From a36283e2b683f172aa1760c77325e50b16c0f792 Mon Sep 17 00:00:00 2001 From: Paolo Abeni Date: Mon, 7 Apr 2025 17:45:41 +0200 Subject: [PATCH 1/2] udp_tunnel: create a fastpath GRO lookup. Most UDP tunnels bind a socket to a local port, with ANY address, no peer and no interface index specified. Additionally it's quite common to have a single tunnel device per namespace. Track in each namespace the UDP tunnel socket respecting the above. When only a single one is present, store a reference in the netns. When such reference is not NULL, UDP tunnel GRO lookup just need to match the incoming packet destination port vs the socket local port. The tunnel socket never sets the reuse[port] flag[s]. When bound to no address and interface, no other socket can exist in the same netns matching the specified local port. Matching packets with non-local destination addresses will be aggregated, and eventually segmented as needed - no behavior changes intended. Restrict the optimization to kernel sockets only: it covers all the relevant use-cases, and user-space owned sockets could be disconnected and rebound after setup_udp_tunnel_sock(), breaking the uniqueness assumption Note that the UDP tunnel socket reference is stored into struct netns_ipv4 for both IPv4 and IPv6 tunnels. That is intentional to keep all the fastpath-related netns fields in the same struct and allow cacheline-based optimization. Currently both the IPv4 and IPv6 socket pointer share the same cacheline as the `udp_table` field. Signed-off-by: Paolo Abeni Reviewed-by: Willem de Bruijn Link: https://patch.msgid.link/41d16bc8d1257d567f9344c445b4ae0b4a91ede4.1744040675.git.pabeni@redhat.com Signed-off-by: Jakub Kicinski --- include/linux/udp.h | 16 ++++++++++++++++ include/net/netns/ipv4.h | 11 +++++++++++ include/net/udp.h | 1 + include/net/udp_tunnel.h | 12 ++++++++++++ net/ipv4/udp.c | 13 ++++++++++++- net/ipv4/udp_offload.c | 37 +++++++++++++++++++++++++++++++++++++ net/ipv4/udp_tunnel_core.c | 13 +++++++++++++ net/ipv6/udp.c | 2 ++ net/ipv6/udp_offload.c | 5 +++++ 9 files changed, 109 insertions(+), 1 deletion(-) diff --git a/include/linux/udp.h b/include/linux/udp.h index 0807e21cfec9..895240177f4f 100644 --- a/include/linux/udp.h +++ b/include/linux/udp.h @@ -101,6 +101,13 @@ struct udp_sock { /* Cache friendly copy of sk->sk_peek_off >= 0 */ bool peeking_with_offset; + + /* + * Accounting for the tunnel GRO fastpath. + * Unprotected by compilers guard, as it uses space available in + * the last UDP socket cacheline. + */ + struct hlist_node tunnel_list; }; #define udp_test_bit(nr, sk) \ @@ -219,4 +226,13 @@ static inline void udp_allow_gso(struct sock *sk) #define IS_UDPLITE(__sk) (__sk->sk_protocol == IPPROTO_UDPLITE) +static inline struct sock *udp_tunnel_sk(const struct net *net, bool is_ipv6) +{ +#if IS_ENABLED(CONFIG_NET_UDP_TUNNEL) + return rcu_dereference(net->ipv4.udp_tunnel_gro[is_ipv6].sk); +#else + return NULL; +#endif +} + #endif /* _LINUX_UDP_H */ diff --git a/include/net/netns/ipv4.h b/include/net/netns/ipv4.h index 650b2dc9199f..6373e3f17da8 100644 --- a/include/net/netns/ipv4.h +++ b/include/net/netns/ipv4.h @@ -47,6 +47,11 @@ struct sysctl_fib_multipath_hash_seed { }; #endif +struct udp_tunnel_gro { + struct sock __rcu *sk; + struct hlist_head list; +}; + struct netns_ipv4 { /* Cacheline organization can be found documented in * Documentation/networking/net_cachelines/netns_ipv4_sysctl.rst. @@ -85,6 +90,11 @@ struct netns_ipv4 { struct inet_timewait_death_row tcp_death_row; struct udp_table *udp_table; +#if IS_ENABLED(CONFIG_NET_UDP_TUNNEL) + /* Not in a pernet subsys because need to be available at GRO stage */ + struct udp_tunnel_gro udp_tunnel_gro[2]; +#endif + #ifdef CONFIG_SYSCTL struct ctl_table_header *forw_hdr; struct ctl_table_header *frags_hdr; @@ -277,4 +287,5 @@ struct netns_ipv4 { struct hlist_head *inet_addr_lst; struct delayed_work addr_chk_work; }; + #endif diff --git a/include/net/udp.h b/include/net/udp.h index 6e89520e100d..a772510b2aa5 100644 --- a/include/net/udp.h +++ b/include/net/udp.h @@ -290,6 +290,7 @@ static inline void udp_lib_init_sock(struct sock *sk) struct udp_sock *up = udp_sk(sk); skb_queue_head_init(&up->reader_queue); + INIT_HLIST_NODE(&up->tunnel_list); up->forward_threshold = sk->sk_rcvbuf >> 2; set_bit(SOCK_CUSTOM_SOCKOPT, &sk->sk_socket->flags); } diff --git a/include/net/udp_tunnel.h b/include/net/udp_tunnel.h index a93dc51f6323..1bb2b852e90e 100644 --- a/include/net/udp_tunnel.h +++ b/include/net/udp_tunnel.h @@ -191,6 +191,18 @@ static inline int udp_tunnel_handle_offloads(struct sk_buff *skb, bool udp_csum) } #endif +#if IS_ENABLED(CONFIG_NET_UDP_TUNNEL) +void udp_tunnel_update_gro_lookup(struct net *net, struct sock *sk, bool add); +#else +static inline void udp_tunnel_update_gro_lookup(struct net *net, + struct sock *sk, bool add) {} +#endif + +static inline void udp_tunnel_cleanup_gro(struct sock *sk) +{ + udp_tunnel_update_gro_lookup(sock_net(sk), sk, false); +} + static inline void udp_tunnel_encap_enable(struct sock *sk) { if (udp_test_and_set_bit(ENCAP_ENABLED, sk)) diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c index 2742cc7602bb..04cd3353f1d4 100644 --- a/net/ipv4/udp.c +++ b/net/ipv4/udp.c @@ -2897,8 +2897,10 @@ void udp_destroy_sock(struct sock *sk) if (encap_destroy) encap_destroy(sk); } - if (udp_test_bit(ENCAP_ENABLED, sk)) + if (udp_test_bit(ENCAP_ENABLED, sk)) { static_branch_dec(&udp_encap_needed_key); + udp_tunnel_cleanup_gro(sk); + } } } @@ -3810,6 +3812,15 @@ static void __net_init udp_set_table(struct net *net) static int __net_init udp_pernet_init(struct net *net) { +#if IS_ENABLED(CONFIG_NET_UDP_TUNNEL) + int i; + + /* No tunnel is configured */ + for (i = 0; i < ARRAY_SIZE(net->ipv4.udp_tunnel_gro); ++i) { + INIT_HLIST_HEAD(&net->ipv4.udp_tunnel_gro[i].list); + RCU_INIT_POINTER(net->ipv4.udp_tunnel_gro[i].sk, NULL); + } +#endif udp_sysctl_init(net); udp_set_table(net); diff --git a/net/ipv4/udp_offload.c b/net/ipv4/udp_offload.c index 2c0725583be3..69fc4eae8250 100644 --- a/net/ipv4/udp_offload.c +++ b/net/ipv4/udp_offload.c @@ -12,6 +12,38 @@ #include #include #include +#include + +#if IS_ENABLED(CONFIG_NET_UDP_TUNNEL) +static DEFINE_SPINLOCK(udp_tunnel_gro_lock); + +void udp_tunnel_update_gro_lookup(struct net *net, struct sock *sk, bool add) +{ + bool is_ipv6 = sk->sk_family == AF_INET6; + struct udp_sock *tup, *up = udp_sk(sk); + struct udp_tunnel_gro *udp_tunnel_gro; + + spin_lock(&udp_tunnel_gro_lock); + udp_tunnel_gro = &net->ipv4.udp_tunnel_gro[is_ipv6]; + if (add) + hlist_add_head(&up->tunnel_list, &udp_tunnel_gro->list); + else if (up->tunnel_list.pprev) + hlist_del_init(&up->tunnel_list); + + if (udp_tunnel_gro->list.first && + !udp_tunnel_gro->list.first->next) { + tup = hlist_entry(udp_tunnel_gro->list.first, struct udp_sock, + tunnel_list); + + rcu_assign_pointer(udp_tunnel_gro->sk, (struct sock *)tup); + } else { + RCU_INIT_POINTER(udp_tunnel_gro->sk, NULL); + } + + spin_unlock(&udp_tunnel_gro_lock); +} +EXPORT_SYMBOL_GPL(udp_tunnel_update_gro_lookup); +#endif static struct sk_buff *__skb_udp_tunnel_segment(struct sk_buff *skb, netdev_features_t features, @@ -635,8 +667,13 @@ static struct sock *udp4_gro_lookup_skb(struct sk_buff *skb, __be16 sport, { const struct iphdr *iph = skb_gro_network_header(skb); struct net *net = dev_net_rcu(skb->dev); + struct sock *sk; int iif, sdif; + sk = udp_tunnel_sk(net, false); + if (sk && dport == htons(sk->sk_num)) + return sk; + inet_get_iif_sdif(skb, &iif, &sdif); return __udp4_lib_lookup(net, iph->saddr, sport, diff --git a/net/ipv4/udp_tunnel_core.c b/net/ipv4/udp_tunnel_core.c index 619a53eb672d..3d1214e6df0e 100644 --- a/net/ipv4/udp_tunnel_core.c +++ b/net/ipv4/udp_tunnel_core.c @@ -58,6 +58,15 @@ int udp_sock_create4(struct net *net, struct udp_port_cfg *cfg, } EXPORT_SYMBOL(udp_sock_create4); +static bool sk_saddr_any(struct sock *sk) +{ +#if IS_ENABLED(CONFIG_IPV6) + return ipv6_addr_any(&sk->sk_v6_rcv_saddr); +#else + return !sk->sk_rcv_saddr; +#endif +} + void setup_udp_tunnel_sock(struct net *net, struct socket *sock, struct udp_tunnel_sock_cfg *cfg) { @@ -80,6 +89,10 @@ void setup_udp_tunnel_sock(struct net *net, struct socket *sock, udp_sk(sk)->gro_complete = cfg->gro_complete; udp_tunnel_encap_enable(sk); + + if (!sk->sk_dport && !sk->sk_bound_dev_if && sk_saddr_any(sk) && + sk->sk_kern_sock) + udp_tunnel_update_gro_lookup(net, sk, true); } EXPORT_SYMBOL_GPL(setup_udp_tunnel_sock); diff --git a/net/ipv6/udp.c b/net/ipv6/udp.c index 024458ef163c..7317f8e053f1 100644 --- a/net/ipv6/udp.c +++ b/net/ipv6/udp.c @@ -46,6 +46,7 @@ #include #include #include +#include #include #include #include @@ -1825,6 +1826,7 @@ void udpv6_destroy_sock(struct sock *sk) if (udp_test_bit(ENCAP_ENABLED, sk)) { static_branch_dec(&udpv6_encap_needed_key); udp_encap_disable(); + udp_tunnel_cleanup_gro(sk); } } } diff --git a/net/ipv6/udp_offload.c b/net/ipv6/udp_offload.c index 404212dfc99a..d8445ac1b2e4 100644 --- a/net/ipv6/udp_offload.c +++ b/net/ipv6/udp_offload.c @@ -118,8 +118,13 @@ static struct sock *udp6_gro_lookup_skb(struct sk_buff *skb, __be16 sport, { const struct ipv6hdr *iph = skb_gro_network_header(skb); struct net *net = dev_net_rcu(skb->dev); + struct sock *sk; int iif, sdif; + sk = udp_tunnel_sk(net, true); + if (sk && dport == htons(sk->sk_num)) + return sk; + inet6_get_iif_sdif(skb, &iif, &sdif); return __udp6_lib_lookup(net, &iph->saddr, sport, From 5d7f5b2f6b935517ee5fd8058dc32342a5cba3e1 Mon Sep 17 00:00:00 2001 From: Paolo Abeni Date: Mon, 7 Apr 2025 17:45:42 +0200 Subject: [PATCH 2/2] udp_tunnel: use static call for GRO hooks when possible It's quite common to have a single UDP tunnel type active in the whole system. In such a case we can replace the indirect call for the UDP tunnel GRO callback with a static call. Add the related accounting in the control path and switch to static call when possible. To keep the code simple use a static array for the registered tunnel types, and size such array based on the kernel config. Note that there are valid kernel configurations leading to UDP_MAX_TUNNEL_TYPES == 0 even with IS_ENABLED(CONFIG_NET_UDP_TUNNEL), Explicitly skip the accounting in such a case, to avoid compile warning when accessing "udp_tunnel_gro_types". Signed-off-by: Paolo Abeni Reviewed-by: Willem de Bruijn Link: https://patch.msgid.link/53d156cdfddcc9678449e873cc83e68fa1582653.1744040675.git.pabeni@redhat.com Signed-off-by: Jakub Kicinski --- include/net/udp_tunnel.h | 4 ++ net/ipv4/udp_offload.c | 135 ++++++++++++++++++++++++++++++++++++++- 2 files changed, 138 insertions(+), 1 deletion(-) diff --git a/include/net/udp_tunnel.h b/include/net/udp_tunnel.h index 1bb2b852e90e..288f06f23a80 100644 --- a/include/net/udp_tunnel.h +++ b/include/net/udp_tunnel.h @@ -193,13 +193,16 @@ static inline int udp_tunnel_handle_offloads(struct sk_buff *skb, bool udp_csum) #if IS_ENABLED(CONFIG_NET_UDP_TUNNEL) void udp_tunnel_update_gro_lookup(struct net *net, struct sock *sk, bool add); +void udp_tunnel_update_gro_rcv(struct sock *sk, bool add); #else static inline void udp_tunnel_update_gro_lookup(struct net *net, struct sock *sk, bool add) {} +static inline void udp_tunnel_update_gro_rcv(struct sock *sk, bool add) {} #endif static inline void udp_tunnel_cleanup_gro(struct sock *sk) { + udp_tunnel_update_gro_rcv(sk, false); udp_tunnel_update_gro_lookup(sock_net(sk), sk, false); } @@ -212,6 +215,7 @@ static inline void udp_tunnel_encap_enable(struct sock *sk) if (READ_ONCE(sk->sk_family) == PF_INET6) ipv6_stub->udpv6_encap_enable(); #endif + udp_tunnel_update_gro_rcv(sk, true); udp_encap_enable(); } diff --git a/net/ipv4/udp_offload.c b/net/ipv4/udp_offload.c index 69fc4eae8250..787b2947d3a0 100644 --- a/net/ipv4/udp_offload.c +++ b/net/ipv4/udp_offload.c @@ -15,6 +15,38 @@ #include #if IS_ENABLED(CONFIG_NET_UDP_TUNNEL) + +/* + * Dummy GRO tunnel callback, exists mainly to avoid dangling/NULL + * values for the udp tunnel static call. + */ +static struct sk_buff *dummy_gro_rcv(struct sock *sk, + struct list_head *head, + struct sk_buff *skb) +{ + NAPI_GRO_CB(skb)->flush = 1; + return NULL; +} + +typedef struct sk_buff *(*udp_tunnel_gro_rcv_t)(struct sock *sk, + struct list_head *head, + struct sk_buff *skb); + +struct udp_tunnel_type_entry { + udp_tunnel_gro_rcv_t gro_receive; + refcount_t count; +}; + +#define UDP_MAX_TUNNEL_TYPES (IS_ENABLED(CONFIG_GENEVE) + \ + IS_ENABLED(CONFIG_VXLAN) * 2 + \ + IS_ENABLED(CONFIG_NET_FOU) * 2 + \ + IS_ENABLED(CONFIG_XFRM) * 2) + +DEFINE_STATIC_CALL(udp_tunnel_gro_rcv, dummy_gro_rcv); +static DEFINE_STATIC_KEY_FALSE(udp_tunnel_static_call); +static struct mutex udp_tunnel_gro_type_lock; +static struct udp_tunnel_type_entry udp_tunnel_gro_types[UDP_MAX_TUNNEL_TYPES]; +static unsigned int udp_tunnel_gro_type_nr; static DEFINE_SPINLOCK(udp_tunnel_gro_lock); void udp_tunnel_update_gro_lookup(struct net *net, struct sock *sk, bool add) @@ -43,6 +75,105 @@ void udp_tunnel_update_gro_lookup(struct net *net, struct sock *sk, bool add) spin_unlock(&udp_tunnel_gro_lock); } EXPORT_SYMBOL_GPL(udp_tunnel_update_gro_lookup); + +void udp_tunnel_update_gro_rcv(struct sock *sk, bool add) +{ + struct udp_tunnel_type_entry *cur = NULL; + struct udp_sock *up = udp_sk(sk); + int i, old_gro_type_nr; + + if (!UDP_MAX_TUNNEL_TYPES || !up->gro_receive) + return; + + mutex_lock(&udp_tunnel_gro_type_lock); + + /* Check if the static call is permanently disabled. */ + if (udp_tunnel_gro_type_nr > UDP_MAX_TUNNEL_TYPES) + goto out; + + for (i = 0; i < udp_tunnel_gro_type_nr; i++) + if (udp_tunnel_gro_types[i].gro_receive == up->gro_receive) + cur = &udp_tunnel_gro_types[i]; + + old_gro_type_nr = udp_tunnel_gro_type_nr; + if (add) { + /* + * Update the matching entry, if found, or add a new one + * if needed + */ + if (cur) { + refcount_inc(&cur->count); + goto out; + } + + if (unlikely(udp_tunnel_gro_type_nr == UDP_MAX_TUNNEL_TYPES)) { + pr_err_once("Too many UDP tunnel types, please increase UDP_MAX_TUNNEL_TYPES\n"); + /* Ensure static call will never be enabled */ + udp_tunnel_gro_type_nr = UDP_MAX_TUNNEL_TYPES + 1; + } else { + cur = &udp_tunnel_gro_types[udp_tunnel_gro_type_nr++]; + refcount_set(&cur->count, 1); + cur->gro_receive = up->gro_receive; + } + } else { + /* + * The stack cleanups only successfully added tunnel, the + * lookup on removal should never fail. + */ + if (WARN_ON_ONCE(!cur)) + goto out; + + if (!refcount_dec_and_test(&cur->count)) + goto out; + + /* Avoid gaps, so that the enable tunnel has always id 0 */ + *cur = udp_tunnel_gro_types[--udp_tunnel_gro_type_nr]; + } + + if (udp_tunnel_gro_type_nr == 1) { + static_call_update(udp_tunnel_gro_rcv, + udp_tunnel_gro_types[0].gro_receive); + static_branch_enable(&udp_tunnel_static_call); + } else if (old_gro_type_nr == 1) { + static_branch_disable(&udp_tunnel_static_call); + static_call_update(udp_tunnel_gro_rcv, dummy_gro_rcv); + } + +out: + mutex_unlock(&udp_tunnel_gro_type_lock); +} +EXPORT_SYMBOL_GPL(udp_tunnel_update_gro_rcv); + +static void udp_tunnel_gro_init(void) +{ + mutex_init(&udp_tunnel_gro_type_lock); +} + +static struct sk_buff *udp_tunnel_gro_rcv(struct sock *sk, + struct list_head *head, + struct sk_buff *skb) +{ + if (static_branch_likely(&udp_tunnel_static_call)) { + if (unlikely(gro_recursion_inc_test(skb))) { + NAPI_GRO_CB(skb)->flush |= 1; + return NULL; + } + return static_call(udp_tunnel_gro_rcv)(sk, head, skb); + } + return call_gro_receive_sk(udp_sk(sk)->gro_receive, sk, head, skb); +} + +#else + +static void udp_tunnel_gro_init(void) {} + +static struct sk_buff *udp_tunnel_gro_rcv(struct sock *sk, + struct list_head *head, + struct sk_buff *skb) +{ + return call_gro_receive_sk(udp_sk(sk)->gro_receive, sk, head, skb); +} + #endif static struct sk_buff *__skb_udp_tunnel_segment(struct sk_buff *skb, @@ -654,7 +785,7 @@ struct sk_buff *udp_gro_receive(struct list_head *head, struct sk_buff *skb, skb_gro_pull(skb, sizeof(struct udphdr)); /* pull encapsulating udp header */ skb_gro_postpull_rcsum(skb, uh, sizeof(struct udphdr)); - pp = call_gro_receive_sk(udp_sk(sk)->gro_receive, sk, head, skb); + pp = udp_tunnel_gro_rcv(sk, head, skb); out: skb_gro_flush_final(skb, pp, flush); @@ -804,5 +935,7 @@ int __init udpv4_offload_init(void) .gro_complete = udp4_gro_complete, }, }; + + udp_tunnel_gro_init(); return inet_add_offload(&net_hotdata.udpv4_offload, IPPROTO_UDP); }