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Date: Mon, 16 Dec 2024 18:03:00 -0800
From: Jakub Kicinski <kuba@kernel.org>
To: longli@linuxonhyperv.com
Cc: Jason Gunthorpe <jgg@ziepe.ca>, Leon Romanovsky <leon@kernel.org>, Ajay
 Sharma <sharmaajay@microsoft.com>, Konstantin Taranov
 <kotaranov@microsoft.com>, "David S. Miller" <davem@davemloft.net>, Eric
 Dumazet <edumazet@google.com>, Paolo Abeni <pabeni@redhat.com>, Stephen
 Hemminger <stephen@networkplumber.org>, linux-rdma@vger.kernel.org,
 netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
 linux-hyperv@vger.kernel.org, Long Li <longli@microsoft.com>
Subject: Re: [Patch net-next v2] hv_netvsc: Set device flags for properly
 indicating bonding in Hyper-V
Message-ID: <20241216180300.23a54f27@kernel.org>
In-Reply-To: <1734120361-26599-1-git-send-email-longli@linuxonhyperv.com>
References: <1734120361-26599-1-git-send-email-longli@linuxonhyperv.com>
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On Fri, 13 Dec 2024 12:06:01 -0800 longli@linuxonhyperv.com wrote:
> Other kernel APIs (e.g those in "include/linux/netdevice.h") check for
> IFF_MASTER, IFF_SLAVE and IFF_BONDING for determing if those are used
> in a master/slave bonded setup. RDMA uses those APIs extensively when
> looking for master/slave devices. Netvsc's bonding setup with its slave
> device falls into this category.
> 
> Make hv_netvsc properly indicate bonding with its slave and change the
> API to reflect this bonding setup.

This is severely lacking in terms of safety analysis.

> @@ -2204,6 +2204,10 @@ static int netvsc_vf_join(struct net_device *vf_netdev,
>  		goto rx_handler_failed;
>  	}
>  
> +	vf_netdev->permanent_bond = 1;
> +	ndev->permanent_bond = 1;
> +	ndev->flags |= IFF_MASTER;

> @@ -2484,7 +2488,15 @@ static int netvsc_unregister_vf(struct net_device *vf_netdev)
>  
>  	reinit_completion(&net_device_ctx->vf_add);
>  	netdev_rx_handler_unregister(vf_netdev);
> +
> +	/* Unlink the slave device and clear flag */
> +	vf_netdev->permanent_bond = 0;
> +	ndev->permanent_bond = 0;

> + *	@permanent_bond: device is permanently bonded to another device

I think we have been taught a definition of the word "permanent"