netdev - Re: [PATCHv3 net-next] udp: call udp_encap_enable for v6 sockets when enabling encap

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Date:   Mon, 25 Jan 2021 21:34:58 -0500
From:   Willem de Bruijn <willemdebruijn.kernel@...il.com>
To:     Xin Long <lucien.xin@...il.com>
Cc:     network dev <netdev@...r.kernel.org>,
        David Miller <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>,
        Willem de Bruijn <willemb@...gle.com>,
        Martin Varghese <martin.varghese@...ia.com>,
        Alexander Duyck <alexander.duyck@...il.com>,
        David Howells <dhowells@...hat.com>
Subject: Re: [PATCHv3 net-next] udp: call udp_encap_enable for v6 sockets when
 enabling encap

On Sun, Jan 24, 2021 at 3:57 AM Xin Long <lucien.xin@...il.com> wrote:
>
> When enabling encap for a ipv6 socket without udp_encap_needed_key
> increased, UDP GRO won't work for v4 mapped v6 address packets as
> sk will be NULL in udp4_gro_receive().
>
> This patch is to enable it by increasing udp_encap_needed_key for
> v6 sockets in udp_tunnel_encap_enable(), and correspondingly
> decrease udp_encap_needed_key in udpv6_destroy_sock().
>
> v1->v2:
>   - add udp_encap_disable() and export it.
> v2->v3:
>   - add the change for rxrpc and bareudp into one patch, as Alex
>     suggested.
>
> Signed-off-by: Xin Long <lucien.xin@...il.com>
> ---
>  drivers/net/bareudp.c    | 6 ------
>  include/net/udp.h        | 1 +
>  include/net/udp_tunnel.h | 3 +--
>  net/ipv4/udp.c           | 6 ++++++
>  net/ipv6/udp.c           | 4 +++-
>  net/rxrpc/local_object.c | 4 +++-
>  6 files changed, 14 insertions(+), 10 deletions(-)
>
> diff --git a/drivers/net/bareudp.c b/drivers/net/bareudp.c
> index 1b8f597..7511bca 100644
> --- a/drivers/net/bareudp.c
> +++ b/drivers/net/bareudp.c
> @@ -240,12 +240,6 @@ static int bareudp_socket_create(struct bareudp_dev *bareudp, __be16 port)
>         tunnel_cfg.encap_destroy = NULL;
>         setup_udp_tunnel_sock(bareudp->net, sock, &tunnel_cfg);
>
> -       /* As the setup_udp_tunnel_sock does not call udp_encap_enable if the
> -        * socket type is v6 an explicit call to udp_encap_enable is needed.
> -        */
> -       if (sock->sk->sk_family == AF_INET6)
> -               udp_encap_enable();
> -
>         rcu_assign_pointer(bareudp->sock, sock);
>         return 0;
>  }
> diff --git a/include/net/udp.h b/include/net/udp.h
> index 877832b..1e7b6cd 100644
> --- a/include/net/udp.h
> +++ b/include/net/udp.h
> @@ -467,6 +467,7 @@ void udp_init(void);
>
>  DECLARE_STATIC_KEY_FALSE(udp_encap_needed_key);
>  void udp_encap_enable(void);
> +void udp_encap_disable(void);
>  #if IS_ENABLED(CONFIG_IPV6)
>  DECLARE_STATIC_KEY_FALSE(udpv6_encap_needed_key);
>  void udpv6_encap_enable(void);
> diff --git a/include/net/udp_tunnel.h b/include/net/udp_tunnel.h
> index 282d10e..afc7ce7 100644
> --- a/include/net/udp_tunnel.h
> +++ b/include/net/udp_tunnel.h
> @@ -181,9 +181,8 @@ static inline void udp_tunnel_encap_enable(struct socket *sock)
>  #if IS_ENABLED(CONFIG_IPV6)
>         if (sock->sk->sk_family == PF_INET6)
>                 ipv6_stub->udpv6_encap_enable();
> -       else
>  #endif
> -               udp_encap_enable();
> +       udp_encap_enable();
>  }
>
>  #define UDP_TUNNEL_NIC_MAX_TABLES      4
> diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
> index 69ea765..48208fb 100644
> --- a/net/ipv4/udp.c
> +++ b/net/ipv4/udp.c
> @@ -596,6 +596,12 @@ void udp_encap_enable(void)
>  }
>  EXPORT_SYMBOL(udp_encap_enable);
>
> +void udp_encap_disable(void)
> +{
> +       static_branch_dec(&udp_encap_needed_key);
> +}
> +EXPORT_SYMBOL(udp_encap_disable);
> +
>  /* Handler for tunnels with arbitrary destination ports: no socket lookup, go
>   * through error handlers in encapsulations looking for a match.
>   */
> diff --git a/net/ipv6/udp.c b/net/ipv6/udp.c
> index b9f3dfd..d754292 100644
> --- a/net/ipv6/udp.c
> +++ b/net/ipv6/udp.c
> @@ -1608,8 +1608,10 @@ void udpv6_destroy_sock(struct sock *sk)
>                         if (encap_destroy)
>                                 encap_destroy(sk);
>                 }
> -               if (up->encap_enabled)
> +               if (up->encap_enabled) {
>                         static_branch_dec(&udpv6_encap_needed_key);
> +                       udp_encap_disable();
> +               }
>         }
>
>         inet6_destroy_sock(sk);
> diff --git a/net/rxrpc/local_object.c b/net/rxrpc/local_object.c
> index 8c28810..fc10234 100644
> --- a/net/rxrpc/local_object.c
> +++ b/net/rxrpc/local_object.c
> @@ -135,11 +135,13 @@ static int rxrpc_open_socket(struct rxrpc_local *local, struct net *net)
>         udp_sk(usk)->gro_receive = NULL;
>         udp_sk(usk)->gro_complete = NULL;
>
> -       udp_encap_enable();
>  #if IS_ENABLED(CONFIG_AF_RXRPC_IPV6)
>         if (local->srx.transport.family == AF_INET6)
>                 udpv6_encap_enable();
> +       else
>  #endif
> +               udp_encap_enable();
> +

If ipv6 this socket will decrement both static branches in
udpv6_destroy_sock. Shouldn't it increment both, then? Similar to
udp_tunnel_encap_enable, but open coded.