netdev - Re: [PATCH net v4] net: cpsw_new: Execute ndo_set_rx

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Message-ID: <20260202161918.54be9315@kernel.org>
Date: Mon, 2 Feb 2026 16:19:18 -0800
From: Jakub Kicinski <kuba@...nel.org>
To: Kevin Hao <haokexin@...il.com>
Cc: netdev@...r.kernel.org, stable@...r.kernel.org, Siddharth Vadapalli
 <s-vadapalli@...com>, Roger Quadros <rogerq@...nel.org>, Andrew Lunn
 <andrew+netdev@...n.ch>, "David S. Miller" <davem@...emloft.net>, Eric
 Dumazet <edumazet@...gle.com>, Paolo Abeni <pabeni@...hat.com>, Vladimir
 Oltean <vladimir.oltean@....com>, Kuniyuki Iwashima <kuniyu@...gle.com>,
 linux-omap@...r.kernel.org
Subject: Re: [PATCH net v4] net: cpsw_new: Execute ndo_set_rx_mode callback
 in a work queue

On Sun, 1 Feb 2026 09:15:10 +0800 Kevin Hao wrote:
> > > -		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?

Unregistered device is not freed yet. The netdev is only freed after
.remove routine returns. Passing unregistered netdev to netif_running()
is safe and will return false.