linux-kernel - Re: [PATCH net-next v18 20/25] ovpn: implement peer add/get/dump/delete via netlink

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Message-ID: <6f907895-4f5f-450f-8aa7-709625e4bb25@openvpn.net>
Date: Wed, 22 Jan 2025 01:40:47 +0100
From: Antonio Quartulli <antonio@...nvpn.net>
To: Sabrina Dubroca <sd@...asysnail.net>
Cc: netdev@...r.kernel.org, Eric Dumazet <edumazet@...gle.com>,
 Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>,
 Donald Hunter <donald.hunter@...il.com>, Shuah Khan <shuah@...nel.org>,
 ryazanov.s.a@...il.com, Andrew Lunn <andrew+netdev@...n.ch>,
 Simon Horman <horms@...nel.org>, linux-kernel@...r.kernel.org,
 linux-kselftest@...r.kernel.org, Xiao Liang <shaw.leon@...il.com>
Subject: Re: [PATCH net-next v18 20/25] ovpn: implement peer
 add/get/dump/delete via netlink

On 17/01/2025 12:48, Sabrina Dubroca wrote:
[...]
> With the delayed socket release (which is similar to what was in v11,
> but now with refcounting on the netdevice which should make
> rtnl_link_unregister in ovpn_cleanup wait [*]), we may return to
> userspace as if the peer was gone, but the socket hasn't been detached
> yet.
> 
> A userspace application that tries to remove the peer and immediately
> re-create it with the same socket could get EBUSY if the workqueue
> hasn't done its job yet. That would be quite confusing to the
> application.
> 
> So I would add a completion to wait here until the socket has been
> fully detached. Something like below.
> 
> [*] I don't think the current refcounting fully protects against that,
> I'll comment on 05/25

Sabrina, after the other changes I acknowledged, do you still have 
comments for 5/25?

Thanks a lot!

Regards,

-- 
Antonio Quartulli
OpenVPN Inc.