| // SPDX-License-Identifier: GPL-2.0-or-later |
| /* Management of Tx window, Tx resend, ACKs and out-of-sequence reception |
| * |
| * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved. |
| * Written by David Howells (dhowells@redhat.com) |
| */ |
| |
| #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt |
| |
| #include <linux/module.h> |
| #include <linux/circ_buf.h> |
| #include <linux/net.h> |
| #include <linux/skbuff.h> |
| #include <linux/slab.h> |
| #include <linux/udp.h> |
| #include <net/sock.h> |
| #include <net/af_rxrpc.h> |
| #include "ar-internal.h" |
| |
| /* |
| * Propose a PING ACK be sent. |
| */ |
| static void rxrpc_propose_ping(struct rxrpc_call *call, |
| bool immediate, bool background) |
| { |
| if (immediate) { |
| if (background && |
| !test_and_set_bit(RXRPC_CALL_EV_PING, &call->events)) |
| rxrpc_queue_call(call); |
| } else { |
| unsigned long now = jiffies; |
| unsigned long ping_at = now + rxrpc_idle_ack_delay; |
| |
| if (time_before(ping_at, call->ping_at)) { |
| WRITE_ONCE(call->ping_at, ping_at); |
| rxrpc_reduce_call_timer(call, ping_at, now, |
| rxrpc_timer_set_for_ping); |
| } |
| } |
| } |
| |
| /* |
| * propose an ACK be sent |
| */ |
| static void __rxrpc_propose_ACK(struct rxrpc_call *call, u8 ack_reason, |
| u32 serial, bool immediate, bool background, |
| enum rxrpc_propose_ack_trace why) |
| { |
| enum rxrpc_propose_ack_outcome outcome = rxrpc_propose_ack_use; |
| unsigned long expiry = rxrpc_soft_ack_delay; |
| s8 prior = rxrpc_ack_priority[ack_reason]; |
| |
| /* Pings are handled specially because we don't want to accidentally |
| * lose a ping response by subsuming it into a ping. |
| */ |
| if (ack_reason == RXRPC_ACK_PING) { |
| rxrpc_propose_ping(call, immediate, background); |
| goto trace; |
| } |
| |
| /* Update DELAY, IDLE, REQUESTED and PING_RESPONSE ACK serial |
| * numbers, but we don't alter the timeout. |
| */ |
| _debug("prior %u %u vs %u %u", |
| ack_reason, prior, |
| call->ackr_reason, rxrpc_ack_priority[call->ackr_reason]); |
| if (ack_reason == call->ackr_reason) { |
| if (RXRPC_ACK_UPDATEABLE & (1 << ack_reason)) { |
| outcome = rxrpc_propose_ack_update; |
| call->ackr_serial = serial; |
| } |
| if (!immediate) |
| goto trace; |
| } else if (prior > rxrpc_ack_priority[call->ackr_reason]) { |
| call->ackr_reason = ack_reason; |
| call->ackr_serial = serial; |
| } else { |
| outcome = rxrpc_propose_ack_subsume; |
| } |
| |
| switch (ack_reason) { |
| case RXRPC_ACK_REQUESTED: |
| if (rxrpc_requested_ack_delay < expiry) |
| expiry = rxrpc_requested_ack_delay; |
| if (serial == 1) |
| immediate = false; |
| break; |
| |
| case RXRPC_ACK_DELAY: |
| if (rxrpc_soft_ack_delay < expiry) |
| expiry = rxrpc_soft_ack_delay; |
| break; |
| |
| case RXRPC_ACK_IDLE: |
| if (rxrpc_idle_ack_delay < expiry) |
| expiry = rxrpc_idle_ack_delay; |
| break; |
| |
| default: |
| immediate = true; |
| break; |
| } |
| |
| if (test_bit(RXRPC_CALL_EV_ACK, &call->events)) { |
| _debug("already scheduled"); |
| } else if (immediate || expiry == 0) { |
| _debug("immediate ACK %lx", call->events); |
| if (!test_and_set_bit(RXRPC_CALL_EV_ACK, &call->events) && |
| background) |
| rxrpc_queue_call(call); |
| } else { |
| unsigned long now = jiffies, ack_at; |
| |
| if (call->peer->srtt_us != 0) |
| ack_at = usecs_to_jiffies(call->peer->srtt_us >> 3); |
| else |
| ack_at = expiry; |
| |
| ack_at += READ_ONCE(call->tx_backoff); |
| ack_at += now; |
| if (time_before(ack_at, call->ack_at)) { |
| WRITE_ONCE(call->ack_at, ack_at); |
| rxrpc_reduce_call_timer(call, ack_at, now, |
| rxrpc_timer_set_for_ack); |
| } |
| } |
| |
| trace: |
| trace_rxrpc_propose_ack(call, why, ack_reason, serial, immediate, |
| background, outcome); |
| } |
| |
| /* |
| * propose an ACK be sent, locking the call structure |
| */ |
| void rxrpc_propose_ACK(struct rxrpc_call *call, u8 ack_reason, |
| u32 serial, bool immediate, bool background, |
| enum rxrpc_propose_ack_trace why) |
| { |
| spin_lock_bh(&call->lock); |
| __rxrpc_propose_ACK(call, ack_reason, serial, |
| immediate, background, why); |
| spin_unlock_bh(&call->lock); |
| } |
| |
| /* |
| * Handle congestion being detected by the retransmit timeout. |
| */ |
| static void rxrpc_congestion_timeout(struct rxrpc_call *call) |
| { |
| set_bit(RXRPC_CALL_RETRANS_TIMEOUT, &call->flags); |
| } |
| |
| /* |
| * Perform retransmission of NAK'd and unack'd packets. |
| */ |
| static void rxrpc_resend(struct rxrpc_call *call, unsigned long now_j) |
| { |
| struct sk_buff *skb; |
| unsigned long resend_at, rto_j; |
| rxrpc_seq_t cursor, seq, top; |
| ktime_t now, max_age, oldest, ack_ts; |
| int ix; |
| u8 annotation, anno_type, retrans = 0, unacked = 0; |
| |
| _enter("{%d,%d}", call->tx_hard_ack, call->tx_top); |
| |
| rto_j = call->peer->rto_j; |
| |
| now = ktime_get_real(); |
| max_age = ktime_sub(now, jiffies_to_usecs(rto_j)); |
| |
| spin_lock_bh(&call->lock); |
| |
| cursor = call->tx_hard_ack; |
| top = call->tx_top; |
| ASSERT(before_eq(cursor, top)); |
| if (cursor == top) |
| goto out_unlock; |
| |
| /* Scan the packet list without dropping the lock and decide which of |
| * the packets in the Tx buffer we're going to resend and what the new |
| * resend timeout will be. |
| */ |
| trace_rxrpc_resend(call, (cursor + 1) & RXRPC_RXTX_BUFF_MASK); |
| oldest = now; |
| for (seq = cursor + 1; before_eq(seq, top); seq++) { |
| ix = seq & RXRPC_RXTX_BUFF_MASK; |
| annotation = call->rxtx_annotations[ix]; |
| anno_type = annotation & RXRPC_TX_ANNO_MASK; |
| annotation &= ~RXRPC_TX_ANNO_MASK; |
| if (anno_type == RXRPC_TX_ANNO_ACK) |
| continue; |
| |
| skb = call->rxtx_buffer[ix]; |
| rxrpc_see_skb(skb, rxrpc_skb_seen); |
| |
| if (anno_type == RXRPC_TX_ANNO_UNACK) { |
| if (ktime_after(skb->tstamp, max_age)) { |
| if (ktime_before(skb->tstamp, oldest)) |
| oldest = skb->tstamp; |
| continue; |
| } |
| if (!(annotation & RXRPC_TX_ANNO_RESENT)) |
| unacked++; |
| } |
| |
| /* Okay, we need to retransmit a packet. */ |
| call->rxtx_annotations[ix] = RXRPC_TX_ANNO_RETRANS | annotation; |
| retrans++; |
| trace_rxrpc_retransmit(call, seq, annotation | anno_type, |
| ktime_to_ns(ktime_sub(skb->tstamp, max_age))); |
| } |
| |
| resend_at = nsecs_to_jiffies(ktime_to_ns(ktime_sub(now, oldest))); |
| resend_at += jiffies + rto_j; |
| WRITE_ONCE(call->resend_at, resend_at); |
| |
| if (unacked) |
| rxrpc_congestion_timeout(call); |
| |
| /* If there was nothing that needed retransmission then it's likely |
| * that an ACK got lost somewhere. Send a ping to find out instead of |
| * retransmitting data. |
| */ |
| if (!retrans) { |
| rxrpc_reduce_call_timer(call, resend_at, now_j, |
| rxrpc_timer_set_for_resend); |
| spin_unlock_bh(&call->lock); |
| ack_ts = ktime_sub(now, call->acks_latest_ts); |
| if (ktime_to_us(ack_ts) < (call->peer->srtt_us >> 3)) |
| goto out; |
| rxrpc_propose_ACK(call, RXRPC_ACK_PING, 0, true, false, |
| rxrpc_propose_ack_ping_for_lost_ack); |
| rxrpc_send_ack_packet(call, true, NULL); |
| goto out; |
| } |
| |
| /* Now go through the Tx window and perform the retransmissions. We |
| * have to drop the lock for each send. If an ACK comes in whilst the |
| * lock is dropped, it may clear some of the retransmission markers for |
| * packets that it soft-ACKs. |
| */ |
| for (seq = cursor + 1; before_eq(seq, top); seq++) { |
| ix = seq & RXRPC_RXTX_BUFF_MASK; |
| annotation = call->rxtx_annotations[ix]; |
| anno_type = annotation & RXRPC_TX_ANNO_MASK; |
| if (anno_type != RXRPC_TX_ANNO_RETRANS) |
| continue; |
| |
| /* We need to reset the retransmission state, but we need to do |
| * so before we drop the lock as a new ACK/NAK may come in and |
| * confuse things |
| */ |
| annotation &= ~RXRPC_TX_ANNO_MASK; |
| annotation |= RXRPC_TX_ANNO_UNACK | RXRPC_TX_ANNO_RESENT; |
| call->rxtx_annotations[ix] = annotation; |
| |
| skb = call->rxtx_buffer[ix]; |
| if (!skb) |
| continue; |
| |
| rxrpc_get_skb(skb, rxrpc_skb_got); |
| spin_unlock_bh(&call->lock); |
| |
| if (rxrpc_send_data_packet(call, skb, true) < 0) { |
| rxrpc_free_skb(skb, rxrpc_skb_freed); |
| return; |
| } |
| |
| if (rxrpc_is_client_call(call)) |
| rxrpc_expose_client_call(call); |
| |
| rxrpc_free_skb(skb, rxrpc_skb_freed); |
| spin_lock_bh(&call->lock); |
| if (after(call->tx_hard_ack, seq)) |
| seq = call->tx_hard_ack; |
| } |
| |
| out_unlock: |
| spin_unlock_bh(&call->lock); |
| out: |
| _leave(""); |
| } |
| |
| /* |
| * Handle retransmission and deferred ACK/abort generation. |
| */ |
| void rxrpc_process_call(struct work_struct *work) |
| { |
| struct rxrpc_call *call = |
| container_of(work, struct rxrpc_call, processor); |
| rxrpc_serial_t *send_ack; |
| unsigned long now, next, t; |
| unsigned int iterations = 0; |
| |
| rxrpc_see_call(call); |
| |
| //printk("\n--------------------\n"); |
| _enter("{%d,%s,%lx}", |
| call->debug_id, rxrpc_call_states[call->state], call->events); |
| |
| recheck_state: |
| /* Limit the number of times we do this before returning to the manager */ |
| iterations++; |
| if (iterations > 5) |
| goto requeue; |
| |
| if (test_and_clear_bit(RXRPC_CALL_EV_ABORT, &call->events)) { |
| rxrpc_send_abort_packet(call); |
| goto recheck_state; |
| } |
| |
| if (call->state == RXRPC_CALL_COMPLETE) { |
| del_timer_sync(&call->timer); |
| rxrpc_notify_socket(call); |
| goto out_put; |
| } |
| |
| /* Work out if any timeouts tripped */ |
| now = jiffies; |
| t = READ_ONCE(call->expect_rx_by); |
| if (time_after_eq(now, t)) { |
| trace_rxrpc_timer(call, rxrpc_timer_exp_normal, now); |
| set_bit(RXRPC_CALL_EV_EXPIRED, &call->events); |
| } |
| |
| t = READ_ONCE(call->expect_req_by); |
| if (call->state == RXRPC_CALL_SERVER_RECV_REQUEST && |
| time_after_eq(now, t)) { |
| trace_rxrpc_timer(call, rxrpc_timer_exp_idle, now); |
| set_bit(RXRPC_CALL_EV_EXPIRED, &call->events); |
| } |
| |
| t = READ_ONCE(call->expect_term_by); |
| if (time_after_eq(now, t)) { |
| trace_rxrpc_timer(call, rxrpc_timer_exp_hard, now); |
| set_bit(RXRPC_CALL_EV_EXPIRED, &call->events); |
| } |
| |
| t = READ_ONCE(call->ack_at); |
| if (time_after_eq(now, t)) { |
| trace_rxrpc_timer(call, rxrpc_timer_exp_ack, now); |
| cmpxchg(&call->ack_at, t, now + MAX_JIFFY_OFFSET); |
| set_bit(RXRPC_CALL_EV_ACK, &call->events); |
| } |
| |
| t = READ_ONCE(call->ack_lost_at); |
| if (time_after_eq(now, t)) { |
| trace_rxrpc_timer(call, rxrpc_timer_exp_lost_ack, now); |
| cmpxchg(&call->ack_lost_at, t, now + MAX_JIFFY_OFFSET); |
| set_bit(RXRPC_CALL_EV_ACK_LOST, &call->events); |
| } |
| |
| t = READ_ONCE(call->keepalive_at); |
| if (time_after_eq(now, t)) { |
| trace_rxrpc_timer(call, rxrpc_timer_exp_keepalive, now); |
| cmpxchg(&call->keepalive_at, t, now + MAX_JIFFY_OFFSET); |
| rxrpc_propose_ACK(call, RXRPC_ACK_PING, 0, true, true, |
| rxrpc_propose_ack_ping_for_keepalive); |
| set_bit(RXRPC_CALL_EV_PING, &call->events); |
| } |
| |
| t = READ_ONCE(call->ping_at); |
| if (time_after_eq(now, t)) { |
| trace_rxrpc_timer(call, rxrpc_timer_exp_ping, now); |
| cmpxchg(&call->ping_at, t, now + MAX_JIFFY_OFFSET); |
| set_bit(RXRPC_CALL_EV_PING, &call->events); |
| } |
| |
| t = READ_ONCE(call->resend_at); |
| if (time_after_eq(now, t)) { |
| trace_rxrpc_timer(call, rxrpc_timer_exp_resend, now); |
| cmpxchg(&call->resend_at, t, now + MAX_JIFFY_OFFSET); |
| set_bit(RXRPC_CALL_EV_RESEND, &call->events); |
| } |
| |
| /* Process events */ |
| if (test_and_clear_bit(RXRPC_CALL_EV_EXPIRED, &call->events)) { |
| if (test_bit(RXRPC_CALL_RX_HEARD, &call->flags) && |
| (int)call->conn->hi_serial - (int)call->rx_serial > 0) { |
| trace_rxrpc_call_reset(call); |
| rxrpc_abort_call("EXP", call, 0, RX_USER_ABORT, -ECONNRESET); |
| } else { |
| rxrpc_abort_call("EXP", call, 0, RX_USER_ABORT, -ETIME); |
| } |
| set_bit(RXRPC_CALL_EV_ABORT, &call->events); |
| goto recheck_state; |
| } |
| |
| send_ack = NULL; |
| if (test_and_clear_bit(RXRPC_CALL_EV_ACK_LOST, &call->events)) { |
| call->acks_lost_top = call->tx_top; |
| rxrpc_propose_ACK(call, RXRPC_ACK_PING, 0, true, false, |
| rxrpc_propose_ack_ping_for_lost_ack); |
| send_ack = &call->acks_lost_ping; |
| } |
| |
| if (test_and_clear_bit(RXRPC_CALL_EV_ACK, &call->events) || |
| send_ack) { |
| if (call->ackr_reason) { |
| rxrpc_send_ack_packet(call, false, send_ack); |
| goto recheck_state; |
| } |
| } |
| |
| if (test_and_clear_bit(RXRPC_CALL_EV_PING, &call->events)) { |
| rxrpc_send_ack_packet(call, true, NULL); |
| goto recheck_state; |
| } |
| |
| if (test_and_clear_bit(RXRPC_CALL_EV_RESEND, &call->events)) { |
| rxrpc_resend(call, now); |
| goto recheck_state; |
| } |
| |
| /* Make sure the timer is restarted */ |
| next = call->expect_rx_by; |
| |
| #define set(T) { t = READ_ONCE(T); if (time_before(t, next)) next = t; } |
| |
| set(call->expect_req_by); |
| set(call->expect_term_by); |
| set(call->ack_at); |
| set(call->ack_lost_at); |
| set(call->resend_at); |
| set(call->keepalive_at); |
| set(call->ping_at); |
| |
| now = jiffies; |
| if (time_after_eq(now, next)) |
| goto recheck_state; |
| |
| rxrpc_reduce_call_timer(call, next, now, rxrpc_timer_restart); |
| |
| /* other events may have been raised since we started checking */ |
| if (call->events && call->state < RXRPC_CALL_COMPLETE) |
| goto requeue; |
| |
| out_put: |
| rxrpc_put_call(call, rxrpc_call_put); |
| out: |
| _leave(""); |
| return; |
| |
| requeue: |
| __rxrpc_queue_call(call); |
| goto out; |
| } |