linux-kernel - Re: [PATCH net 1/3] net/mlx5e: Harden uplink netdev access against device unbind

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Message-ID: <20250910174519.2ec85ac2@kernel.org>
Date: Wed, 10 Sep 2025 17:45:19 -0700
From: Jakub Kicinski <kuba@...nel.org>
To: Jianbo Liu <jianbol@...dia.com>
Cc: Tariq Toukan <tariqt@...dia.com>, Eric Dumazet <edumazet@...gle.com>,
 Paolo Abeni <pabeni@...hat.com>, Andrew Lunn <andrew+netdev@...n.ch>,
 "David S. Miller" <davem@...emloft.net>, Saeed Mahameed
 <saeedm@...dia.com>, Leon Romanovsky <leon@...nel.org>, "Mark Bloch"
 <mbloch@...dia.com>, <netdev@...r.kernel.org>,
 <linux-rdma@...r.kernel.org>, <linux-kernel@...r.kernel.org>, Gal Pressman
 <gal@...dia.com>
Subject: Re: [PATCH net 1/3] net/mlx5e: Harden uplink netdev access against
 device unbind

On Wed, 10 Sep 2025 11:23:09 +0800 Jianbo Liu wrote:
> On 9/10/2025 9:23 AM, Jakub Kicinski wrote:
> > On Mon, 8 Sep 2025 13:07:04 +0300 Tariq Toukan wrote:  
> >> +	struct net_device *netdev = mlx5_uplink_netdev_get(dev);
> >> +	struct mlx5e_priv *priv;
> >> +	int err;
> >> +
> >> +	if (!netdev)
> >> +		return 0;  
> > 
> > Please don't call in variable init functions which require cleanup
> > or error checking.  
> 
> But in this function, a NULL return from mlx5_uplink_netdev_get is a 
> valid condition where it should simply return 0. No cleanup or error 
> check is needed.

You have to check if it succeeded, and if so, you need to clean up
later. Do no hide meaningful code in variable init.