diff --git a/Documentation/networking/mptcp-sysctl.rst b/Documentation/networking/mptcp-sysctl.rst index 76d939e688b8485a2eacb33d19f44ee89eaba3b0..b0d4da71e68efb62f825e104bb3cde2aefed4a85 100644 --- a/Documentation/networking/mptcp-sysctl.rst +++ b/Documentation/networking/mptcp-sysctl.rst @@ -45,3 +45,15 @@ allow_join_initial_addr_port - BOOLEAN This is a per-namespace sysctl. Default: 1 + +stale_loss_cnt - INTEGER + The number of MPTCP-level retransmission intervals with no traffic and + pending outstanding data on a given subflow required to declare it stale. + The packet scheduler ignores stale subflows. + A low stale_loss_cnt value allows for fast active-backup switch-over, + an high value maximize links utilization on edge scenarios e.g. lossy + link with high BER or peer pausing the data processing. + + This is a per-namespace sysctl. + + Default: 4 diff --git a/net/mptcp/ctrl.c b/net/mptcp/ctrl.c index 63bba9d8e289fb5c50672b04972e2a9e66296ee9..8b235468c88ffa0847465ce20cec22c5338de888 100644 --- a/net/mptcp/ctrl.c +++ b/net/mptcp/ctrl.c @@ -22,6 +22,7 @@ struct mptcp_pernet { #endif unsigned int add_addr_timeout; + unsigned int stale_loss_cnt; u8 mptcp_enabled; u8 checksum_enabled; u8 allow_join_initial_addr_port; @@ -52,12 +53,18 @@ int mptcp_allow_join_id0(const struct net *net) return mptcp_get_pernet(net)->allow_join_initial_addr_port; } +unsigned int mptcp_stale_loss_cnt(const struct net *net) +{ + return mptcp_get_pernet(net)->stale_loss_cnt; +} + static void mptcp_pernet_set_defaults(struct mptcp_pernet *pernet) { pernet->mptcp_enabled = 1; pernet->add_addr_timeout = TCP_RTO_MAX; pernet->checksum_enabled = 0; pernet->allow_join_initial_addr_port = 1; + pernet->stale_loss_cnt = 4; } #ifdef CONFIG_SYSCTL @@ -95,6 +102,12 @@ static struct ctl_table mptcp_sysctl_table[] = { .extra1 = SYSCTL_ZERO, .extra2 = SYSCTL_ONE }, + { + .procname = "stale_loss_cnt", + .maxlen = sizeof(unsigned int), + .mode = 0644, + .proc_handler = proc_douintvec_minmax, + }, {} }; @@ -114,6 +127,7 @@ static int mptcp_pernet_new_table(struct net *net, struct mptcp_pernet *pernet) table[1].data = &pernet->add_addr_timeout; table[2].data = &pernet->checksum_enabled; table[3].data = &pernet->allow_join_initial_addr_port; + table[4].data = &pernet->stale_loss_cnt; hdr = register_net_sysctl(net, MPTCP_SYSCTL_PATH, table); if (!hdr) diff --git a/net/mptcp/pm.c b/net/mptcp/pm.c index 9ff17c5205ceba04508ed99ab73a1016c87db0ca..d8a85fe923609e92d06c133087fb6c805b5ff3b2 100644 --- a/net/mptcp/pm.c +++ b/net/mptcp/pm.c @@ -320,8 +320,10 @@ void mptcp_pm_subflow_chk_stale(const struct mptcp_sock *msk, struct sock *ssk) } else if (subflow->stale_rcv_tstamp == rcv_tstamp) { if (subflow->stale_count < U8_MAX) subflow->stale_count++; + mptcp_pm_nl_subflow_chk_stale(msk, ssk); } else { subflow->stale_count = 0; + mptcp_subflow_set_active(subflow); } } diff --git a/net/mptcp/pm_netlink.c b/net/mptcp/pm_netlink.c index 56263c2c4014cd81359a5bd84bccd227f56c60c5..c0eb14e05beafdaf0fad5fff714e8bdc5caa91e3 100644 --- a/net/mptcp/pm_netlink.c +++ b/net/mptcp/pm_netlink.c @@ -46,6 +46,7 @@ struct pm_nl_pernet { spinlock_t lock; struct list_head local_addr_list; unsigned int addrs; + unsigned int stale_loss_cnt; unsigned int add_addr_signal_max; unsigned int add_addr_accept_max; unsigned int local_addr_max; @@ -899,6 +900,42 @@ static const struct nla_policy mptcp_pm_policy[MPTCP_PM_ATTR_MAX + 1] = { [MPTCP_PM_ATTR_SUBFLOWS] = { .type = NLA_U32, }, }; +void mptcp_pm_nl_subflow_chk_stale(const struct mptcp_sock *msk, struct sock *ssk) +{ + struct mptcp_subflow_context *iter, *subflow = mptcp_subflow_ctx(ssk); + struct sock *sk = (struct sock *)msk; + unsigned int active_max_loss_cnt; + struct net *net = sock_net(sk); + unsigned int stale_loss_cnt; + bool slow; + + stale_loss_cnt = mptcp_stale_loss_cnt(net); + if (subflow->stale || !stale_loss_cnt || subflow->stale_count <= stale_loss_cnt) + return; + + /* look for another available subflow not in loss state */ + active_max_loss_cnt = max_t(int, stale_loss_cnt - 1, 1); + mptcp_for_each_subflow(msk, iter) { + if (iter != subflow && mptcp_subflow_active(iter) && + iter->stale_count < active_max_loss_cnt) { + /* we have some alternatives, try to mark this subflow as idle ...*/ + slow = lock_sock_fast(ssk); + if (!tcp_rtx_and_write_queues_empty(ssk)) { + subflow->stale = 1; + __mptcp_retransmit_pending_data(sk); + } + unlock_sock_fast(ssk, slow); + + /* always try to push the pending data regarless of re-injections: + * we can possibly use backup subflows now, and subflow selection + * is cheap under the msk socket lock + */ + __mptcp_push_pending(sk, 0); + return; + } + } +} + static int mptcp_pm_family_to_addr(int family) { #if IS_ENABLED(CONFIG_MPTCP_IPV6) @@ -1922,6 +1959,7 @@ static int __net_init pm_nl_init_net(struct net *net) INIT_LIST_HEAD_RCU(&pernet->local_addr_list); pernet->next_id = 1; + pernet->stale_loss_cnt = 4; spin_lock_init(&pernet->lock); /* No need to initialize other pernet fields, the struct is zeroed at diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c index 5fafa7a4cd6958d4317240bd7ebeaaf90c3d5982..18d3adccba5c52190b5d4cdf176a68417631f19a 100644 --- a/net/mptcp/protocol.c +++ b/net/mptcp/protocol.c @@ -1391,6 +1391,27 @@ struct subflow_send_info { u64 ratio; }; +void mptcp_subflow_set_active(struct mptcp_subflow_context *subflow) +{ + if (!subflow->stale) + return; + + subflow->stale = 0; +} + +bool mptcp_subflow_active(struct mptcp_subflow_context *subflow) +{ + if (unlikely(subflow->stale)) { + u32 rcv_tstamp = READ_ONCE(tcp_sk(mptcp_subflow_tcp_sock(subflow))->rcv_tstamp); + + if (subflow->stale_rcv_tstamp == rcv_tstamp) + return false; + + mptcp_subflow_set_active(subflow); + } + return __mptcp_subflow_active(subflow); +} + /* implement the mptcp packet scheduler; * returns the subflow that will transmit the next DSS * additionally updates the rtx timeout @@ -1472,7 +1493,7 @@ static void mptcp_push_release(struct sock *sk, struct sock *ssk, release_sock(ssk); } -static void __mptcp_push_pending(struct sock *sk, unsigned int flags) +void __mptcp_push_pending(struct sock *sk, unsigned int flags) { struct sock *prev_ssk = NULL, *ssk = NULL; struct mptcp_sock *msk = mptcp_sk(sk); @@ -2115,7 +2136,7 @@ static void mptcp_timeout_timer(struct timer_list *t) * * A backup subflow is returned only if that is the only kind available. */ -static struct sock *mptcp_subflow_get_retrans(const struct mptcp_sock *msk) +static struct sock *mptcp_subflow_get_retrans(struct mptcp_sock *msk) { struct sock *backup = NULL, *pick = NULL; struct mptcp_subflow_context *subflow; @@ -2129,7 +2150,7 @@ static struct sock *mptcp_subflow_get_retrans(const struct mptcp_sock *msk) mptcp_for_each_subflow(msk, subflow) { struct sock *ssk = mptcp_subflow_tcp_sock(subflow); - if (!mptcp_subflow_active(subflow)) + if (!__mptcp_subflow_active(subflow)) continue; /* still data outstanding at TCP level? skip this */ diff --git a/net/mptcp/protocol.h b/net/mptcp/protocol.h index 43ff6c5baddc7cae5d1400e84a97404c82f4a277..8bdd038def3838169dbd3e023769a85d06cff1b9 100644 --- a/net/mptcp/protocol.h +++ b/net/mptcp/protocol.h @@ -432,7 +432,8 @@ struct mptcp_subflow_context { send_mp_prio : 1, rx_eof : 1, can_ack : 1, /* only after processing the remote a key */ - disposable : 1; /* ctx can be free at ulp release time */ + disposable : 1, /* ctx can be free at ulp release time */ + stale : 1; /* unable to snd/rcv data, do not use for xmit */ enum mptcp_data_avail data_avail; u32 remote_nonce; u64 thmac; @@ -560,9 +561,11 @@ int mptcp_is_enabled(const struct net *net); unsigned int mptcp_get_add_addr_timeout(const struct net *net); int mptcp_is_checksum_enabled(const struct net *net); int mptcp_allow_join_id0(const struct net *net); +unsigned int mptcp_stale_loss_cnt(const struct net *net); void mptcp_subflow_fully_established(struct mptcp_subflow_context *subflow, struct mptcp_options_received *mp_opt); bool __mptcp_retransmit_pending_data(struct sock *sk); +void __mptcp_push_pending(struct sock *sk, unsigned int flags); bool mptcp_subflow_data_available(struct sock *sk); void __init mptcp_subflow_init(void); void mptcp_subflow_shutdown(struct sock *sk, struct sock *ssk, int how); @@ -581,7 +584,7 @@ void mptcp_info2sockaddr(const struct mptcp_addr_info *info, struct sockaddr_storage *addr, unsigned short family); -static inline bool mptcp_subflow_active(struct mptcp_subflow_context *subflow) +static inline bool __mptcp_subflow_active(struct mptcp_subflow_context *subflow) { struct sock *ssk = mptcp_subflow_tcp_sock(subflow); @@ -593,6 +596,10 @@ static inline bool mptcp_subflow_active(struct mptcp_subflow_context *subflow) return ((1 << ssk->sk_state) & (TCPF_ESTABLISHED | TCPF_CLOSE_WAIT)); } +void mptcp_subflow_set_active(struct mptcp_subflow_context *subflow); + +bool mptcp_subflow_active(struct mptcp_subflow_context *subflow); + static inline void mptcp_subflow_tcp_fallback(struct sock *sk, struct mptcp_subflow_context *ctx) { @@ -699,6 +706,7 @@ void mptcp_crypto_hmac_sha(u64 key1, u64 key2, u8 *msg, int len, void *hmac); void __init mptcp_pm_init(void); void mptcp_pm_data_init(struct mptcp_sock *msk); void mptcp_pm_subflow_chk_stale(const struct mptcp_sock *msk, struct sock *ssk); +void mptcp_pm_nl_subflow_chk_stale(const struct mptcp_sock *msk, struct sock *ssk); void mptcp_pm_new_connection(struct mptcp_sock *msk, const struct sock *ssk, int server_side); void mptcp_pm_fully_established(struct mptcp_sock *msk, const struct sock *ssk, gfp_t gfp); bool mptcp_pm_allow_new_subflow(struct mptcp_sock *msk);