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_wire_header *whdr;
 143         struct rxrpc_skb_priv *sp;
 144         struct sk_buff *skb;
 145         rxrpc_seq_t cursor, seq, top;
 146         unsigned long resend_at, now;
 147         int ix;
 148         u8 annotation;
 149
 150         _enter("{%d,%d}", call->tx_hard_ack, call->tx_top);
 151
 152         spin_lock_bh(&call->lock);
 153
 154         cursor = call->tx_hard_ack;
 155         top = call->tx_top;
 156         ASSERT(before_eq(cursor, top));
 157         if (cursor == top)
 158                 goto out_unlock;
 159
 160         /* Scan the packet list without dropping the lock and decide which of
 161          * the packets in the Tx buffer we're going to resend and what the new
 162          * resend timeout will be.
 163          */
 164         now = jiffies;
 165         resend_at = now + rxrpc_resend_timeout;
 166         for (seq = cursor + 1; before_eq(seq, top); seq++) {
 167                 ix = seq & RXRPC_RXTX_BUFF_MASK;
 168                 annotation = call->rxtx_annotations[ix];
 169                 if (annotation == RXRPC_TX_ANNO_ACK)
 170                         continue;
 171
 172                 skb = call->rxtx_buffer[ix];
 173                 rxrpc_see_skb(skb, rxrpc_skb_tx_seen);
 174                 sp = rxrpc_skb(skb);
 175
 176                 if (annotation == RXRPC_TX_ANNO_UNACK) {
 177                         if (time_after(sp->resend_at, now)) {
 178                                 if (time_before(sp->resend_at, resend_at))
 179                                         resend_at = sp->resend_at;
 180                                 continue;
 181                         }
 182                 }
 183
 184                 /* Okay, we need to retransmit a packet. */
 185                 call->rxtx_annotations[ix] = RXRPC_TX_ANNO_RETRANS;
 186         }
 187
 188         call->resend_at = resend_at;
 189
 190         /* Now go through the Tx window and perform the retransmissions.  We
 191          * have to drop the lock for each send.  If an ACK comes in whilst the
 192          * lock is dropped, it may clear some of the retransmission markers for
 193          * packets that it soft-ACKs.
 194          */
 195         for (seq = cursor + 1; before_eq(seq, top); seq++) {
 196                 ix = seq & RXRPC_RXTX_BUFF_MASK;
 197                 annotation = call->rxtx_annotations[ix];
 198                 if (annotation != RXRPC_TX_ANNO_RETRANS)
 199                         continue;
 200
 201                 skb = call->rxtx_buffer[ix];
 202                 rxrpc_get_skb(skb, rxrpc_skb_tx_got);
 203                 spin_unlock_bh(&call->lock);
 204                 sp = rxrpc_skb(skb);
 205
 206                 /* Each Tx packet needs a new serial number */
 207                 sp->hdr.serial = atomic_inc_return(&call->conn->serial);
 208
 209                 whdr = (struct rxrpc_wire_header *)skb->head;
 210                 whdr->serial = htonl(sp->hdr.serial);
 211
 212                 if (rxrpc_send_data_packet(call->conn, skb) < 0) {
 213                         call->resend_at = now + 2;
 214                         rxrpc_free_skb(skb, rxrpc_skb_tx_freed);
 215                         return;
 216                 }
 217
 218                 if (rxrpc_is_client_call(call))
 219                         rxrpc_expose_client_call(call);
 220                 sp->resend_at = now + rxrpc_resend_timeout;
 221
 222                 rxrpc_free_skb(skb, rxrpc_skb_tx_freed);
 223                 spin_lock_bh(&call->lock);
 224
 225                 /* We need to clear the retransmit state, but there are two
 226                  * things we need to be aware of: A new ACK/NAK might have been
 227                  * received and the packet might have been hard-ACK'd (in which
 228                  * case it will no longer be in the buffer).
 229                  */
 230                 if (after(seq, call->tx_hard_ack) &&
 231                     (call->rxtx_annotations[ix] == RXRPC_TX_ANNO_RETRANS ||
 232                      call->rxtx_annotations[ix] == RXRPC_TX_ANNO_NAK))
 233                         call->rxtx_annotations[ix] = RXRPC_TX_ANNO_UNACK;
 234
 235                 if (after(call->tx_hard_ack, seq))
 236                         seq = call->tx_hard_ack;
 237         }
 238
 239 out_unlock:
 240         spin_unlock_bh(&call->lock);
 241         _leave("");
 242 }
 243
 244 /*
 245  * Handle retransmission and deferred ACK/abort generation.
 246  */
 247 void rxrpc_process_call(struct work_struct *work)
 248 {
 249         struct rxrpc_call *call =
 250                 container_of(work, struct rxrpc_call, processor);
 251         unsigned long now;
 252
 253         rxrpc_see_call(call);
 254
 255         //printk("\n--------------------\n");
 256         _enter("{%d,%s,%lx}",
 257                call->debug_id, rxrpc_call_states[call->state], call->events);
 258
 259 recheck_state:
 260         if (test_and_clear_bit(RXRPC_CALL_EV_ABORT, &call->events)) {
 261                 rxrpc_send_call_packet(call, RXRPC_PACKET_TYPE_ABORT);
 262                 goto recheck_state;
 263         }
 264
 265         if (call->state == RXRPC_CALL_COMPLETE) {
 266                 del_timer_sync(&call->timer);
 267                 goto out_put;
 268         }
 269
 270         now = jiffies;
 271         if (time_after_eq(now, call->expire_at)) {
 272                 rxrpc_abort_call("EXP", call, 0, RX_CALL_TIMEOUT, ETIME);
 273                 set_bit(RXRPC_CALL_EV_ABORT, &call->events);
 274         }
 275
 276         if (test_and_clear_bit(RXRPC_CALL_EV_ACK, &call->events) ||
 277             time_after_eq(now, call->ack_at)) {
 278                 call->ack_at = call->expire_at;
 279                 if (call->ackr_reason) {
 280                         rxrpc_send_call_packet(call, RXRPC_PACKET_TYPE_ACK);
 281                         goto recheck_state;
 282                 }
 283         }
 284
 285         if (test_and_clear_bit(RXRPC_CALL_EV_RESEND, &call->events) ||
 286             time_after_eq(now, call->resend_at)) {
 287                 rxrpc_resend(call);
 288                 goto recheck_state;
 289         }
 290
 291         rxrpc_set_timer(call);
 292
 293         /* other events may have been raised since we started checking */
 294         if (call->events && call->state < RXRPC_CALL_COMPLETE) {
 295                 __rxrpc_queue_call(call);
 296                 goto out;
 297         }
 298
 299 out_put:
 300         rxrpc_put_call(call, rxrpc_call_put);
 301 out:
 302         _leave("");
 303 }