| // SPDX-License-Identifier: GPL-2.0-only |
| /* |
| * INET An implementation of the TCP/IP protocol suite for the LINUX |
| * operating system. INET is implemented using the BSD Socket |
| * interface as the means of communication with the user level. |
| * |
| * Implementation of the Transmission Control Protocol(TCP). |
| * |
| * Authors: Ross Biro |
| * Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG> |
| * Mark Evans, <evansmp@uhura.aston.ac.uk> |
| * Corey Minyard <wf-rch!minyard@relay.EU.net> |
| * Florian La Roche, <flla@stud.uni-sb.de> |
| * Charles Hedrick, <hedrick@klinzhai.rutgers.edu> |
| * Linus Torvalds, <torvalds@cs.helsinki.fi> |
| * Alan Cox, <gw4pts@gw4pts.ampr.org> |
| * Matthew Dillon, <dillon@apollo.west.oic.com> |
| * Arnt Gulbrandsen, <agulbra@nvg.unit.no> |
| * Jorge Cwik, <jorge@laser.satlink.net> |
| */ |
| |
| /* |
| * Changes: Pedro Roque : Retransmit queue handled by TCP. |
| * : Fragmentation on mtu decrease |
| * : Segment collapse on retransmit |
| * : AF independence |
| * |
| * Linus Torvalds : send_delayed_ack |
| * David S. Miller : Charge memory using the right skb |
| * during syn/ack processing. |
| * David S. Miller : Output engine completely rewritten. |
| * Andrea Arcangeli: SYNACK carry ts_recent in tsecr. |
| * Cacophonix Gaul : draft-minshall-nagle-01 |
| * J Hadi Salim : ECN support |
| * |
| */ |
| |
| #define pr_fmt(fmt) "TCP: " fmt |
| |
| #include <net/tcp.h> |
| #include <net/mptcp.h> |
| |
| #include <linux/compiler.h> |
| #include <linux/gfp.h> |
| #include <linux/module.h> |
| #include <linux/static_key.h> |
| |
| #include <trace/events/tcp.h> |
| |
| /* Refresh clocks of a TCP socket, |
| * ensuring monotically increasing values. |
| */ |
| void tcp_mstamp_refresh(struct tcp_sock *tp) |
| { |
| u64 val = tcp_clock_ns(); |
| |
| tp->tcp_clock_cache = val; |
| tp->tcp_mstamp = div_u64(val, NSEC_PER_USEC); |
| } |
| |
| static bool tcp_write_xmit(struct sock *sk, unsigned int mss_now, int nonagle, |
| int push_one, gfp_t gfp); |
| |
| /* Account for new data that has been sent to the network. */ |
| static void tcp_event_new_data_sent(struct sock *sk, struct sk_buff *skb) |
| { |
| struct inet_connection_sock *icsk = inet_csk(sk); |
| struct tcp_sock *tp = tcp_sk(sk); |
| unsigned int prior_packets = tp->packets_out; |
| |
| WRITE_ONCE(tp->snd_nxt, TCP_SKB_CB(skb)->end_seq); |
| |
| __skb_unlink(skb, &sk->sk_write_queue); |
| tcp_rbtree_insert(&sk->tcp_rtx_queue, skb); |
| |
| if (tp->highest_sack == NULL) |
| tp->highest_sack = skb; |
| |
| tp->packets_out += tcp_skb_pcount(skb); |
| if (!prior_packets || icsk->icsk_pending == ICSK_TIME_LOSS_PROBE) |
| tcp_rearm_rto(sk); |
| |
| NET_ADD_STATS(sock_net(sk), LINUX_MIB_TCPORIGDATASENT, |
| tcp_skb_pcount(skb)); |
| tcp_check_space(sk); |
| } |
| |
| /* SND.NXT, if window was not shrunk or the amount of shrunk was less than one |
| * window scaling factor due to loss of precision. |
| * If window has been shrunk, what should we make? It is not clear at all. |
| * Using SND.UNA we will fail to open window, SND.NXT is out of window. :-( |
| * Anything in between SND.UNA...SND.UNA+SND.WND also can be already |
| * invalid. OK, let's make this for now: |
| */ |
| static inline __u32 tcp_acceptable_seq(const struct sock *sk) |
| { |
| const struct tcp_sock *tp = tcp_sk(sk); |
| |
| if (!before(tcp_wnd_end(tp), tp->snd_nxt) || |
| (tp->rx_opt.wscale_ok && |
| ((tp->snd_nxt - tcp_wnd_end(tp)) < (1 << tp->rx_opt.rcv_wscale)))) |
| return tp->snd_nxt; |
| else |
| return tcp_wnd_end(tp); |
| } |
| |
| /* Calculate mss to advertise in SYN segment. |
| * RFC1122, RFC1063, draft-ietf-tcpimpl-pmtud-01 state that: |
| * |
| * 1. It is independent of path mtu. |
| * 2. Ideally, it is maximal possible segment size i.e. 65535-40. |
| * 3. For IPv4 it is reasonable to calculate it from maximal MTU of |
| * attached devices, because some buggy hosts are confused by |
| * large MSS. |
| * 4. We do not make 3, we advertise MSS, calculated from first |
| * hop device mtu, but allow to raise it to ip_rt_min_advmss. |
| * This may be overridden via information stored in routing table. |
| * 5. Value 65535 for MSS is valid in IPv6 and means "as large as possible, |
| * probably even Jumbo". |
| */ |
| static __u16 tcp_advertise_mss(struct sock *sk) |
| { |
| struct tcp_sock *tp = tcp_sk(sk); |
| const struct dst_entry *dst = __sk_dst_get(sk); |
| int mss = tp->advmss; |
| |
| if (dst) { |
| unsigned int metric = dst_metric_advmss(dst); |
| |
| if (metric < mss) { |
| mss = metric; |
| tp->advmss = mss; |
| } |
| } |
| |
| return (__u16)mss; |
| } |
| |
| /* RFC2861. Reset CWND after idle period longer RTO to "restart window". |
| * This is the first part of cwnd validation mechanism. |
| */ |
| void tcp_cwnd_restart(struct sock *sk, s32 delta) |
| { |
| struct tcp_sock *tp = tcp_sk(sk); |
| u32 restart_cwnd = tcp_init_cwnd(tp, __sk_dst_get(sk)); |
| u32 cwnd = tcp_snd_cwnd(tp); |
| |
| tcp_ca_event(sk, CA_EVENT_CWND_RESTART); |
| |
| tp->snd_ssthresh = tcp_current_ssthresh(sk); |
| restart_cwnd = min(restart_cwnd, cwnd); |
| |
| while ((delta -= inet_csk(sk)->icsk_rto) > 0 && cwnd > restart_cwnd) |
| cwnd >>= 1; |
| tcp_snd_cwnd_set(tp, max(cwnd, restart_cwnd)); |
| tp->snd_cwnd_stamp = tcp_jiffies32; |
| tp->snd_cwnd_used = 0; |
| } |
| |
| /* Congestion state accounting after a packet has been sent. */ |
| static void tcp_event_data_sent(struct tcp_sock *tp, |
| struct sock *sk) |
| { |
| struct inet_connection_sock *icsk = inet_csk(sk); |
| const u32 now = tcp_jiffies32; |
| |
| if (tcp_packets_in_flight(tp) == 0) |
| tcp_ca_event(sk, CA_EVENT_TX_START); |
| |
| tp->lsndtime = now; |
| |
| /* If it is a reply for ato after last received |
| * packet, enter pingpong mode. |
| */ |
| if ((u32)(now - icsk->icsk_ack.lrcvtime) < icsk->icsk_ack.ato) |
| inet_csk_enter_pingpong_mode(sk); |
| } |
| |
| /* Account for an ACK we sent. */ |
| static inline void tcp_event_ack_sent(struct sock *sk, u32 rcv_nxt) |
| { |
| struct tcp_sock *tp = tcp_sk(sk); |
| |
| if (unlikely(tp->compressed_ack)) { |
| NET_ADD_STATS(sock_net(sk), LINUX_MIB_TCPACKCOMPRESSED, |
| tp->compressed_ack); |
| tp->compressed_ack = 0; |
| if (hrtimer_try_to_cancel(&tp->compressed_ack_timer) == 1) |
| __sock_put(sk); |
| } |
| |
| if (unlikely(rcv_nxt != tp->rcv_nxt)) |
| return; /* Special ACK sent by DCTCP to reflect ECN */ |
| tcp_dec_quickack_mode(sk); |
| inet_csk_clear_xmit_timer(sk, ICSK_TIME_DACK); |
| } |
| |
| /* Determine a window scaling and initial window to offer. |
| * Based on the assumption that the given amount of space |
| * will be offered. Store the results in the tp structure. |
| * NOTE: for smooth operation initial space offering should |
| * be a multiple of mss if possible. We assume here that mss >= 1. |
| * This MUST be enforced by all callers. |
| */ |
| void tcp_select_initial_window(const struct sock *sk, int __space, __u32 mss, |
| __u32 *rcv_wnd, __u32 *window_clamp, |
| int wscale_ok, __u8 *rcv_wscale, |
| __u32 init_rcv_wnd) |
| { |
| unsigned int space = (__space < 0 ? 0 : __space); |
| |
| /* If no clamp set the clamp to the max possible scaled window */ |
| if (*window_clamp == 0) |
| (*window_clamp) = (U16_MAX << TCP_MAX_WSCALE); |
| space = min(*window_clamp, space); |
| |
| /* Quantize space offering to a multiple of mss if possible. */ |
| if (space > mss) |
| space = rounddown(space, mss); |
| |
| /* NOTE: offering an initial window larger than 32767 |
| * will break some buggy TCP stacks. If the admin tells us |
| * it is likely we could be speaking with such a buggy stack |
| * we will truncate our initial window offering to 32K-1 |
| * unless the remote has sent us a window scaling option, |
| * which we interpret as a sign the remote TCP is not |
| * misinterpreting the window field as a signed quantity. |
| */ |
| if (READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_workaround_signed_windows)) |
| (*rcv_wnd) = min(space, MAX_TCP_WINDOW); |
| else |
| (*rcv_wnd) = min_t(u32, space, U16_MAX); |
| |
| if (init_rcv_wnd) |
| *rcv_wnd = min(*rcv_wnd, init_rcv_wnd * mss); |
| |
| *rcv_wscale = 0; |
| if (wscale_ok) { |
| /* Set window scaling on max possible window */ |
| space = max_t(u32, space, READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_rmem[2])); |
| space = max_t(u32, space, READ_ONCE(sysctl_rmem_max)); |
| space = min_t(u32, space, *window_clamp); |
| *rcv_wscale = clamp_t(int, ilog2(space) - 15, |
| 0, TCP_MAX_WSCALE); |
| } |
| /* Set the clamp no higher than max representable value */ |
| (*window_clamp) = min_t(__u32, U16_MAX << (*rcv_wscale), *window_clamp); |
| } |
| EXPORT_SYMBOL(tcp_select_initial_window); |
| |
| /* Chose a new window to advertise, update state in tcp_sock for the |
| * socket, and return result with RFC1323 scaling applied. The return |
| * value can be stuffed directly into th->window for an outgoing |
| * frame. |
| */ |
| static u16 tcp_select_window(struct sock *sk) |
| { |
| struct tcp_sock *tp = tcp_sk(sk); |
| u32 old_win = tp->rcv_wnd; |
| u32 cur_win = tcp_receive_window(tp); |
| u32 new_win = __tcp_select_window(sk); |
| |
| /* Never shrink the offered window */ |
| if (new_win < cur_win) { |
| /* Danger Will Robinson! |
| * Don't update rcv_wup/rcv_wnd here or else |
| * we will not be able to advertise a zero |
| * window in time. --DaveM |
| * |
| * Relax Will Robinson. |
| */ |
| if (new_win == 0) |
| NET_INC_STATS(sock_net(sk), |
| LINUX_MIB_TCPWANTZEROWINDOWADV); |
| new_win = ALIGN(cur_win, 1 << tp->rx_opt.rcv_wscale); |
| } |
| tp->rcv_wnd = new_win; |
| tp->rcv_wup = tp->rcv_nxt; |
| |
| /* Make sure we do not exceed the maximum possible |
| * scaled window. |
| */ |
| if (!tp->rx_opt.rcv_wscale && |
| READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_workaround_signed_windows)) |
| new_win = min(new_win, MAX_TCP_WINDOW); |
| else |
| new_win = min(new_win, (65535U << tp->rx_opt.rcv_wscale)); |
| |
| /* RFC1323 scaling applied */ |
| new_win >>= tp->rx_opt.rcv_wscale; |
| |
| /* If we advertise zero window, disable fast path. */ |
| if (new_win == 0) { |
| tp->pred_flags = 0; |
| if (old_win) |
| NET_INC_STATS(sock_net(sk), |
| LINUX_MIB_TCPTOZEROWINDOWADV); |
| } else if (old_win == 0) { |
| NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPFROMZEROWINDOWADV); |
| } |
| |
| return new_win; |
| } |
| |
| /* Packet ECN state for a SYN-ACK */ |
| static void tcp_ecn_send_synack(struct sock *sk, struct sk_buff *skb) |
| { |
| const struct tcp_sock *tp = tcp_sk(sk); |
| |
| TCP_SKB_CB(skb)->tcp_flags &= ~TCPHDR_CWR; |
| if (!(tp->ecn_flags & TCP_ECN_OK)) |
| TCP_SKB_CB(skb)->tcp_flags &= ~TCPHDR_ECE; |
| else if (tcp_ca_needs_ecn(sk) || |
| tcp_bpf_ca_needs_ecn(sk)) |
| INET_ECN_xmit(sk); |
| } |
| |
| /* Packet ECN state for a SYN. */ |
| static void tcp_ecn_send_syn(struct sock *sk, struct sk_buff *skb) |
| { |
| struct tcp_sock *tp = tcp_sk(sk); |
| bool bpf_needs_ecn = tcp_bpf_ca_needs_ecn(sk); |
| bool use_ecn = READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_ecn) == 1 || |
| tcp_ca_needs_ecn(sk) || bpf_needs_ecn; |
| |
| if (!use_ecn) { |
| const struct dst_entry *dst = __sk_dst_get(sk); |
| |
| if (dst && dst_feature(dst, RTAX_FEATURE_ECN)) |
| use_ecn = true; |
| } |
| |
| tp->ecn_flags = 0; |
| |
| if (use_ecn) { |
| TCP_SKB_CB(skb)->tcp_flags |= TCPHDR_ECE | TCPHDR_CWR; |
| tp->ecn_flags = TCP_ECN_OK; |
| if (tcp_ca_needs_ecn(sk) || bpf_needs_ecn) |
| INET_ECN_xmit(sk); |
| } |
| } |
| |
| static void tcp_ecn_clear_syn(struct sock *sk, struct sk_buff *skb) |
| { |
| if (READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_ecn_fallback)) |
| /* tp->ecn_flags are cleared at a later point in time when |
| * SYN ACK is ultimatively being received. |
| */ |
| TCP_SKB_CB(skb)->tcp_flags &= ~(TCPHDR_ECE | TCPHDR_CWR); |
| } |
| |
| static void |
| tcp_ecn_make_synack(const struct request_sock *req, struct tcphdr *th) |
| { |
| if (inet_rsk(req)->ecn_ok) |
| th->ece = 1; |
| } |
| |
| /* Set up ECN state for a packet on a ESTABLISHED socket that is about to |
| * be sent. |
| */ |
| static void tcp_ecn_send(struct sock *sk, struct sk_buff *skb, |
| struct tcphdr *th, int tcp_header_len) |
| { |
| struct tcp_sock *tp = tcp_sk(sk); |
| |
| if (tp->ecn_flags & TCP_ECN_OK) { |
| /* Not-retransmitted data segment: set ECT and inject CWR. */ |
| if (skb->len != tcp_header_len && |
| !before(TCP_SKB_CB(skb)->seq, tp->snd_nxt)) { |
| INET_ECN_xmit(sk); |
| if (tp->ecn_flags & TCP_ECN_QUEUE_CWR) { |
| tp->ecn_flags &= ~TCP_ECN_QUEUE_CWR; |
| th->cwr = 1; |
| skb_shinfo(skb)->gso_type |= SKB_GSO_TCP_ECN; |
| } |
| } else if (!tcp_ca_needs_ecn(sk)) { |
| /* ACK or retransmitted segment: clear ECT|CE */ |
| INET_ECN_dontxmit(sk); |
| } |
| if (tp->ecn_flags & TCP_ECN_DEMAND_CWR) |
| th->ece = 1; |
| } |
| } |
| |
| /* Constructs common control bits of non-data skb. If SYN/FIN is present, |
| * auto increment end seqno. |
| */ |
| static void tcp_init_nondata_skb(struct sk_buff *skb, u32 seq, u8 flags) |
| { |
| skb->ip_summed = CHECKSUM_PARTIAL; |
| |
| TCP_SKB_CB(skb)->tcp_flags = flags; |
| |
| tcp_skb_pcount_set(skb, 1); |
| |
| TCP_SKB_CB(skb)->seq = seq; |
| if (flags & (TCPHDR_SYN | TCPHDR_FIN)) |
| seq++; |
| TCP_SKB_CB(skb)->end_seq = seq; |
| } |
| |
| static inline bool tcp_urg_mode(const struct tcp_sock *tp) |
| { |
| return tp->snd_una != tp->snd_up; |
| } |
| |
| #define OPTION_SACK_ADVERTISE BIT(0) |
| #define OPTION_TS BIT(1) |
| #define OPTION_MD5 BIT(2) |
| #define OPTION_WSCALE BIT(3) |
| #define OPTION_FAST_OPEN_COOKIE BIT(8) |
| #define OPTION_SMC BIT(9) |
| #define OPTION_MPTCP BIT(10) |
| |
| static void smc_options_write(__be32 *ptr, u16 *options) |
| { |
| #if IS_ENABLED(CONFIG_SMC) |
| if (static_branch_unlikely(&tcp_have_smc)) { |
| if (unlikely(OPTION_SMC & *options)) { |
| *ptr++ = htonl((TCPOPT_NOP << 24) | |
| (TCPOPT_NOP << 16) | |
| (TCPOPT_EXP << 8) | |
| (TCPOLEN_EXP_SMC_BASE)); |
| *ptr++ = htonl(TCPOPT_SMC_MAGIC); |
| } |
| } |
| #endif |
| } |
| |
| struct tcp_out_options { |
| u16 options; /* bit field of OPTION_* */ |
| u16 mss; /* 0 to disable */ |
| u8 ws; /* window scale, 0 to disable */ |
| u8 num_sack_blocks; /* number of SACK blocks to include */ |
| u8 hash_size; /* bytes in hash_location */ |
| u8 bpf_opt_len; /* length of BPF hdr option */ |
| __u8 *hash_location; /* temporary pointer, overloaded */ |
| __u32 tsval, tsecr; /* need to include OPTION_TS */ |
| struct tcp_fastopen_cookie *fastopen_cookie; /* Fast open cookie */ |
| struct mptcp_out_options mptcp; |
| }; |
| |
| static void mptcp_options_write(struct tcphdr *th, __be32 *ptr, |
| struct tcp_sock *tp, |
| struct tcp_out_options *opts) |
| { |
| #if IS_ENABLED(CONFIG_MPTCP) |
| if (unlikely(OPTION_MPTCP & opts->options)) |
| mptcp_write_options(th, ptr, tp, &opts->mptcp); |
| #endif |
| } |
| |
| #ifdef CONFIG_CGROUP_BPF |
| static int bpf_skops_write_hdr_opt_arg0(struct sk_buff *skb, |
| enum tcp_synack_type synack_type) |
| { |
| if (unlikely(!skb)) |
| return BPF_WRITE_HDR_TCP_CURRENT_MSS; |
| |
| if (unlikely(synack_type == TCP_SYNACK_COOKIE)) |
| return BPF_WRITE_HDR_TCP_SYNACK_COOKIE; |
| |
| return 0; |
| } |
| |
| /* req, syn_skb and synack_type are used when writing synack */ |
| static void bpf_skops_hdr_opt_len(struct sock *sk, struct sk_buff *skb, |
| struct request_sock *req, |
| struct sk_buff *syn_skb, |
| enum tcp_synack_type synack_type, |
| struct tcp_out_options *opts, |
| unsigned int *remaining) |
| { |
| struct bpf_sock_ops_kern sock_ops; |
| int err; |
| |
| if (likely(!BPF_SOCK_OPS_TEST_FLAG(tcp_sk(sk), |
| BPF_SOCK_OPS_WRITE_HDR_OPT_CB_FLAG)) || |
| !*remaining) |
| return; |
| |
| /* *remaining has already been aligned to 4 bytes, so *remaining >= 4 */ |
| |
| /* init sock_ops */ |
| memset(&sock_ops, 0, offsetof(struct bpf_sock_ops_kern, temp)); |
| |
| sock_ops.op = BPF_SOCK_OPS_HDR_OPT_LEN_CB; |
| |
| if (req) { |
| /* The listen "sk" cannot be passed here because |
| * it is not locked. It would not make too much |
| * sense to do bpf_setsockopt(listen_sk) based |
| * on individual connection request also. |
| * |
| * Thus, "req" is passed here and the cgroup-bpf-progs |
| * of the listen "sk" will be run. |
| * |
| * "req" is also used here for fastopen even the "sk" here is |
| * a fullsock "child" sk. It is to keep the behavior |
| * consistent between fastopen and non-fastopen on |
| * the bpf programming side. |
| */ |
| sock_ops.sk = (struct sock *)req; |
| sock_ops.syn_skb = syn_skb; |
| } else { |
| sock_owned_by_me(sk); |
| |
| sock_ops.is_fullsock = 1; |
| sock_ops.sk = sk; |
| } |
| |
| sock_ops.args[0] = bpf_skops_write_hdr_opt_arg0(skb, synack_type); |
| sock_ops.remaining_opt_len = *remaining; |
| /* tcp_current_mss() does not pass a skb */ |
| if (skb) |
| bpf_skops_init_skb(&sock_ops, skb, 0); |
| |
| err = BPF_CGROUP_RUN_PROG_SOCK_OPS_SK(&sock_ops, sk); |
| |
| if (err || sock_ops.remaining_opt_len == *remaining) |
| return; |
| |
| opts->bpf_opt_len = *remaining - sock_ops.remaining_opt_len; |
| /* round up to 4 bytes */ |
| opts->bpf_opt_len = (opts->bpf_opt_len + 3) & ~3; |
| |
| *remaining -= opts->bpf_opt_len; |
| } |
| |
| static void bpf_skops_write_hdr_opt(struct sock *sk, struct sk_buff *skb, |
| struct request_sock *req, |
| struct sk_buff *syn_skb, |
| enum tcp_synack_type synack_type, |
| struct tcp_out_options *opts) |
| { |
| u8 first_opt_off, nr_written, max_opt_len = opts->bpf_opt_len; |
| struct bpf_sock_ops_kern sock_ops; |
| int err; |
| |
| if (likely(!max_opt_len)) |
| return; |
| |
| memset(&sock_ops, 0, offsetof(struct bpf_sock_ops_kern, temp)); |
| |
| sock_ops.op = BPF_SOCK_OPS_WRITE_HDR_OPT_CB; |
| |
| if (req) { |
| sock_ops.sk = (struct sock *)req; |
| sock_ops.syn_skb = syn_skb; |
| } else { |
| sock_owned_by_me(sk); |
| |
| sock_ops.is_fullsock = 1; |
| sock_ops.sk = sk; |
| } |
| |
| sock_ops.args[0] = bpf_skops_write_hdr_opt_arg0(skb, synack_type); |
| sock_ops.remaining_opt_len = max_opt_len; |
| first_opt_off = tcp_hdrlen(skb) - max_opt_len; |
| bpf_skops_init_skb(&sock_ops, skb, first_opt_off); |
| |
| err = BPF_CGROUP_RUN_PROG_SOCK_OPS_SK(&sock_ops, sk); |
| |
| if (err) |
| nr_written = 0; |
| else |
| nr_written = max_opt_len - sock_ops.remaining_opt_len; |
| |
| if (nr_written < max_opt_len) |
| memset(skb->data + first_opt_off + nr_written, TCPOPT_NOP, |
| max_opt_len - nr_written); |
| } |
| #else |
| static void bpf_skops_hdr_opt_len(struct sock *sk, struct sk_buff *skb, |
| struct request_sock *req, |
| struct sk_buff *syn_skb, |
| enum tcp_synack_type synack_type, |
| struct tcp_out_options *opts, |
| unsigned int *remaining) |
| { |
| } |
| |
| static void bpf_skops_write_hdr_opt(struct sock *sk, struct sk_buff *skb, |
| struct request_sock *req, |
| struct sk_buff *syn_skb, |
| enum tcp_synack_type synack_type, |
| struct tcp_out_options *opts) |
| { |
| } |
| #endif |
| |
| /* Write previously computed TCP options to the packet. |
| * |
| * Beware: Something in the Internet is very sensitive to the ordering of |
| * TCP options, we learned this through the hard way, so be careful here. |
| * Luckily we can at least blame others for their non-compliance but from |
| * inter-operability perspective it seems that we're somewhat stuck with |
| * the ordering which we have been using if we want to keep working with |
| * those broken things (not that it currently hurts anybody as there isn't |
| * particular reason why the ordering would need to be changed). |
| * |
| * At least SACK_PERM as the first option is known to lead to a disaster |
| * (but it may well be that other scenarios fail similarly). |
| */ |
| static void tcp_options_write(struct tcphdr *th, struct tcp_sock *tp, |
| struct tcp_out_options *opts) |
| { |
| __be32 *ptr = (__be32 *)(th + 1); |
| u16 options = opts->options; /* mungable copy */ |
| |
| if (unlikely(OPTION_MD5 & options)) { |
| *ptr++ = htonl((TCPOPT_NOP << 24) | (TCPOPT_NOP << 16) | |
| (TCPOPT_MD5SIG << 8) | TCPOLEN_MD5SIG); |
| /* overload cookie hash location */ |
| opts->hash_location = (__u8 *)ptr; |
| ptr += 4; |
| } |
| |
| if (unlikely(opts->mss)) { |
| *ptr++ = htonl((TCPOPT_MSS << 24) | |
| (TCPOLEN_MSS << 16) | |
| opts->mss); |
| } |
| |
| if (likely(OPTION_TS & options)) { |
| if (unlikely(OPTION_SACK_ADVERTISE & options)) { |
| *ptr++ = htonl((TCPOPT_SACK_PERM << 24) | |
| (TCPOLEN_SACK_PERM << 16) | |
| (TCPOPT_TIMESTAMP << 8) | |
| TCPOLEN_TIMESTAMP); |
| options &= ~OPTION_SACK_ADVERTISE; |
| } else { |
| *ptr++ = htonl((TCPOPT_NOP << 24) | |
| (TCPOPT_NOP << 16) | |
| (TCPOPT_TIMESTAMP << 8) | |
| TCPOLEN_TIMESTAMP); |
| } |
| *ptr++ = htonl(opts->tsval); |
| *ptr++ = htonl(opts->tsecr); |
| } |
| |
| if (unlikely(OPTION_SACK_ADVERTISE & options)) { |
| *ptr++ = htonl((TCPOPT_NOP << 24) | |
| (TCPOPT_NOP << 16) | |
| (TCPOPT_SACK_PERM << 8) | |
| TCPOLEN_SACK_PERM); |
| } |
| |
| if (unlikely(OPTION_WSCALE & options)) { |
| *ptr++ = htonl((TCPOPT_NOP << 24) | |
| (TCPOPT_WINDOW << 16) | |
| (TCPOLEN_WINDOW << 8) | |
| opts->ws); |
| } |
| |
| if (unlikely(opts->num_sack_blocks)) { |
| struct tcp_sack_block *sp = tp->rx_opt.dsack ? |
| tp->duplicate_sack : tp->selective_acks; |
| int this_sack; |
| |
| *ptr++ = htonl((TCPOPT_NOP << 24) | |
| (TCPOPT_NOP << 16) | |
| (TCPOPT_SACK << 8) | |
| (TCPOLEN_SACK_BASE + (opts->num_sack_blocks * |
| TCPOLEN_SACK_PERBLOCK))); |
| |
| for (this_sack = 0; this_sack < opts->num_sack_blocks; |
| ++this_sack) { |
| *ptr++ = htonl(sp[this_sack].start_seq); |
| *ptr++ = htonl(sp[this_sack].end_seq); |
| } |
| |
| tp->rx_opt.dsack = 0; |
| } |
| |
| if (unlikely(OPTION_FAST_OPEN_COOKIE & options)) { |
| struct tcp_fastopen_cookie *foc = opts->fastopen_cookie; |
| u8 *p = (u8 *)ptr; |
| u32 len; /* Fast Open option length */ |
| |
| if (foc->exp) { |
| len = TCPOLEN_EXP_FASTOPEN_BASE + foc->len; |
| *ptr = htonl((TCPOPT_EXP << 24) | (len << 16) | |
| TCPOPT_FASTOPEN_MAGIC); |
| p += TCPOLEN_EXP_FASTOPEN_BASE; |
| } else { |
| len = TCPOLEN_FASTOPEN_BASE + foc->len; |
| *p++ = TCPOPT_FASTOPEN; |
| *p++ = len; |
| } |
| |
| memcpy(p, foc->val, foc->len); |
| if ((len & 3) == 2) { |
| p[foc->len] = TCPOPT_NOP; |
| p[foc->len + 1] = TCPOPT_NOP; |
| } |
| ptr += (len + 3) >> 2; |
| } |
| |
| smc_options_write(ptr, &options); |
| |
| mptcp_options_write(th, ptr, tp, opts); |
| } |
| |
| static void smc_set_option(const struct tcp_sock *tp, |
| struct tcp_out_options *opts, |
| unsigned int *remaining) |
| { |
| #if IS_ENABLED(CONFIG_SMC) |
| if (static_branch_unlikely(&tcp_have_smc)) { |
| if (tp->syn_smc) { |
| if (*remaining >= TCPOLEN_EXP_SMC_BASE_ALIGNED) { |
| opts->options |= OPTION_SMC; |
| *remaining -= TCPOLEN_EXP_SMC_BASE_ALIGNED; |
| } |
| } |
| } |
| #endif |
| } |
| |
| static void smc_set_option_cond(const struct tcp_sock *tp, |
| const struct inet_request_sock *ireq, |
| struct tcp_out_options *opts, |
| unsigned int *remaining) |
| { |
| #if IS_ENABLED(CONFIG_SMC) |
| if (static_branch_unlikely(&tcp_have_smc)) { |
| if (tp->syn_smc && ireq->smc_ok) { |
| if (*remaining >= TCPOLEN_EXP_SMC_BASE_ALIGNED) { |
| opts->options |= OPTION_SMC; |
| *remaining -= TCPOLEN_EXP_SMC_BASE_ALIGNED; |
| } |
| } |
| } |
| #endif |
| } |
| |
| static void mptcp_set_option_cond(const struct request_sock *req, |
| struct tcp_out_options *opts, |
| unsigned int *remaining) |
| { |
| if (rsk_is_mptcp(req)) { |
| unsigned int size; |
| |
| if (mptcp_synack_options(req, &size, &opts->mptcp)) { |
| if (*remaining >= size) { |
| opts->options |= OPTION_MPTCP; |
| *remaining -= size; |
| } |
| } |
| } |
| } |
| |
| /* Compute TCP options for SYN packets. This is not the final |
| * network wire format yet. |
| */ |
| static unsigned int tcp_syn_options(struct sock *sk, struct sk_buff *skb, |
| struct tcp_out_options *opts, |
| struct tcp_md5sig_key **md5) |
| { |
| struct tcp_sock *tp = tcp_sk(sk); |
| unsigned int remaining = MAX_TCP_OPTION_SPACE; |
| struct tcp_fastopen_request *fastopen = tp->fastopen_req; |
| |
| *md5 = NULL; |
| #ifdef CONFIG_TCP_MD5SIG |
| if (static_branch_unlikely(&tcp_md5_needed) && |
| rcu_access_pointer(tp->md5sig_info)) { |
| *md5 = tp->af_specific->md5_lookup(sk, sk); |
| if (*md5) { |
| opts->options |= OPTION_MD5; |
| remaining -= TCPOLEN_MD5SIG_ALIGNED; |
| } |
| } |
| #endif |
| |
| /* We always get an MSS option. The option bytes which will be seen in |
| * normal data packets should timestamps be used, must be in the MSS |
| * advertised. But we subtract them from tp->mss_cache so that |
| * calculations in tcp_sendmsg are simpler etc. So account for this |
| * fact here if necessary. If we don't do this correctly, as a |
| * receiver we won't recognize data packets as being full sized when we |
| * should, and thus we won't abide by the delayed ACK rules correctly. |
| * SACKs don't matter, we never delay an ACK when we have any of those |
| * going out. */ |
| opts->mss = tcp_advertise_mss(sk); |
| remaining -= TCPOLEN_MSS_ALIGNED; |
| |
| if (likely(READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_timestamps) && !*md5)) { |
| opts->options |= OPTION_TS; |
| opts->tsval = tcp_skb_timestamp(skb) + tp->tsoffset; |
| opts->tsecr = tp->rx_opt.ts_recent; |
| remaining -= TCPOLEN_TSTAMP_ALIGNED; |
| } |
| if (likely(READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_window_scaling))) { |
| opts->ws = tp->rx_opt.rcv_wscale; |
| opts->options |= OPTION_WSCALE; |
| remaining -= TCPOLEN_WSCALE_ALIGNED; |
| } |
| if (likely(READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_sack))) { |
| opts->options |= OPTION_SACK_ADVERTISE; |
| if (unlikely(!(OPTION_TS & opts->options))) |
| remaining -= TCPOLEN_SACKPERM_ALIGNED; |
| } |
| |
| if (fastopen && fastopen->cookie.len >= 0) { |
| u32 need = fastopen->cookie.len; |
| |
| need += fastopen->cookie.exp ? TCPOLEN_EXP_FASTOPEN_BASE : |
| TCPOLEN_FASTOPEN_BASE; |
| need = (need + 3) & ~3U; /* Align to 32 bits */ |
| if (remaining >= need) { |
| opts->options |= OPTION_FAST_OPEN_COOKIE; |
| opts->fastopen_cookie = &fastopen->cookie; |
| remaining -= need; |
| tp->syn_fastopen = 1; |
| tp->syn_fastopen_exp = fastopen->cookie.exp ? 1 : 0; |
| } |
| } |
| |
| smc_set_option(tp, opts, &remaining); |
| |
| if (sk_is_mptcp(sk)) { |
| unsigned int size; |
| |
| if (mptcp_syn_options(sk, skb, &size, &opts->mptcp)) { |
| opts->options |= OPTION_MPTCP; |
| remaining -= size; |
| } |
| } |
| |
| bpf_skops_hdr_opt_len(sk, skb, NULL, NULL, 0, opts, &remaining); |
| |
| return MAX_TCP_OPTION_SPACE - remaining; |
| } |
| |
| /* Set up TCP options for SYN-ACKs. */ |
| static unsigned int tcp_synack_options(const struct sock *sk, |
| struct request_sock *req, |
| unsigned int mss, struct sk_buff *skb, |
| struct tcp_out_options *opts, |
| const struct tcp_md5sig_key *md5, |
| struct tcp_fastopen_cookie *foc, |
| enum tcp_synack_type synack_type, |
| struct sk_buff *syn_skb) |
| { |
| struct inet_request_sock *ireq = inet_rsk(req); |
| unsigned int remaining = MAX_TCP_OPTION_SPACE; |
| |
| #ifdef CONFIG_TCP_MD5SIG |
| if (md5) { |
| opts->options |= OPTION_MD5; |
| remaining -= TCPOLEN_MD5SIG_ALIGNED; |
| |
| /* We can't fit any SACK blocks in a packet with MD5 + TS |
| * options. There was discussion about disabling SACK |
| * rather than TS in order to fit in better with old, |
| * buggy kernels, but that was deemed to be unnecessary. |
| */ |
| if (synack_type != TCP_SYNACK_COOKIE) |
| ireq->tstamp_ok &= !ireq->sack_ok; |
| } |
| #endif |
| |
| /* We always send an MSS option. */ |
| opts->mss = mss; |
| remaining -= TCPOLEN_MSS_ALIGNED; |
| |
| if (likely(ireq->wscale_ok)) { |
| opts->ws = ireq->rcv_wscale; |
| opts->options |= OPTION_WSCALE; |
| remaining -= TCPOLEN_WSCALE_ALIGNED; |
| } |
| if (likely(ireq->tstamp_ok)) { |
| opts->options |= OPTION_TS; |
| opts->tsval = tcp_skb_timestamp(skb) + tcp_rsk(req)->ts_off; |
| opts->tsecr = READ_ONCE(req->ts_recent); |
| remaining -= TCPOLEN_TSTAMP_ALIGNED; |
| } |
| if (likely(ireq->sack_ok)) { |
| opts->options |= OPTION_SACK_ADVERTISE; |
| if (unlikely(!ireq->tstamp_ok)) |
| remaining -= TCPOLEN_SACKPERM_ALIGNED; |
| } |
| if (foc != NULL && foc->len >= 0) { |
| u32 need = foc->len; |
| |
| need += foc->exp ? TCPOLEN_EXP_FASTOPEN_BASE : |
| TCPOLEN_FASTOPEN_BASE; |
| need = (need + 3) & ~3U; /* Align to 32 bits */ |
| if (remaining >= need) { |
| opts->options |= OPTION_FAST_OPEN_COOKIE; |
| opts->fastopen_cookie = foc; |
| remaining -= need; |
| } |
| } |
| |
| mptcp_set_option_cond(req, opts, &remaining); |
| |
| smc_set_option_cond(tcp_sk(sk), ireq, opts, &remaining); |
| |
| bpf_skops_hdr_opt_len((struct sock *)sk, skb, req, syn_skb, |
| synack_type, opts, &remaining); |
| |
| return MAX_TCP_OPTION_SPACE - remaining; |
| } |
| |
| /* Compute TCP options for ESTABLISHED sockets. This is not the |
| * final wire format yet. |
| */ |
| static unsigned int tcp_established_options(struct sock *sk, struct sk_buff *skb, |
| struct tcp_out_options *opts, |
| struct tcp_md5sig_key **md5) |
| { |
| struct tcp_sock *tp = tcp_sk(sk); |
| unsigned int size = 0; |
| unsigned int eff_sacks; |
| |
| opts->options = 0; |
| |
| *md5 = NULL; |
| #ifdef CONFIG_TCP_MD5SIG |
| if (static_branch_unlikely(&tcp_md5_needed) && |
| rcu_access_pointer(tp->md5sig_info)) { |
| *md5 = tp->af_specific->md5_lookup(sk, sk); |
| if (*md5) { |
| opts->options |= OPTION_MD5; |
| size += TCPOLEN_MD5SIG_ALIGNED; |
| } |
| } |
| #endif |
| |
| if (likely(tp->rx_opt.tstamp_ok)) { |
| opts->options |= OPTION_TS; |
| opts->tsval = skb ? tcp_skb_timestamp(skb) + tp->tsoffset : 0; |
| opts->tsecr = tp->rx_opt.ts_recent; |
| size += TCPOLEN_TSTAMP_ALIGNED; |
| } |
| |
| /* MPTCP options have precedence over SACK for the limited TCP |
| * option space because a MPTCP connection would be forced to |
| * fall back to regular TCP if a required multipath option is |
| * missing. SACK still gets a chance to use whatever space is |
| * left. |
| */ |
| if (sk_is_mptcp(sk)) { |
| unsigned int remaining = MAX_TCP_OPTION_SPACE - size; |
| unsigned int opt_size = 0; |
| |
| if (mptcp_established_options(sk, skb, &opt_size, remaining, |
| &opts->mptcp)) { |
| opts->options |= OPTION_MPTCP; |
| size += opt_size; |
| } |
| } |
| |
| eff_sacks = tp->rx_opt.num_sacks + tp->rx_opt.dsack; |
| if (unlikely(eff_sacks)) { |
| const unsigned int remaining = MAX_TCP_OPTION_SPACE - size; |
| if (unlikely(remaining < TCPOLEN_SACK_BASE_ALIGNED + |
| TCPOLEN_SACK_PERBLOCK)) |
| return size; |
| |
| opts->num_sack_blocks = |
| min_t(unsigned int, eff_sacks, |
| (remaining - TCPOLEN_SACK_BASE_ALIGNED) / |
| TCPOLEN_SACK_PERBLOCK); |
| |
| size += TCPOLEN_SACK_BASE_ALIGNED + |
| opts->num_sack_blocks * TCPOLEN_SACK_PERBLOCK; |
| } |
| |
| if (unlikely(BPF_SOCK_OPS_TEST_FLAG(tp, |
| BPF_SOCK_OPS_WRITE_HDR_OPT_CB_FLAG))) { |
| unsigned int remaining = MAX_TCP_OPTION_SPACE - size; |
| |
| bpf_skops_hdr_opt_len(sk, skb, NULL, NULL, 0, opts, &remaining); |
| |
| size = MAX_TCP_OPTION_SPACE - remaining; |
| } |
| |
| return size; |
| } |
| |
| |
| /* TCP SMALL QUEUES (TSQ) |
| * |
| * TSQ goal is to keep small amount of skbs per tcp flow in tx queues (qdisc+dev) |
| * to reduce RTT and bufferbloat. |
| * We do this using a special skb destructor (tcp_wfree). |
| * |
| * Its important tcp_wfree() can be replaced by sock_wfree() in the event skb |
| * needs to be reallocated in a driver. |
| * The invariant being skb->truesize subtracted from sk->sk_wmem_alloc |
| * |
| * Since transmit from skb destructor is forbidden, we use a tasklet |
| * to process all sockets that eventually need to send more skbs. |
| * We use one tasklet per cpu, with its own queue of sockets. |
| */ |
| struct tsq_tasklet { |
| struct tasklet_struct tasklet; |
| struct list_head head; /* queue of tcp sockets */ |
| }; |
| static DEFINE_PER_CPU(struct tsq_tasklet, tsq_tasklet); |
| |
| static void tcp_tsq_write(struct sock *sk) |
| { |
| if ((1 << sk->sk_state) & |
| (TCPF_ESTABLISHED | TCPF_FIN_WAIT1 | TCPF_CLOSING | |
| TCPF_CLOSE_WAIT | TCPF_LAST_ACK)) { |
| struct tcp_sock *tp = tcp_sk(sk); |
| |
| if (tp->lost_out > tp->retrans_out && |
| tcp_snd_cwnd(tp) > tcp_packets_in_flight(tp)) { |
| tcp_mstamp_refresh(tp); |
| tcp_xmit_retransmit_queue(sk); |
| } |
| |
| tcp_write_xmit(sk, tcp_current_mss(sk), tp->nonagle, |
| 0, GFP_ATOMIC); |
| } |
| } |
| |
| static void tcp_tsq_handler(struct sock *sk) |
| { |
| bh_lock_sock(sk); |
| if (!sock_owned_by_user(sk)) |
| tcp_tsq_write(sk); |
| else if (!test_and_set_bit(TCP_TSQ_DEFERRED, &sk->sk_tsq_flags)) |
| sock_hold(sk); |
| bh_unlock_sock(sk); |
| } |
| /* |
| * One tasklet per cpu tries to send more skbs. |
| * We run in tasklet context but need to disable irqs when |
| * transferring tsq->head because tcp_wfree() might |
| * interrupt us (non NAPI drivers) |
| */ |
| static void tcp_tasklet_func(struct tasklet_struct *t) |
| { |
| struct tsq_tasklet *tsq = from_tasklet(tsq, t, tasklet); |
| LIST_HEAD(list); |
| unsigned long flags; |
| struct list_head *q, *n; |
| struct tcp_sock *tp; |
| struct sock *sk; |
| |
| local_irq_save(flags); |
| list_splice_init(&tsq->head, &list); |
| local_irq_restore(flags); |
| |
| list_for_each_safe(q, n, &list) { |
| tp = list_entry(q, struct tcp_sock, tsq_node); |
| list_del(&tp->tsq_node); |
| |
| sk = (struct sock *)tp; |
| smp_mb__before_atomic(); |
| clear_bit(TSQ_QUEUED, &sk->sk_tsq_flags); |
| |
| tcp_tsq_handler(sk); |
| sk_free(sk); |
| } |
| } |
| |
| #define TCP_DEFERRED_ALL (TCPF_TSQ_DEFERRED | \ |
| TCPF_WRITE_TIMER_DEFERRED | \ |
| TCPF_DELACK_TIMER_DEFERRED | \ |
| TCPF_MTU_REDUCED_DEFERRED) |
| /** |
| * tcp_release_cb - tcp release_sock() callback |
| * @sk: socket |
| * |
| * called from release_sock() to perform protocol dependent |
| * actions before socket release. |
| */ |
| void tcp_release_cb(struct sock *sk) |
| { |
| unsigned long flags, nflags; |
| |
| /* perform an atomic operation only if at least one flag is set */ |
| do { |
| flags = sk->sk_tsq_flags; |
| if (!(flags & TCP_DEFERRED_ALL)) |
| return; |
| nflags = flags & ~TCP_DEFERRED_ALL; |
| } while (cmpxchg(&sk->sk_tsq_flags, flags, nflags) != flags); |
| |
| if (flags & TCPF_TSQ_DEFERRED) { |
| tcp_tsq_write(sk); |
| __sock_put(sk); |
| } |
| /* Here begins the tricky part : |
| * We are called from release_sock() with : |
| * 1) BH disabled |
| * 2) sk_lock.slock spinlock held |
| * 3) socket owned by us (sk->sk_lock.owned == 1) |
| * |
| * But following code is meant to be called from BH handlers, |
| * so we should keep BH disabled, but early release socket ownership |
| */ |
| sock_release_ownership(sk); |
| |
| if (flags & TCPF_WRITE_TIMER_DEFERRED) { |
| tcp_write_timer_handler(sk); |
| __sock_put(sk); |
| } |
| if (flags & TCPF_DELACK_TIMER_DEFERRED) { |
| tcp_delack_timer_handler(sk); |
| __sock_put(sk); |
| } |
| if (flags & TCPF_MTU_REDUCED_DEFERRED) { |
| inet_csk(sk)->icsk_af_ops->mtu_reduced(sk); |
| __sock_put(sk); |
| } |
| } |
| EXPORT_SYMBOL(tcp_release_cb); |
| |
| void __init tcp_tasklet_init(void) |
| { |
| int i; |
| |
| for_each_possible_cpu(i) { |
| struct tsq_tasklet *tsq = &per_cpu(tsq_tasklet, i); |
| |
| INIT_LIST_HEAD(&tsq->head); |
| tasklet_setup(&tsq->tasklet, tcp_tasklet_func); |
| } |
| } |
| |
| /* |
| * Write buffer destructor automatically called from kfree_skb. |
| * We can't xmit new skbs from this context, as we might already |
| * hold qdisc lock. |
| */ |
| void tcp_wfree(struct sk_buff *skb) |
| { |
| struct sock *sk = skb->sk; |
| struct tcp_sock *tp = tcp_sk(sk); |
| unsigned long flags, nval, oval; |
| |
| /* Keep one reference on sk_wmem_alloc. |
| * Will be released by sk_free() from here or tcp_tasklet_func() |
| */ |
| WARN_ON(refcount_sub_and_test(skb->truesize - 1, &sk->sk_wmem_alloc)); |
| |
| /* If this softirq is serviced by ksoftirqd, we are likely under stress. |
| * Wait until our queues (qdisc + devices) are drained. |
| * This gives : |
| * - less callbacks to tcp_write_xmit(), reducing stress (batches) |
| * - chance for incoming ACK (processed by another cpu maybe) |
| * to migrate this flow (skb->ooo_okay will be eventually set) |
| */ |
| if (refcount_read(&sk->sk_wmem_alloc) >= SKB_TRUESIZE(1) && this_cpu_ksoftirqd() == current) |
| goto out; |
| |
| for (oval = READ_ONCE(sk->sk_tsq_flags);; oval = nval) { |
| struct tsq_tasklet *tsq; |
| bool empty; |
| |
| if (!(oval & TSQF_THROTTLED) || (oval & TSQF_QUEUED)) |
| goto out; |
| |
| nval = (oval & ~TSQF_THROTTLED) | TSQF_QUEUED; |
| nval = cmpxchg(&sk->sk_tsq_flags, oval, nval); |
| if (nval != oval) |
| continue; |
| |
| /* queue this socket to tasklet queue */ |
| local_irq_save(flags); |
| tsq = this_cpu_ptr(&tsq_tasklet); |
| empty = list_empty(&tsq->head); |
| list_add(&tp->tsq_node, &tsq->head); |
| if (empty) |
| tasklet_schedule(&tsq->tasklet); |
| local_irq_restore(flags); |
| return; |
| } |
| out: |
| sk_free(sk); |
| } |
| |
| /* Note: Called under soft irq. |
| * We can call TCP stack right away, unless socket is owned by user. |
| */ |
| enum hrtimer_restart tcp_pace_kick(struct hrtimer *timer) |
| { |
| struct tcp_sock *tp = container_of(timer, struct tcp_sock, pacing_timer); |
| struct sock *sk = (struct sock *)tp; |
| |
| tcp_tsq_handler(sk); |
| sock_put(sk); |
| |
| return HRTIMER_NORESTART; |
| } |
| |
| static void tcp_update_skb_after_send(struct sock *sk, struct sk_buff *skb, |
| u64 prior_wstamp) |
| { |
| struct tcp_sock *tp = tcp_sk(sk); |
| |
| if (sk->sk_pacing_status != SK_PACING_NONE) { |
| unsigned long rate = sk->sk_pacing_rate; |
| |
| /* Original sch_fq does not pace first 10 MSS |
| * Note that tp->data_segs_out overflows after 2^32 packets, |
| * this is a minor annoyance. |
| */ |
| if (rate != ~0UL && rate && tp->data_segs_out >= 10) { |
| u64 len_ns = div64_ul((u64)skb->len * NSEC_PER_SEC, rate); |
| u64 credit = tp->tcp_wstamp_ns - prior_wstamp; |
| |
| /* take into account OS jitter */ |
| len_ns -= min_t(u64, len_ns / 2, credit); |
| tp->tcp_wstamp_ns += len_ns; |
| } |
| } |
| list_move_tail(&skb->tcp_tsorted_anchor, &tp->tsorted_sent_queue); |
| } |
| |
| INDIRECT_CALLABLE_DECLARE(int ip_queue_xmit(struct sock *sk, struct sk_buff *skb, struct flowi *fl)); |
| INDIRECT_CALLABLE_DECLARE(int inet6_csk_xmit(struct sock *sk, struct sk_buff *skb, struct flowi *fl)); |
| INDIRECT_CALLABLE_DECLARE(void tcp_v4_send_check(struct sock *sk, struct sk_buff *skb)); |
| |
| /* This routine actually transmits TCP packets queued in by |
| * tcp_do_sendmsg(). This is used by both the initial |
| * transmission and possible later retransmissions. |
| * All SKB's seen here are completely headerless. It is our |
| * job to build the TCP header, and pass the packet down to |
| * IP so it can do the same plus pass the packet off to the |
| * device. |
| * |
| * We are working here with either a clone of the original |
| * SKB, or a fresh unique copy made by the retransmit engine. |
| */ |
| static int __tcp_transmit_skb(struct sock *sk, struct sk_buff *skb, |
| int clone_it, gfp_t gfp_mask, u32 rcv_nxt) |
| { |
| const struct inet_connection_sock *icsk = inet_csk(sk); |
| struct inet_sock *inet; |
| struct tcp_sock *tp; |
| struct tcp_skb_cb *tcb; |
| struct tcp_out_options opts; |
| unsigned int tcp_options_size, tcp_header_size; |
| struct sk_buff *oskb = NULL; |
| struct tcp_md5sig_key *md5; |
| struct tcphdr *th; |
| u64 prior_wstamp; |
| int err; |
| |
| BUG_ON(!skb || !tcp_skb_pcount(skb)); |
| tp = tcp_sk(sk); |
| prior_wstamp = tp->tcp_wstamp_ns; |
| tp->tcp_wstamp_ns = max(tp->tcp_wstamp_ns, tp->tcp_clock_cache); |
| skb_set_delivery_time(skb, tp->tcp_wstamp_ns, true); |
| if (clone_it) { |
| oskb = skb; |
| |
| tcp_skb_tsorted_save(oskb) { |
| if (unlikely(skb_cloned(oskb))) |
| skb = pskb_copy(oskb, gfp_mask); |
| else |
| skb = skb_clone(oskb, gfp_mask); |
| } tcp_skb_tsorted_restore(oskb); |
| |
| if (unlikely(!skb)) |
| return -ENOBUFS; |
| /* retransmit skbs might have a non zero value in skb->dev |
| * because skb->dev is aliased with skb->rbnode.rb_left |
| */ |
| skb->dev = NULL; |
| } |
| |
| inet = inet_sk(sk); |
| tcb = TCP_SKB_CB(skb); |
| memset(&opts, 0, sizeof(opts)); |
| |
| if (unlikely(tcb->tcp_flags & TCPHDR_SYN)) { |
| tcp_options_size = tcp_syn_options(sk, skb, &opts, &md5); |
| } else { |
| tcp_options_size = tcp_established_options(sk, skb, &opts, |
| &md5); |
| /* Force a PSH flag on all (GSO) packets to expedite GRO flush |
| * at receiver : This slightly improve GRO performance. |
| * Note that we do not force the PSH flag for non GSO packets, |
| * because they might be sent under high congestion events, |
| * and in this case it is better to delay the delivery of 1-MSS |
| * packets and thus the corresponding ACK packet that would |
| * release the following packet. |
| */ |
| if (tcp_skb_pcount(skb) > 1) |
| tcb->tcp_flags |= TCPHDR_PSH; |
| } |
| tcp_header_size = tcp_options_size + sizeof(struct tcphdr); |
| |
| /* if no packet is in qdisc/device queue, then allow XPS to select |
| * another queue. We can be called from tcp_tsq_handler() |
| * which holds one reference to sk. |
| * |
| * TODO: Ideally, in-flight pure ACK packets should not matter here. |
| * One way to get this would be to set skb->truesize = 2 on them. |
| */ |
| skb->ooo_okay = sk_wmem_alloc_get(sk) < SKB_TRUESIZE(1); |
| |
| /* If we had to use memory reserve to allocate this skb, |
| * this might cause drops if packet is looped back : |
| * Other socket might not have SOCK_MEMALLOC. |
| * Packets not looped back do not care about pfmemalloc. |
| */ |
| skb->pfmemalloc = 0; |
| |
| skb_push(skb, tcp_header_size); |
| skb_reset_transport_header(skb); |
| |
| skb_orphan(skb); |
| skb->sk = sk; |
| skb->destructor = skb_is_tcp_pure_ack(skb) ? __sock_wfree : tcp_wfree; |
| refcount_add(skb->truesize, &sk->sk_wmem_alloc); |
| |
| skb_set_dst_pending_confirm(skb, READ_ONCE(sk->sk_dst_pending_confirm)); |
| |
| /* Build TCP header and checksum it. */ |
| th = (struct tcphdr *)skb->data; |
| th->source = inet->inet_sport; |
| th->dest = inet->inet_dport; |
| th->seq = htonl(tcb->seq); |
| th->ack_seq = htonl(rcv_nxt); |
| *(((__be16 *)th) + 6) = htons(((tcp_header_size >> 2) << 12) | |
| tcb->tcp_flags); |
| |
| th->check = 0; |
| th->urg_ptr = 0; |
| |
| /* The urg_mode check is necessary during a below snd_una win probe */ |
| if (unlikely(tcp_urg_mode(tp) && before(tcb->seq, tp->snd_up))) { |
| if (before(tp->snd_up, tcb->seq + 0x10000)) { |
| th->urg_ptr = htons(tp->snd_up - tcb->seq); |
| th->urg = 1; |
| } else if (after(tcb->seq + 0xFFFF, tp->snd_nxt)) { |
| th->urg_ptr = htons(0xFFFF); |
| th->urg = 1; |
| } |
| } |
| |
| skb_shinfo(skb)->gso_type = sk->sk_gso_type; |
| if (likely(!(tcb->tcp_flags & TCPHDR_SYN))) { |
| th->window = htons(tcp_select_window(sk)); |
| tcp_ecn_send(sk, skb, th, tcp_header_size); |
| } else { |
| /* RFC1323: The window in SYN & SYN/ACK segments |
| * is never scaled. |
| */ |
| th->window = htons(min(tp->rcv_wnd, 65535U)); |
| } |
| |
| tcp_options_write(th, tp, &opts); |
| |
| #ifdef CONFIG_TCP_MD5SIG |
| /* Calculate the MD5 hash, as we have all we need now */ |
| if (md5) { |
| sk_gso_disable(sk); |
| tp->af_specific->calc_md5_hash(opts.hash_location, |
| md5, sk, skb); |
| } |
| #endif |
| |
| /* BPF prog is the last one writing header option */ |
| bpf_skops_write_hdr_opt(sk, skb, NULL, NULL, 0, &opts); |
| |
| INDIRECT_CALL_INET(icsk->icsk_af_ops->send_check, |
| tcp_v6_send_check, tcp_v4_send_check, |
| sk, skb); |
| |
| if (likely(tcb->tcp_flags & TCPHDR_ACK)) |
| tcp_event_ack_sent(sk, rcv_nxt); |
| |
| if (skb->len != tcp_header_size) { |
| tcp_event_data_sent(tp, sk); |
| tp->data_segs_out += tcp_skb_pcount(skb); |
| tp->bytes_sent += skb->len - tcp_header_size; |
| } |
| |
| if (after(tcb->end_seq, tp->snd_nxt) || tcb->seq == tcb->end_seq) |
| TCP_ADD_STATS(sock_net(sk), TCP_MIB_OUTSEGS, |
| tcp_skb_pcount(skb)); |
| |
| tp->segs_out += tcp_skb_pcount(skb); |
| skb_set_hash_from_sk(skb, sk); |
| /* OK, its time to fill skb_shinfo(skb)->gso_{segs|size} */ |
| skb_shinfo(skb)->gso_segs = tcp_skb_pcount(skb); |
| skb_shinfo(skb)->gso_size = tcp_skb_mss(skb); |
| |
| /* Leave earliest departure time in skb->tstamp (skb->skb_mstamp_ns) */ |
| |
| /* Cleanup our debris for IP stacks */ |
| memset(skb->cb, 0, max(sizeof(struct inet_skb_parm), |
| sizeof(struct inet6_skb_parm))); |
| |
| tcp_add_tx_delay(skb, tp); |
| |
| err = INDIRECT_CALL_INET(icsk->icsk_af_ops->queue_xmit, |
| inet6_csk_xmit, ip_queue_xmit, |
| sk, skb, &inet->cork.fl); |
| |
| if (unlikely(err > 0)) { |
| tcp_enter_cwr(sk); |
| err = net_xmit_eval(err); |
| } |
| if (!err && oskb) { |
| tcp_update_skb_after_send(sk, oskb, prior_wstamp); |
| tcp_rate_skb_sent(sk, oskb); |
| } |
| return err; |
| } |
| |
| static int tcp_transmit_skb(struct sock *sk, struct sk_buff *skb, int clone_it, |
| gfp_t gfp_mask) |
| { |
| return __tcp_transmit_skb(sk, skb, clone_it, gfp_mask, |
| tcp_sk(sk)->rcv_nxt); |
| } |
| |
| /* This routine just queues the buffer for sending. |
| * |
| * NOTE: probe0 timer is not checked, do not forget tcp_push_pending_frames, |
| * otherwise socket can stall. |
| */ |
| static void tcp_queue_skb(struct sock *sk, struct sk_buff *skb) |
| { |
| struct tcp_sock *tp = tcp_sk(sk); |
| |
| /* Advance write_seq and place onto the write_queue. */ |
| WRITE_ONCE(tp->write_seq, TCP_SKB_CB(skb)->end_seq); |
| __skb_header_release(skb); |
| tcp_add_write_queue_tail(sk, skb); |
| sk_wmem_queued_add(sk, skb->truesize); |
| sk_mem_charge(sk, skb->truesize); |
| } |
| |
| /* Initialize TSO segments for a packet. */ |
| static void tcp_set_skb_tso_segs(struct sk_buff *skb, unsigned int mss_now) |
| { |
| if (skb->len <= mss_now) { |
| /* Avoid the costly divide in the normal |
| * non-TSO case. |
| */ |
| tcp_skb_pcount_set(skb, 1); |
| TCP_SKB_CB(skb)->tcp_gso_size = 0; |
| } else { |
| tcp_skb_pcount_set(skb, DIV_ROUND_UP(skb->len, mss_now)); |
| TCP_SKB_CB(skb)->tcp_gso_size = mss_now; |
| } |
| } |
| |
| /* Pcount in the middle of the write queue got changed, we need to do various |
| * tweaks to fix counters |
| */ |
| static void tcp_adjust_pcount(struct sock *sk, const struct sk_buff *skb, int decr) |
| { |
| struct tcp_sock *tp = tcp_sk(sk); |
| |
| tp->packets_out -= decr; |
| |
| if (TCP_SKB_CB(skb)->sacked & TCPCB_SACKED_ACKED) |
| tp->sacked_out -= decr; |
| if (TCP_SKB_CB(skb)->sacked & TCPCB_SACKED_RETRANS) |
| tp->retrans_out -= decr; |
| if (TCP_SKB_CB(skb)->sacked & TCPCB_LOST) |
| tp->lost_out -= decr; |
| |
| /* Reno case is special. Sigh... */ |
| if (tcp_is_reno(tp) && decr > 0) |
| tp->sacked_out -= min_t(u32, tp->sacked_out, decr); |
| |
| if (tp->lost_skb_hint && |
| before(TCP_SKB_CB(skb)->seq, TCP_SKB_CB(tp->lost_skb_hint)->seq) && |
| (TCP_SKB_CB(skb)->sacked & TCPCB_SACKED_ACKED)) |
| tp->lost_cnt_hint -= decr; |
| |
| tcp_verify_left_out(tp); |
| } |
| |
| static bool tcp_has_tx_tstamp(const struct sk_buff *skb) |
| { |
| return TCP_SKB_CB(skb)->txstamp_ack || |
| (skb_shinfo(skb)->tx_flags & SKBTX_ANY_TSTAMP); |
| } |
| |
| static void tcp_fragment_tstamp(struct sk_buff *skb, struct sk_buff *skb2) |
| { |
| struct skb_shared_info *shinfo = skb_shinfo(skb); |
| |
| if (unlikely(tcp_has_tx_tstamp(skb)) && |
| !before(shinfo->tskey, TCP_SKB_CB(skb2)->seq)) { |
| struct skb_shared_info *shinfo2 = skb_shinfo(skb2); |
| u8 tsflags = shinfo->tx_flags & SKBTX_ANY_TSTAMP; |
| |
| shinfo->tx_flags &= ~tsflags; |
| shinfo2->tx_flags |= tsflags; |
| swap(shinfo->tskey, shinfo2->tskey); |
| TCP_SKB_CB(skb2)->txstamp_ack = TCP_SKB_CB(skb)->txstamp_ack; |
| TCP_SKB_CB(skb)->txstamp_ack = 0; |
| } |
| } |
| |
| static void tcp_skb_fragment_eor(struct sk_buff *skb, struct sk_buff *skb2) |
| { |
| TCP_SKB_CB(skb2)->eor = TCP_SKB_CB(skb)->eor; |
| TCP_SKB_CB(skb)->eor = 0; |
| } |
| |
| /* Insert buff after skb on the write or rtx queue of sk. */ |
| static void tcp_insert_write_queue_after(struct sk_buff *skb, |
| struct sk_buff *buff, |
| struct sock *sk, |
| enum tcp_queue tcp_queue) |
| { |
| if (tcp_queue == TCP_FRAG_IN_WRITE_QUEUE) |
| __skb_queue_after(&sk->sk_write_queue, skb, buff); |
| else |
| tcp_rbtree_insert(&sk->tcp_rtx_queue, buff); |
| } |
| |
| /* Function to create two new TCP segments. Shrinks the given segment |
| * to the specified size and appends a new segment with the rest of the |
| * packet to the list. This won't be called frequently, I hope. |
| * Remember, these are still headerless SKBs at this point. |
| */ |
| int tcp_fragment(struct sock *sk, enum tcp_queue tcp_queue, |
| struct sk_buff *skb, u32 len, |
| unsigned int mss_now, gfp_t gfp) |
| { |
| struct tcp_sock *tp = tcp_sk(sk); |
| struct sk_buff *buff; |
| int nsize, old_factor; |
| long limit; |
| int nlen; |
| u8 flags; |
| |
| if (WARN_ON(len > skb->len)) |
| return -EINVAL; |
| |
| nsize = skb_headlen(skb) - len; |
| if (nsize < 0) |
| nsize = 0; |
| |
| /* tcp_sendmsg() can overshoot sk_wmem_queued by one full size skb. |
| * We need some allowance to not penalize applications setting small |
| * SO_SNDBUF values. |
| * Also allow first and last skb in retransmit queue to be split. |
| */ |
| limit = sk->sk_sndbuf + 2 * SKB_TRUESIZE(GSO_LEGACY_MAX_SIZE); |
| if (unlikely((sk->sk_wmem_queued >> 1) > limit && |
| tcp_queue != TCP_FRAG_IN_WRITE_QUEUE && |
| skb != tcp_rtx_queue_head(sk) && |
| skb != tcp_rtx_queue_tail(sk))) { |
| NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPWQUEUETOOBIG); |
| return -ENOMEM; |
| } |
| |
| if (skb_unclone_keeptruesize(skb, gfp)) |
| return -ENOMEM; |
| |
| /* Get a new skb... force flag on. */ |
| buff = tcp_stream_alloc_skb(sk, nsize, gfp, true); |
| if (!buff) |
| return -ENOMEM; /* We'll just try again later. */ |
| skb_copy_decrypted(buff, skb); |
| mptcp_skb_ext_copy(buff, skb); |
| |
| sk_wmem_queued_add(sk, buff->truesize); |
| sk_mem_charge(sk, buff->truesize); |
| nlen = skb->len - len - nsize; |
| buff->truesize += nlen; |
| skb->truesize -= nlen; |
| |
| /* Correct the sequence numbers. */ |
| TCP_SKB_CB(buff)->seq = TCP_SKB_CB(skb)->seq + len; |
| TCP_SKB_CB(buff)->end_seq = TCP_SKB_CB(skb)->end_seq; |
| TCP_SKB_CB(skb)->end_seq = TCP_SKB_CB(buff)->seq; |
| |
| /* PSH and FIN should only be set in the second packet. */ |
| flags = TCP_SKB_CB(skb)->tcp_flags; |
| TCP_SKB_CB(skb)->tcp_flags = flags & ~(TCPHDR_FIN | TCPHDR_PSH); |
| TCP_SKB_CB(buff)->tcp_flags = flags; |
| TCP_SKB_CB(buff)->sacked = TCP_SKB_CB(skb)->sacked; |
| tcp_skb_fragment_eor(skb, buff); |
| |
| skb_split(skb, buff, len); |
| |
| skb_set_delivery_time(buff, skb->tstamp, true); |
| tcp_fragment_tstamp(skb, buff); |
| |
| old_factor = tcp_skb_pcount(skb); |
| |
| /* Fix up tso_factor for both original and new SKB. */ |
| tcp_set_skb_tso_segs(skb, mss_now); |
| tcp_set_skb_tso_segs(buff, mss_now); |
| |
| /* Update delivered info for the new segment */ |
| TCP_SKB_CB(buff)->tx = TCP_SKB_CB(skb)->tx; |
| |
| /* If this packet has been sent out already, we must |
| * adjust the various packet counters. |
| */ |
| if (!before(tp->snd_nxt, TCP_SKB_CB(buff)->end_seq)) { |
| int diff = old_factor - tcp_skb_pcount(skb) - |
| tcp_skb_pcount(buff); |
| |
| if (diff) |
| tcp_adjust_pcount(sk, skb, diff); |
| } |
| |
| /* Link BUFF into the send queue. */ |
| __skb_header_release(buff); |
| tcp_insert_write_queue_after(skb, buff, sk, tcp_queue); |
| if (tcp_queue == TCP_FRAG_IN_RTX_QUEUE) |
| list_add(&buff->tcp_tsorted_anchor, &skb->tcp_tsorted_anchor); |
| |
| return 0; |
| } |
| |
| /* This is similar to __pskb_pull_tail(). The difference is that pulled |
| * data is not copied, but immediately discarded. |
| */ |
| static int __pskb_trim_head(struct sk_buff *skb, int len) |
| { |
| struct skb_shared_info *shinfo; |
| int i, k, eat; |
| |
| eat = min_t(int, len, skb_headlen(skb)); |
| if (eat) { |
| __skb_pull(skb, eat); |
| len -= eat; |
| if (!len) |
| return 0; |
| } |
| eat = len; |
| k = 0; |
| shinfo = skb_shinfo(skb); |
| for (i = 0; i < shinfo->nr_frags; i++) { |
| int size = skb_frag_size(&shinfo->frags[i]); |
| |
| if (size <= eat) { |
| skb_frag_unref(skb, i); |
| eat -= size; |
| } else { |
| shinfo->frags[k] = shinfo->frags[i]; |
| if (eat) { |
| skb_frag_off_add(&shinfo->frags[k], eat); |
| skb_frag_size_sub(&shinfo->frags[k], eat); |
| eat = 0; |
| } |
| k++; |
| } |
| } |
| shinfo->nr_frags = k; |
| |
| skb->data_len -= len; |
| skb->len = skb->data_len; |
| return len; |
| } |
| |
| /* Remove acked data from a packet in the transmit queue. */ |
| int tcp_trim_head(struct sock *sk, struct sk_buff *skb, u32 len) |
| { |
| u32 delta_truesize; |
| |
| if (skb_unclone_keeptruesize(skb, GFP_ATOMIC)) |
| return -ENOMEM; |
| |
| delta_truesize = __pskb_trim_head(skb, len); |
| |
| TCP_SKB_CB(skb)->seq += len; |
| |
| if (delta_truesize) { |
| skb->truesize -= delta_truesize; |
| sk_wmem_queued_add(sk, -delta_truesize); |
| if (!skb_zcopy_pure(skb)) |
| sk_mem_uncharge(sk, delta_truesize); |
| } |
| |
| /* Any change of skb->len requires recalculation of tso factor. */ |
| if (tcp_skb_pcount(skb) > 1) |
| tcp_set_skb_tso_segs(skb, tcp_skb_mss(skb)); |
| |
| return 0; |
| } |
| |
| /* Calculate MSS not accounting any TCP options. */ |
| static inline int __tcp_mtu_to_mss(struct sock *sk, int pmtu) |
| { |
| const struct tcp_sock *tp = tcp_sk(sk); |
| const struct inet_connection_sock *icsk = inet_csk(sk); |
| int mss_now; |
| |
| /* Calculate base mss without TCP options: |
| It is MMS_S - sizeof(tcphdr) of rfc1122 |
| */ |
| mss_now = pmtu - icsk->icsk_af_ops->net_header_len - sizeof(struct tcphdr); |
| |
| /* IPv6 adds a frag_hdr in case RTAX_FEATURE_ALLFRAG is set */ |
| if (icsk->icsk_af_ops->net_frag_header_len) { |
| const struct dst_entry *dst = __sk_dst_get(sk); |
| |
| if (dst && dst_allfrag(dst)) |
| mss_now -= icsk->icsk_af_ops->net_frag_header_len; |
| } |
| |
| /* Clamp it (mss_clamp does not include tcp options) */ |
| if (mss_now > tp->rx_opt.mss_clamp) |
| mss_now = tp->rx_opt.mss_clamp; |
| |
| /* Now subtract optional transport overhead */ |
| mss_now -= icsk->icsk_ext_hdr_len; |
| |
| /* Then reserve room for full set of TCP options and 8 bytes of data */ |
| mss_now = max(mss_now, |
| READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_min_snd_mss)); |
| return mss_now; |
| } |
| |
| /* Calculate MSS. Not accounting for SACKs here. */ |
| int tcp_mtu_to_mss(struct sock *sk, int pmtu) |
| { |
| /* Subtract TCP options size, not including SACKs */ |
| return __tcp_mtu_to_mss(sk, pmtu) - |
| (tcp_sk(sk)->tcp_header_len - sizeof(struct tcphdr)); |
| } |
| EXPORT_SYMBOL(tcp_mtu_to_mss); |
| |
| /* Inverse of above */ |
| int tcp_mss_to_mtu(struct sock *sk, int mss) |
| { |
| const struct tcp_sock *tp = tcp_sk(sk); |
| const struct inet_connection_sock *icsk = inet_csk(sk); |
| int mtu; |
| |
| mtu = mss + |
| tp->tcp_header_len + |
| icsk->icsk_ext_hdr_len + |
| icsk->icsk_af_ops->net_header_len; |
| |
| /* IPv6 adds a frag_hdr in case RTAX_FEATURE_ALLFRAG is set */ |
| if (icsk->icsk_af_ops->net_frag_header_len) { |
| const struct dst_entry *dst = __sk_dst_get(sk); |
| |
| if (dst && dst_allfrag(dst)) |
| mtu += icsk->icsk_af_ops->net_frag_header_len; |
| } |
| return mtu; |
| } |
| EXPORT_SYMBOL(tcp_mss_to_mtu); |
| |
| /* MTU probing init per socket */ |
| void tcp_mtup_init(struct sock *sk) |
| { |
| struct tcp_sock *tp = tcp_sk(sk); |
| struct inet_connection_sock *icsk = inet_csk(sk); |
| struct net *net = sock_net(sk); |
| |
| icsk->icsk_mtup.enabled = READ_ONCE(net->ipv4.sysctl_tcp_mtu_probing) > 1; |
| icsk->icsk_mtup.search_high = tp->rx_opt.mss_clamp + sizeof(struct tcphdr) + |
| icsk->icsk_af_ops->net_header_len; |
| icsk->icsk_mtup.search_low = tcp_mss_to_mtu(sk, READ_ONCE(net->ipv4.sysctl_tcp_base_mss)); |
| icsk->icsk_mtup.probe_size = 0; |
| if (icsk->icsk_mtup.enabled) |
| icsk->icsk_mtup.probe_timestamp = tcp_jiffies32; |
| } |
| EXPORT_SYMBOL(tcp_mtup_init); |
| |
| /* This function synchronize snd mss to current pmtu/exthdr set. |
| |
| tp->rx_opt.user_mss is mss set by user by TCP_MAXSEG. It does NOT counts |
| for TCP options, but includes only bare TCP header. |
| |
| tp->rx_opt.mss_clamp is mss negotiated at connection setup. |
| It is minimum of user_mss and mss received with SYN. |
| It also does not include TCP options. |
| |
| inet_csk(sk)->icsk_pmtu_cookie is last pmtu, seen by this function. |
| |
| tp->mss_cache is current effective sending mss, including |
| all tcp options except for SACKs. It is evaluated, |
| taking into account current pmtu, but never exceeds |
| tp->rx_opt.mss_clamp. |
| |
| NOTE1. rfc1122 clearly states that advertised MSS |
| DOES NOT include either tcp or ip options. |
| |
| NOTE2. inet_csk(sk)->icsk_pmtu_cookie and tp->mss_cache |
| are READ ONLY outside this function. --ANK (980731) |
| */ |
| unsigned int tcp_sync_mss(struct sock *sk, u32 pmtu) |
| { |
| struct tcp_sock *tp = tcp_sk(sk); |
| struct inet_connection_sock *icsk = inet_csk(sk); |
| int mss_now; |
| |
| if (icsk->icsk_mtup.search_high > pmtu) |
| icsk->icsk_mtup.search_high = pmtu; |
| |
| mss_now = tcp_mtu_to_mss(sk, pmtu); |
| mss_now = tcp_bound_to_half_wnd(tp, mss_now); |
| |
| /* And store cached results */ |
| icsk->icsk_pmtu_cookie = pmtu; |
| if (icsk->icsk_mtup.enabled) |
| mss_now = min(mss_now, tcp_mtu_to_mss(sk, icsk->icsk_mtup.search_low)); |
| tp->mss_cache = mss_now; |
| |
| return mss_now; |
| } |
| EXPORT_SYMBOL(tcp_sync_mss); |
| |
| /* Compute the current effective MSS, taking SACKs and IP options, |
| * and even PMTU discovery events into account. |
| */ |
| unsigned int tcp_current_mss(struct sock *sk) |
| { |
| const struct tcp_sock *tp = tcp_sk(sk); |
| const struct dst_entry *dst = __sk_dst_get(sk); |
| u32 mss_now; |
| unsigned int header_len; |
| struct tcp_out_options opts; |
| struct tcp_md5sig_key *md5; |
| |
| mss_now = tp->mss_cache; |
| |
| if (dst) { |
| u32 mtu = dst_mtu(dst); |
| if (mtu != inet_csk(sk)->icsk_pmtu_cookie) |
| mss_now = tcp_sync_mss(sk, mtu); |
| } |
| |
| header_len = tcp_established_options(sk, NULL, &opts, &md5) + |
| sizeof(struct tcphdr); |
| /* The mss_cache is sized based on tp->tcp_header_len, which assumes |
| * some common options. If this is an odd packet (because we have SACK |
| * blocks etc) then our calculated header_len will be different, and |
| * we have to adjust mss_now correspondingly */ |
| if (header_len != tp->tcp_header_len) { |
| int delta = (int) header_len - tp->tcp_header_len; |
| mss_now -= delta; |
| } |
| |
| return mss_now; |
| } |
| |
| /* RFC2861, slow part. Adjust cwnd, after it was not full during one rto. |
| * As additional protections, we do not touch cwnd in retransmission phases, |
| * and if application hit its sndbuf limit recently. |
| */ |
| static void tcp_cwnd_application_limited(struct sock *sk) |
| { |
| struct tcp_sock *tp = tcp_sk(sk); |
| |
| if (inet_csk(sk)->icsk_ca_state == TCP_CA_Open && |
| sk->sk_socket && !test_bit(SOCK_NOSPACE, &sk->sk_socket->flags)) { |
| /* Limited by application or receiver window. */ |
| u32 init_win = tcp_init_cwnd(tp, __sk_dst_get(sk)); |
| u32 win_used = max(tp->snd_cwnd_used, init_win); |
| if (win_used < tcp_snd_cwnd(tp)) { |
| tp->snd_ssthresh = tcp_current_ssthresh(sk); |
| tcp_snd_cwnd_set(tp, (tcp_snd_cwnd(tp) + win_used) >> 1); |
| } |
| tp->snd_cwnd_used = 0; |
| } |
| tp->snd_cwnd_stamp = tcp_jiffies32; |
| } |
| |
| static void tcp_cwnd_validate(struct sock *sk, bool is_cwnd_limited) |
| { |
| const struct tcp_congestion_ops *ca_ops = inet_csk(sk)->icsk_ca_ops; |
| struct tcp_sock *tp = tcp_sk(sk); |
| |
| /* Track the strongest available signal of the degree to which the cwnd |
| * is fully utilized. If cwnd-limited then remember that fact for the |
| * current window. If not cwnd-limited then track the maximum number of |
| * outstanding packets in the current window. (If cwnd-limited then we |
| * chose to not update tp->max_packets_out to avoid an extra else |
| * clause with no functional impact.) |
| */ |
| if (!before(tp->snd_una, tp->cwnd_usage_seq) || |
| is_cwnd_limited || |
| (!tp->is_cwnd_limited && |
| tp->packets_out > tp->max_packets_out)) { |
| tp->is_cwnd_limited = is_cwnd_limited; |
| tp->max_packets_out = tp->packets_out; |
| tp->cwnd_usage_seq = tp->snd_nxt; |
| } |
| |
| if (tcp_is_cwnd_limited(sk)) { |
| /* Network is feed fully. */ |
| tp->snd_cwnd_used = 0; |
| tp->snd_cwnd_stamp = tcp_jiffies32; |
| } else { |
| /* Network starves. */ |
| if (tp->packets_out > tp->snd_cwnd_used) |
| tp->snd_cwnd_used = tp->packets_out; |
| |
| if (READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_slow_start_after_idle) && |
| (s32)(tcp_jiffies32 - tp->snd_cwnd_stamp) >= inet_csk(sk)->icsk_rto && |
| !ca_ops->cong_control) |
| tcp_cwnd_application_limited(sk); |
| |
| /* The following conditions together indicate the starvation |
| * is caused by insufficient sender buffer: |
| * 1) just sent some data (see tcp_write_xmit) |
| * 2) not cwnd limited (this else condition) |
| * 3) no more data to send (tcp_write_queue_empty()) |
| * 4) application is hitting buffer limit (SOCK_NOSPACE) |
| */ |
| if (tcp_write_queue_empty(sk) && sk->sk_socket && |
| test_bit(SOCK_NOSPACE, &sk->sk_socket->flags) && |
| (1 << sk->sk_state) & (TCPF_ESTABLISHED | TCPF_CLOSE_WAIT)) |
| tcp_chrono_start(sk, TCP_CHRONO_SNDBUF_LIMITED); |
| } |
| } |
| |
| /* Minshall's variant of the Nagle send check. */ |
| static bool tcp_minshall_check(const struct tcp_sock *tp) |
| { |
| return after(tp->snd_sml, tp->snd_una) && |
| !after(tp->snd_sml, tp->snd_nxt); |
| } |
| |
| /* Update snd_sml if this skb is under mss |
| * Note that a TSO packet might end with a sub-mss segment |
| * The test is really : |
| * if ((skb->len % mss) != 0) |
| * tp->snd_sml = TCP_SKB_CB(skb)->end_seq; |
| * But we can avoid doing the divide again given we already have |
| * skb_pcount = skb->len / mss_now |
| */ |
| static void tcp_minshall_update(struct tcp_sock *tp, unsigned int mss_now, |
| const struct sk_buff *skb) |
| { |
| if (skb->len < tcp_skb_pcount(skb) * mss_now) |
| tp->snd_sml = TCP_SKB_CB(skb)->end_seq; |
| } |
| |
| /* Return false, if packet can be sent now without violation Nagle's rules: |
| * 1. It is full sized. (provided by caller in %partial bool) |
| * 2. Or it contains FIN. (already checked by caller) |
| * 3. Or TCP_CORK is not set, and TCP_NODELAY is set. |
| * 4. Or TCP_CORK is not set, and all sent packets are ACKed. |
| * With Minshall's modification: all sent small packets are ACKed. |
| */ |
| static bool tcp_nagle_check(bool partial, const struct tcp_sock *tp, |
| int nonagle) |
| { |
| return partial && |
| ((nonagle & TCP_NAGLE_CORK) || |
| (!nonagle && tp->packets_out && tcp_minshall_check(tp))); |
| } |
| |
| /* Return how many segs we'd like on a TSO packet, |
| * depending on current pacing rate, and how close the peer is. |
| * |
| * Rationale is: |
| * - For close peers, we rather send bigger packets to reduce |
| * cpu costs, because occasional losses will be repaired fast. |
| * - For long distance/rtt flows, we would like to get ACK clocking |
| * with 1 ACK per ms. |
| * |
| * Use min_rtt to help adapt TSO burst size, with smaller min_rtt resulting |
| * in bigger TSO bursts. We we cut the RTT-based allowance in half |
| * for every 2^9 usec (aka 512 us) of RTT, so that the RTT-based allowance |
| * is below 1500 bytes after 6 * ~500 usec = 3ms. |
| */ |
| static u32 tcp_tso_autosize(const struct sock *sk, unsigned int mss_now, |
| int min_tso_segs) |
| { |
| unsigned long bytes; |
| u32 r; |
| |
| bytes = sk->sk_pacing_rate >> READ_ONCE(sk->sk_pacing_shift); |
| |
| r = tcp_min_rtt(tcp_sk(sk)) >> READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_tso_rtt_log); |
| if (r < BITS_PER_TYPE(sk->sk_gso_max_size)) |
| bytes += sk->sk_gso_max_size >> r; |
| |
| bytes = min_t(unsigned long, bytes, sk->sk_gso_max_size); |
| |
| return max_t(u32, bytes / mss_now, min_tso_segs); |
| } |
| |
| /* Return the number of segments we want in the skb we are transmitting. |
| * See if congestion control module wants to decide; otherwise, autosize. |
| */ |
| static u32 tcp_tso_segs(struct sock *sk, unsigned int mss_now) |
| { |
| const struct tcp_congestion_ops *ca_ops = inet_csk(sk)->icsk_ca_ops; |
| u32 min_tso, tso_segs; |
| |
| min_tso = ca_ops->min_tso_segs ? |
| ca_ops->min_tso_segs(sk) : |
| READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_min_tso_segs); |
| |
| tso_segs = tcp_tso_autosize(sk, mss_now, min_tso); |
| return min_t(u32, tso_segs, sk->sk_gso_max_segs); |
| } |
| |
| /* Returns the portion of skb which can be sent right away */ |
| static unsigned int tcp_mss_split_point(const struct sock *sk, |
| const struct sk_buff *skb, |
| unsigned int mss_now, |
| unsigned int max_segs, |
| int nonagle) |
| { |
| const struct tcp_sock *tp = tcp_sk(sk); |
| u32 partial, needed, window, max_len; |
| |
| window = tcp_wnd_end(tp) - TCP_SKB_CB(skb)->seq; |
| max_len = mss_now * max_segs; |
| |
| if (likely(max_len <= window && skb != tcp_write_queue_tail(sk))) |
| return max_len; |
| |
| needed = min(skb->len, window); |
| |
| if (max_len <= needed) |
| return max_len; |
| |
| partial = needed % mss_now; |
| /* If last segment is not a full MSS, check if Nagle rules allow us |
| * to include this last segment in this skb. |
| * Otherwise, we'll split the skb at last MSS boundary |
| */ |
| if (tcp_nagle_check(partial != 0, tp, nonagle)) |
| return needed - partial; |
| |
| return needed; |
| } |
| |
| /* Can at least one segment of SKB be sent right now, according to the |
| * congestion window rules? If so, return how many segments are allowed. |
| */ |
| static inline unsigned int tcp_cwnd_test(const struct tcp_sock *tp, |
| const struct sk_buff *skb) |
| { |
| u32 in_flight, cwnd, halfcwnd; |
| |
| /* Don't be strict about the congestion window for the final FIN. */ |
| if ((TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN) && |
| tcp_skb_pcount(skb) == 1) |
| return 1; |
| |
| in_flight = tcp_packets_in_flight(tp); |
| cwnd = tcp_snd_cwnd(tp); |
| if (in_flight >= cwnd) |
| return 0; |
| |
| /* For better scheduling, ensure we have at least |
| * 2 GSO packets in flight. |
| */ |
| halfcwnd = max(cwnd >> 1, 1U); |
| return min(halfcwnd, cwnd - in_flight); |
| } |
| |
| /* Initialize TSO state of a skb. |
| * This must be invoked the first time we consider transmitting |
| * SKB onto the wire. |
| */ |
| static int tcp_init_tso_segs(struct sk_buff *skb, unsigned int mss_now) |
| { |
| int tso_segs = tcp_skb_pcount(skb); |
| |
| if (!tso_segs || (tso_segs > 1 && tcp_skb_mss(skb) != mss_now)) { |
| tcp_set_skb_tso_segs(skb, mss_now); |
| tso_segs = tcp_skb_pcount(skb); |
| } |
| return tso_segs; |
| } |
| |
| |
| /* Return true if the Nagle test allows this packet to be |
| * sent now. |
| */ |
| static inline bool tcp_nagle_test(const struct tcp_sock *tp, const struct sk_buff *skb, |
| unsigned int cur_mss, int nonagle) |
| { |
| /* Nagle rule does not apply to frames, which sit in the middle of the |
| * write_queue (they have no chances to get new data). |
| * |
| * This is implemented in the callers, where they modify the 'nonagle' |
| * argument based upon the location of SKB in the send queue. |
| */ |
| if (nonagle & TCP_NAGLE_PUSH) |
| return true; |
| |
| /* Don't use the nagle rule for urgent data (or for the final FIN). */ |
| if (tcp_urg_mode(tp) || (TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN)) |
| return true; |
| |
| if (!tcp_nagle_check(skb->len < cur_mss, tp, nonagle)) |
| return true; |
| |
| return false; |
| } |
| |
| /* Does at least the first segment of SKB fit into the send window? */ |
| static bool tcp_snd_wnd_test(const struct tcp_sock *tp, |
| const struct sk_buff *skb, |
| unsigned int cur_mss) |
| { |
| u32 end_seq = TCP_SKB_CB(skb)->end_seq; |
| |
| if (skb->len > cur_mss) |
| end_seq = TCP_SKB_CB(skb)->seq + cur_mss; |
| |
| return !after(end_seq, tcp_wnd_end(tp)); |
| } |
| |
| /* Trim TSO SKB to LEN bytes, put the remaining data into a new packet |
| * which is put after SKB on the list. It is very much like |
| * tcp_fragment() except that it may make several kinds of assumptions |
| * in order to speed up the splitting operation. In particular, we |
| * know that all the data is in scatter-gather pages, and that the |
| * packet has never been sent out before (and thus is not cloned). |
| */ |
| static int tso_fragment(struct sock *sk, struct sk_buff *skb, unsigned int len, |
| unsigned int mss_now, gfp_t gfp) |
| { |
| int nlen = skb->len - len; |
| struct sk_buff *buff; |
| u8 flags; |
| |
| /* All of a TSO frame must be composed of paged data. */ |
| if (skb->len != skb->data_len) |
| return tcp_fragment(sk, TCP_FRAG_IN_WRITE_QUEUE, |
| skb, len, mss_now, gfp); |
| |
| buff = tcp_stream_alloc_skb(sk, 0, gfp, true); |
| if (unlikely(!buff)) |
| return -ENOMEM; |
| skb_copy_decrypted(buff, skb); |
| mptcp_skb_ext_copy(buff, skb); |
| |
| sk_wmem_queued_add(sk, buff->truesize); |
| sk_mem_charge(sk, buff->truesize); |
| buff->truesize += nlen; |
| skb->truesize -= nlen; |
| |
| /* Correct the sequence numbers. */ |
| TCP_SKB_CB(buff)->seq = TCP_SKB_CB(skb)->seq + len; |
| TCP_SKB_CB(buff)->end_seq = TCP_SKB_CB(skb)->end_seq; |
| TCP_SKB_CB(skb)->end_seq = TCP_SKB_CB(buff)->seq; |
| |
| /* PSH and FIN should only be set in the second packet. */ |
| flags = TCP_SKB_CB(skb)->tcp_flags; |
| TCP_SKB_CB(skb)->tcp_flags = flags & ~(TCPHDR_FIN | TCPHDR_PSH); |
| TCP_SKB_CB(buff)->tcp_flags = flags; |
| |
| tcp_skb_fragment_eor(skb, buff); |
| |
| skb_split(skb, buff, len); |
| tcp_fragment_tstamp(skb, buff); |
| |
| /* Fix up tso_factor for both original and new SKB. */ |
| tcp_set_skb_tso_segs(skb, mss_now); |
| tcp_set_skb_tso_segs(buff, mss_now); |
| |
| /* Link BUFF into the send queue. */ |
| __skb_header_release(buff); |
| tcp_insert_write_queue_after(skb, buff, sk, TCP_FRAG_IN_WRITE_QUEUE); |
| |
| return 0; |
| } |
| |
| /* Try to defer sending, if possible, in order to minimize the amount |
| * of TSO splitting we do. View it as a kind of TSO Nagle test. |
| * |
| * This algorithm is from John Heffner. |
| */ |
| static bool tcp_tso_should_defer(struct sock *sk, struct sk_buff *skb, |
| bool *is_cwnd_limited, |
| bool *is_rwnd_limited, |
| u32 max_segs) |
| { |
| const struct inet_connection_sock *icsk = inet_csk(sk); |
| u32 send_win, cong_win, limit, in_flight; |
| struct tcp_sock *tp = tcp_sk(sk); |
| struct sk_buff *head; |
| int win_divisor; |
| s64 delta; |
| |
| if (icsk->icsk_ca_state >= TCP_CA_Recovery) |
| goto send_now; |
| |
| /* Avoid bursty behavior by allowing defer |
| * only if the last write was recent (1 ms). |
| * Note that tp->tcp_wstamp_ns can be in the future if we have |
| * packets waiting in a qdisc or device for EDT delivery. |
| */ |
| delta = tp->tcp_clock_cache - tp->tcp_wstamp_ns - NSEC_PER_MSEC; |
| if (delta > 0) |
| goto send_now; |
| |
| in_flight = tcp_packets_in_flight(tp); |
| |
| BUG_ON(tcp_skb_pcount(skb) <= 1); |
| BUG_ON(tcp_snd_cwnd(tp) <= in_flight); |
| |
| send_win = tcp_wnd_end(tp) - TCP_SKB_CB(skb)->seq; |
| |
| /* From in_flight test above, we know that cwnd > in_flight. */ |
| cong_win = (tcp_snd_cwnd(tp) - in_flight) * tp->mss_cache; |
| |
| limit = min(send_win, cong_win); |
| |
| /* If a full-sized TSO skb can be sent, do it. */ |
| if (limit >= max_segs * tp->mss_cache) |
| goto send_now; |
| |
| /* Middle in queue won't get any more data, full sendable already? */ |
| if ((skb != tcp_write_queue_tail(sk)) && (limit >= skb->len)) |
| goto send_now; |
| |
| win_divisor = READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_tso_win_divisor); |
| if (win_divisor) { |
| u32 chunk = min(tp->snd_wnd, tcp_snd_cwnd(tp) * tp->mss_cache); |
| |
| /* If at least some fraction of a window is available, |
| * just use it. |
| */ |
| chunk /= win_divisor; |
| if (limit >= chunk) |
| goto send_now; |
| } else { |
| /* Different approach, try not to defer past a single |
| * ACK. Receiver should ACK every other full sized |
| * frame, so if we have space for more than 3 frames |
| * then send now. |
| */ |
| if (limit > tcp_max_tso_deferred_mss(tp) * tp->mss_cache) |
| goto send_now; |
| } |
| |
| /* TODO : use tsorted_sent_queue ? */ |
| head = tcp_rtx_queue_head(sk); |
| if (!head) |
| goto send_now; |
| delta = tp->tcp_clock_cache - head->tstamp; |
| /* If next ACK is likely to come too late (half srtt), do not defer */ |
| if ((s64)(delta - (u64)NSEC_PER_USEC * (tp->srtt_us >> 4)) < 0) |
| goto send_now; |
| |
| /* Ok, it looks like it is advisable to defer. |
| * Three cases are tracked : |
| * 1) We are cwnd-limited |
| * 2) We are rwnd-limited |
| * 3) We are application limited. |
| */ |
| if (cong_win < send_win) { |
| if (cong_win <= skb->len) { |
| *is_cwnd_limited = true; |
| return true; |
| } |
| } else { |
| if (send_win <= skb->len) { |
| *is_rwnd_limited = true; |
| return true; |
| } |
| } |
| |
| /* If this packet won't get more data, do not wait. */ |
| if ((TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN) || |
| TCP_SKB_CB(skb)->eor) |
| goto send_now; |
| |
| return true; |
| |
| send_now: |
| return false; |
| } |
| |
| static inline void tcp_mtu_check_reprobe(struct sock *sk) |
| { |
| struct inet_connection_sock *icsk = inet_csk(sk); |
| struct tcp_sock *tp = tcp_sk(sk); |
| struct net *net = sock_net(sk); |
| u32 interval; |
| s32 delta; |
| |
| interval = READ_ONCE(net->ipv4.sysctl_tcp_probe_interval); |
| delta = tcp_jiffies32 - icsk->icsk_mtup.probe_timestamp; |
| if (unlikely(delta >= interval * HZ)) { |
| int mss = tcp_current_mss(sk); |
| |
| /* Update current search range */ |
| icsk->icsk_mtup.probe_size = 0; |
| icsk->icsk_mtup.search_high = tp->rx_opt.mss_clamp + |
| sizeof(struct tcphdr) + |
| icsk->icsk_af_ops->net_header_len; |
| icsk->icsk_mtup.search_low = tcp_mss_to_mtu(sk, mss); |
| |
| /* Update probe time stamp */ |
| icsk->icsk_mtup.probe_timestamp = tcp_jiffies32; |
| } |
| } |
| |
| static bool tcp_can_coalesce_send_queue_head(struct sock *sk, int len) |
| { |
| struct sk_buff *skb, *next; |
| |
| skb = tcp_send_head(sk); |
| tcp_for_write_queue_from_safe(skb, next, sk) { |
| if (len <= skb->len) |
| break; |
| |
| if (unlikely(TCP_SKB_CB(skb)->eor) || |
| tcp_has_tx_tstamp(skb) || |
| !skb_pure_zcopy_same(skb, next)) |
| return false; |
| |
| len -= skb->len; |
| } |
| |
| return true; |
| } |
| |
| /* Create a new MTU probe if we are ready. |
| * MTU probe is regularly attempting to increase the path MTU by |
| * deliberately sending larger packets. This discovers routing |
| * changes resulting in larger path MTUs. |
| * |
| * Returns 0 if we should wait to probe (no cwnd available), |
| * 1 if a probe was sent, |
| * -1 otherwise |
| */ |
| static int tcp_mtu_probe(struct sock *sk) |
| { |
| struct inet_connection_sock *icsk = inet_csk(sk); |
| struct tcp_sock *tp = tcp_sk(sk); |
| struct sk_buff *skb, *nskb, *next; |
| struct net *net = sock_net(sk); |
| int probe_size; |
| int size_needed; |
| int copy, len; |
| int mss_now; |
| int interval; |
| |
| /* Not currently probing/verifying, |
| * not in recovery, |
| * have enough cwnd, and |
| * not SACKing (the variable headers throw things off) |
| */ |
| if (likely(!icsk->icsk_mtup.enabled || |
| icsk->icsk_mtup.probe_size || |
| inet_csk(sk)->icsk_ca_state != TCP_CA_Open || |
| tcp_snd_cwnd(tp) < 11 || |
| tp->rx_opt.num_sacks || tp->rx_opt.dsack)) |
| return -1; |
| |
| /* Use binary search for probe_size between tcp_mss_base, |
| * and current mss_clamp. if (search_high - search_low) |
| * smaller than a threshold, backoff from probing. |
| */ |
| mss_now = tcp_current_mss(sk); |
| probe_size = tcp_mtu_to_mss(sk, (icsk->icsk_mtup.search_high + |
| icsk->icsk_mtup.search_low) >> 1); |
| size_needed = probe_size + (tp->reordering + 1) * tp->mss_cache; |
| interval = icsk->icsk_mtup.search_high - icsk->icsk_mtup.search_low; |
| /* When misfortune happens, we are reprobing actively, |
| * and then reprobe timer has expired. We stick with current |
| * probing process by not resetting search range to its orignal. |
| */ |
| if (probe_size > tcp_mtu_to_mss(sk, icsk->icsk_mtup.search_high) || |
| interval < READ_ONCE(net->ipv4.sysctl_tcp_probe_threshold)) { |
| /* Check whether enough time has elaplased for |
| * another round of probing. |
| */ |
| tcp_mtu_check_reprobe(sk); |
| return -1; |
| } |
| |
| /* Have enough data in the send queue to probe? */ |
| if (tp->write_seq - tp->snd_nxt < size_needed) |
| return -1; |
| |
| if (tp->snd_wnd < size_needed) |
| return -1; |
| if (after(tp->snd_nxt + size_needed, tcp_wnd_end(tp))) |
| return 0; |
| |
| /* Do we need to wait to drain cwnd? With none in flight, don't stall */ |
| if (tcp_packets_in_flight(tp) + 2 > tcp_snd_cwnd(tp)) { |
| if (!tcp_packets_in_flight(tp)) |
| return -1; |
| else |
| return 0; |
| } |
| |
| if (!tcp_can_coalesce_send_queue_head(sk, probe_size)) |
| return -1; |
| |
| /* We're allowed to probe. Build it now. */ |
| nskb = tcp_stream_alloc_skb(sk, probe_size, GFP_ATOMIC, false); |
| if (!nskb) |
| return -1; |
| sk_wmem_queued_add(sk, nskb->truesize); |
| sk_mem_charge(sk, nskb->truesize); |
| |
| skb = tcp_send_head(sk); |
| skb_copy_decrypted(nskb, skb); |
| mptcp_skb_ext_copy(nskb, skb); |
| |
| TCP_SKB_CB(nskb)->seq = TCP_SKB_CB(skb)->seq; |
| TCP_SKB_CB(nskb)->end_seq = TCP_SKB_CB(skb)->seq + probe_size; |
| TCP_SKB_CB(nskb)->tcp_flags = TCPHDR_ACK; |
| |
| tcp_insert_write_queue_before(nskb, skb, sk); |
| tcp_highest_sack_replace(sk, skb, nskb); |
| |
| len = 0; |
| tcp_for_write_queue_from_safe(skb, next, sk) { |
| copy = min_t(int, skb->len, probe_size - len); |
| skb_copy_bits(skb, 0, skb_put(nskb, copy), copy); |
| |
| if (skb->len <= copy) { |
| /* We've eaten all the data from this skb. |
| * Throw it away. */ |
| TCP_SKB_CB(nskb)->tcp_flags |= TCP_SKB_CB(skb)->tcp_flags; |
| /* If this is the last SKB we copy and eor is set |
| * we need to propagate it to the new skb. |
| */ |
| TCP_SKB_CB(nskb)->eor = TCP_SKB_CB(skb)->eor; |
| tcp_skb_collapse_tstamp(nskb, skb); |
| tcp_unlink_write_queue(skb, sk); |
| tcp_wmem_free_skb(sk, skb); |
| } else { |
| TCP_SKB_CB(nskb)->tcp_flags |= TCP_SKB_CB(skb)->tcp_flags & |
| ~(TCPHDR_FIN|TCPHDR_PSH); |
| if (!skb_shinfo(skb)->nr_frags) { |
| skb_pull(skb, copy); |
| } else { |
| __pskb_trim_head(skb, copy); |
| tcp_set_skb_tso_segs(skb, mss_now); |
| } |
| TCP_SKB_CB(skb)->seq += copy; |
| } |
| |
| len += copy; |
| |
| if (len >= probe_size) |
| break; |
| } |
| tcp_init_tso_segs(nskb, nskb->len); |
| |
| /* We're ready to send. If this fails, the probe will |
| * be resegmented into mss-sized pieces by tcp_write_xmit(). |
| */ |
| if (!tcp_transmit_skb(sk, nskb, 1, GFP_ATOMIC)) { |
| /* Decrement cwnd here because we are sending |
| * effectively two packets. */ |
| tcp_snd_cwnd_set(tp, tcp_snd_cwnd(tp) - 1); |
| tcp_event_new_data_sent(sk, nskb); |
| |
| icsk->icsk_mtup.probe_size = tcp_mss_to_mtu(sk, nskb->len); |
| tp->mtu_probe.probe_seq_start = TCP_SKB_CB(nskb)->seq; |
| tp->mtu_probe.probe_seq_end = TCP_SKB_CB(nskb)->end_seq; |
| |
| return 1; |
| } |
| |
| return -1; |
| } |
| |
| static bool tcp_pacing_check(struct sock *sk) |
| { |
| struct tcp_sock *tp = tcp_sk(sk); |
| |
| if (!tcp_needs_internal_pacing(sk)) |
| return false; |
| |
| if (tp->tcp_wstamp_ns <= tp->tcp_clock_cache) |
| return false; |
| |
| if (!hrtimer_is_queued(&tp->pacing_timer)) { |
| hrtimer_start(&tp->pacing_timer, |
| ns_to_ktime(tp->tcp_wstamp_ns), |
| HRTIMER_MODE_ABS_PINNED_SOFT); |
| sock_hold(sk); |
| } |
| return true; |
| } |
| |
| static bool tcp_rtx_queue_empty_or_single_skb(const struct sock *sk) |
| { |
| const struct rb_node *node = sk->tcp_rtx_queue.rb_node; |
| |
| /* No skb in the rtx queue. */ |
| if (!node) |
| return true; |
| |
| /* Only one skb in rtx queue. */ |
| return !node->rb_left && !node->rb_right; |
| } |
| |
| /* TCP Small Queues : |
| * Control number of packets in qdisc/devices to two packets / or ~1 ms. |
| * (These limits are doubled for retransmits) |
| * This allows for : |
| * - better RTT estimation and ACK scheduling |
| * - faster recovery |
| * - high rates |
| * Alas, some drivers / subsystems require a fair amount |
| * of queued bytes to ensure line rate. |
| * One example is wifi aggregation (802.11 AMPDU) |
| */ |
| static bool tcp_small_queue_check(struct sock *sk, const struct sk_buff *skb, |
| unsigned int factor) |
| { |
| unsigned long limit; |
| |
| limit = max_t(unsigned long, |
| 2 * skb->truesize, |
| sk->sk_pacing_rate >> READ_ONCE(sk->sk_pacing_shift)); |
| if (sk->sk_pacing_status == SK_PACING_NONE) |
| limit = min_t(unsigned long, limit, |
| READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_limit_output_bytes)); |
| limit <<= factor; |
| |
| if (static_branch_unlikely(&tcp_tx_delay_enabled) && |
| tcp_sk(sk)->tcp_tx_delay) { |
| u64 extra_bytes = (u64)sk->sk_pacing_rate * tcp_sk(sk)->tcp_tx_delay; |
| |
| /* TSQ is based on skb truesize sum (sk_wmem_alloc), so we |
| * approximate our needs assuming an ~100% skb->truesize overhead. |
| * USEC_PER_SEC is approximated by 2^20. |
| * do_div(extra_bytes, USEC_PER_SEC/2) is replaced by a right shift. |
| */ |
| extra_bytes >>= (20 - 1); |
| limit += extra_bytes; |
| } |
| if (refcount_read(&sk->sk_wmem_alloc) > limit) { |
| /* Always send skb if rtx queue is empty or has one skb. |
| * No need to wait for TX completion to call us back, |
| * after softirq/tasklet schedule. |
| * This helps when TX completions are delayed too much. |
| */ |
| if (tcp_rtx_queue_empty_or_single_skb(sk)) |
| return false; |
| |
| set_bit(TSQ_THROTTLED, &sk->sk_tsq_flags); |
| /* It is possible TX completion already happened |
| * before we set TSQ_THROTTLED, so we must |
| * test again the condition. |
| */ |
| smp_mb__after_atomic(); |
| if (refcount_read(&sk->sk_wmem_alloc) > limit) |
| return true; |
| } |
| return false; |
| } |
| |
| static void tcp_chrono_set(struct tcp_sock *tp, const enum tcp_chrono new) |
| { |
| const u32 now = tcp_jiffies32; |
| enum tcp_chrono old = tp->chrono_type; |
| |
| if (old > TCP_CHRONO_UNSPEC) |
| tp->chrono_stat[old - 1] += now - tp->chrono_start; |
| tp->chrono_start = now; |
| tp->chrono_type = new; |
| } |
| |
| void tcp_chrono_start(struct sock *sk, const enum tcp_chrono type) |
| { |
| struct tcp_sock *tp = tcp_sk(sk); |
| |
| /* If there are multiple conditions worthy of tracking in a |
| * chronograph then the highest priority enum takes precedence |
| * over the other conditions. So that if something "more interesting" |
| * starts happening, stop the previous chrono and start a new one. |
| */ |
| if (type > tp->chrono_type) |
| tcp_chrono_set(tp, type); |
| } |
| |
| void tcp_chrono_stop(struct sock *sk, const enum tcp_chrono type) |
| { |
| struct tcp_sock *tp = tcp_sk(sk); |
| |
| |
| /* There are multiple conditions worthy of tracking in a |
| * chronograph, so that the highest priority enum takes |
| * precedence over the other conditions (see tcp_chrono_start). |
| * If a condition stops, we only stop chrono tracking if |
| * it's the "most interesting" or current chrono we are |
| * tracking and starts busy chrono if we have pending data. |
| */ |
| if (tcp_rtx_and_write_queues_empty(sk)) |
| tcp_chrono_set(tp, TCP_CHRONO_UNSPEC); |
| else if (type == tp->chrono_type) |
| tcp_chrono_set(tp, TCP_CHRONO_BUSY); |
| } |
| |
| /* This routine writes packets to the network. It advances the |
| * send_head. This happens as incoming acks open up the remote |
| * window for us. |
| * |
| * LARGESEND note: !tcp_urg_mode is overkill, only frames between |
| * snd_up-64k-mss .. snd_up cannot be large. However, taking into |
| * account rare use of URG, this is not a big flaw. |
| * |
| * Send at most one packet when push_one > 0. Temporarily ignore |
| * cwnd limit to force at most one packet out when push_one == 2. |
| |
| * Returns true, if no segments are in flight and we have queued segments, |
| * but cannot send anything now because of SWS or another problem. |
| */ |
| static bool tcp_write_xmit(struct sock *sk, unsigned int mss_now, int nonagle, |
| int push_one, gfp_t gfp) |
| { |
| struct tcp_sock *tp = tcp_sk(sk); |
| struct sk_buff *skb; |
| unsigned int tso_segs, sent_pkts; |
| int cwnd_quota; |
| int result; |
| bool is_cwnd_limited = false, is_rwnd_limited = false; |
| u32 max_segs; |
| |
| sent_pkts = 0; |
| |
| tcp_mstamp_refresh(tp); |
| if (!push_one) { |
| /* Do MTU probing. */ |
| result = tcp_mtu_probe(sk); |
| if (!result) { |
| return false; |
| } else if (result > 0) { |
| sent_pkts = 1; |
| } |
| } |
| |
| max_segs = tcp_tso_segs(sk, mss_now); |
| while ((skb = tcp_send_head(sk))) { |
| unsigned int limit; |
| |
| if (unlikely(tp->repair) && tp->repair_queue == TCP_SEND_QUEUE) { |
| /* "skb_mstamp_ns" is used as a start point for the retransmit timer */ |
| tp->tcp_wstamp_ns = tp->tcp_clock_cache; |
| skb_set_delivery_time(skb, tp->tcp_wstamp_ns, true); |
| list_move_tail(&skb->tcp_tsorted_anchor, &tp->tsorted_sent_queue); |
| tcp_init_tso_segs(skb, mss_now); |
| goto repair; /* Skip network transmission */ |
| } |
| |
| if (tcp_pacing_check(sk)) |
| break; |
| |
| tso_segs = tcp_init_tso_segs(skb, mss_now); |
| BUG_ON(!tso_segs); |
| |
| cwnd_quota = tcp_cwnd_test(tp, skb); |
| if (!cwnd_quota) { |
| if (push_one == 2) |
| /* Force out a loss probe pkt. */ |
| cwnd_quota = 1; |
| else |
| break; |
| } |
| |
| if (unlikely(!tcp_snd_wnd_test(tp, skb, mss_now))) { |
| is_rwnd_limited = true; |
| break; |
| } |
| |
| if (tso_segs == 1) { |
| if (unlikely(!tcp_nagle_test(tp, skb, mss_now, |
| (tcp_skb_is_last(sk, skb) ? |
| nonagle : TCP_NAGLE_PUSH)))) |
| break; |
| } else { |
| if (!push_one && |
| tcp_tso_should_defer(sk, skb, &is_cwnd_limited, |
| &is_rwnd_limited, max_segs)) |
| break; |
| } |
| |
| limit = mss_now; |
| if (tso_segs > 1 && !tcp_urg_mode(tp)) |
| limit = tcp_mss_split_point(sk, skb, mss_now, |
| min_t(unsigned int, |
| cwnd_quota, |
| max_segs), |
| nonagle); |
| |
| if (skb->len > limit && |
| unlikely(tso_fragment(sk, skb, limit, mss_now, gfp))) |
| break; |
| |
| if (tcp_small_queue_check(sk, skb, 0)) |
| break; |
| |
| /* Argh, we hit an empty skb(), presumably a thread |
| * is sleeping in sendmsg()/sk_stream_wait_memory(). |
| * We do not want to send a pure-ack packet and have |
| * a strange looking rtx queue with empty packet(s). |
| */ |
| if (TCP_SKB_CB(skb)->end_seq == TCP_SKB_CB(skb)->seq) |
| break; |
| |
| if (unlikely(tcp_transmit_skb(sk, skb, 1, gfp))) |
| break; |
| |
| repair: |
| /* Advance the send_head. This one is sent out. |
| * This call will increment packets_out. |
| */ |
| tcp_event_new_data_sent(sk, skb); |
| |
| tcp_minshall_update(tp, mss_now, skb); |
| sent_pkts += tcp_skb_pcount(skb); |
| |
| if (push_one) |
| break; |
| } |
| |
| if (is_rwnd_limited) |
| tcp_chrono_start(sk, TCP_CHRONO_RWND_LIMITED); |
| else |
| tcp_chrono_stop(sk, TCP_CHRONO_RWND_LIMITED); |
| |
| is_cwnd_limited |= (tcp_packets_in_flight(tp) >= tcp_snd_cwnd(tp)); |
| if (likely(sent_pkts || is_cwnd_limited)) |
| tcp_cwnd_validate(sk, is_cwnd_limited); |
| |
| if (likely(sent_pkts)) { |
| if (tcp_in_cwnd_reduction(sk)) |
| tp->prr_out += sent_pkts; |
| |
| /* Send one loss probe per tail loss episode. */ |
| if (push_one != 2) |
| tcp_schedule_loss_probe(sk, false); |
| return false; |
| } |
| return !tp->packets_out && !tcp_write_queue_empty(sk); |
| } |
| |
| bool tcp_schedule_loss_probe(struct sock *sk, bool advancing_rto) |
| { |
| struct inet_connection_sock *icsk = inet_csk(sk); |
| struct tcp_sock *tp = tcp_sk(sk); |
| u32 timeout, timeout_us, rto_delta_us; |
| int early_retrans; |
| |
| /* Don't do any loss probe on a Fast Open connection before 3WHS |
| * finishes. |
| */ |
| if (rcu_access_pointer(tp->fastopen_rsk)) |
| return false; |
| |
| early_retrans = READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_early_retrans); |
| /* Schedule a loss probe in 2*RTT for SACK capable connections |
| * not in loss recovery, that are either limited by cwnd or application. |
| */ |
| if ((early_retrans != 3 && early_retrans != 4) || |
| !tp->packets_out || !tcp_is_sack(tp) || |
| (icsk->icsk_ca_state != TCP_CA_Open && |
| icsk->icsk_ca_state != TCP_CA_CWR)) |
| return false; |
| |
| /* Probe timeout is 2*rtt. Add minimum RTO to account |
| * for delayed ack when there's one outstanding packet. If no RTT |
| * sample is available then probe after TCP_TIMEOUT_INIT. |
| */ |
| if (tp->srtt_us) { |
| timeout_us = tp->srtt_us >> 2; |
| if (tp->packets_out == 1) |
| timeout_us += tcp_rto_min_us(sk); |
| else |
| timeout_us += TCP_TIMEOUT_MIN_US; |
| timeout = usecs_to_jiffies(timeout_us); |
| } else { |
| timeout = TCP_TIMEOUT_INIT; |
| } |
| |
| /* If the RTO formula yields an earlier time, then use that time. */ |
| rto_delta_us = advancing_rto ? |
| jiffies_to_usecs(inet_csk(sk)->icsk_rto) : |
| tcp_rto_delta_us(sk); /* How far in future is RTO? */ |
| if (rto_delta_us > 0) |
| timeout = min_t(u32, timeout, usecs_to_jiffies(rto_delta_us)); |
| |
| tcp_reset_xmit_timer(sk, ICSK_TIME_LOSS_PROBE, timeout, TCP_RTO_MAX); |
| return true; |
| } |
| |
| /* Thanks to skb fast clones, we can detect if a prior transmit of |
| * a packet is still in a qdisc or driver queue. |
| * In this case, there is very little point doing a retransmit ! |
| */ |
| static bool skb_still_in_host_queue(struct sock *sk, |
| const struct sk_buff *skb) |
| { |
| if (unlikely(skb_fclone_busy(sk, skb))) { |
| set_bit(TSQ_THROTTLED, &sk->sk_tsq_flags); |
| smp_mb__after_atomic(); |
| if (skb_fclone_busy(sk, skb)) { |
| NET_INC_STATS(sock_net(sk), |
| LINUX_MIB_TCPSPURIOUS_RTX_HOSTQUEUES); |
| return true; |
| } |
| } |
| return false; |
| } |
| |
| /* When probe timeout (PTO) fires, try send a new segment if possible, else |
| * retransmit the last segment. |
| */ |
| void tcp_send_loss_probe(struct sock *sk) |
| { |
| struct tcp_sock *tp = tcp_sk(sk); |
| struct sk_buff *skb; |
| int pcount; |
| int mss = tcp_current_mss(sk); |
| |
| /* At most one outstanding TLP */ |
| if (tp->tlp_high_seq) |
| goto rearm_timer; |
| |
| tp->tlp_retrans = 0; |
| skb = tcp_send_head(sk); |
| if (skb && tcp_snd_wnd_test(tp, skb, mss)) { |
| pcount = tp->packets_out; |
| tcp_write_xmit(sk, mss, TCP_NAGLE_OFF, 2, GFP_ATOMIC); |
| if (tp->packets_out > pcount) |
| goto probe_sent; |
| goto rearm_timer; |
| } |
| skb = skb_rb_last(&sk->tcp_rtx_queue); |
| if (unlikely(!skb)) { |
| WARN_ONCE(tp->packets_out, |
| "invalid inflight: %u state %u cwnd %u mss %d\n", |
| tp->packets_out, sk->sk_state, tcp_snd_cwnd(tp), mss); |
| inet_csk(sk)->icsk_pending = 0; |
| return; |
| } |
| |
| if (skb_still_in_host_queue(sk, skb)) |
| goto rearm_timer; |
| |
| pcount = tcp_skb_pcount(skb); |
| if (WARN_ON(!pcount)) |
| goto rearm_timer; |
| |
| if ((pcount > 1) && (skb->len > (pcount - 1) * mss)) { |
| if (unlikely(tcp_fragment(sk, TCP_FRAG_IN_RTX_QUEUE, skb, |
| (pcount - 1) * mss, mss, |
| GFP_ATOMIC))) |
| goto rearm_timer; |
| skb = skb_rb_next(skb); |
| } |
| |
| if (WARN_ON(!skb || !tcp_skb_pcount(skb))) |
| goto rearm_timer; |
| |
| if (__tcp_retransmit_skb(sk, skb, 1)) |
| goto rearm_timer; |
| |
| tp->tlp_retrans = 1; |
| |
| probe_sent: |
| /* Record snd_nxt for loss detection. */ |
| tp->tlp_high_seq = tp->snd_nxt; |
| |
| NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPLOSSPROBES); |
| /* Reset s.t. tcp_rearm_rto will restart timer from now */ |
| inet_csk(sk)->icsk_pending = 0; |
| rearm_timer: |
| tcp_rearm_rto(sk); |
| } |
| |
| /* Push out any pending frames which were held back due to |
| * TCP_CORK or attempt at coalescing tiny packets. |
| * The socket must be locked by the caller. |
| */ |
| void __tcp_push_pending_frames(struct sock *sk, unsigned int cur_mss, |
| int nonagle) |
| { |
| /* If we are closed, the bytes will have to remain here. |
| * In time closedown will finish, we empty the write queue and |
| * all will be happy. |
| */ |
| if (unlikely(sk->sk_state == TCP_CLOSE)) |
| return; |
| |
| if (tcp_write_xmit(sk, cur_mss, nonagle, 0, |
| sk_gfp_mask(sk, GFP_ATOMIC))) |
| tcp_check_probe_timer(sk); |
| } |
| |
| /* Send _single_ skb sitting at the send head. This function requires |
| * true push pending frames to setup probe timer etc. |
| */ |
| void tcp_push_one(struct sock *sk, unsigned int mss_now) |
| { |
| struct sk_buff *skb = tcp_send_head(sk); |
| |
| BUG_ON(!skb || skb->len < mss_now); |
| |
| tcp_write_xmit(sk, mss_now, TCP_NAGLE_PUSH, 1, sk->sk_allocation); |
| } |
| |
| /* This function returns the amount that we can raise the |
| * usable window based on the following constraints |
| * |
| * 1. The window can never be shrunk once it is offered (RFC 793) |
| * 2. We limit memory per socket |
| * |
| * RFC 1122: |
| * "the suggested [SWS] avoidance algorithm for the receiver is to keep |
| * RECV.NEXT + RCV.WIN fixed until: |
| * RCV.BUFF - RCV.USER - RCV.WINDOW >= min(1/2 RCV.BUFF, MSS)" |
| * |
| * i.e. don't raise the right edge of the window until you can raise |
| * it at least MSS bytes. |
| * |
| * Unfortunately, the recommended algorithm breaks header prediction, |
| * since header prediction assumes th->window stays fixed. |
| * |
| * Strictly speaking, keeping th->window fixed violates the receiver |
| * side SWS prevention criteria. The problem is that under this rule |
| * a stream of single byte packets will cause the right side of the |
| * window to always advance by a single byte. |
| * |
| * Of course, if the sender implements sender side SWS prevention |
| * then this will not be a problem. |
| * |
| * BSD seems to make the following compromise: |
| * |
| * If the free space is less than the 1/4 of the maximum |
| * space available and the free space is less than 1/2 mss, |
| * then set the window to 0. |
| * [ Actually, bsd uses MSS and 1/4 of maximal _window_ ] |
| * Otherwise, just prevent the window from shrinking |
| * and from being larger than the largest representable value. |
| * |
| * This prevents incremental opening of the window in the regime |
| * where TCP is limited by the speed of the reader side taking |
| * data out of the TCP receive queue. It does nothing about |
| * those cases where the window is constrained on the sender side |
| * because the pipeline is full. |
| * |
| * BSD also seems to "accidentally" limit itself to windows that are a |
| * multiple of MSS, at least until the free space gets quite small. |
| * This would appear to be a side effect of the mbuf implementation. |
| * Combining these two algorithms results in the observed behavior |
| * of having a fixed window size at almost all times. |
| * |
| * Below we obtain similar behavior by forcing the offered window to |
| * a multiple of the mss when it is feasible to do so. |
| * |
| * Note, we don't "adjust" for TIMESTAMP or SACK option bytes. |
| * Regular options like TIMESTAMP are taken into account. |
| */ |
| u32 __tcp_select_window(struct sock *sk) |
| { |
| struct inet_connection_sock *icsk = inet_csk(sk); |
| struct tcp_sock *tp = tcp_sk(sk); |
| /* MSS for the peer's data. Previous versions used mss_clamp |
| * here. I don't know if the value based on our guesses |
| * of peer's MSS is better for the performance. It's more correct |
| * but may be worse for the performance because of rcv_mss |
| * fluctuations. --SAW 1998/11/1 |
| */ |
| int mss = icsk->icsk_ack.rcv_mss; |
| int free_space = tcp_space(sk); |
| int allowed_space = tcp_full_space(sk); |
| int full_space, window; |
| |
| if (sk_is_mptcp(sk)) |
| mptcp_space(sk, &free_space, &allowed_space); |
| |
| full_space = min_t(int, tp->window_clamp, allowed_space); |
| |
| if (unlikely(mss > full_space)) { |
| mss = full_space; |
| if (mss <= 0) |
| return 0; |
| } |
| if (free_space < (full_space >> 1)) { |
| icsk->icsk_ack.quick = 0; |
| |
| if (tcp_under_memory_pressure(sk)) |
| tcp_adjust_rcv_ssthresh(sk); |
| |
| /* free_space might become our new window, make sure we don't |
| * increase it due to wscale. |
| */ |
| free_space = round_down(free_space, 1 << tp->rx_opt.rcv_wscale); |
| |
| /* if free space is less than mss estimate, or is below 1/16th |
| * of the maximum allowed, try to move to zero-window, else |
| * tcp_clamp_window() will grow rcv buf up to tcp_rmem[2], and |
| * new incoming data is dropped due to memory limits. |
| * With large window, mss test triggers way too late in order |
| * to announce zero window in time before rmem limit kicks in. |
| */ |
| if (free_space < (allowed_space >> 4) || free_space < mss) |
| return 0; |
| } |
| |
| if (free_space > tp->rcv_ssthresh) |
| free_space = tp->rcv_ssthresh; |
| |
| /* Don't do rounding if we are using window scaling, since the |
| * scaled window will not line up with the MSS boundary anyway. |
| */ |
| if (tp->rx_opt.rcv_wscale) { |
| window = free_space; |
| |
| /* Advertise enough space so that it won't get scaled away. |
| * Import case: prevent zero window announcement if |
| * 1<<rcv_wscale > mss. |
| */ |
| window = ALIGN(window, (1 << tp->rx_opt.rcv_wscale)); |
| } else { |
| window = tp->rcv_wnd; |
| /* Get the largest window that is a nice multiple of mss. |
| * Window clamp already applied above. |
| * If our current window offering is within 1 mss of the |
| * free space we just keep it. This prevents the divide |
| * and multiply from happening most of the time. |
| * We also don't do any window rounding when the free space |
| * is too small. |
| */ |
| if (window <= free_space - mss || window > free_space) |
| window = rounddown(free_space, mss); |
| else if (mss == full_space && |
| free_space > window + (full_space >> 1)) |
| window = free_space; |
| } |
| |
| return window; |
| } |
| |
| void tcp_skb_collapse_tstamp(struct sk_buff *skb, |
| const struct sk_buff *next_skb) |
| { |
| if (unlikely(tcp_has_tx_tstamp(next_skb))) { |
| const struct skb_shared_info *next_shinfo = |
| skb_shinfo(next_skb); |
| struct skb_shared_info *shinfo = skb_shinfo(skb); |
| |
| shinfo->tx_flags |= next_shinfo->tx_flags & SKBTX_ANY_TSTAMP; |
| shinfo->tskey = next_shinfo->tskey; |
| TCP_SKB_CB(skb)->txstamp_ack |= |
| TCP_SKB_CB(next_skb)->txstamp_ack; |
| } |
| } |
| |
| /* Collapses two adjacent SKB's during retransmission. */ |
| static bool tcp_collapse_retrans(struct sock *sk, struct sk_buff *skb) |
| { |
| struct tcp_sock *tp = tcp_sk(sk); |
| struct sk_buff *next_skb = skb_rb_next( |