register_netdev() is called.
> 4. Update commit message describing the cause for moving the call to
>    devlink_port_type_eth_set().
> 
> v2: https://lore.kernel.org/r/20220704073040.7542-1-s-vadapalli@ti.com/
> v1: https://lore.kernel.org/r/20220623044337.6179-1-s-vadapalli@ti.com/
> 
>  drivers/net/ethernet/ti/am65-cpsw-nuss.c | 17 ++++++++++-------
>  1 file changed, 10 insertions(+), 7 deletions(-)
> 
> diff --git a/drivers/net/ethernet/ti/am65-cpsw-nuss.c b/drivers/net/ethernet/ti/am65-cpsw-nuss.c
> index fb92d4c1547d..f4a6b590a1e3 100644
> --- a/drivers/net/ethernet/ti/am65-cpsw-nuss.c
> +++ b/drivers/net/ethernet/ti/am65-cpsw-nuss.c
> @@ -2467,7 +2467,6 @@ static int am65_cpsw_nuss_register_devlink(struct am65_cpsw_common *common)
>  				port->port_id, ret);
>  			goto dl_port_unreg;
>  		}
> -		devlink_port_type_eth_set(dl_port, port->ndev);
>  	}
>  	devlink_register(common->devlink);
>  	return ret;
> @@ -2511,6 +2510,7 @@ static void am65_cpsw_unregister_devlink(struct am65_cpsw_common *common)
>  static int am65_cpsw_nuss_register_ndevs(struct am65_cpsw_common *common)
>  {
>  	struct device *dev = common->dev;
> +	struct devlink_port *dl_port;
>  	struct am65_cpsw_port *port;
>  	int ret = 0, i;
>  
> @@ -2527,6 +2527,10 @@ static int am65_cpsw_nuss_register_ndevs(struct am65_cpsw_common *common)
>  		return ret;
>  	}
>  
> +	ret = am65_cpsw_nuss_register_devlink(common);
> +	if (ret)
> +		return ret;
> +
>  	for (i = 0; i < common->port_num; i++) {
>  		port = &common->ports[i];
>  
> @@ -2539,25 +2543,24 @@ static int am65_cpsw_nuss_register_ndevs(struct am65_cpsw_common *common)
>  				i, ret);
>  			goto err_cleanup_ndev;
>  		}
> +
> +		dl_port = &port->devlink_port;
> +		devlink_port_type_eth_set(dl_port, port->ndev);
>  	}
>  
>  	ret = am65_cpsw_register_notifiers(common);
>  	if (ret)
>  		goto err_cleanup_ndev;
>  
> -	ret = am65_cpsw_nuss_register_devlink(common);
> -	if (ret)
> -		goto clean_unregister_notifiers;
> -
>  	/* can't auto unregister ndev using devm_add_action() due to
>  	 * devres release sequence in DD core for DMA
>  	 */
>  
>  	return 0;
> -clean_unregister_notifiers:
> -	am65_cpsw_unregister_notifiers(common);
> +
>  err_cleanup_ndev:
>  	am65_cpsw_nuss_cleanup_ndev(common);
> +	am65_cpsw_unregister_devlink(common);

It looks strange that there is no error path leading to
am65_cpsw_unregister_devlink() only.

Why we don't need to call it when/if devm_request_irq() fails? 

Not strictly related to this patch, but it looks like there is another
suspect cleanup point: if a 'register_netdev()' call fails, the cleanup
code will still call unregister_netdev() on the relevant device and the
later ones, hitting a WARN_ON(1) in unregister_netdevice_many().

Thanks!

Paolo