| /* 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) |
| * |
| * This program is free software; you can redistribute it and/or |
| * modify it under the terms of the GNU General Public License |
| * as published by the Free Software Foundation; either version |
| * 2 of the License, or (at your option) any later version. |
| */ |
| |
| #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" |
| |
| /* |
| * Set the timer |
| */ |
| void rxrpc_set_timer(struct rxrpc_call *call, enum rxrpc_timer_trace why, |
| ktime_t now) |
| { |
| unsigned long t_j, now_j = jiffies; |
| ktime_t t; |
| bool queue = false; |
| |
| read_lock_bh(&call->state_lock); |
| |
| if (call->state < RXRPC_CALL_COMPLETE) { |
| t = call->expire_at; |
| if (!ktime_after(t, now)) |
| goto out; |
| |
| if (!ktime_after(call->resend_at, now)) { |
| call->resend_at = call->expire_at; |
| if (!test_and_set_bit(RXRPC_CALL_EV_RESEND, &call->events)) |
| queue = true; |
| } else if (ktime_before(call->resend_at, t)) { |
| t = call->resend_at; |
| } |
| |
| if (!ktime_after(call->ack_at, now)) { |
| call->ack_at = call->expire_at; |
| if (!test_and_set_bit(RXRPC_CALL_EV_ACK, &call->events)) |
| queue = true; |
| } else if (ktime_before(call->ack_at, t)) { |
| t = call->ack_at; |
| } |
| |
| t_j = nsecs_to_jiffies(ktime_to_ns(ktime_sub(t, now))); |
| t_j += jiffies; |
| |
| /* We have to make sure that the calculated jiffies value falls |
| * at or after the nsec value, or we may loop ceaselessly |
| * because the timer times out, but we haven't reached the nsec |
| * timeout yet. |
| */ |
| t_j++; |
| |
| if (call->timer.expires != t_j || !timer_pending(&call->timer)) { |
| mod_timer(&call->timer, t_j); |
| trace_rxrpc_timer(call, why, now, now_j); |
| } |
| |
| if (queue) |
| rxrpc_queue_call(call); |
| } |
| |
| out: |
| read_unlock_bh(&call->state_lock); |
| } |
| |
| /* |
| * propose an ACK be sent |
| */ |
| static void __rxrpc_propose_ACK(struct rxrpc_call *call, u8 ack_reason, |
| u16 skew, u32 serial, bool immediate, |
| bool background, |
| enum rxrpc_propose_ack_trace why) |
| { |
| enum rxrpc_propose_ack_outcome outcome = rxrpc_propose_ack_use; |
| unsigned int expiry = rxrpc_soft_ack_delay; |
| ktime_t now, ack_at; |
| s8 prior = rxrpc_ack_priority[ack_reason]; |
| |
| /* 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; |
| call->ackr_skew = skew; |
| } |
| if (!immediate) |
| goto trace; |
| } else if (prior > rxrpc_ack_priority[call->ackr_reason]) { |
| call->ackr_reason = ack_reason; |
| call->ackr_serial = serial; |
| call->ackr_skew = skew; |
| } 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_PING: |
| 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 { |
| now = ktime_get_real(); |
| ack_at = ktime_add_ms(now, expiry); |
| if (ktime_before(ack_at, call->ack_at)) { |
| call->ack_at = ack_at; |
| rxrpc_set_timer(call, rxrpc_timer_set_for_ack, now); |
| } |
| } |
| |
| 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, |
| u16 skew, u32 serial, bool immediate, bool background, |
| enum rxrpc_propose_ack_trace why) |
| { |
| spin_lock_bh(&call->lock); |
| __rxrpc_propose_ACK(call, ack_reason, skew, 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, ktime_t now) |
| { |
| struct rxrpc_skb_priv *sp; |
| struct sk_buff *skb; |
| rxrpc_seq_t cursor, seq, top; |
| ktime_t 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); |
| |
| max_age = ktime_sub_ms(now, rxrpc_resend_timeout); |
| |
| 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. |
| */ |
| 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_tx_seen); |
| sp = rxrpc_skb(skb); |
| |
| 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))); |
| } |
| |
| call->resend_at = ktime_add_ms(oldest, rxrpc_resend_timeout); |
| |
| 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_set_timer(call, rxrpc_timer_set_for_resend, now); |
| spin_unlock_bh(&call->lock); |
| ack_ts = ktime_sub(now, call->acks_latest_ts); |
| if (ktime_to_ns(ack_ts) < call->peer->rtt) |
| goto out; |
| rxrpc_propose_ACK(call, RXRPC_ACK_PING, 0, 0, true, false, |
| rxrpc_propose_ack_ping_for_lost_ack); |
| rxrpc_send_call_packet(call, RXRPC_PACKET_TYPE_ACK); |
| 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; |
| |
| skb = call->rxtx_buffer[ix]; |
| rxrpc_get_skb(skb, rxrpc_skb_tx_got); |
| spin_unlock_bh(&call->lock); |
| |
| if (rxrpc_send_data_packet(call, skb, true) < 0) { |
| rxrpc_free_skb(skb, rxrpc_skb_tx_freed); |
| return; |
| } |
| |
| if (rxrpc_is_client_call(call)) |
| rxrpc_expose_client_call(call); |
| |
| rxrpc_free_skb(skb, rxrpc_skb_tx_freed); |
| spin_lock_bh(&call->lock); |
| |
| /* We need to clear the retransmit state, but there are two |
| * things we need to be aware of: A new ACK/NAK might have been |
| * received and the packet might have been hard-ACK'd (in which |
| * case it will no longer be in the buffer). |
| */ |
| if (after(seq, call->tx_hard_ack)) { |
| annotation = call->rxtx_annotations[ix]; |
| anno_type = annotation & RXRPC_TX_ANNO_MASK; |
| if (anno_type == RXRPC_TX_ANNO_RETRANS || |
| anno_type == RXRPC_TX_ANNO_NAK) { |
| annotation &= ~RXRPC_TX_ANNO_MASK; |
| annotation |= RXRPC_TX_ANNO_UNACK; |
| } |
| annotation |= RXRPC_TX_ANNO_RESENT; |
| call->rxtx_annotations[ix] = annotation; |
| } |
| |
| 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); |
| ktime_t now; |
| |
| rxrpc_see_call(call); |
| |
| //printk("\n--------------------\n"); |
| _enter("{%d,%s,%lx}", |
| call->debug_id, rxrpc_call_states[call->state], call->events); |
| |
| recheck_state: |
| if (test_and_clear_bit(RXRPC_CALL_EV_ABORT, &call->events)) { |
| rxrpc_send_call_packet(call, RXRPC_PACKET_TYPE_ABORT); |
| goto recheck_state; |
| } |
| |
| if (call->state == RXRPC_CALL_COMPLETE) { |
| del_timer_sync(&call->timer); |
| goto out_put; |
| } |
| |
| now = ktime_get_real(); |
| if (ktime_before(call->expire_at, now)) { |
| rxrpc_abort_call("EXP", call, 0, RX_CALL_TIMEOUT, ETIME); |
| set_bit(RXRPC_CALL_EV_ABORT, &call->events); |
| goto recheck_state; |
| } |
| |
| if (test_and_clear_bit(RXRPC_CALL_EV_ACK, &call->events)) { |
| call->ack_at = call->expire_at; |
| if (call->ackr_reason) { |
| rxrpc_send_call_packet(call, RXRPC_PACKET_TYPE_ACK); |
| goto recheck_state; |
| } |
| } |
| |
| if (test_and_clear_bit(RXRPC_CALL_EV_RESEND, &call->events)) { |
| rxrpc_resend(call, now); |
| goto recheck_state; |
| } |
| |
| rxrpc_set_timer(call, rxrpc_timer_set_for_resend, now); |
| |
| /* other events may have been raised since we started checking */ |
| if (call->events && call->state < RXRPC_CALL_COMPLETE) { |
| __rxrpc_queue_call(call); |
| goto out; |
| } |
| |
| out_put: |
| rxrpc_put_call(call, rxrpc_call_put); |
| out: |
| _leave(""); |
| } |