linux-kernel - Re: [PATCH RFC net-next v4 09/12] vsock/loopback: add netns support

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Message-ID: <20250806191239.GF61519@horms.kernel.org>
Date: Wed, 6 Aug 2025 20:12:39 +0100
From: Simon Horman <horms@...nel.org>
To: Bobby Eshleman <bobbyeshleman@...il.com>
Cc: Stefano Garzarella <sgarzare@...hat.com>, Shuah Khan <shuah@...nel.org>,
	"David S. Miller" <davem@...emloft.net>,
	Eric Dumazet <edumazet@...gle.com>,
	Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>,
	Stefan Hajnoczi <stefanha@...hat.com>,
	"Michael S. Tsirkin" <mst@...hat.com>,
	Jason Wang <jasowang@...hat.com>,
	Xuan Zhuo <xuanzhuo@...ux.alibaba.com>,
	Eugenio Pérez <eperezma@...hat.com>,
	"K. Y. Srinivasan" <kys@...rosoft.com>,
	Haiyang Zhang <haiyangz@...rosoft.com>,
	Wei Liu <wei.liu@...nel.org>, Dexuan Cui <decui@...rosoft.com>,
	Bryan Tan <bryan-bt.tan@...adcom.com>,
	Vishnu Dasa <vishnu.dasa@...adcom.com>,
	Broadcom internal kernel review list <bcm-kernel-feedback-list@...adcom.com>,
	virtualization@...ts.linux.dev, netdev@...r.kernel.org,
	linux-kselftest@...r.kernel.org, linux-kernel@...r.kernel.org,
	kvm@...r.kernel.org, linux-hyperv@...r.kernel.org,
	berrange@...hat.com, Bobby Eshleman <bobbyeshleman@...a.com>
Subject: Re: [PATCH RFC net-next v4 09/12] vsock/loopback: add netns support

On Tue, Aug 05, 2025 at 02:49:17PM -0700, Bobby Eshleman wrote:
> From: Bobby Eshleman <bobbyeshleman@...a.com>
> 
> Add NS support to vsock loopback. Sockets in a global mode netns
> communicate with each other, regardless of namespace. Sockets in a local
> mode netns may only communicate with other sockets within the same
> namespace.
> 
> Signed-off-by: Bobby Eshleman <bobbyeshleman@...a.com>

...

> diff --git a/net/vmw_vsock/vsock_loopback.c b/net/vmw_vsock/vsock_loopback.c

...

> @@ -46,7 +57,7 @@ static int vsock_loopback_cancel_pkt(struct vsock_sock *vsk)
>  	return 0;
>  }
>  
> -static bool vsock_loopback_seqpacket_allow(u32 remote_cid);
> +static bool vsock_loopback_seqpacket_allow(struct vsock_sock *vsk, u32 remote_cid);

This change needs to be squashed into
PATCH 3/12 vsock: add netns to af_vsock core

To avoid build breakage.

Likewise with the other change to vsock_loopback_seqpacket_allow below.
And I think also for a number of other changes made by PATCH 3/12.

Please make sure that patches don't introduce transient build failures.
It breaks bisection.


On the topic of vsock_loopback_seqpacket_allow, also:

* Please line wrap this so that the code is 80 columns wide or less,
  as is still preferred for Networking code.

  Flagged by checkpatch.pl --max-line-length=80

* Can we move the definition of vsock_loopback_seqpacket_allow() here?
  The function itself is is trivial. And doing so would avoid a forward
  declaration.

>  static bool vsock_loopback_msgzerocopy_allow(void)
>  {
>  	return true;

...

> +int vsock_loopback_init_net(struct net *net)
> +{
> +	net->vsock.loopback = kmalloc(GFP_KERNEL, sizeof(struct vsock_loopback));
> +	if (!net->vsock.loopback)
> +		return -ENOMEM;
> +
> +	return vsock_loopback_init_vsock(net->vsock.loopback);
> +}
> +
> +void vsock_loopback_exit_net(struct net *net)
> +{
> +	vsock_loopback_deinit_vsock(net->vsock.loopback);
> +	kfree(net->vsock.loopback);
> +}

I think EXPORT_SYMBOL_GPL is needed for both vsock_loopback_exit_net and
vsock_loopback_init_net for the case where CONFIG_VSOCKETS=m

Also, in Kconfig VSOCKETS_LOOPBACK depends on VSOCKETS. But this code adds
a reverse dependency. As it stands it's possible to configure VSOCKETS
without VSOCKETS_LOOPBACK, which will not compile.

Perhaps stub implementations of vsock_loopback_init_net and
vsock_loopback_exit_net should be implemented in af_vsock.h if
VSOCKETS_LOOPBACK is not enabled?

...

-- 
pw-bot: changes-requested