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

[Paolo Abeni]

On Thu, 2022-07-07 at 14:41 +0530, Siddharth Vadapalli wrote:
> Hello Paolo,
> 
> On 07/07/22 13:00, Paolo Abeni wrote:
> > 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@xxxxxx>
> > > ---
> > > 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@xxxxxx/
> > > v1: https://lore.kernel.org/r/20220623044337.6179-1-s-vadapalli@xxxxxx/
> > > 
> > >  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? 
> 
> am65_cpsw_nuss_register_devlink() is invoked after devm_request_irq() and
> devm_request_irq()'s associated error handling.

Whoops, I misread the exact location were
am65_cpsw_nuss_register_devlink() is located after this patch.  

That error path now LGTM.

> > 
> > 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().
> 
> Thank you for pointing it out. I will look at it and address it in a separate
> cleanup patch.

Thanks!

Paolo