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mptcp: keep track of advertised windows right edge
Before sending 'x' new bytes also check that the new snd_una would be within the permitted receive window. For every ACK that also contains a DSS ack, check whether its tcp-level receive window would advance the current mptcp window right edge and update it if so. Signed-off-by: Florian Westphal <fw@strlen.de> Co-developed-by: Paolo Abeni <pabeni@redhat.com> Signed-off-by: Paolo Abeni <pabeni@redhat.com> Signed-off-by: Jakub Kicinski <kuba@kernel.org>
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@ -809,11 +809,14 @@ static u64 expand_ack(u64 old_ack, u64 cur_ack, bool use_64bit)
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return cur_ack;
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}
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static void update_una(struct mptcp_sock *msk,
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struct mptcp_options_received *mp_opt)
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static void ack_update_msk(struct mptcp_sock *msk,
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const struct sock *ssk,
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struct mptcp_options_received *mp_opt)
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{
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u64 new_snd_una, snd_una, old_snd_una = atomic64_read(&msk->snd_una);
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u64 new_wnd_end, wnd_end, old_wnd_end = atomic64_read(&msk->wnd_end);
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u64 snd_nxt = READ_ONCE(msk->snd_nxt);
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struct sock *sk = (struct sock *)msk;
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/* avoid ack expansion on update conflict, to reduce the risk of
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* wrongly expanding to a future ack sequence number, which is way
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@ -825,12 +828,25 @@ static void update_una(struct mptcp_sock *msk,
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if (after64(new_snd_una, snd_nxt))
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new_snd_una = old_snd_una;
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new_wnd_end = new_snd_una + tcp_sk(ssk)->snd_wnd;
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while (after64(new_wnd_end, old_wnd_end)) {
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wnd_end = old_wnd_end;
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old_wnd_end = atomic64_cmpxchg(&msk->wnd_end, wnd_end,
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new_wnd_end);
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if (old_wnd_end == wnd_end) {
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if (mptcp_send_head(sk))
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mptcp_schedule_work(sk);
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break;
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}
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}
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while (after64(new_snd_una, old_snd_una)) {
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snd_una = old_snd_una;
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old_snd_una = atomic64_cmpxchg(&msk->snd_una, snd_una,
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new_snd_una);
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if (old_snd_una == snd_una) {
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mptcp_data_acked((struct sock *)msk);
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mptcp_data_acked(sk);
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break;
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}
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}
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@ -930,7 +946,7 @@ void mptcp_incoming_options(struct sock *sk, struct sk_buff *skb)
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* monodirectional flows will stuck
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*/
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if (mp_opt.use_ack)
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update_una(msk, &mp_opt);
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ack_update_msk(msk, sk, &mp_opt);
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/* Zero-data-length packets are dropped by the caller and not
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* propagated to the MPTCP layer, so the skb extension does not
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@ -57,6 +57,12 @@ static struct socket *__mptcp_nmpc_socket(const struct mptcp_sock *msk)
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return msk->subflow;
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}
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/* Returns end sequence number of the receiver's advertised window */
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static u64 mptcp_wnd_end(const struct mptcp_sock *msk)
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{
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return atomic64_read(&msk->wnd_end);
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}
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static bool mptcp_is_tcpsk(struct sock *sk)
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{
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struct socket *sock = sk->sk_socket;
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@ -174,6 +180,7 @@ static void mptcp_data_queue_ofo(struct mptcp_sock *msk, struct sk_buff *skb)
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if (after64(seq, max_seq)) {
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/* out of window */
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mptcp_drop(sk, skb);
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pr_debug("oow by %ld", (unsigned long)seq - (unsigned long)max_seq);
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MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_NODSSWINDOW);
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return;
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}
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@ -847,6 +854,7 @@ static void mptcp_clean_una(struct sock *sk)
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*/
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if (__mptcp_check_fallback(msk))
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atomic64_set(&msk->snd_una, msk->snd_nxt);
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snd_una = atomic64_read(&msk->snd_una);
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list_for_each_entry_safe(dfrag, dtmp, &msk->rtx_queue, list) {
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@ -944,12 +952,30 @@ struct mptcp_sendmsg_info {
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unsigned int flags;
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};
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static int mptcp_check_allowed_size(struct mptcp_sock *msk, u64 data_seq,
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int avail_size)
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{
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u64 window_end = mptcp_wnd_end(msk);
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if (__mptcp_check_fallback(msk))
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return avail_size;
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if (!before64(data_seq + avail_size, window_end)) {
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u64 allowed_size = window_end - data_seq;
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return min_t(unsigned int, allowed_size, avail_size);
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}
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return avail_size;
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}
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static int mptcp_sendmsg_frag(struct sock *sk, struct sock *ssk,
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struct mptcp_data_frag *dfrag,
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struct mptcp_sendmsg_info *info)
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{
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u64 data_seq = dfrag->data_seq + info->sent;
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struct mptcp_sock *msk = mptcp_sk(sk);
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bool zero_window_probe = false;
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struct mptcp_ext *mpext = NULL;
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struct sk_buff *skb, *tail;
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bool can_collapse = false;
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@ -979,6 +1005,16 @@ static int mptcp_sendmsg_frag(struct sock *sk, struct sock *ssk,
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avail_size = info->size_goal - skb->len;
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}
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/* Zero window and all data acked? Probe. */
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avail_size = mptcp_check_allowed_size(msk, data_seq, avail_size);
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if (avail_size == 0) {
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if (skb || atomic64_read(&msk->snd_una) != msk->snd_nxt)
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return 0;
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zero_window_probe = true;
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data_seq = atomic64_read(&msk->snd_una) - 1;
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avail_size = 1;
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}
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if (WARN_ON_ONCE(info->sent > info->limit ||
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info->limit > dfrag->data_len))
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return 0;
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@ -996,6 +1032,7 @@ static int mptcp_sendmsg_frag(struct sock *sk, struct sock *ssk,
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if (skb == tail) {
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WARN_ON_ONCE(!can_collapse);
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mpext->data_len += ret;
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WARN_ON_ONCE(zero_window_probe);
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goto out;
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}
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@ -1013,6 +1050,12 @@ static int mptcp_sendmsg_frag(struct sock *sk, struct sock *ssk,
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mpext->data_seq, mpext->subflow_seq, mpext->data_len,
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mpext->dsn64);
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if (zero_window_probe) {
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mptcp_subflow_ctx(ssk)->rel_write_seq += ret;
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mpext->frozen = 1;
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ret = 0;
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tcp_push_pending_frames(ssk);
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}
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out:
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mptcp_subflow_ctx(ssk)->rel_write_seq += ret;
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return ret;
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@ -1866,7 +1909,7 @@ static void mptcp_worker(struct work_struct *work)
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info.limit = dfrag->already_sent;
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while (info.sent < dfrag->already_sent) {
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ret = mptcp_sendmsg_frag(sk, ssk, dfrag, &info);
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if (ret < 0)
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if (ret <= 0)
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break;
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MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_RETRANSSEGS);
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@ -2226,6 +2269,8 @@ struct sock *mptcp_sk_clone(const struct sock *sk,
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msk->write_seq = subflow_req->idsn + 1;
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msk->snd_nxt = msk->write_seq;
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atomic64_set(&msk->snd_una, msk->write_seq);
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atomic64_set(&msk->wnd_end, msk->snd_nxt + req->rsk_rcv_wnd);
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if (mp_opt->mp_capable) {
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msk->can_ack = true;
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msk->remote_key = mp_opt->sndr_key;
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@ -2258,6 +2303,8 @@ void mptcp_rcv_space_init(struct mptcp_sock *msk, const struct sock *ssk)
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TCP_INIT_CWND * tp->advmss);
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if (msk->rcvq_space.space == 0)
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msk->rcvq_space.space = TCP_INIT_CWND * TCP_MSS_DEFAULT;
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atomic64_set(&msk->wnd_end, msk->snd_nxt + tcp_sk(ssk)->snd_wnd);
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}
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static struct sock *mptcp_accept(struct sock *sk, int flags, int *err,
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@ -215,6 +215,7 @@ struct mptcp_sock {
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struct sock *last_snd;
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int snd_burst;
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atomic64_t snd_una;
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atomic64_t wnd_end;
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unsigned long timer_ival;
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u32 token;
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unsigned long flags;
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