rxrpc: Partially handle OpenAFS's improper termination of calls
[cascardo/linux.git] / net / rxrpc / input.c
index 70bb778..44fb8d8 100644 (file)
@@ -1,6 +1,6 @@
 /* RxRPC packet reception
  *
- * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
+ * Copyright (C) 2007, 2016 Red Hat, Inc. All Rights Reserved.
  * Written by David Howells (dhowells@redhat.com)
  *
  * This program is free software; you can redistribute it and/or
 #include <net/net_namespace.h>
 #include "ar-internal.h"
 
+static void rxrpc_proto_abort(const char *why,
+                             struct rxrpc_call *call, rxrpc_seq_t seq)
+{
+       if (rxrpc_abort_call(why, call, seq, RX_PROTOCOL_ERROR, EBADMSG)) {
+               set_bit(RXRPC_CALL_EV_ABORT, &call->events);
+               rxrpc_queue_call(call);
+       }
+}
+
 /*
- * queue a packet for recvmsg to pass to userspace
- * - the caller must hold a lock on call->lock
- * - must not be called with interrupts disabled (sk_filter() disables BH's)
- * - eats the packet whether successful or not
- * - there must be just one reference to the packet, which the caller passes to
- *   this function
+ * Do TCP-style congestion management [RFC 5681].
  */
-int rxrpc_queue_rcv_skb(struct rxrpc_call *call, struct sk_buff *skb,
-                       bool force, bool terminal)
+static void rxrpc_congestion_management(struct rxrpc_call *call,
+                                       struct sk_buff *skb,
+                                       struct rxrpc_ack_summary *summary,
+                                       rxrpc_serial_t acked_serial)
 {
-       struct rxrpc_skb_priv *sp;
-       struct rxrpc_sock *rx = call->socket;
-       struct sock *sk;
-       int ret;
+       enum rxrpc_congest_change change = rxrpc_cong_no_change;
+       unsigned int cumulative_acks = call->cong_cumul_acks;
+       unsigned int cwnd = call->cong_cwnd;
+       bool resend = false;
+
+       summary->flight_size =
+               (call->tx_top - call->tx_hard_ack) - summary->nr_acks;
+
+       if (test_and_clear_bit(RXRPC_CALL_RETRANS_TIMEOUT, &call->flags)) {
+               summary->retrans_timeo = true;
+               call->cong_ssthresh = max_t(unsigned int,
+                                           summary->flight_size / 2, 2);
+               cwnd = 1;
+               if (cwnd >= call->cong_ssthresh &&
+                   call->cong_mode == RXRPC_CALL_SLOW_START) {
+                       call->cong_mode = RXRPC_CALL_CONGEST_AVOIDANCE;
+                       call->cong_tstamp = skb->tstamp;
+                       cumulative_acks = 0;
+               }
+       }
 
-       _enter(",,%d,%d", force, terminal);
+       cumulative_acks += summary->nr_new_acks;
+       cumulative_acks += summary->nr_rot_new_acks;
+       if (cumulative_acks > 255)
+               cumulative_acks = 255;
+
+       summary->mode = call->cong_mode;
+       summary->cwnd = call->cong_cwnd;
+       summary->ssthresh = call->cong_ssthresh;
+       summary->cumulative_acks = cumulative_acks;
+       summary->dup_acks = call->cong_dup_acks;
+
+       switch (call->cong_mode) {
+       case RXRPC_CALL_SLOW_START:
+               if (summary->nr_nacks > 0)
+                       goto packet_loss_detected;
+               if (summary->cumulative_acks > 0)
+                       cwnd += 1;
+               if (cwnd >= call->cong_ssthresh) {
+                       call->cong_mode = RXRPC_CALL_CONGEST_AVOIDANCE;
+                       call->cong_tstamp = skb->tstamp;
+               }
+               goto out;
 
-       ASSERT(!irqs_disabled());
+       case RXRPC_CALL_CONGEST_AVOIDANCE:
+               if (summary->nr_nacks > 0)
+                       goto packet_loss_detected;
 
-       sp = rxrpc_skb(skb);
-       ASSERTCMP(sp->call, ==, call);
-
-       /* if we've already posted the terminal message for a call, then we
-        * don't post any more */
-       if (test_bit(RXRPC_CALL_TERMINAL_MSG, &call->flags)) {
-               _debug("already terminated");
-               ASSERTCMP(call->state, >=, RXRPC_CALL_COMPLETE);
-               rxrpc_free_skb(skb);
-               return 0;
-       }
-
-       sk = &rx->sk;
-
-       if (!force) {
-               /* cast skb->rcvbuf to unsigned...  It's pointless, but
-                * reduces number of warnings when compiling with -W
-                * --ANK */
-//             ret = -ENOBUFS;
-//             if (atomic_read(&sk->sk_rmem_alloc) + skb->truesize >=
-//                 (unsigned int) sk->sk_rcvbuf)
-//                     goto out;
-
-               ret = sk_filter(sk, skb);
-               if (ret < 0)
+               /* We analyse the number of packets that get ACK'd per RTT
+                * period and increase the window if we managed to fill it.
+                */
+               if (call->peer->rtt_usage == 0)
                        goto out;
-       }
+               if (ktime_before(skb->tstamp,
+                                ktime_add_ns(call->cong_tstamp,
+                                             call->peer->rtt)))
+                       goto out_no_clear_ca;
+               change = rxrpc_cong_rtt_window_end;
+               call->cong_tstamp = skb->tstamp;
+               if (cumulative_acks >= cwnd)
+                       cwnd++;
+               goto out;
 
-       spin_lock_bh(&sk->sk_receive_queue.lock);
-       if (!test_bit(RXRPC_CALL_TERMINAL_MSG, &call->flags) &&
-           !test_bit(RXRPC_CALL_RELEASED, &call->flags) &&
-           call->socket->sk.sk_state != RXRPC_CLOSE) {
-               skb->destructor = rxrpc_packet_destructor;
-               skb->dev = NULL;
-               skb->sk = sk;
-               atomic_add(skb->truesize, &sk->sk_rmem_alloc);
+       case RXRPC_CALL_PACKET_LOSS:
+               if (summary->nr_nacks == 0)
+                       goto resume_normality;
 
-               if (terminal) {
-                       _debug("<<<< TERMINAL MESSAGE >>>>");
-                       set_bit(RXRPC_CALL_TERMINAL_MSG, &call->flags);
+               if (summary->new_low_nack) {
+                       change = rxrpc_cong_new_low_nack;
+                       call->cong_dup_acks = 1;
+                       if (call->cong_extra > 1)
+                               call->cong_extra = 1;
+                       goto send_extra_data;
                }
 
-               /* allow interception by a kernel service */
-               if (rx->interceptor) {
-                       rx->interceptor(sk, call->user_call_ID, skb);
-                       spin_unlock_bh(&sk->sk_receive_queue.lock);
-               } else {
-                       _net("post skb %p", skb);
-                       __skb_queue_tail(&sk->sk_receive_queue, skb);
-                       spin_unlock_bh(&sk->sk_receive_queue.lock);
+               call->cong_dup_acks++;
+               if (call->cong_dup_acks < 3)
+                       goto send_extra_data;
+
+               change = rxrpc_cong_begin_retransmission;
+               call->cong_mode = RXRPC_CALL_FAST_RETRANSMIT;
+               call->cong_ssthresh = max_t(unsigned int,
+                                           summary->flight_size / 2, 2);
+               cwnd = call->cong_ssthresh + 3;
+               call->cong_extra = 0;
+               call->cong_dup_acks = 0;
+               resend = true;
+               goto out;
 
-                       if (!sock_flag(sk, SOCK_DEAD))
-                               sk->sk_data_ready(sk);
+       case RXRPC_CALL_FAST_RETRANSMIT:
+               if (!summary->new_low_nack) {
+                       if (summary->nr_new_acks == 0)
+                               cwnd += 1;
+                       call->cong_dup_acks++;
+                       if (call->cong_dup_acks == 2) {
+                               change = rxrpc_cong_retransmit_again;
+                               call->cong_dup_acks = 0;
+                               resend = true;
+                       }
+               } else {
+                       change = rxrpc_cong_progress;
+                       cwnd = call->cong_ssthresh;
+                       if (summary->nr_nacks == 0)
+                               goto resume_normality;
                }
-               skb = NULL;
-       } else {
-               spin_unlock_bh(&sk->sk_receive_queue.lock);
+               goto out;
+
+       default:
+               BUG();
+               goto out;
        }
-       ret = 0;
 
+resume_normality:
+       change = rxrpc_cong_cleared_nacks;
+       call->cong_dup_acks = 0;
+       call->cong_extra = 0;
+       call->cong_tstamp = skb->tstamp;
+       if (cwnd < call->cong_ssthresh)
+               call->cong_mode = RXRPC_CALL_SLOW_START;
+       else
+               call->cong_mode = RXRPC_CALL_CONGEST_AVOIDANCE;
 out:
-       rxrpc_free_skb(skb);
+       cumulative_acks = 0;
+out_no_clear_ca:
+       if (cwnd >= RXRPC_RXTX_BUFF_SIZE - 1)
+               cwnd = RXRPC_RXTX_BUFF_SIZE - 1;
+       call->cong_cwnd = cwnd;
+       call->cong_cumul_acks = cumulative_acks;
+       trace_rxrpc_congest(call, summary, acked_serial, change);
+       if (resend && !test_and_set_bit(RXRPC_CALL_EV_RESEND, &call->events))
+               rxrpc_queue_call(call);
+       return;
+
+packet_loss_detected:
+       change = rxrpc_cong_saw_nack;
+       call->cong_mode = RXRPC_CALL_PACKET_LOSS;
+       call->cong_dup_acks = 0;
+       goto send_extra_data;
 
-       _leave(" = %d", ret);
-       return ret;
+send_extra_data:
+       /* Send some previously unsent DATA if we have some to advance the ACK
+        * state.
+        */
+       if (call->rxtx_annotations[call->tx_top & RXRPC_RXTX_BUFF_MASK] &
+           RXRPC_TX_ANNO_LAST ||
+           summary->nr_acks != call->tx_top - call->tx_hard_ack) {
+               call->cong_extra++;
+               wake_up(&call->waitq);
+       }
+       goto out_no_clear_ca;
 }
 
 /*
- * process a DATA packet, posting the packet to the appropriate queue
- * - eats the packet if successful
+ * Ping the other end to fill our RTT cache and to retrieve the rwind
+ * and MTU parameters.
  */
-static int rxrpc_fast_process_data(struct rxrpc_call *call,
-                                  struct sk_buff *skb, u32 seq)
+static void rxrpc_send_ping(struct rxrpc_call *call, struct sk_buff *skb,
+                           int skew)
 {
-       struct rxrpc_skb_priv *sp;
-       bool terminal;
-       int ret, ackbit, ack;
-       u32 serial;
-       u8 flags;
+       struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
+       ktime_t now = skb->tstamp;
 
-       _enter("{%u,%u},,{%u}", call->rx_data_post, call->rx_first_oos, seq);
+       if (call->peer->rtt_usage < 3 ||
+           ktime_before(ktime_add_ms(call->peer->rtt_last_req, 1000), now))
+               rxrpc_propose_ACK(call, RXRPC_ACK_PING, skew, sp->hdr.serial,
+                                 true, true,
+                                 rxrpc_propose_ack_ping_for_params);
+}
 
-       sp = rxrpc_skb(skb);
-       ASSERTCMP(sp->call, ==, NULL);
-       flags = sp->hdr.flags;
-       serial = sp->hdr.serial;
+/*
+ * Apply a hard ACK by advancing the Tx window.
+ */
+static void rxrpc_rotate_tx_window(struct rxrpc_call *call, rxrpc_seq_t to,
+                                  struct rxrpc_ack_summary *summary)
+{
+       struct sk_buff *skb, *list = NULL;
+       int ix;
+       u8 annotation;
+
+       if (call->acks_lowest_nak == call->tx_hard_ack) {
+               call->acks_lowest_nak = to;
+       } else if (before_eq(call->acks_lowest_nak, to)) {
+               summary->new_low_nack = true;
+               call->acks_lowest_nak = to;
+       }
 
        spin_lock(&call->lock);
 
-       if (call->state > RXRPC_CALL_COMPLETE)
-               goto discard;
+       while (before(call->tx_hard_ack, to)) {
+               call->tx_hard_ack++;
+               ix = call->tx_hard_ack & RXRPC_RXTX_BUFF_MASK;
+               skb = call->rxtx_buffer[ix];
+               annotation = call->rxtx_annotations[ix];
+               rxrpc_see_skb(skb, rxrpc_skb_tx_rotated);
+               call->rxtx_buffer[ix] = NULL;
+               call->rxtx_annotations[ix] = 0;
+               skb->next = list;
+               list = skb;
+
+               if (annotation & RXRPC_TX_ANNO_LAST)
+                       set_bit(RXRPC_CALL_TX_LAST, &call->flags);
+               if ((annotation & RXRPC_TX_ANNO_MASK) != RXRPC_TX_ANNO_ACK)
+                       summary->nr_rot_new_acks++;
+       }
 
-       ASSERTCMP(call->rx_data_expect, >=, call->rx_data_post);
-       ASSERTCMP(call->rx_data_post, >=, call->rx_data_recv);
-       ASSERTCMP(call->rx_data_recv, >=, call->rx_data_eaten);
+       spin_unlock(&call->lock);
 
-       if (seq < call->rx_data_post) {
-               _debug("dup #%u [-%u]", seq, call->rx_data_post);
-               ack = RXRPC_ACK_DUPLICATE;
-               ret = -ENOBUFS;
-               goto discard_and_ack;
-       }
+       trace_rxrpc_transmit(call, (test_bit(RXRPC_CALL_TX_LAST, &call->flags) ?
+                                   rxrpc_transmit_rotate_last :
+                                   rxrpc_transmit_rotate));
+       wake_up(&call->waitq);
 
-       /* we may already have the packet in the out of sequence queue */
-       ackbit = seq - (call->rx_data_eaten + 1);
-       ASSERTCMP(ackbit, >=, 0);
-       if (__test_and_set_bit(ackbit, call->ackr_window)) {
-               _debug("dup oos #%u [%u,%u]",
-                      seq, call->rx_data_eaten, call->rx_data_post);
-               ack = RXRPC_ACK_DUPLICATE;
-               goto discard_and_ack;
+       while (list) {
+               skb = list;
+               list = skb->next;
+               skb->next = NULL;
+               rxrpc_free_skb(skb, rxrpc_skb_tx_freed);
        }
+}
 
-       if (seq >= call->ackr_win_top) {
-               _debug("exceed #%u [%u]", seq, call->ackr_win_top);
-               __clear_bit(ackbit, call->ackr_window);
-               ack = RXRPC_ACK_EXCEEDS_WINDOW;
-               goto discard_and_ack;
-       }
+/*
+ * End the transmission phase of a call.
+ *
+ * This occurs when we get an ACKALL packet, the first DATA packet of a reply,
+ * or a final ACK packet.
+ */
+static bool rxrpc_end_tx_phase(struct rxrpc_call *call, bool reply_begun,
+                              const char *abort_why)
+{
 
-       if (seq == call->rx_data_expect) {
-               clear_bit(RXRPC_CALL_EXPECT_OOS, &call->flags);
-               call->rx_data_expect++;
-       } else if (seq > call->rx_data_expect) {
-               _debug("oos #%u [%u]", seq, call->rx_data_expect);
-               call->rx_data_expect = seq + 1;
-               if (test_and_set_bit(RXRPC_CALL_EXPECT_OOS, &call->flags)) {
-                       ack = RXRPC_ACK_OUT_OF_SEQUENCE;
-                       goto enqueue_and_ack;
-               }
-               goto enqueue_packet;
-       }
+       ASSERT(test_bit(RXRPC_CALL_TX_LAST, &call->flags));
 
-       if (seq != call->rx_data_post) {
-               _debug("ahead #%u [%u]", seq, call->rx_data_post);
-               goto enqueue_packet;
-       }
+       write_lock(&call->state_lock);
 
-       if (test_bit(RXRPC_CALL_RCVD_LAST, &call->flags))
-               goto protocol_error;
+       switch (call->state) {
+       case RXRPC_CALL_CLIENT_SEND_REQUEST:
+       case RXRPC_CALL_CLIENT_AWAIT_REPLY:
+               if (reply_begun)
+                       call->state = RXRPC_CALL_CLIENT_RECV_REPLY;
+               else
+                       call->state = RXRPC_CALL_CLIENT_AWAIT_REPLY;
+               break;
 
-       /* if the packet need security things doing to it, then it goes down
-        * the slow path */
-       if (call->conn->security_ix)
-               goto enqueue_packet;
+       case RXRPC_CALL_SERVER_AWAIT_ACK:
+               __rxrpc_call_completed(call);
+               rxrpc_notify_socket(call);
+               break;
 
-       sp->call = call;
-       rxrpc_get_call(call);
-       atomic_inc(&call->skb_count);
-       terminal = ((flags & RXRPC_LAST_PACKET) &&
-                   !(flags & RXRPC_CLIENT_INITIATED));
-       ret = rxrpc_queue_rcv_skb(call, skb, false, terminal);
-       if (ret < 0) {
-               if (ret == -ENOMEM || ret == -ENOBUFS) {
-                       __clear_bit(ackbit, call->ackr_window);
-                       ack = RXRPC_ACK_NOSPACE;
-                       goto discard_and_ack;
-               }
-               goto out;
+       default:
+               goto bad_state;
        }
 
-       skb = NULL;
-       sp = NULL;
-
-       _debug("post #%u", seq);
-       ASSERTCMP(call->rx_data_post, ==, seq);
-       call->rx_data_post++;
+       write_unlock(&call->state_lock);
+       if (call->state == RXRPC_CALL_CLIENT_AWAIT_REPLY) {
+               rxrpc_propose_ACK(call, RXRPC_ACK_IDLE, 0, 0, false, true,
+                                 rxrpc_propose_ack_client_tx_end);
+               trace_rxrpc_transmit(call, rxrpc_transmit_await_reply);
+       } else {
+               trace_rxrpc_transmit(call, rxrpc_transmit_end);
+       }
+       _leave(" = ok");
+       return true;
+
+bad_state:
+       write_unlock(&call->state_lock);
+       kdebug("end_tx %s", rxrpc_call_states[call->state]);
+       rxrpc_proto_abort(abort_why, call, call->tx_top);
+       return false;
+}
 
-       if (flags & RXRPC_LAST_PACKET)
-               set_bit(RXRPC_CALL_RCVD_LAST, &call->flags);
+/*
+ * Begin the reply reception phase of a call.
+ */
+static bool rxrpc_receiving_reply(struct rxrpc_call *call)
+{
+       struct rxrpc_ack_summary summary = { 0 };
+       rxrpc_seq_t top = READ_ONCE(call->tx_top);
+
+       if (call->ackr_reason) {
+               spin_lock_bh(&call->lock);
+               call->ackr_reason = 0;
+               call->resend_at = call->expire_at;
+               call->ack_at = call->expire_at;
+               spin_unlock_bh(&call->lock);
+               rxrpc_set_timer(call, rxrpc_timer_init_for_reply,
+                               ktime_get_real());
+       }
 
-       /* if we've reached an out of sequence packet then we need to drain
-        * that queue into the socket Rx queue now */
-       if (call->rx_data_post == call->rx_first_oos) {
-               _debug("drain rx oos now");
-               read_lock(&call->state_lock);
-               if (call->state < RXRPC_CALL_COMPLETE &&
-                   !test_and_set_bit(RXRPC_CALL_EV_DRAIN_RX_OOS, &call->events))
-                       rxrpc_queue_call(call);
-               read_unlock(&call->state_lock);
+       if (!test_bit(RXRPC_CALL_TX_LAST, &call->flags))
+               rxrpc_rotate_tx_window(call, top, &summary);
+       if (!test_bit(RXRPC_CALL_TX_LAST, &call->flags)) {
+               rxrpc_proto_abort("TXL", call, top);
+               return false;
        }
+       if (!rxrpc_end_tx_phase(call, true, "ETD"))
+               return false;
+       call->tx_phase = false;
+       return true;
+}
 
-       spin_unlock(&call->lock);
-       atomic_inc(&call->ackr_not_idle);
-       rxrpc_propose_ACK(call, RXRPC_ACK_DELAY, serial, false);
-       _leave(" = 0 [posted]");
-       return 0;
+/*
+ * Scan a jumbo packet to validate its structure and to work out how many
+ * subpackets it contains.
+ *
+ * A jumbo packet is a collection of consecutive packets glued together with
+ * little headers between that indicate how to change the initial header for
+ * each subpacket.
+ *
+ * RXRPC_JUMBO_PACKET must be set on all but the last subpacket - and all but
+ * the last are RXRPC_JUMBO_DATALEN in size.  The last subpacket may be of any
+ * size.
+ */
+static bool rxrpc_validate_jumbo(struct sk_buff *skb)
+{
+       struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
+       unsigned int offset = sizeof(struct rxrpc_wire_header);
+       unsigned int len = skb->len;
+       int nr_jumbo = 1;
+       u8 flags = sp->hdr.flags;
 
-protocol_error:
-       ret = -EBADMSG;
-out:
-       spin_unlock(&call->lock);
-       _leave(" = %d", ret);
-       return ret;
+       do {
+               nr_jumbo++;
+               if (len - offset < RXRPC_JUMBO_SUBPKTLEN)
+                       goto protocol_error;
+               if (flags & RXRPC_LAST_PACKET)
+                       goto protocol_error;
+               offset += RXRPC_JUMBO_DATALEN;
+               if (skb_copy_bits(skb, offset, &flags, 1) < 0)
+                       goto protocol_error;
+               offset += sizeof(struct rxrpc_jumbo_header);
+       } while (flags & RXRPC_JUMBO_PACKET);
 
-discard_and_ack:
-       _debug("discard and ACK packet %p", skb);
-       __rxrpc_propose_ACK(call, ack, serial, true);
-discard:
-       spin_unlock(&call->lock);
-       rxrpc_free_skb(skb);
-       _leave(" = 0 [discarded]");
-       return 0;
+       sp->nr_jumbo = nr_jumbo;
+       return true;
 
-enqueue_and_ack:
-       __rxrpc_propose_ACK(call, ack, serial, true);
-enqueue_packet:
-       _net("defer skb %p", skb);
-       spin_unlock(&call->lock);
-       skb_queue_tail(&call->rx_queue, skb);
-       atomic_inc(&call->ackr_not_idle);
-       read_lock(&call->state_lock);
-       if (call->state < RXRPC_CALL_DEAD)
-               rxrpc_queue_call(call);
-       read_unlock(&call->state_lock);
-       _leave(" = 0 [queued]");
-       return 0;
+protocol_error:
+       return false;
 }
 
 /*
- * assume an implicit ACKALL of the transmission phase of a client socket upon
- * reception of the first reply packet
+ * Handle reception of a duplicate packet.
+ *
+ * We have to take care to avoid an attack here whereby we're given a series of
+ * jumbograms, each with a sequence number one before the preceding one and
+ * filled up to maximum UDP size.  If they never send us the first packet in
+ * the sequence, they can cause us to have to hold on to around 2MiB of kernel
+ * space until the call times out.
+ *
+ * We limit the space usage by only accepting three duplicate jumbo packets per
+ * call.  After that, we tell the other side we're no longer accepting jumbos
+ * (that information is encoded in the ACK packet).
  */
-static void rxrpc_assume_implicit_ackall(struct rxrpc_call *call, u32 serial)
+static void rxrpc_input_dup_data(struct rxrpc_call *call, rxrpc_seq_t seq,
+                                u8 annotation, bool *_jumbo_bad)
 {
-       write_lock_bh(&call->state_lock);
-
-       switch (call->state) {
-       case RXRPC_CALL_CLIENT_AWAIT_REPLY:
-               call->state = RXRPC_CALL_CLIENT_RECV_REPLY;
-               call->acks_latest = serial;
-
-               _debug("implicit ACKALL %%%u", call->acks_latest);
-               set_bit(RXRPC_CALL_EV_RCVD_ACKALL, &call->events);
-               write_unlock_bh(&call->state_lock);
-
-               if (try_to_del_timer_sync(&call->resend_timer) >= 0) {
-                       clear_bit(RXRPC_CALL_EV_RESEND_TIMER, &call->events);
-                       clear_bit(RXRPC_CALL_EV_RESEND, &call->events);
-                       clear_bit(RXRPC_CALL_RUN_RTIMER, &call->flags);
-               }
-               break;
+       /* Discard normal packets that are duplicates. */
+       if (annotation == 0)
+               return;
 
-       default:
-               write_unlock_bh(&call->state_lock);
-               break;
+       /* Skip jumbo subpackets that are duplicates.  When we've had three or
+        * more partially duplicate jumbo packets, we refuse to take any more
+        * jumbos for this call.
+        */
+       if (!*_jumbo_bad) {
+               call->nr_jumbo_bad++;
+               *_jumbo_bad = true;
        }
 }
 
 /*
- * post an incoming packet to the nominated call to deal with
- * - must get rid of the sk_buff, either by freeing it or by queuing it
+ * Process a DATA packet, adding the packet to the Rx ring.
  */
-void rxrpc_fast_process_packet(struct rxrpc_call *call, struct sk_buff *skb)
+static void rxrpc_input_data(struct rxrpc_call *call, struct sk_buff *skb,
+                            u16 skew)
 {
        struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
-       __be32 wtmp;
-       u32 hi_serial, abort_code;
+       unsigned int offset = sizeof(struct rxrpc_wire_header);
+       unsigned int ix;
+       rxrpc_serial_t serial = sp->hdr.serial, ack_serial = 0;
+       rxrpc_seq_t seq = sp->hdr.seq, hard_ack;
+       bool immediate_ack = false, jumbo_bad = false, queued;
+       u16 len;
+       u8 ack = 0, flags, annotation = 0;
 
-       _enter("%p,%p", call, skb);
+       _enter("{%u,%u},{%u,%u}",
+              call->rx_hard_ack, call->rx_top, skb->len, seq);
 
-       ASSERT(!irqs_disabled());
+       _proto("Rx DATA %%%u { #%u f=%02x }",
+              sp->hdr.serial, seq, sp->hdr.flags);
+
+       if (call->state >= RXRPC_CALL_COMPLETE)
+               return;
+
+       /* Received data implicitly ACKs all of the request packets we sent
+        * when we're acting as a client.
+        */
+       if ((call->state == RXRPC_CALL_CLIENT_SEND_REQUEST ||
+            call->state == RXRPC_CALL_CLIENT_AWAIT_REPLY) &&
+           !rxrpc_receiving_reply(call))
+               return;
+
+       call->ackr_prev_seq = seq;
 
-#if 0 // INJECT RX ERROR
-       if (sp->hdr.type == RXRPC_PACKET_TYPE_DATA) {
-               static int skip = 0;
-               if (++skip == 3) {
-                       printk("DROPPED 3RD PACKET!!!!!!!!!!!!!\n");
-                       skip = 0;
-                       goto free_packet;
+       hard_ack = READ_ONCE(call->rx_hard_ack);
+       if (after(seq, hard_ack + call->rx_winsize)) {
+               ack = RXRPC_ACK_EXCEEDS_WINDOW;
+               ack_serial = serial;
+               goto ack;
+       }
+
+       flags = sp->hdr.flags;
+       if (flags & RXRPC_JUMBO_PACKET) {
+               if (call->nr_jumbo_bad > 3) {
+                       ack = RXRPC_ACK_NOSPACE;
+                       ack_serial = serial;
+                       goto ack;
                }
+               annotation = 1;
        }
-#endif
 
-       /* track the latest serial number on this connection for ACK packet
-        * information */
-       hi_serial = atomic_read(&call->conn->hi_serial);
-       while (sp->hdr.serial > hi_serial)
-               hi_serial = atomic_cmpxchg(&call->conn->hi_serial, hi_serial,
-                                          sp->hdr.serial);
+next_subpacket:
+       queued = false;
+       ix = seq & RXRPC_RXTX_BUFF_MASK;
+       len = skb->len;
+       if (flags & RXRPC_JUMBO_PACKET)
+               len = RXRPC_JUMBO_DATALEN;
+
+       if (flags & RXRPC_LAST_PACKET) {
+               if (test_bit(RXRPC_CALL_RX_LAST, &call->flags) &&
+                   seq != call->rx_top)
+                       return rxrpc_proto_abort("LSN", call, seq);
+       } else {
+               if (test_bit(RXRPC_CALL_RX_LAST, &call->flags) &&
+                   after_eq(seq, call->rx_top))
+                       return rxrpc_proto_abort("LSA", call, seq);
+       }
 
-       /* request ACK generation for any ACK or DATA packet that requests
-        * it */
-       if (sp->hdr.flags & RXRPC_REQUEST_ACK) {
-               _proto("ACK Requested on %%%u", sp->hdr.serial);
-               rxrpc_propose_ACK(call, RXRPC_ACK_REQUESTED, sp->hdr.serial, false);
+       if (before_eq(seq, hard_ack)) {
+               ack = RXRPC_ACK_DUPLICATE;
+               ack_serial = serial;
+               goto skip;
        }
 
-       switch (sp->hdr.type) {
-       case RXRPC_PACKET_TYPE_ABORT:
-               _debug("abort");
+       if (flags & RXRPC_REQUEST_ACK && !ack) {
+               ack = RXRPC_ACK_REQUESTED;
+               ack_serial = serial;
+       }
 
-               if (skb_copy_bits(skb, 0, &wtmp, sizeof(wtmp)) < 0)
-                       goto protocol_error;
+       if (call->rxtx_buffer[ix]) {
+               rxrpc_input_dup_data(call, seq, annotation, &jumbo_bad);
+               if (ack != RXRPC_ACK_DUPLICATE) {
+                       ack = RXRPC_ACK_DUPLICATE;
+                       ack_serial = serial;
+               }
+               immediate_ack = true;
+               goto skip;
+       }
 
-               abort_code = ntohl(wtmp);
-               _proto("Rx ABORT %%%u { %x }", sp->hdr.serial, abort_code);
+       /* Queue the packet.  We use a couple of memory barriers here as need
+        * to make sure that rx_top is perceived to be set after the buffer
+        * pointer and that the buffer pointer is set after the annotation and
+        * the skb data.
+        *
+        * Barriers against rxrpc_recvmsg_data() and rxrpc_rotate_rx_window()
+        * and also rxrpc_fill_out_ack().
+        */
+       rxrpc_get_skb(skb, rxrpc_skb_rx_got);
+       call->rxtx_annotations[ix] = annotation;
+       smp_wmb();
+       call->rxtx_buffer[ix] = skb;
+       if (after(seq, call->rx_top)) {
+               smp_store_release(&call->rx_top, seq);
+       } else if (before(seq, call->rx_top)) {
+               /* Send an immediate ACK if we fill in a hole */
+               if (!ack) {
+                       ack = RXRPC_ACK_DELAY;
+                       ack_serial = serial;
+               }
+               immediate_ack = true;
+       }
+       if (flags & RXRPC_LAST_PACKET) {
+               set_bit(RXRPC_CALL_RX_LAST, &call->flags);
+               trace_rxrpc_receive(call, rxrpc_receive_queue_last, serial, seq);
+       } else {
+               trace_rxrpc_receive(call, rxrpc_receive_queue, serial, seq);
+       }
+       queued = true;
 
-               write_lock_bh(&call->state_lock);
-               if (call->state < RXRPC_CALL_COMPLETE) {
-                       call->state = RXRPC_CALL_REMOTELY_ABORTED;
-                       call->remote_abort = abort_code;
-                       set_bit(RXRPC_CALL_EV_RCVD_ABORT, &call->events);
-                       rxrpc_queue_call(call);
+       if (after_eq(seq, call->rx_expect_next)) {
+               if (after(seq, call->rx_expect_next)) {
+                       _net("OOS %u > %u", seq, call->rx_expect_next);
+                       ack = RXRPC_ACK_OUT_OF_SEQUENCE;
+                       ack_serial = serial;
                }
-               goto free_packet_unlock;
+               call->rx_expect_next = seq + 1;
+       }
 
-       case RXRPC_PACKET_TYPE_BUSY:
-               _proto("Rx BUSY %%%u", sp->hdr.serial);
+skip:
+       offset += len;
+       if (flags & RXRPC_JUMBO_PACKET) {
+               if (skb_copy_bits(skb, offset, &flags, 1) < 0)
+                       return rxrpc_proto_abort("XJF", call, seq);
+               offset += sizeof(struct rxrpc_jumbo_header);
+               seq++;
+               serial++;
+               annotation++;
+               if (flags & RXRPC_JUMBO_PACKET)
+                       annotation |= RXRPC_RX_ANNO_JLAST;
+               if (after(seq, hard_ack + call->rx_winsize)) {
+                       ack = RXRPC_ACK_EXCEEDS_WINDOW;
+                       ack_serial = serial;
+                       if (!jumbo_bad) {
+                               call->nr_jumbo_bad++;
+                               jumbo_bad = true;
+                       }
+                       goto ack;
+               }
 
-               if (rxrpc_conn_is_service(call->conn))
-                       goto protocol_error;
+               _proto("Rx DATA Jumbo %%%u", serial);
+               goto next_subpacket;
+       }
 
-               write_lock_bh(&call->state_lock);
-               switch (call->state) {
-               case RXRPC_CALL_CLIENT_SEND_REQUEST:
-                       call->state = RXRPC_CALL_SERVER_BUSY;
-                       set_bit(RXRPC_CALL_EV_RCVD_BUSY, &call->events);
-                       rxrpc_queue_call(call);
-               case RXRPC_CALL_SERVER_BUSY:
-                       goto free_packet_unlock;
-               default:
-                       goto protocol_error_locked;
-               }
+       if (queued && flags & RXRPC_LAST_PACKET && !ack) {
+               ack = RXRPC_ACK_DELAY;
+               ack_serial = serial;
+       }
 
-       default:
-               _proto("Rx %s %%%u", rxrpc_pkts[sp->hdr.type], sp->hdr.serial);
-               goto protocol_error;
+ack:
+       if (ack)
+               rxrpc_propose_ACK(call, ack, skew, ack_serial,
+                                 immediate_ack, true,
+                                 rxrpc_propose_ack_input_data);
 
-       case RXRPC_PACKET_TYPE_DATA:
-               _proto("Rx DATA %%%u { #%u }", sp->hdr.serial, sp->hdr.seq);
+       if (sp->hdr.seq == READ_ONCE(call->rx_hard_ack) + 1)
+               rxrpc_notify_socket(call);
+       _leave(" [queued]");
+}
 
-               if (sp->hdr.seq == 0)
-                       goto protocol_error;
+/*
+ * Process a requested ACK.
+ */
+static void rxrpc_input_requested_ack(struct rxrpc_call *call,
+                                     ktime_t resp_time,
+                                     rxrpc_serial_t orig_serial,
+                                     rxrpc_serial_t ack_serial)
+{
+       struct rxrpc_skb_priv *sp;
+       struct sk_buff *skb;
+       ktime_t sent_at;
+       int ix;
+
+       for (ix = 0; ix < RXRPC_RXTX_BUFF_SIZE; ix++) {
+               skb = call->rxtx_buffer[ix];
+               if (!skb)
+                       continue;
+
+               sp = rxrpc_skb(skb);
+               if (sp->hdr.serial != orig_serial)
+                       continue;
+               smp_rmb();
+               sent_at = skb->tstamp;
+               goto found;
+       }
+       return;
 
-               call->ackr_prev_seq = sp->hdr.seq;
+found:
+       rxrpc_peer_add_rtt(call, rxrpc_rtt_rx_requested_ack,
+                          orig_serial, ack_serial, sent_at, resp_time);
+}
 
-               /* received data implicitly ACKs all of the request packets we
-                * sent when we're acting as a client */
-               if (call->state == RXRPC_CALL_CLIENT_AWAIT_REPLY)
-                       rxrpc_assume_implicit_ackall(call, sp->hdr.serial);
+/*
+ * Process a ping response.
+ */
+static void rxrpc_input_ping_response(struct rxrpc_call *call,
+                                     ktime_t resp_time,
+                                     rxrpc_serial_t orig_serial,
+                                     rxrpc_serial_t ack_serial)
+{
+       rxrpc_serial_t ping_serial;
+       ktime_t ping_time;
 
-               switch (rxrpc_fast_process_data(call, skb, sp->hdr.seq)) {
-               case 0:
-                       skb = NULL;
-                       goto done;
+       ping_time = call->ping_time;
+       smp_rmb();
+       ping_serial = call->ping_serial;
 
-               default:
-                       BUG();
+       if (!test_bit(RXRPC_CALL_PINGING, &call->flags) ||
+           before(orig_serial, ping_serial))
+               return;
+       clear_bit(RXRPC_CALL_PINGING, &call->flags);
+       if (after(orig_serial, ping_serial))
+               return;
 
-                       /* data packet received beyond the last packet */
-               case -EBADMSG:
-                       goto protocol_error;
-               }
+       rxrpc_peer_add_rtt(call, rxrpc_rtt_rx_ping_response,
+                          orig_serial, ack_serial, ping_time, resp_time);
+}
 
-       case RXRPC_PACKET_TYPE_ACKALL:
-       case RXRPC_PACKET_TYPE_ACK:
-               /* ACK processing is done in process context */
-               read_lock_bh(&call->state_lock);
-               if (call->state < RXRPC_CALL_DEAD) {
-                       skb_queue_tail(&call->rx_queue, skb);
-                       rxrpc_queue_call(call);
-                       skb = NULL;
-               }
-               read_unlock_bh(&call->state_lock);
-               goto free_packet;
+/*
+ * Process the extra information that may be appended to an ACK packet
+ */
+static void rxrpc_input_ackinfo(struct rxrpc_call *call, struct sk_buff *skb,
+                               struct rxrpc_ackinfo *ackinfo)
+{
+       struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
+       struct rxrpc_peer *peer;
+       unsigned int mtu;
+       u32 rwind = ntohl(ackinfo->rwind);
+
+       _proto("Rx ACK %%%u Info { rx=%u max=%u rwin=%u jm=%u }",
+              sp->hdr.serial,
+              ntohl(ackinfo->rxMTU), ntohl(ackinfo->maxMTU),
+              rwind, ntohl(ackinfo->jumbo_max));
+
+       if (rwind > RXRPC_RXTX_BUFF_SIZE - 1)
+               rwind = RXRPC_RXTX_BUFF_SIZE - 1;
+       call->tx_winsize = rwind;
+       if (call->cong_ssthresh > rwind)
+               call->cong_ssthresh = rwind;
+
+       mtu = min(ntohl(ackinfo->rxMTU), ntohl(ackinfo->maxMTU));
+
+       peer = call->peer;
+       if (mtu < peer->maxdata) {
+               spin_lock_bh(&peer->lock);
+               peer->maxdata = mtu;
+               peer->mtu = mtu + peer->hdrsize;
+               spin_unlock_bh(&peer->lock);
+               _net("Net MTU %u (maxdata %u)", peer->mtu, peer->maxdata);
        }
+}
 
-protocol_error:
-       _debug("protocol error");
-       write_lock_bh(&call->state_lock);
-protocol_error_locked:
-       if (call->state <= RXRPC_CALL_COMPLETE) {
-               call->state = RXRPC_CALL_LOCALLY_ABORTED;
-               call->local_abort = RX_PROTOCOL_ERROR;
-               set_bit(RXRPC_CALL_EV_ABORT, &call->events);
-               rxrpc_queue_call(call);
+/*
+ * Process individual soft ACKs.
+ *
+ * Each ACK in the array corresponds to one packet and can be either an ACK or
+ * a NAK.  If we get find an explicitly NAK'd packet we resend immediately;
+ * packets that lie beyond the end of the ACK list are scheduled for resend by
+ * the timer on the basis that the peer might just not have processed them at
+ * the time the ACK was sent.
+ */
+static void rxrpc_input_soft_acks(struct rxrpc_call *call, u8 *acks,
+                                 rxrpc_seq_t seq, int nr_acks,
+                                 struct rxrpc_ack_summary *summary)
+{
+       int ix;
+       u8 annotation, anno_type;
+
+       for (; nr_acks > 0; nr_acks--, seq++) {
+               ix = seq & RXRPC_RXTX_BUFF_MASK;
+               annotation = call->rxtx_annotations[ix];
+               anno_type = annotation & RXRPC_TX_ANNO_MASK;
+               annotation &= ~RXRPC_TX_ANNO_MASK;
+               switch (*acks++) {
+               case RXRPC_ACK_TYPE_ACK:
+                       summary->nr_acks++;
+                       if (anno_type == RXRPC_TX_ANNO_ACK)
+                               continue;
+                       summary->nr_new_acks++;
+                       call->rxtx_annotations[ix] =
+                               RXRPC_TX_ANNO_ACK | annotation;
+                       break;
+               case RXRPC_ACK_TYPE_NACK:
+                       if (!summary->nr_nacks &&
+                           call->acks_lowest_nak != seq) {
+                               call->acks_lowest_nak = seq;
+                               summary->new_low_nack = true;
+                       }
+                       summary->nr_nacks++;
+                       if (anno_type == RXRPC_TX_ANNO_NAK)
+                               continue;
+                       summary->nr_new_nacks++;
+                       if (anno_type == RXRPC_TX_ANNO_RETRANS)
+                               continue;
+                       call->rxtx_annotations[ix] =
+                               RXRPC_TX_ANNO_NAK | annotation;
+                       break;
+               default:
+                       return rxrpc_proto_abort("SFT", call, 0);
+               }
        }
-free_packet_unlock:
-       write_unlock_bh(&call->state_lock);
-free_packet:
-       rxrpc_free_skb(skb);
-done:
-       _leave("");
 }
 
 /*
- * split up a jumbo data packet
+ * Process an ACK packet.
+ *
+ * ack.firstPacket is the sequence number of the first soft-ACK'd/NAK'd packet
+ * in the ACK array.  Anything before that is hard-ACK'd and may be discarded.
+ *
+ * A hard-ACK means that a packet has been processed and may be discarded; a
+ * soft-ACK means that the packet may be discarded and retransmission
+ * requested.  A phase is complete when all packets are hard-ACK'd.
  */
-static void rxrpc_process_jumbo_packet(struct rxrpc_call *call,
-                                      struct sk_buff *jumbo)
+static void rxrpc_input_ack(struct rxrpc_call *call, struct sk_buff *skb,
+                           u16 skew)
 {
-       struct rxrpc_jumbo_header jhdr;
-       struct rxrpc_skb_priv *sp;
-       struct sk_buff *part;
+       struct rxrpc_ack_summary summary = { 0 };
+       struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
+       union {
+               struct rxrpc_ackpacket ack;
+               struct rxrpc_ackinfo info;
+               u8 acks[RXRPC_MAXACKS];
+       } buf;
+       rxrpc_serial_t acked_serial;
+       rxrpc_seq_t first_soft_ack, hard_ack;
+       int nr_acks, offset, ioffset;
+
+       _enter("");
+
+       offset = sizeof(struct rxrpc_wire_header);
+       if (skb_copy_bits(skb, offset, &buf.ack, sizeof(buf.ack)) < 0) {
+               _debug("extraction failure");
+               return rxrpc_proto_abort("XAK", call, 0);
+       }
+       offset += sizeof(buf.ack);
+
+       acked_serial = ntohl(buf.ack.serial);
+       first_soft_ack = ntohl(buf.ack.firstPacket);
+       hard_ack = first_soft_ack - 1;
+       nr_acks = buf.ack.nAcks;
+       summary.ack_reason = (buf.ack.reason < RXRPC_ACK__INVALID ?
+                             buf.ack.reason : RXRPC_ACK__INVALID);
+
+       trace_rxrpc_rx_ack(call, first_soft_ack, summary.ack_reason, nr_acks);
+
+       _proto("Rx ACK %%%u { m=%hu f=#%u p=#%u s=%%%u r=%s n=%u }",
+              sp->hdr.serial,
+              ntohs(buf.ack.maxSkew),
+              first_soft_ack,
+              ntohl(buf.ack.previousPacket),
+              acked_serial,
+              rxrpc_ack_names[summary.ack_reason],
+              buf.ack.nAcks);
+
+       if (buf.ack.reason == RXRPC_ACK_PING_RESPONSE)
+               rxrpc_input_ping_response(call, skb->tstamp, acked_serial,
+                                         sp->hdr.serial);
+       if (buf.ack.reason == RXRPC_ACK_REQUESTED)
+               rxrpc_input_requested_ack(call, skb->tstamp, acked_serial,
+                                         sp->hdr.serial);
+
+       if (buf.ack.reason == RXRPC_ACK_PING) {
+               _proto("Rx ACK %%%u PING Request", sp->hdr.serial);
+               rxrpc_propose_ACK(call, RXRPC_ACK_PING_RESPONSE,
+                                 skew, sp->hdr.serial, true, true,
+                                 rxrpc_propose_ack_respond_to_ping);
+       } else if (sp->hdr.flags & RXRPC_REQUEST_ACK) {
+               rxrpc_propose_ACK(call, RXRPC_ACK_REQUESTED,
+                                 skew, sp->hdr.serial, true, true,
+                                 rxrpc_propose_ack_respond_to_ack);
+       }
 
-       _enter(",{%u,%u}", jumbo->data_len, jumbo->len);
+       ioffset = offset + nr_acks + 3;
+       if (skb->len >= ioffset + sizeof(buf.info)) {
+               if (skb_copy_bits(skb, ioffset, &buf.info, sizeof(buf.info)) < 0)
+                       return rxrpc_proto_abort("XAI", call, 0);
+               rxrpc_input_ackinfo(call, skb, &buf.info);
+       }
 
-       sp = rxrpc_skb(jumbo);
+       if (first_soft_ack == 0)
+               return rxrpc_proto_abort("AK0", call, 0);
 
-       do {
-               sp->hdr.flags &= ~RXRPC_JUMBO_PACKET;
-
-               /* make a clone to represent the first subpacket in what's left
-                * of the jumbo packet */
-               part = skb_clone(jumbo, GFP_ATOMIC);
-               if (!part) {
-                       /* simply ditch the tail in the event of ENOMEM */
-                       pskb_trim(jumbo, RXRPC_JUMBO_DATALEN);
-                       break;
-               }
-               rxrpc_new_skb(part);
+       /* Ignore ACKs unless we are or have just been transmitting. */
+       switch (call->state) {
+       case RXRPC_CALL_CLIENT_SEND_REQUEST:
+       case RXRPC_CALL_CLIENT_AWAIT_REPLY:
+       case RXRPC_CALL_SERVER_SEND_REPLY:
+       case RXRPC_CALL_SERVER_AWAIT_ACK:
+               break;
+       default:
+               return;
+       }
 
-               pskb_trim(part, RXRPC_JUMBO_DATALEN);
+       /* Discard any out-of-order or duplicate ACKs. */
+       if (before_eq(sp->hdr.serial, call->acks_latest)) {
+               _debug("discard ACK %d <= %d",
+                      sp->hdr.serial, call->acks_latest);
+               return;
+       }
+       call->acks_latest_ts = skb->tstamp;
+       call->acks_latest = sp->hdr.serial;
+
+       if (before(hard_ack, call->tx_hard_ack) ||
+           after(hard_ack, call->tx_top))
+               return rxrpc_proto_abort("AKW", call, 0);
+       if (nr_acks > call->tx_top - hard_ack)
+               return rxrpc_proto_abort("AKN", call, 0);
+
+       if (after(hard_ack, call->tx_hard_ack))
+               rxrpc_rotate_tx_window(call, hard_ack, &summary);
+
+       if (nr_acks > 0) {
+               if (skb_copy_bits(skb, offset, buf.acks, nr_acks) < 0)
+                       return rxrpc_proto_abort("XSA", call, 0);
+               rxrpc_input_soft_acks(call, buf.acks, first_soft_ack, nr_acks,
+                                     &summary);
+       }
 
-               if (!pskb_pull(jumbo, RXRPC_JUMBO_DATALEN))
-                       goto protocol_error;
+       if (test_bit(RXRPC_CALL_TX_LAST, &call->flags)) {
+               rxrpc_end_tx_phase(call, false, "ETA");
+               return;
+       }
 
-               if (skb_copy_bits(jumbo, 0, &jhdr, sizeof(jhdr)) < 0)
-                       goto protocol_error;
-               if (!pskb_pull(jumbo, sizeof(jhdr)))
-                       BUG();
+       if (call->rxtx_annotations[call->tx_top & RXRPC_RXTX_BUFF_MASK] &
+           RXRPC_TX_ANNO_LAST &&
+           summary.nr_acks == call->tx_top - hard_ack &&
+           rxrpc_is_client_call(call))
+               rxrpc_propose_ACK(call, RXRPC_ACK_PING, skew, sp->hdr.serial,
+                                 false, true,
+                                 rxrpc_propose_ack_ping_for_lost_reply);
 
-               sp->hdr.seq     += 1;
-               sp->hdr.serial  += 1;
-               sp->hdr.flags   = jhdr.flags;
-               sp->hdr._rsvd   = ntohs(jhdr._rsvd);
+       return rxrpc_congestion_management(call, skb, &summary, acked_serial);
+}
 
-               _proto("Rx DATA Jumbo %%%u", sp->hdr.serial - 1);
+/*
+ * Process an ACKALL packet.
+ */
+static void rxrpc_input_ackall(struct rxrpc_call *call, struct sk_buff *skb)
+{
+       struct rxrpc_ack_summary summary = { 0 };
+       struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
 
-               rxrpc_fast_process_packet(call, part);
-               part = NULL;
+       _proto("Rx ACKALL %%%u", sp->hdr.serial);
 
-       } while (sp->hdr.flags & RXRPC_JUMBO_PACKET);
+       rxrpc_rotate_tx_window(call, call->tx_top, &summary);
+       if (test_bit(RXRPC_CALL_TX_LAST, &call->flags))
+               rxrpc_end_tx_phase(call, false, "ETL");
+}
 
-       rxrpc_fast_process_packet(call, jumbo);
-       _leave("");
-       return;
+/*
+ * Process an ABORT packet.
+ */
+static void rxrpc_input_abort(struct rxrpc_call *call, struct sk_buff *skb)
+{
+       struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
+       __be32 wtmp;
+       u32 abort_code = RX_CALL_DEAD;
 
-protocol_error:
-       _debug("protocol error");
-       rxrpc_free_skb(part);
-       rxrpc_free_skb(jumbo);
-       write_lock_bh(&call->state_lock);
-       if (call->state <= RXRPC_CALL_COMPLETE) {
-               call->state = RXRPC_CALL_LOCALLY_ABORTED;
-               call->local_abort = RX_PROTOCOL_ERROR;
-               set_bit(RXRPC_CALL_EV_ABORT, &call->events);
-               rxrpc_queue_call(call);
-       }
-       write_unlock_bh(&call->state_lock);
-       _leave("");
+       _enter("");
+
+       if (skb->len >= 4 &&
+           skb_copy_bits(skb, sizeof(struct rxrpc_wire_header),
+                         &wtmp, sizeof(wtmp)) >= 0)
+               abort_code = ntohl(wtmp);
+
+       _proto("Rx ABORT %%%u { %x }", sp->hdr.serial, abort_code);
+
+       if (rxrpc_set_call_completion(call, RXRPC_CALL_REMOTELY_ABORTED,
+                                     abort_code, ECONNABORTED))
+               rxrpc_notify_socket(call);
 }
 
 /*
- * post an incoming packet to the appropriate call/socket to deal with
- * - must get rid of the sk_buff, either by freeing it or by queuing it
+ * Process an incoming call packet.
  */
-static void rxrpc_post_packet_to_call(struct rxrpc_call *call,
-                                     struct sk_buff *skb)
+static void rxrpc_input_call_packet(struct rxrpc_call *call,
+                                   struct sk_buff *skb, u16 skew)
 {
-       struct rxrpc_skb_priv *sp;
+       struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
 
        _enter("%p,%p", call, skb);
 
-       sp = rxrpc_skb(skb);
+       switch (sp->hdr.type) {
+       case RXRPC_PACKET_TYPE_DATA:
+               rxrpc_input_data(call, skb, skew);
+               break;
+
+       case RXRPC_PACKET_TYPE_ACK:
+               rxrpc_input_ack(call, skb, skew);
+               break;
 
-       _debug("extant call [%d]", call->state);
+       case RXRPC_PACKET_TYPE_BUSY:
+               _proto("Rx BUSY %%%u", sp->hdr.serial);
+
+               /* Just ignore BUSY packets from the server; the retry and
+                * lifespan timers will take care of business.  BUSY packets
+                * from the client don't make sense.
+                */
+               break;
+
+       case RXRPC_PACKET_TYPE_ABORT:
+               rxrpc_input_abort(call, skb);
+               break;
 
-       read_lock(&call->state_lock);
+       case RXRPC_PACKET_TYPE_ACKALL:
+               rxrpc_input_ackall(call, skb);
+               break;
+
+       default:
+               _proto("Rx %s %%%u", rxrpc_pkts[sp->hdr.type], sp->hdr.serial);
+               break;
+       }
+
+       _leave("");
+}
+
+/*
+ * Handle a new call on a channel implicitly completing the preceding call on
+ * that channel.
+ *
+ * TODO: If callNumber > call_id + 1, renegotiate security.
+ */
+static void rxrpc_input_implicit_end_call(struct rxrpc_connection *conn,
+                                         struct rxrpc_call *call)
+{
        switch (call->state) {
-       case RXRPC_CALL_LOCALLY_ABORTED:
-               if (!test_and_set_bit(RXRPC_CALL_EV_ABORT, &call->events)) {
-                       rxrpc_queue_call(call);
-                       goto free_unlock;
-               }
-       case RXRPC_CALL_REMOTELY_ABORTED:
-       case RXRPC_CALL_NETWORK_ERROR:
-       case RXRPC_CALL_DEAD:
-               goto dead_call;
+       case RXRPC_CALL_SERVER_AWAIT_ACK:
+               rxrpc_call_completed(call);
+               break;
        case RXRPC_CALL_COMPLETE:
-       case RXRPC_CALL_CLIENT_FINAL_ACK:
-               /* complete server call */
-               if (rxrpc_conn_is_service(call->conn))
-                       goto dead_call;
-               /* resend last packet of a completed call */
-               _debug("final ack again");
-               rxrpc_get_call(call);
-               set_bit(RXRPC_CALL_EV_ACK_FINAL, &call->events);
-               rxrpc_queue_call(call);
-               goto free_unlock;
+               break;
        default:
+               if (rxrpc_abort_call("IMP", call, 0, RX_CALL_DEAD, ESHUTDOWN)) {
+                       set_bit(RXRPC_CALL_EV_ABORT, &call->events);
+                       rxrpc_queue_call(call);
+               }
                break;
        }
 
-       read_unlock(&call->state_lock);
-       rxrpc_get_call(call);
-
-       if (sp->hdr.type == RXRPC_PACKET_TYPE_DATA &&
-           sp->hdr.flags & RXRPC_JUMBO_PACKET)
-               rxrpc_process_jumbo_packet(call, skb);
-       else
-               rxrpc_fast_process_packet(call, skb);
-
-       rxrpc_put_call(call);
-       goto done;
-
-dead_call:
-       if (sp->hdr.type != RXRPC_PACKET_TYPE_ABORT) {
-               skb->priority = RX_CALL_DEAD;
-               rxrpc_reject_packet(call->conn->params.local, skb);
-               goto unlock;
-       }
-free_unlock:
-       rxrpc_free_skb(skb);
-unlock:
-       read_unlock(&call->state_lock);
-done:
-       _leave("");
+       __rxrpc_disconnect_call(conn, call);
+       rxrpc_notify_socket(call);
 }
 
 /*
  * post connection-level events to the connection
- * - this includes challenges, responses and some aborts
+ * - this includes challenges, responses, some aborts and call terminal packet
+ *   retransmission.
  */
 static void rxrpc_post_packet_to_conn(struct rxrpc_connection *conn,
                                      struct sk_buff *skb)
@@ -594,6 +992,17 @@ static void rxrpc_post_packet_to_local(struct rxrpc_local *local,
        rxrpc_queue_local(local);
 }
 
+/*
+ * put a packet up for transport-level abort
+ */
+static void rxrpc_reject_packet(struct rxrpc_local *local, struct sk_buff *skb)
+{
+       CHECK_SLAB_OKAY(&local->usage);
+
+       skb_queue_tail(&local->reject_queue, skb);
+       rxrpc_queue_local(local);
+}
+
 /*
  * Extract the wire header from a packet and translate the byte order.
  */
@@ -605,8 +1014,6 @@ int rxrpc_extract_header(struct rxrpc_skb_priv *sp, struct sk_buff *skb)
        /* dig out the RxRPC connection details */
        if (skb_copy_bits(skb, 0, &whdr, sizeof(whdr)) < 0)
                return -EBADMSG;
-       if (!pskb_pull(skb, sizeof(whdr)))
-               BUG();
 
        memset(sp, 0, sizeof(*sp));
        sp->hdr.epoch           = ntohl(whdr.epoch);
@@ -631,19 +1038,22 @@ int rxrpc_extract_header(struct rxrpc_skb_priv *sp, struct sk_buff *skb)
  * shut down and the local endpoint from going away, thus sk_user_data will not
  * be cleared until this function returns.
  */
-void rxrpc_data_ready(struct sock *sk)
+void rxrpc_data_ready(struct sock *udp_sk)
 {
        struct rxrpc_connection *conn;
+       struct rxrpc_channel *chan;
+       struct rxrpc_call *call;
        struct rxrpc_skb_priv *sp;
-       struct rxrpc_local *local = sk->sk_user_data;
+       struct rxrpc_local *local = udp_sk->sk_user_data;
        struct sk_buff *skb;
-       int ret;
+       unsigned int channel;
+       int ret, skew;
 
-       _enter("%p", sk);
+       _enter("%p", udp_sk);
 
        ASSERT(!irqs_disabled());
 
-       skb = skb_recv_datagram(sk, 0, 1, &ret);
+       skb = skb_recv_datagram(udp_sk, 0, 1, &ret);
        if (!skb) {
                if (ret == -EAGAIN)
                        return;
@@ -651,13 +1061,13 @@ void rxrpc_data_ready(struct sock *sk)
                return;
        }
 
-       rxrpc_new_skb(skb);
+       rxrpc_new_skb(skb, rxrpc_skb_rx_received);
 
        _net("recv skb %p", skb);
 
        /* we'll probably need to checksum it (didn't call sock_recvmsg) */
        if (skb_checksum_complete(skb)) {
-               rxrpc_free_skb(skb);
+               rxrpc_free_skb(skb, rxrpc_skb_rx_freed);
                __UDP_INC_STATS(&init_net, UDP_MIB_INERRORS, 0);
                _leave(" [CSUM failed]");
                return;
@@ -671,13 +1081,21 @@ void rxrpc_data_ready(struct sock *sk)
        skb_orphan(skb);
        sp = rxrpc_skb(skb);
 
-       _net("Rx UDP packet from %08x:%04hu",
-            ntohl(ip_hdr(skb)->saddr), ntohs(udp_hdr(skb)->source));
-
        /* dig out the RxRPC connection details */
        if (rxrpc_extract_header(sp, skb) < 0)
                goto bad_message;
 
+       if (IS_ENABLED(CONFIG_AF_RXRPC_INJECT_LOSS)) {
+               static int lose;
+               if ((lose++ & 7) == 7) {
+                       trace_rxrpc_rx_lose(sp);
+                       rxrpc_lose_skb(skb, rxrpc_skb_rx_lost);
+                       return;
+               }
+       }
+
+       trace_rxrpc_rx_packet(sp);
+
        _net("Rx RxRPC %s ep=%x call=%x:%x",
             sp->hdr.flags & RXRPC_CLIENT_INITIATED ? "ToServer" : "ToClient",
             sp->hdr.epoch, sp->hdr.cid, sp->hdr.callNumber);
@@ -688,70 +1106,135 @@ void rxrpc_data_ready(struct sock *sk)
                goto bad_message;
        }
 
-       if (sp->hdr.type == RXRPC_PACKET_TYPE_VERSION) {
+       switch (sp->hdr.type) {
+       case RXRPC_PACKET_TYPE_VERSION:
                rxrpc_post_packet_to_local(local, skb);
                goto out;
-       }
 
-       if (sp->hdr.type == RXRPC_PACKET_TYPE_DATA &&
-           (sp->hdr.callNumber == 0 || sp->hdr.seq == 0))
-               goto bad_message;
+       case RXRPC_PACKET_TYPE_BUSY:
+               if (sp->hdr.flags & RXRPC_CLIENT_INITIATED)
+                       goto discard;
+
+       case RXRPC_PACKET_TYPE_DATA:
+               if (sp->hdr.callNumber == 0)
+                       goto bad_message;
+               if (sp->hdr.flags & RXRPC_JUMBO_PACKET &&
+                   !rxrpc_validate_jumbo(skb))
+                       goto bad_message;
+               break;
+       }
 
        rcu_read_lock();
 
        conn = rxrpc_find_connection_rcu(local, skb);
-       if (!conn)
-               goto cant_route_call;
+       if (conn) {
+               if (sp->hdr.securityIndex != conn->security_ix)
+                       goto wrong_security;
+
+               if (sp->hdr.callNumber == 0) {
+                       /* Connection-level packet */
+                       _debug("CONN %p {%d}", conn, conn->debug_id);
+                       rxrpc_post_packet_to_conn(conn, skb);
+                       goto out_unlock;
+               }
+
+               /* Note the serial number skew here */
+               skew = (int)sp->hdr.serial - (int)conn->hi_serial;
+               if (skew >= 0) {
+                       if (skew > 0)
+                               conn->hi_serial = sp->hdr.serial;
+               } else {
+                       skew = -skew;
+                       skew = min(skew, 65535);
+               }
 
-       if (sp->hdr.callNumber == 0) {
-               /* Connection-level packet */
-               _debug("CONN %p {%d}", conn, conn->debug_id);
-               rxrpc_post_packet_to_conn(conn, skb);
-       } else {
                /* Call-bound packets are routed by connection channel. */
-               unsigned int channel = sp->hdr.cid & RXRPC_CHANNELMASK;
-               struct rxrpc_channel *chan = &conn->channels[channel];
-               struct rxrpc_call *call = rcu_dereference(chan->call);
+               channel = sp->hdr.cid & RXRPC_CHANNELMASK;
+               chan = &conn->channels[channel];
+
+               /* Ignore really old calls */
+               if (sp->hdr.callNumber < chan->last_call)
+                       goto discard_unlock;
+
+               if (sp->hdr.callNumber == chan->last_call) {
+                       /* For the previous service call, if completed successfully, we
+                        * discard all further packets.
+                        */
+                       if (rxrpc_conn_is_service(conn) &&
+                           (chan->last_type == RXRPC_PACKET_TYPE_ACK ||
+                            sp->hdr.type == RXRPC_PACKET_TYPE_ABORT))
+                               goto discard_unlock;
+
+                       /* But otherwise we need to retransmit the final packet from
+                        * data cached in the connection record.
+                        */
+                       rxrpc_post_packet_to_conn(conn, skb);
+                       goto out_unlock;
+               }
 
-               if (!call || atomic_read(&call->usage) == 0)
-                       goto cant_route_call;
+               call = rcu_dereference(chan->call);
+
+               if (sp->hdr.callNumber > chan->call_id) {
+                       if (!(sp->hdr.flags & RXRPC_CLIENT_INITIATED)) {
+                               rcu_read_unlock();
+                               goto reject_packet;
+                       }
+                       if (call)
+                               rxrpc_input_implicit_end_call(conn, call);
+                       call = NULL;
+               }
+       } else {
+               skew = 0;
+               call = NULL;
+       }
 
-               rxrpc_post_packet_to_call(call, skb);
+       if (!call || atomic_read(&call->usage) == 0) {
+               if (!(sp->hdr.type & RXRPC_CLIENT_INITIATED) ||
+                   sp->hdr.callNumber == 0 ||
+                   sp->hdr.type != RXRPC_PACKET_TYPE_DATA)
+                       goto bad_message_unlock;
+               if (sp->hdr.seq != 1)
+                       goto discard_unlock;
+               call = rxrpc_new_incoming_call(local, conn, skb);
+               if (!call) {
+                       rcu_read_unlock();
+                       goto reject_packet;
+               }
+               rxrpc_send_ping(call, skb, skew);
        }
 
+       rxrpc_input_call_packet(call, skb, skew);
+       goto discard_unlock;
+
+discard_unlock:
        rcu_read_unlock();
+discard:
+       rxrpc_free_skb(skb, rxrpc_skb_rx_freed);
 out:
+       trace_rxrpc_rx_done(0, 0);
        return;
 
-cant_route_call:
+out_unlock:
        rcu_read_unlock();
+       goto out;
 
-       _debug("can't route call");
-       if (sp->hdr.flags & RXRPC_CLIENT_INITIATED &&
-           sp->hdr.type == RXRPC_PACKET_TYPE_DATA) {
-               if (sp->hdr.seq == 1) {
-                       _debug("first packet");
-                       skb_queue_tail(&local->accept_queue, skb);
-                       rxrpc_queue_work(&local->processor);
-                       _leave(" [incoming]");
-                       return;
-               }
-               skb->priority = RX_INVALID_OPERATION;
-       } else {
-               skb->priority = RX_CALL_DEAD;
-       }
-
-       if (sp->hdr.type != RXRPC_PACKET_TYPE_ABORT) {
-               _debug("reject type %d",sp->hdr.type);
-               rxrpc_reject_packet(local, skb);
-       } else {
-               rxrpc_free_skb(skb);
-       }
-       _leave(" [no call]");
-       return;
+wrong_security:
+       rcu_read_unlock();
+       trace_rxrpc_abort("SEC", sp->hdr.cid, sp->hdr.callNumber, sp->hdr.seq,
+                         RXKADINCONSISTENCY, EBADMSG);
+       skb->priority = RXKADINCONSISTENCY;
+       goto post_abort;
 
+bad_message_unlock:
+       rcu_read_unlock();
 bad_message:
+       trace_rxrpc_abort("BAD", sp->hdr.cid, sp->hdr.callNumber, sp->hdr.seq,
+                         RX_PROTOCOL_ERROR, EBADMSG);
        skb->priority = RX_PROTOCOL_ERROR;
+post_abort:
+       skb->mark = RXRPC_SKB_MARK_LOCAL_ABORT;
+reject_packet:
+       trace_rxrpc_rx_done(skb->mark, skb->priority);
        rxrpc_reject_packet(local, skb);
        _leave(" [badmsg]");
 }