netdev - Re: [PATCH net 1/5] ovpn: properly deconfigure UDP-tunnel

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Message-ID: <0b48468a-8635-4211-b7fe-27fd146debe1@openvpn.net>
Date: Tue, 3 Jun 2025 11:08:42 +0200
From: Antonio Quartulli <antonio@...nvpn.net>
To: Paolo Abeni <pabeni@...hat.com>, netdev@...r.kernel.org
Cc: Sabrina Dubroca <sd@...asysnail.net>,
 "David S . Miller" <davem@...emloft.net>, Eric Dumazet
 <edumazet@...gle.com>, Jakub Kicinski <kuba@...nel.org>,
 Oleksandr Natalenko <oleksandr@...alenko.name>
Subject: Re: [PATCH net 1/5] ovpn: properly deconfigure UDP-tunnel

On 03/06/2025 11:02, Paolo Abeni wrote:
> On 5/30/25 12:12 PM, Antonio Quartulli wrote:
>> diff --git a/drivers/net/ovpn/udp.c b/drivers/net/ovpn/udp.c
>> index aef8c0406ec9..89bb50f94ddb 100644
>> --- a/drivers/net/ovpn/udp.c
>> +++ b/drivers/net/ovpn/udp.c
>> @@ -442,8 +442,16 @@ int ovpn_udp_socket_attach(struct ovpn_socket *ovpn_sock,
>>    */
>>   void ovpn_udp_socket_detach(struct ovpn_socket *ovpn_sock)
>>   {
>> -	struct udp_tunnel_sock_cfg cfg = { };
>> +	struct sock *sk = ovpn_sock->sock->sk;
>>   
>> -	setup_udp_tunnel_sock(sock_net(ovpn_sock->sock->sk), ovpn_sock->sock,
>> -			      &cfg);
>> +	/* Re-enable multicast loopback */
>> +	inet_set_bit(MC_LOOP, sk);
>> +	/* Disable CHECKSUM_UNNECESSARY to CHECKSUM_COMPLETE conversion */
>> +	inet_dec_convert_csum(sk);
>> +
>> +	udp_sk(sk)->encap_type = 0;
>> +	udp_sk(sk)->encap_rcv = NULL;
>> +	udp_sk(sk)->encap_destroy = NULL;
> 
> I'm sorry for not noticing this earlier, but you need to add
> WRITE_ONCE() annotation to the above statements, because readers access
> such fields lockless.

I should have noticed the READ_ONCE on the reader side..

Any specific reason why setup_udp_tunnel_sock() does not use WRITE_ONCE 
though?

Regards,

-- 
Antonio Quartulli
OpenVPN Inc.