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Date:   Thu, 26 Oct 2023 09:48:41 -0700
From:   Stephen Hemminger <stephen@networkplumber.org>
To:     longli@linuxonhyperv.com
Cc:     "K. Y. Srinivasan" <kys@microsoft.com>,
        Haiyang Zhang <haiyangz@microsoft.com>,
        Wei Liu <wei.liu@kernel.org>, Dexuan Cui <decui@microsoft.com>,
        "David S. Miller" <davem@davemloft.net>,
        Eric Dumazet <edumazet@google.com>,
        Jakub Kicinski <kuba@kernel.org>,
        Paolo Abeni <pabeni@redhat.com>, linux-hyperv@vger.kernel.org,
        netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
        linux-rdma@vger.kernel.org, Long Li <longli@microsoft.com>
Subject: Re: [PATCH] hv_netvsc: Mark VF as slave before exposing it to
 user-mode
Message-ID: <20231026094841.39f01d26@hermes.local>
In-Reply-To: <1698274250-653-1-git-send-email-longli@linuxonhyperv.com>
References: <1698274250-653-1-git-send-email-longli@linuxonhyperv.com>
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On Wed, 25 Oct 2023 15:50:50 -0700
longli@linuxonhyperv.com wrote:

> @@ -2347,6 +2342,12 @@ static int netvsc_register_vf(struct net_device *vf_netdev)
>  	if (!ndev)
>  		return NOTIFY_DONE;
>  
> +	if (event == NETDEV_POST_INIT) {
> +		/* set slave flag before open to prevent IPv6 addrconf */
> +		vf_netdev->flags |= IFF_SLAVE;
> +		return NOTIFY_DONE;
> +	}
> +
>  	net_device_ctx = netdev_priv(ndev);
>  	netvsc_dev = rtnl_dereference(net_device_ctx->nvdev);
>  	if (!netvsc_dev || rtnl_dereference(net_device_ctx->vf_netdev))
> @@ -2753,8 +2754,9 @@ static int netvsc_netdev_event(struct notifier_block *this,
>  		return NOTIFY_DONE;
>  
>  	switch (event) {
> +	case NETDEV_POST_INIT:
>  	case NETDEV_REGISTER:
> -		return netvsc_register_vf(event_dev);
> +		return netvsc_register_vf(event_dev, event);

Although correct, this is an awkward way to write this.
There are two events which call register_vf() but the post init
one short circuits and doesn't really register the VF.

The code is clearer if flag is set in switch statement.

@@ -2206,9 +2206,6 @@ static int netvsc_vf_join(struct net_device *vf_netdev,
 		goto upper_link_failed;
 	}
 
-	/* set slave flag before open to prevent IPv6 addrconf */
-	vf_netdev->flags |= IFF_SLAVE;
-
 	schedule_delayed_work(&ndev_ctx->vf_takeover, VF_TAKEOVER_INT);
 
 	call_netdevice_notifiers(NETDEV_JOIN, vf_netdev);
@@ -2753,6 +2750,10 @@ static int netvsc_netdev_event(struct notifier_block *this,
 		return NOTIFY_DONE;
 
 	switch (event) {
+	case NETDEV_POST_INIT:
+		/* set slave flag before open to prevent IPv6 addrconf */
+		vf_netdev->flags |= IFF_SLAVE;
+		return NOTIFY_DONE;
 	case NETDEV_REGISTER:
 		return netvsc_register_vf(event_dev);
 	case NETDEV_UNREGISTER: