[net-next] udp: gro behind static key

From: Willem de Bruijn <willemb@google.com>

Avoid the socket lookup cost in udp_gro_receive if no socket has a
udp tunnel callback configured.

udp_sk(sk)->gro_receive requires a registration with
setup_udp_tunnel_sock, which enables the static key.

Signed-off-by: Willem de Bruijn <willemb@google.com>
---
 include/net/udp.h      | 2 ++
 net/ipv4/udp.c         | 2 +-
 net/ipv4/udp_offload.c | 2 +-
 net/ipv6/udp.c         | 2 +-
 net/ipv6/udp_offload.c | 2 +-
 5 files changed, 6 insertions(+), 4 deletions(-)

On Fri, 2018-10-05 at 11:31 -0400, Willem de Bruijn wrote:
> From: Willem de Bruijn <willemb@google.com>
> 
> Avoid the socket lookup cost in udp_gro_receive if no socket has a
> udp tunnel callback configured.
> 
> udp_sk(sk)->gro_receive requires a registration with
> setup_udp_tunnel_sock, which enables the static key.
> 
> Signed-off-by: Willem de Bruijn <willemb@google.com>
> ---
>  include/net/udp.h      | 2 ++
>  net/ipv4/udp.c         | 2 +-
>  net/ipv4/udp_offload.c | 2 +-
>  net/ipv6/udp.c         | 2 +-
>  net/ipv6/udp_offload.c | 2 +-
>  5 files changed, 6 insertions(+), 4 deletions(-)
> 
> diff --git a/include/net/udp.h b/include/net/udp.h
> index 8482a990b0bb..9e82cb391dea 100644
> --- a/include/net/udp.h
> +++ b/include/net/udp.h
> @@ -443,8 +443,10 @@ int udpv4_offload_init(void);
>  
>  void udp_init(void);
>  
> +DECLARE_STATIC_KEY_FALSE(udp_encap_needed_key);
>  void udp_encap_enable(void);
>  #if IS_ENABLED(CONFIG_IPV6)
> +DECLARE_STATIC_KEY_FALSE(udpv6_encap_needed_key);
>  void udpv6_encap_enable(void);
>  #endif
>  
> diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
> index 5fc4beb1c336..1bec2203d558 100644
> --- a/net/ipv4/udp.c
> +++ b/net/ipv4/udp.c
> @@ -1889,7 +1889,7 @@ static int __udp_queue_rcv_skb(struct sock *sk, struct sk_buff *skb)
>  	return 0;
>  }
>  
> -static DEFINE_STATIC_KEY_FALSE(udp_encap_needed_key);
> +DEFINE_STATIC_KEY_FALSE(udp_encap_needed_key);
>  void udp_encap_enable(void)
>  {
>  	static_branch_enable(&udp_encap_needed_key);
> diff --git a/net/ipv4/udp_offload.c b/net/ipv4/udp_offload.c
> index 0c0522b79b43..802f2bc00d69 100644
> --- a/net/ipv4/udp_offload.c
> +++ b/net/ipv4/udp_offload.c
> @@ -405,7 +405,7 @@ static struct sk_buff *udp4_gro_receive(struct list_head *head,
>  {
>  	struct udphdr *uh = udp_gro_udphdr(skb);
>  
> -	if (unlikely(!uh))
> +	if (unlikely(!uh) || !static_branch_unlikely(&udp_encap_needed_key))
>  		goto flush;
>  
>  	/* Don't bother verifying checksum if we're going to flush anyway. */
> diff --git a/net/ipv6/udp.c b/net/ipv6/udp.c
> index 28c4aa5078fc..374e7d302f26 100644
> --- a/net/ipv6/udp.c
> +++ b/net/ipv6/udp.c
> @@ -548,7 +548,7 @@ static __inline__ void udpv6_err(struct sk_buff *skb,
>  	__udp6_lib_err(skb, opt, type, code, offset, info, &udp_table);
>  }
>  
> -static DEFINE_STATIC_KEY_FALSE(udpv6_encap_needed_key);
> +DEFINE_STATIC_KEY_FALSE(udpv6_encap_needed_key);
>  void udpv6_encap_enable(void)
>  {
>  	static_branch_enable(&udpv6_encap_needed_key);
> diff --git a/net/ipv6/udp_offload.c b/net/ipv6/udp_offload.c
> index 95dee9ca8d22..1b8e161ac527 100644
> --- a/net/ipv6/udp_offload.c
> +++ b/net/ipv6/udp_offload.c
> @@ -119,7 +119,7 @@ static struct sk_buff *udp6_gro_receive(struct list_head *head,
>  {
>  	struct udphdr *uh = udp_gro_udphdr(skb);
>  
> -	if (unlikely(!uh))
> +	if (unlikely(!uh) || !static_branch_unlikely(&udpv6_encap_needed_key))
>  		goto flush;
>  
>  	/* Don't bother verifying checksum if we're going to flush anyway. */

Acked-by: Paolo Abeni <pabeni@redhat.com>

From: Willem de Bruijn <willemdebruijn.kernel@gmail.com>
Date: Fri,  5 Oct 2018 11:31:40 -0400

> From: Willem de Bruijn <willemb@google.com>
> 
> Avoid the socket lookup cost in udp_gro_receive if no socket has a
> udp tunnel callback configured.
> 
> udp_sk(sk)->gro_receive requires a registration with
> setup_udp_tunnel_sock, which enables the static key.
> 
> Signed-off-by: Willem de Bruijn <willemb@google.com>

Applied, thanks.