netdev - Re: [PATCH net 2/2] net: cpsw_new: Fix potential unregister of netdev that has not been registered yet

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Message-ID: <ddd1f32c073f155f61104ad92d4fe7de327ca11d.camel@gmail.com>
Date: Thu, 05 Feb 2026 20:03:45 +0100
From: Alexander Sverdlin <alexander.sverdlin@...il.com>
To: Kevin Hao <haokexin@...il.com>, netdev@...r.kernel.org
Cc: 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>, Jakub
 Kicinski <kuba@...nel.org>, Paolo Abeni	 <pabeni@...hat.com>, Vladimir
 Oltean <vladimir.oltean@....com>, Saeed Mahameed	 <saeedm@...dia.com>,
 Daniel Zahka <daniel.zahka@...il.com>, Lorenzo Bianconi	
 <lorenzo@...nel.org>, Nicolas Dichtel <nicolas.dichtel@...nd.com>, Murali
 Karicheri <m-karicheri2@...com>, Ilias Apalodimas
 <ilias.apalodimas@...aro.org>, Grygorii Strashko	
 <grygorii.strashko@...com>, linux-omap@...r.kernel.org,
 stable@...r.kernel.org
Subject: Re: [PATCH net 2/2] net: cpsw_new: Fix potential unregister of
 netdev that has not been registered yet

On Thu, 2026-02-05 at 10:47 +0800, Kevin Hao wrote:
> If an error occurs during register_netdev() for the first MAC in
> cpsw_register_ports(), even though cpsw->slaves[0].ndev is set to NULL,
> cpsw->slaves[1].ndev would remain unchanged. This could later cause
> cpsw_unregister_ports() to attempt unregistering the second MAC.
> To address this, add a check for ndev->reg_state before calling
> unregister_netdev(). With this change, setting cpsw->slaves[i].ndev
> to NULL becomes unnecessary and can be removed accordingly.
> 
> Fixes: ed3525eda4c4 ("net: ethernet: ti: introduce cpsw switchdev based driver part 1 - dual-emac")
> Signed-off-by: Kevin Hao <haokexin@...il.com>

Reviewed-by: Alexander Sverdlin <alexander.sverdlin@...il.com>

> Cc: stable@...r.kernel.org
> ---
>  drivers/net/ethernet/ti/cpsw_new.c | 3 +--
>  1 file changed, 1 insertion(+), 2 deletions(-)
> 
> diff --git a/drivers/net/ethernet/ti/cpsw_new.c b/drivers/net/ethernet/ti/cpsw_new.c
> index b9fc31eb06134dae33427eaba06341c39eb4b41c..7f42f58a4b031fab4c93680c153383e8eeb8f7f8 100644
> --- a/drivers/net/ethernet/ti/cpsw_new.c
> +++ b/drivers/net/ethernet/ti/cpsw_new.c
> @@ -1472,7 +1472,7 @@ static void cpsw_unregister_ports(struct cpsw_common *cpsw)
>  
>  	for (i = 0; i < cpsw->data.slaves; i++) {
>  		ndev = cpsw->slaves[i].ndev;
> -		if (!ndev)
> +		if (!ndev || ndev->reg_state != NETREG_REGISTERED)
>  			continue;
>  
>  		priv = netdev_priv(ndev);
> @@ -1494,7 +1494,6 @@ static int cpsw_register_ports(struct cpsw_common *cpsw)
>  		if (ret) {
>  			dev_err(cpsw->dev,
>  				"cpsw: err registering net device%d\n", i);
> -			cpsw->slaves[i].ndev = NULL;
>  			break;
>  		}
>  	}

-- 
Alexander Sverdlin.