Re: [PATCH net v4] net: cpsw_new: Execute ndo_set_rx_mode callback in a work queue

[Kevin Hao <haokexin@gmail.com>]

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On Sat, Jan 31, 2026 at 12:41:20PM -0800, Jakub Kicinski wrote:
> On Fri, 30 Jan 2026 13:34:07 +0800 Kevin Hao wrote:
> > --- a/drivers/net/ethernet/ti/cpsw_new.c
> > +++ b/drivers/net/ethernet/ti/cpsw_new.c
> 
> What's your plan for fixing drivers/net/ethernet/ti/cpsw.c ?
> My preference would be to post both of the fixes at once,

Sure, I will include the fix for cpsw.c in the next version.

> I think this version is quite close, just a couple of nit picks
> below..
> 
> > @@ -248,15 +248,25 @@ static int cpsw_purge_all_mc(struct net_device *ndev, const u8 *addr, int num)
> >  	return 0;
> >  }
> >  
> > -static void cpsw_ndo_set_rx_mode(struct net_device *ndev)
> > +static void cpsw_ndo_set_rx_mode_work(struct work_struct *work)
> >  {
> > -	struct cpsw_priv *priv = netdev_priv(ndev);
> > +	struct cpsw_priv *priv = container_of(work, struct cpsw_priv, rx_mode_work);
> >  	struct cpsw_common *cpsw = priv->cpsw;
> > +	struct net_device *ndev = priv->ndev;
> >  
> > +	rtnl_lock();
> > +	if (!netif_running(ndev)) {
> > +		rtnl_unlock();
> > +		return;
> 
> since the "undo" logic is getting complex you should use a goto.
> Replace the unlock and the return; here with:
> 
> 		goto unlock_rtnl;
> 
> > +	}
> > +
> > +	netif_addr_lock_bh(ndev);
> >  	if (ndev->flags & IFF_PROMISC) {
> >  		/* Enable promiscuous mode */
> >  		cpsw_set_promiscious(ndev, true);
> >  		cpsw_ale_set_allmulti(cpsw->ale, IFF_ALLMULTI, priv->emac_port);
> > +		netif_addr_unlock_bh(ndev);
> > +		rtnl_unlock();
> 
> 
> 		goto unlock_addr;
> 
> >  		return;
> >  	}
> >  
> > @@ -270,6 +280,15 @@ static void cpsw_ndo_set_rx_mode(struct net_device *ndev)
> >  	/* add/remove mcast address either for real netdev or for vlan */
> >  	__hw_addr_ref_sync_dev(&ndev->mc, ndev, cpsw_add_mc_addr,
> >  			       cpsw_del_mc_addr);
> 
> And place a labels here:
> 
> unlock_addr:
> 
> > +	netif_addr_unlock_bh(ndev);
> 
> unlock_rtnl:

Will do. Thanks.

> 
> > +	rtnl_unlock();
> > +}
> 
> >  	for (i = 0; i < cpsw->data.slaves; i++) {
> > -		if (!cpsw->slaves[i].ndev)
> > +		ndev = cpsw->slaves[i].ndev;
> > +		if (!ndev)
> >  			continue;
> >  
> > -		unregister_netdev(cpsw->slaves[i].ndev);
> > +		priv = netdev_priv(ndev);
> > +		disable_work_sync(&priv->rx_mode_work);
> > +		unregister_netdev(ndev);
> 
> I understand that this is safe but I think that more logical ordering
> would be to shut things down _after_ object is unregistered.

I'm a bit confused—are you suggesting that we move disable_work_sync() after
unregister_netdev()? If that's the case, the scheduled cpsw_ndo_set_rx_mode_work()
could potentially run after the network device has been unregistered, leading to
a use-after-free issue. Or am I misunderstanding something here?

Thanks,
Kevin

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