net/rxrpc/call_event.c

   1 /* Management of Tx window, Tx resend, ACKs and out-of-sequence reception
   2  *
   3  * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
   4  * Written by David Howells (dhowells@redhat.com)
   5  *
   6  * This program is free software; you can redistribute it and/or
   7  * modify it under the terms of the GNU General Public License
   8  * as published by the Free Software Foundation; either version
   9  * 2 of the License, or (at your option) any later version.
  10  */
  11
  12 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  13
  14 #include <linux/module.h>
  15 #include <linux/circ_buf.h>
  16 #include <linux/net.h>
  17 #include <linux/skbuff.h>
  18 #include <linux/slab.h>
  19 #include <linux/udp.h>
  20 #include <net/sock.h>
  21 #include <net/af_rxrpc.h>
  22 #include "ar-internal.h"
  23
  24 /*
  25  * Set the timer
  26  */
  27 static void rxrpc_set_timer(struct rxrpc_call *call)
  28 {
  29         unsigned long t, now = jiffies;
  30
  31         _enter("{%ld,%ld,%ld:%ld}",
  32                call->ack_at - now, call->resend_at - now, call->expire_at - now,
  33                call->timer.expires - now);
  34
  35         read_lock_bh(&call->state_lock);
  36
  37         if (call->state < RXRPC_CALL_COMPLETE) {
  38                 t = call->ack_at;
  39                 if (time_before(call->resend_at, t))
  40                         t = call->resend_at;
  41                 if (time_before(call->expire_at, t))
  42                         t = call->expire_at;
  43                 if (!timer_pending(&call->timer) ||
  44                     time_before(t, call->timer.expires)) {
  45                         _debug("set timer %ld", t - now);
  46                         mod_timer(&call->timer, t);
  47                 }
  48         }
  49         read_unlock_bh(&call->state_lock);
  50 }
  51
  52 /*
  53  * propose an ACK be sent
  54  */
  55 static void __rxrpc_propose_ACK(struct rxrpc_call *call, u8 ack_reason,
  56                                 u16 skew, u32 serial, bool immediate,
  57                                 bool background)
  58 {
  59         unsigned long now, ack_at, expiry = rxrpc_soft_ack_delay;
  60         s8 prior = rxrpc_ack_priority[ack_reason];
  61
  62         _enter("{%d},%s,%%%x,%u",
  63                call->debug_id, rxrpc_acks(ack_reason), serial, immediate);
  64
  65         /* Update DELAY, IDLE, REQUESTED and PING_RESPONSE ACK serial
  66          * numbers, but we don't alter the timeout.
  67          */
  68         _debug("prior %u %u vs %u %u",
  69                ack_reason, prior,
  70                call->ackr_reason, rxrpc_ack_priority[call->ackr_reason]);
  71         if (ack_reason == call->ackr_reason) {
  72                 if (RXRPC_ACK_UPDATEABLE & (1 << ack_reason)) {
  73                         call->ackr_serial = serial;
  74                         call->ackr_skew = skew;
  75                 }
  76                 if (!immediate)
  77                         return;
  78         } else if (prior > rxrpc_ack_priority[call->ackr_reason]) {
  79                 call->ackr_reason = ack_reason;
  80                 call->ackr_serial = serial;
  81                 call->ackr_skew = skew;
  82         }
  83
  84         switch (ack_reason) {
  85         case RXRPC_ACK_REQUESTED:
  86                 if (rxrpc_requested_ack_delay < expiry)
  87                         expiry = rxrpc_requested_ack_delay;
  88                 if (serial == 1)
  89                         immediate = false;
  90                 break;
  91
  92         case RXRPC_ACK_DELAY:
  93                 if (rxrpc_soft_ack_delay < expiry)
  94                         expiry = rxrpc_soft_ack_delay;
  95                 break;
  96
  97         case RXRPC_ACK_IDLE:
  98                 if (rxrpc_idle_ack_delay < expiry)
  99                         expiry = rxrpc_idle_ack_delay;
 100                 break;
 101
 102         default:
 103                 immediate = true;
 104                 break;
 105         }
 106
 107         now = jiffies;
 108         if (test_bit(RXRPC_CALL_EV_ACK, &call->events)) {
 109                 _debug("already scheduled");
 110         } else if (immediate || expiry == 0) {
 111                 _debug("immediate ACK %lx", call->events);
 112                 if (!test_and_set_bit(RXRPC_CALL_EV_ACK, &call->events) &&
 113                     background)
 114                         rxrpc_queue_call(call);
 115         } else {
 116                 ack_at = now + expiry;
 117                 _debug("deferred ACK %ld < %ld", expiry, call->ack_at - now);
 118                 if (time_before(ack_at, call->ack_at)) {
 119                         call->ack_at = ack_at;
 120                         rxrpc_set_timer(call);
 121                 }
 122         }
 123 }
 124
 125 /*
 126  * propose an ACK be sent, locking the call structure
 127  */
 128 void rxrpc_propose_ACK(struct rxrpc_call *call, u8 ack_reason,
 129                        u16 skew, u32 serial, bool immediate, bool background)
 130 {
 131         spin_lock_bh(&call->lock);
 132         __rxrpc_propose_ACK(call, ack_reason, skew, serial,
 133                             immediate, background);
 134         spin_unlock_bh(&call->lock);
 135 }
 136
 137 /*
 138  * Perform retransmission of NAK'd and unack'd packets.
 139  */
 140 static void rxrpc_resend(struct rxrpc_call *call)
 141 {
 142         struct rxrpc_skb_priv *sp;
 143         struct sk_buff *skb;
 144         rxrpc_seq_t cursor, seq, top;
 145         ktime_t now = ktime_get_real(), max_age, oldest,  resend_at;
 146         int ix;
 147         u8 annotation, anno_type;
 148
 149         _enter("{%d,%d}", call->tx_hard_ack, call->tx_top);
 150
 151         max_age = ktime_sub_ms(now, rxrpc_resend_timeout);
 152
 153         spin_lock_bh(&call->lock);
 154
 155         cursor = call->tx_hard_ack;
 156         top = call->tx_top;
 157         ASSERT(before_eq(cursor, top));
 158         if (cursor == top)
 159                 goto out_unlock;
 160
 161         /* Scan the packet list without dropping the lock and decide which of
 162          * the packets in the Tx buffer we're going to resend and what the new
 163          * resend timeout will be.
 164          */
 165         oldest = now;
 166         for (seq = cursor + 1; before_eq(seq, top); seq++) {
 167                 ix = seq & RXRPC_RXTX_BUFF_MASK;
 168                 annotation = call->rxtx_annotations[ix];
 169                 anno_type = annotation & RXRPC_TX_ANNO_MASK;
 170                 annotation &= ~RXRPC_TX_ANNO_MASK;
 171                 if (anno_type == RXRPC_TX_ANNO_ACK)
 172                         continue;
 173
 174                 skb = call->rxtx_buffer[ix];
 175                 rxrpc_see_skb(skb, rxrpc_skb_tx_seen);
 176                 sp = rxrpc_skb(skb);
 177
 178                 if (anno_type == RXRPC_TX_ANNO_UNACK) {
 179                         if (ktime_after(skb->tstamp, max_age)) {
 180                                 if (ktime_before(skb->tstamp, oldest))
 181                                         oldest = skb->tstamp;
 182                                 continue;
 183                         }
 184                 }
 185
 186                 /* Okay, we need to retransmit a packet. */
 187                 call->rxtx_annotations[ix] = RXRPC_TX_ANNO_RETRANS | annotation;
 188         }
 189
 190         resend_at = ktime_sub(ktime_add_ns(oldest, rxrpc_resend_timeout), now);
 191         call->resend_at = jiffies + nsecs_to_jiffies(ktime_to_ns(resend_at));
 192
 193         /* Now go through the Tx window and perform the retransmissions.  We
 194          * have to drop the lock for each send.  If an ACK comes in whilst the
 195          * lock is dropped, it may clear some of the retransmission markers for
 196          * packets that it soft-ACKs.
 197          */
 198         for (seq = cursor + 1; before_eq(seq, top); seq++) {
 199                 ix = seq & RXRPC_RXTX_BUFF_MASK;
 200                 annotation = call->rxtx_annotations[ix];
 201                 anno_type = annotation & RXRPC_TX_ANNO_MASK;
 202                 if (anno_type != RXRPC_TX_ANNO_RETRANS)
 203                         continue;
 204
 205                 skb = call->rxtx_buffer[ix];
 206                 rxrpc_get_skb(skb, rxrpc_skb_tx_got);
 207                 spin_unlock_bh(&call->lock);
 208
 209                 if (rxrpc_send_data_packet(call, skb) < 0) {
 210                         rxrpc_free_skb(skb, rxrpc_skb_tx_freed);
 211                         return;
 212                 }
 213
 214                 if (rxrpc_is_client_call(call))
 215                         rxrpc_expose_client_call(call);
 216
 217                 rxrpc_free_skb(skb, rxrpc_skb_tx_freed);
 218                 spin_lock_bh(&call->lock);
 219
 220                 /* We need to clear the retransmit state, but there are two
 221                  * things we need to be aware of: A new ACK/NAK might have been
 222                  * received and the packet might have been hard-ACK'd (in which
 223                  * case it will no longer be in the buffer).
 224                  */
 225                 if (after(seq, call->tx_hard_ack)) {
 226                         annotation = call->rxtx_annotations[ix];
 227                         anno_type = annotation & RXRPC_TX_ANNO_MASK;
 228                         if (anno_type == RXRPC_TX_ANNO_RETRANS ||
 229                             anno_type == RXRPC_TX_ANNO_NAK) {
 230                                 annotation &= ~RXRPC_TX_ANNO_MASK;
 231                                 annotation |= RXRPC_TX_ANNO_UNACK;
 232                         }
 233                         annotation |= RXRPC_TX_ANNO_RESENT;
 234                         call->rxtx_annotations[ix] = annotation;
 235                 }
 236
 237                 if (after(call->tx_hard_ack, seq))
 238                         seq = call->tx_hard_ack;
 239         }
 240
 241 out_unlock:
 242         spin_unlock_bh(&call->lock);
 243         _leave("");
 244 }
 245
 246 /*
 247  * Handle retransmission and deferred ACK/abort generation.
 248  */
 249 void rxrpc_process_call(struct work_struct *work)
 250 {
 251         struct rxrpc_call *call =
 252                 container_of(work, struct rxrpc_call, processor);
 253         unsigned long now;
 254
 255         rxrpc_see_call(call);
 256
 257         //printk("\n--------------------\n");
 258         _enter("{%d,%s,%lx}",
 259                call->debug_id, rxrpc_call_states[call->state], call->events);
 260
 261 recheck_state:
 262         if (test_and_clear_bit(RXRPC_CALL_EV_ABORT, &call->events)) {
 263                 rxrpc_send_call_packet(call, RXRPC_PACKET_TYPE_ABORT);
 264                 goto recheck_state;
 265         }
 266
 267         if (call->state == RXRPC_CALL_COMPLETE) {
 268                 del_timer_sync(&call->timer);
 269                 goto out_put;
 270         }
 271
 272         now = jiffies;
 273         if (time_after_eq(now, call->expire_at)) {
 274                 rxrpc_abort_call("EXP", call, 0, RX_CALL_TIMEOUT, ETIME);
 275                 set_bit(RXRPC_CALL_EV_ABORT, &call->events);
 276         }
 277
 278         if (test_and_clear_bit(RXRPC_CALL_EV_ACK, &call->events) ||
 279             time_after_eq(now, call->ack_at)) {
 280                 call->ack_at = call->expire_at;
 281                 if (call->ackr_reason) {
 282                         rxrpc_send_call_packet(call, RXRPC_PACKET_TYPE_ACK);
 283                         goto recheck_state;
 284                 }
 285         }
 286
 287         if (test_and_clear_bit(RXRPC_CALL_EV_RESEND, &call->events) ||
 288             time_after_eq(now, call->resend_at)) {
 289                 rxrpc_resend(call);
 290                 goto recheck_state;
 291         }
 292
 293         rxrpc_set_timer(call);
 294
 295         /* other events may have been raised since we started checking */
 296         if (call->events && call->state < RXRPC_CALL_COMPLETE) {
 297                 __rxrpc_queue_call(call);
 298                 goto out;
 299         }
 300
 301 out_put:
 302         rxrpc_put_call(call, rxrpc_call_put);
 303 out:
 304         _leave("");
 305 }