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TOMOYO Linux Cross Reference
Linux/net/rxrpc/ar-ack.c

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  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 #include <linux/module.h>
 13 #include <linux/circ_buf.h>
 14 #include <linux/net.h>
 15 #include <linux/skbuff.h>
 16 #include <linux/slab.h>
 17 #include <linux/udp.h>
 18 #include <net/sock.h>
 19 #include <net/af_rxrpc.h>
 20 #include "ar-internal.h"
 21 
 22 /*
 23  * How long to wait before scheduling ACK generation after seeing a
 24  * packet with RXRPC_REQUEST_ACK set (in jiffies).
 25  */
 26 unsigned rxrpc_requested_ack_delay = 1;
 27 
 28 /*
 29  * How long to wait before scheduling an ACK with subtype DELAY (in jiffies).
 30  *
 31  * We use this when we've received new data packets.  If those packets aren't
 32  * all consumed within this time we will send a DELAY ACK if an ACK was not
 33  * requested to let the sender know it doesn't need to resend.
 34  */
 35 unsigned rxrpc_soft_ack_delay = 1 * HZ;
 36 
 37 /*
 38  * How long to wait before scheduling an ACK with subtype IDLE (in jiffies).
 39  *
 40  * We use this when we've consumed some previously soft-ACK'd packets when
 41  * further packets aren't immediately received to decide when to send an IDLE
 42  * ACK let the other end know that it can free up its Tx buffer space.
 43  */
 44 unsigned rxrpc_idle_ack_delay = 0.5 * HZ;
 45 
 46 /*
 47  * Receive window size in packets.  This indicates the maximum number of
 48  * unconsumed received packets we're willing to retain in memory.  Once this
 49  * limit is hit, we should generate an EXCEEDS_WINDOW ACK and discard further
 50  * packets.
 51  */
 52 unsigned rxrpc_rx_window_size = 32;
 53 
 54 /*
 55  * Maximum Rx MTU size.  This indicates to the sender the size of jumbo packet
 56  * made by gluing normal packets together that we're willing to handle.
 57  */
 58 unsigned rxrpc_rx_mtu = 5692;
 59 
 60 /*
 61  * The maximum number of fragments in a received jumbo packet that we tell the
 62  * sender that we're willing to handle.
 63  */
 64 unsigned rxrpc_rx_jumbo_max = 4;
 65 
 66 static const char *rxrpc_acks(u8 reason)
 67 {
 68         static const char *const str[] = {
 69                 "---", "REQ", "DUP", "OOS", "WIN", "MEM", "PNG", "PNR", "DLY",
 70                 "IDL", "-?-"
 71         };
 72 
 73         if (reason >= ARRAY_SIZE(str))
 74                 reason = ARRAY_SIZE(str) - 1;
 75         return str[reason];
 76 }
 77 
 78 static const s8 rxrpc_ack_priority[] = {
 79         [0]                             = 0,
 80         [RXRPC_ACK_DELAY]               = 1,
 81         [RXRPC_ACK_REQUESTED]           = 2,
 82         [RXRPC_ACK_IDLE]                = 3,
 83         [RXRPC_ACK_PING_RESPONSE]       = 4,
 84         [RXRPC_ACK_DUPLICATE]           = 5,
 85         [RXRPC_ACK_OUT_OF_SEQUENCE]     = 6,
 86         [RXRPC_ACK_EXCEEDS_WINDOW]      = 7,
 87         [RXRPC_ACK_NOSPACE]             = 8,
 88 };
 89 
 90 /*
 91  * propose an ACK be sent
 92  */
 93 void __rxrpc_propose_ACK(struct rxrpc_call *call, u8 ack_reason,
 94                          __be32 serial, bool immediate)
 95 {
 96         unsigned long expiry;
 97         s8 prior = rxrpc_ack_priority[ack_reason];
 98 
 99         ASSERTCMP(prior, >, 0);
100 
101         _enter("{%d},%s,%%%x,%u",
102                call->debug_id, rxrpc_acks(ack_reason), ntohl(serial),
103                immediate);
104 
105         if (prior < rxrpc_ack_priority[call->ackr_reason]) {
106                 if (immediate)
107                         goto cancel_timer;
108                 return;
109         }
110 
111         /* update DELAY, IDLE, REQUESTED and PING_RESPONSE ACK serial
112          * numbers */
113         if (prior == rxrpc_ack_priority[call->ackr_reason]) {
114                 if (prior <= 4)
115                         call->ackr_serial = serial;
116                 if (immediate)
117                         goto cancel_timer;
118                 return;
119         }
120 
121         call->ackr_reason = ack_reason;
122         call->ackr_serial = serial;
123 
124         switch (ack_reason) {
125         case RXRPC_ACK_DELAY:
126                 _debug("run delay timer");
127                 expiry = rxrpc_soft_ack_delay;
128                 goto run_timer;
129 
130         case RXRPC_ACK_IDLE:
131                 if (!immediate) {
132                         _debug("run defer timer");
133                         expiry = rxrpc_idle_ack_delay;
134                         goto run_timer;
135                 }
136                 goto cancel_timer;
137 
138         case RXRPC_ACK_REQUESTED:
139                 expiry = rxrpc_requested_ack_delay;
140                 if (!expiry)
141                         goto cancel_timer;
142                 if (!immediate || serial == cpu_to_be32(1)) {
143                         _debug("run defer timer");
144                         goto run_timer;
145                 }
146 
147         default:
148                 _debug("immediate ACK");
149                 goto cancel_timer;
150         }
151 
152 run_timer:
153         expiry += jiffies;
154         if (!timer_pending(&call->ack_timer) ||
155             time_after(call->ack_timer.expires, expiry))
156                 mod_timer(&call->ack_timer, expiry);
157         return;
158 
159 cancel_timer:
160         _debug("cancel timer %%%u", ntohl(serial));
161         try_to_del_timer_sync(&call->ack_timer);
162         read_lock_bh(&call->state_lock);
163         if (call->state <= RXRPC_CALL_COMPLETE &&
164             !test_and_set_bit(RXRPC_CALL_ACK, &call->events))
165                 rxrpc_queue_call(call);
166         read_unlock_bh(&call->state_lock);
167 }
168 
169 /*
170  * propose an ACK be sent, locking the call structure
171  */
172 void rxrpc_propose_ACK(struct rxrpc_call *call, u8 ack_reason,
173                        __be32 serial, bool immediate)
174 {
175         s8 prior = rxrpc_ack_priority[ack_reason];
176 
177         if (prior > rxrpc_ack_priority[call->ackr_reason]) {
178                 spin_lock_bh(&call->lock);
179                 __rxrpc_propose_ACK(call, ack_reason, serial, immediate);
180                 spin_unlock_bh(&call->lock);
181         }
182 }
183 
184 /*
185  * set the resend timer
186  */
187 static void rxrpc_set_resend(struct rxrpc_call *call, u8 resend,
188                              unsigned long resend_at)
189 {
190         read_lock_bh(&call->state_lock);
191         if (call->state >= RXRPC_CALL_COMPLETE)
192                 resend = 0;
193 
194         if (resend & 1) {
195                 _debug("SET RESEND");
196                 set_bit(RXRPC_CALL_RESEND, &call->events);
197         }
198 
199         if (resend & 2) {
200                 _debug("MODIFY RESEND TIMER");
201                 set_bit(RXRPC_CALL_RUN_RTIMER, &call->flags);
202                 mod_timer(&call->resend_timer, resend_at);
203         } else {
204                 _debug("KILL RESEND TIMER");
205                 del_timer_sync(&call->resend_timer);
206                 clear_bit(RXRPC_CALL_RESEND_TIMER, &call->events);
207                 clear_bit(RXRPC_CALL_RUN_RTIMER, &call->flags);
208         }
209         read_unlock_bh(&call->state_lock);
210 }
211 
212 /*
213  * resend packets
214  */
215 static void rxrpc_resend(struct rxrpc_call *call)
216 {
217         struct rxrpc_skb_priv *sp;
218         struct rxrpc_header *hdr;
219         struct sk_buff *txb;
220         unsigned long *p_txb, resend_at;
221         bool stop;
222         int loop;
223         u8 resend;
224 
225         _enter("{%d,%d,%d,%d},",
226                call->acks_hard, call->acks_unacked,
227                atomic_read(&call->sequence),
228                CIRC_CNT(call->acks_head, call->acks_tail, call->acks_winsz));
229 
230         stop = false;
231         resend = 0;
232         resend_at = 0;
233 
234         for (loop = call->acks_tail;
235              loop != call->acks_head || stop;
236              loop = (loop + 1) &  (call->acks_winsz - 1)
237              ) {
238                 p_txb = call->acks_window + loop;
239                 smp_read_barrier_depends();
240                 if (*p_txb & 1)
241                         continue;
242 
243                 txb = (struct sk_buff *) *p_txb;
244                 sp = rxrpc_skb(txb);
245 
246                 if (sp->need_resend) {
247                         sp->need_resend = false;
248 
249                         /* each Tx packet has a new serial number */
250                         sp->hdr.serial =
251                                 htonl(atomic_inc_return(&call->conn->serial));
252 
253                         hdr = (struct rxrpc_header *) txb->head;
254                         hdr->serial = sp->hdr.serial;
255 
256                         _proto("Tx DATA %%%u { #%d }",
257                                ntohl(sp->hdr.serial), ntohl(sp->hdr.seq));
258                         if (rxrpc_send_packet(call->conn->trans, txb) < 0) {
259                                 stop = true;
260                                 sp->resend_at = jiffies + 3;
261                         } else {
262                                 sp->resend_at =
263                                         jiffies + rxrpc_resend_timeout;
264                         }
265                 }
266 
267                 if (time_after_eq(jiffies + 1, sp->resend_at)) {
268                         sp->need_resend = true;
269                         resend |= 1;
270                 } else if (resend & 2) {
271                         if (time_before(sp->resend_at, resend_at))
272                                 resend_at = sp->resend_at;
273                 } else {
274                         resend_at = sp->resend_at;
275                         resend |= 2;
276                 }
277         }
278 
279         rxrpc_set_resend(call, resend, resend_at);
280         _leave("");
281 }
282 
283 /*
284  * handle resend timer expiry
285  */
286 static void rxrpc_resend_timer(struct rxrpc_call *call)
287 {
288         struct rxrpc_skb_priv *sp;
289         struct sk_buff *txb;
290         unsigned long *p_txb, resend_at;
291         int loop;
292         u8 resend;
293 
294         _enter("%d,%d,%d",
295                call->acks_tail, call->acks_unacked, call->acks_head);
296 
297         if (call->state >= RXRPC_CALL_COMPLETE)
298                 return;
299 
300         resend = 0;
301         resend_at = 0;
302 
303         for (loop = call->acks_unacked;
304              loop != call->acks_head;
305              loop = (loop + 1) &  (call->acks_winsz - 1)
306              ) {
307                 p_txb = call->acks_window + loop;
308                 smp_read_barrier_depends();
309                 txb = (struct sk_buff *) (*p_txb & ~1);
310                 sp = rxrpc_skb(txb);
311 
312                 ASSERT(!(*p_txb & 1));
313 
314                 if (sp->need_resend) {
315                         ;
316                 } else if (time_after_eq(jiffies + 1, sp->resend_at)) {
317                         sp->need_resend = true;
318                         resend |= 1;
319                 } else if (resend & 2) {
320                         if (time_before(sp->resend_at, resend_at))
321                                 resend_at = sp->resend_at;
322                 } else {
323                         resend_at = sp->resend_at;
324                         resend |= 2;
325                 }
326         }
327 
328         rxrpc_set_resend(call, resend, resend_at);
329         _leave("");
330 }
331 
332 /*
333  * process soft ACKs of our transmitted packets
334  * - these indicate packets the peer has or has not received, but hasn't yet
335  *   given to the consumer, and so can still be discarded and re-requested
336  */
337 static int rxrpc_process_soft_ACKs(struct rxrpc_call *call,
338                                    struct rxrpc_ackpacket *ack,
339                                    struct sk_buff *skb)
340 {
341         struct rxrpc_skb_priv *sp;
342         struct sk_buff *txb;
343         unsigned long *p_txb, resend_at;
344         int loop;
345         u8 sacks[RXRPC_MAXACKS], resend;
346 
347         _enter("{%d,%d},{%d},",
348                call->acks_hard,
349                CIRC_CNT(call->acks_head, call->acks_tail, call->acks_winsz),
350                ack->nAcks);
351 
352         if (skb_copy_bits(skb, 0, sacks, ack->nAcks) < 0)
353                 goto protocol_error;
354 
355         resend = 0;
356         resend_at = 0;
357         for (loop = 0; loop < ack->nAcks; loop++) {
358                 p_txb = call->acks_window;
359                 p_txb += (call->acks_tail + loop) & (call->acks_winsz - 1);
360                 smp_read_barrier_depends();
361                 txb = (struct sk_buff *) (*p_txb & ~1);
362                 sp = rxrpc_skb(txb);
363 
364                 switch (sacks[loop]) {
365                 case RXRPC_ACK_TYPE_ACK:
366                         sp->need_resend = false;
367                         *p_txb |= 1;
368                         break;
369                 case RXRPC_ACK_TYPE_NACK:
370                         sp->need_resend = true;
371                         *p_txb &= ~1;
372                         resend = 1;
373                         break;
374                 default:
375                         _debug("Unsupported ACK type %d", sacks[loop]);
376                         goto protocol_error;
377                 }
378         }
379 
380         smp_mb();
381         call->acks_unacked = (call->acks_tail + loop) & (call->acks_winsz - 1);
382 
383         /* anything not explicitly ACK'd is implicitly NACK'd, but may just not
384          * have been received or processed yet by the far end */
385         for (loop = call->acks_unacked;
386              loop != call->acks_head;
387              loop = (loop + 1) &  (call->acks_winsz - 1)
388              ) {
389                 p_txb = call->acks_window + loop;
390                 smp_read_barrier_depends();
391                 txb = (struct sk_buff *) (*p_txb & ~1);
392                 sp = rxrpc_skb(txb);
393 
394                 if (*p_txb & 1) {
395                         /* packet must have been discarded */
396                         sp->need_resend = true;
397                         *p_txb &= ~1;
398                         resend |= 1;
399                 } else if (sp->need_resend) {
400                         ;
401                 } else if (time_after_eq(jiffies + 1, sp->resend_at)) {
402                         sp->need_resend = true;
403                         resend |= 1;
404                 } else if (resend & 2) {
405                         if (time_before(sp->resend_at, resend_at))
406                                 resend_at = sp->resend_at;
407                 } else {
408                         resend_at = sp->resend_at;
409                         resend |= 2;
410                 }
411         }
412 
413         rxrpc_set_resend(call, resend, resend_at);
414         _leave(" = 0");
415         return 0;
416 
417 protocol_error:
418         _leave(" = -EPROTO");
419         return -EPROTO;
420 }
421 
422 /*
423  * discard hard-ACK'd packets from the Tx window
424  */
425 static void rxrpc_rotate_tx_window(struct rxrpc_call *call, u32 hard)
426 {
427         unsigned long _skb;
428         int tail = call->acks_tail, old_tail;
429         int win = CIRC_CNT(call->acks_head, tail, call->acks_winsz);
430 
431         _enter("{%u,%u},%u", call->acks_hard, win, hard);
432 
433         ASSERTCMP(hard - call->acks_hard, <=, win);
434 
435         while (call->acks_hard < hard) {
436                 smp_read_barrier_depends();
437                 _skb = call->acks_window[tail] & ~1;
438                 rxrpc_free_skb((struct sk_buff *) _skb);
439                 old_tail = tail;
440                 tail = (tail + 1) & (call->acks_winsz - 1);
441                 call->acks_tail = tail;
442                 if (call->acks_unacked == old_tail)
443                         call->acks_unacked = tail;
444                 call->acks_hard++;
445         }
446 
447         wake_up(&call->tx_waitq);
448 }
449 
450 /*
451  * clear the Tx window in the event of a failure
452  */
453 static void rxrpc_clear_tx_window(struct rxrpc_call *call)
454 {
455         rxrpc_rotate_tx_window(call, atomic_read(&call->sequence));
456 }
457 
458 /*
459  * drain the out of sequence received packet queue into the packet Rx queue
460  */
461 static int rxrpc_drain_rx_oos_queue(struct rxrpc_call *call)
462 {
463         struct rxrpc_skb_priv *sp;
464         struct sk_buff *skb;
465         bool terminal;
466         int ret;
467 
468         _enter("{%d,%d}", call->rx_data_post, call->rx_first_oos);
469 
470         spin_lock_bh(&call->lock);
471 
472         ret = -ECONNRESET;
473         if (test_bit(RXRPC_CALL_RELEASED, &call->flags))
474                 goto socket_unavailable;
475 
476         skb = skb_dequeue(&call->rx_oos_queue);
477         if (skb) {
478                 sp = rxrpc_skb(skb);
479 
480                 _debug("drain OOS packet %d [%d]",
481                        ntohl(sp->hdr.seq), call->rx_first_oos);
482 
483                 if (ntohl(sp->hdr.seq) != call->rx_first_oos) {
484                         skb_queue_head(&call->rx_oos_queue, skb);
485                         call->rx_first_oos = ntohl(rxrpc_skb(skb)->hdr.seq);
486                         _debug("requeue %p {%u}", skb, call->rx_first_oos);
487                 } else {
488                         skb->mark = RXRPC_SKB_MARK_DATA;
489                         terminal = ((sp->hdr.flags & RXRPC_LAST_PACKET) &&
490                                 !(sp->hdr.flags & RXRPC_CLIENT_INITIATED));
491                         ret = rxrpc_queue_rcv_skb(call, skb, true, terminal);
492                         BUG_ON(ret < 0);
493                         _debug("drain #%u", call->rx_data_post);
494                         call->rx_data_post++;
495 
496                         /* find out what the next packet is */
497                         skb = skb_peek(&call->rx_oos_queue);
498                         if (skb)
499                                 call->rx_first_oos =
500                                         ntohl(rxrpc_skb(skb)->hdr.seq);
501                         else
502                                 call->rx_first_oos = 0;
503                         _debug("peek %p {%u}", skb, call->rx_first_oos);
504                 }
505         }
506 
507         ret = 0;
508 socket_unavailable:
509         spin_unlock_bh(&call->lock);
510         _leave(" = %d", ret);
511         return ret;
512 }
513 
514 /*
515  * insert an out of sequence packet into the buffer
516  */
517 static void rxrpc_insert_oos_packet(struct rxrpc_call *call,
518                                     struct sk_buff *skb)
519 {
520         struct rxrpc_skb_priv *sp, *psp;
521         struct sk_buff *p;
522         u32 seq;
523 
524         sp = rxrpc_skb(skb);
525         seq = ntohl(sp->hdr.seq);
526         _enter(",,{%u}", seq);
527 
528         skb->destructor = rxrpc_packet_destructor;
529         ASSERTCMP(sp->call, ==, NULL);
530         sp->call = call;
531         rxrpc_get_call(call);
532 
533         /* insert into the buffer in sequence order */
534         spin_lock_bh(&call->lock);
535 
536         skb_queue_walk(&call->rx_oos_queue, p) {
537                 psp = rxrpc_skb(p);
538                 if (ntohl(psp->hdr.seq) > seq) {
539                         _debug("insert oos #%u before #%u",
540                                seq, ntohl(psp->hdr.seq));
541                         skb_insert(p, skb, &call->rx_oos_queue);
542                         goto inserted;
543                 }
544         }
545 
546         _debug("append oos #%u", seq);
547         skb_queue_tail(&call->rx_oos_queue, skb);
548 inserted:
549 
550         /* we might now have a new front to the queue */
551         if (call->rx_first_oos == 0 || seq < call->rx_first_oos)
552                 call->rx_first_oos = seq;
553 
554         read_lock(&call->state_lock);
555         if (call->state < RXRPC_CALL_COMPLETE &&
556             call->rx_data_post == call->rx_first_oos) {
557                 _debug("drain rx oos now");
558                 set_bit(RXRPC_CALL_DRAIN_RX_OOS, &call->events);
559         }
560         read_unlock(&call->state_lock);
561 
562         spin_unlock_bh(&call->lock);
563         _leave(" [stored #%u]", call->rx_first_oos);
564 }
565 
566 /*
567  * clear the Tx window on final ACK reception
568  */
569 static void rxrpc_zap_tx_window(struct rxrpc_call *call)
570 {
571         struct rxrpc_skb_priv *sp;
572         struct sk_buff *skb;
573         unsigned long _skb, *acks_window;
574         u8 winsz = call->acks_winsz;
575         int tail;
576 
577         acks_window = call->acks_window;
578         call->acks_window = NULL;
579 
580         while (CIRC_CNT(call->acks_head, call->acks_tail, winsz) > 0) {
581                 tail = call->acks_tail;
582                 smp_read_barrier_depends();
583                 _skb = acks_window[tail] & ~1;
584                 smp_mb();
585                 call->acks_tail = (call->acks_tail + 1) & (winsz - 1);
586 
587                 skb = (struct sk_buff *) _skb;
588                 sp = rxrpc_skb(skb);
589                 _debug("+++ clear Tx %u", ntohl(sp->hdr.seq));
590                 rxrpc_free_skb(skb);
591         }
592 
593         kfree(acks_window);
594 }
595 
596 /*
597  * process the extra information that may be appended to an ACK packet
598  */
599 static void rxrpc_extract_ackinfo(struct rxrpc_call *call, struct sk_buff *skb,
600                                   unsigned int latest, int nAcks)
601 {
602         struct rxrpc_ackinfo ackinfo;
603         struct rxrpc_peer *peer;
604         unsigned int mtu;
605 
606         if (skb_copy_bits(skb, nAcks + 3, &ackinfo, sizeof(ackinfo)) < 0) {
607                 _leave(" [no ackinfo]");
608                 return;
609         }
610 
611         _proto("Rx ACK %%%u Info { rx=%u max=%u rwin=%u jm=%u }",
612                latest,
613                ntohl(ackinfo.rxMTU), ntohl(ackinfo.maxMTU),
614                ntohl(ackinfo.rwind), ntohl(ackinfo.jumbo_max));
615 
616         mtu = min(ntohl(ackinfo.rxMTU), ntohl(ackinfo.maxMTU));
617 
618         peer = call->conn->trans->peer;
619         if (mtu < peer->maxdata) {
620                 spin_lock_bh(&peer->lock);
621                 peer->maxdata = mtu;
622                 peer->mtu = mtu + peer->hdrsize;
623                 spin_unlock_bh(&peer->lock);
624                 _net("Net MTU %u (maxdata %u)", peer->mtu, peer->maxdata);
625         }
626 }
627 
628 /*
629  * process packets in the reception queue
630  */
631 static int rxrpc_process_rx_queue(struct rxrpc_call *call,
632                                   u32 *_abort_code)
633 {
634         struct rxrpc_ackpacket ack;
635         struct rxrpc_skb_priv *sp;
636         struct sk_buff *skb;
637         bool post_ACK;
638         int latest;
639         u32 hard, tx;
640 
641         _enter("");
642 
643 process_further:
644         skb = skb_dequeue(&call->rx_queue);
645         if (!skb)
646                 return -EAGAIN;
647 
648         _net("deferred skb %p", skb);
649 
650         sp = rxrpc_skb(skb);
651 
652         _debug("process %s [st %d]", rxrpc_pkts[sp->hdr.type], call->state);
653 
654         post_ACK = false;
655 
656         switch (sp->hdr.type) {
657                 /* data packets that wind up here have been received out of
658                  * order, need security processing or are jumbo packets */
659         case RXRPC_PACKET_TYPE_DATA:
660                 _proto("OOSQ DATA %%%u { #%u }",
661                        ntohl(sp->hdr.serial), ntohl(sp->hdr.seq));
662 
663                 /* secured packets must be verified and possibly decrypted */
664                 if (rxrpc_verify_packet(call, skb, _abort_code) < 0)
665                         goto protocol_error;
666 
667                 rxrpc_insert_oos_packet(call, skb);
668                 goto process_further;
669 
670                 /* partial ACK to process */
671         case RXRPC_PACKET_TYPE_ACK:
672                 if (skb_copy_bits(skb, 0, &ack, sizeof(ack)) < 0) {
673                         _debug("extraction failure");
674                         goto protocol_error;
675                 }
676                 if (!skb_pull(skb, sizeof(ack)))
677                         BUG();
678 
679                 latest = ntohl(sp->hdr.serial);
680                 hard = ntohl(ack.firstPacket);
681                 tx = atomic_read(&call->sequence);
682 
683                 _proto("Rx ACK %%%u { m=%hu f=#%u p=#%u s=%%%u r=%s n=%u }",
684                        latest,
685                        ntohs(ack.maxSkew),
686                        hard,
687                        ntohl(ack.previousPacket),
688                        ntohl(ack.serial),
689                        rxrpc_acks(ack.reason),
690                        ack.nAcks);
691 
692                 rxrpc_extract_ackinfo(call, skb, latest, ack.nAcks);
693 
694                 if (ack.reason == RXRPC_ACK_PING) {
695                         _proto("Rx ACK %%%u PING Request", latest);
696                         rxrpc_propose_ACK(call, RXRPC_ACK_PING_RESPONSE,
697                                           sp->hdr.serial, true);
698                 }
699 
700                 /* discard any out-of-order or duplicate ACKs */
701                 if (latest - call->acks_latest <= 0) {
702                         _debug("discard ACK %d <= %d",
703                                latest, call->acks_latest);
704                         goto discard;
705                 }
706                 call->acks_latest = latest;
707 
708                 if (call->state != RXRPC_CALL_CLIENT_SEND_REQUEST &&
709                     call->state != RXRPC_CALL_CLIENT_AWAIT_REPLY &&
710                     call->state != RXRPC_CALL_SERVER_SEND_REPLY &&
711                     call->state != RXRPC_CALL_SERVER_AWAIT_ACK)
712                         goto discard;
713 
714                 _debug("Tx=%d H=%u S=%d", tx, call->acks_hard, call->state);
715 
716                 if (hard > 0) {
717                         if (hard - 1 > tx) {
718                                 _debug("hard-ACK'd packet %d not transmitted"
719                                        " (%d top)",
720                                        hard - 1, tx);
721                                 goto protocol_error;
722                         }
723 
724                         if ((call->state == RXRPC_CALL_CLIENT_AWAIT_REPLY ||
725                              call->state == RXRPC_CALL_SERVER_AWAIT_ACK) &&
726                             hard > tx)
727                                 goto all_acked;
728 
729                         smp_rmb();
730                         rxrpc_rotate_tx_window(call, hard - 1);
731                 }
732 
733                 if (ack.nAcks > 0) {
734                         if (hard - 1 + ack.nAcks > tx) {
735                                 _debug("soft-ACK'd packet %d+%d not"
736                                        " transmitted (%d top)",
737                                        hard - 1, ack.nAcks, tx);
738                                 goto protocol_error;
739                         }
740 
741                         if (rxrpc_process_soft_ACKs(call, &ack, skb) < 0)
742                                 goto protocol_error;
743                 }
744                 goto discard;
745 
746                 /* complete ACK to process */
747         case RXRPC_PACKET_TYPE_ACKALL:
748                 goto all_acked;
749 
750                 /* abort and busy are handled elsewhere */
751         case RXRPC_PACKET_TYPE_BUSY:
752         case RXRPC_PACKET_TYPE_ABORT:
753                 BUG();
754 
755                 /* connection level events - also handled elsewhere */
756         case RXRPC_PACKET_TYPE_CHALLENGE:
757         case RXRPC_PACKET_TYPE_RESPONSE:
758         case RXRPC_PACKET_TYPE_DEBUG:
759                 BUG();
760         }
761 
762         /* if we've had a hard ACK that covers all the packets we've sent, then
763          * that ends that phase of the operation */
764 all_acked:
765         write_lock_bh(&call->state_lock);
766         _debug("ack all %d", call->state);
767 
768         switch (call->state) {
769         case RXRPC_CALL_CLIENT_AWAIT_REPLY:
770                 call->state = RXRPC_CALL_CLIENT_RECV_REPLY;
771                 break;
772         case RXRPC_CALL_SERVER_AWAIT_ACK:
773                 _debug("srv complete");
774                 call->state = RXRPC_CALL_COMPLETE;
775                 post_ACK = true;
776                 break;
777         case RXRPC_CALL_CLIENT_SEND_REQUEST:
778         case RXRPC_CALL_SERVER_RECV_REQUEST:
779                 goto protocol_error_unlock; /* can't occur yet */
780         default:
781                 write_unlock_bh(&call->state_lock);
782                 goto discard; /* assume packet left over from earlier phase */
783         }
784 
785         write_unlock_bh(&call->state_lock);
786 
787         /* if all the packets we sent are hard-ACK'd, then we can discard
788          * whatever we've got left */
789         _debug("clear Tx %d",
790                CIRC_CNT(call->acks_head, call->acks_tail, call->acks_winsz));
791 
792         del_timer_sync(&call->resend_timer);
793         clear_bit(RXRPC_CALL_RUN_RTIMER, &call->flags);
794         clear_bit(RXRPC_CALL_RESEND_TIMER, &call->events);
795 
796         if (call->acks_window)
797                 rxrpc_zap_tx_window(call);
798 
799         if (post_ACK) {
800                 /* post the final ACK message for userspace to pick up */
801                 _debug("post ACK");
802                 skb->mark = RXRPC_SKB_MARK_FINAL_ACK;
803                 sp->call = call;
804                 rxrpc_get_call(call);
805                 spin_lock_bh(&call->lock);
806                 if (rxrpc_queue_rcv_skb(call, skb, true, true) < 0)
807                         BUG();
808                 spin_unlock_bh(&call->lock);
809                 goto process_further;
810         }
811 
812 discard:
813         rxrpc_free_skb(skb);
814         goto process_further;
815 
816 protocol_error_unlock:
817         write_unlock_bh(&call->state_lock);
818 protocol_error:
819         rxrpc_free_skb(skb);
820         _leave(" = -EPROTO");
821         return -EPROTO;
822 }
823 
824 /*
825  * post a message to the socket Rx queue for recvmsg() to pick up
826  */
827 static int rxrpc_post_message(struct rxrpc_call *call, u32 mark, u32 error,
828                               bool fatal)
829 {
830         struct rxrpc_skb_priv *sp;
831         struct sk_buff *skb;
832         int ret;
833 
834         _enter("{%d,%lx},%u,%u,%d",
835                call->debug_id, call->flags, mark, error, fatal);
836 
837         /* remove timers and things for fatal messages */
838         if (fatal) {
839                 del_timer_sync(&call->resend_timer);
840                 del_timer_sync(&call->ack_timer);
841                 clear_bit(RXRPC_CALL_RUN_RTIMER, &call->flags);
842         }
843 
844         if (mark != RXRPC_SKB_MARK_NEW_CALL &&
845             !test_bit(RXRPC_CALL_HAS_USERID, &call->flags)) {
846                 _leave("[no userid]");
847                 return 0;
848         }
849 
850         if (!test_bit(RXRPC_CALL_TERMINAL_MSG, &call->flags)) {
851                 skb = alloc_skb(0, GFP_NOFS);
852                 if (!skb)
853                         return -ENOMEM;
854 
855                 rxrpc_new_skb(skb);
856 
857                 skb->mark = mark;
858 
859                 sp = rxrpc_skb(skb);
860                 memset(sp, 0, sizeof(*sp));
861                 sp->error = error;
862                 sp->call = call;
863                 rxrpc_get_call(call);
864 
865                 spin_lock_bh(&call->lock);
866                 ret = rxrpc_queue_rcv_skb(call, skb, true, fatal);
867                 spin_unlock_bh(&call->lock);
868                 BUG_ON(ret < 0);
869         }
870 
871         return 0;
872 }
873 
874 /*
875  * handle background processing of incoming call packets and ACK / abort
876  * generation
877  */
878 void rxrpc_process_call(struct work_struct *work)
879 {
880         struct rxrpc_call *call =
881                 container_of(work, struct rxrpc_call, processor);
882         struct rxrpc_ackpacket ack;
883         struct rxrpc_ackinfo ackinfo;
884         struct rxrpc_header hdr;
885         struct msghdr msg;
886         struct kvec iov[5];
887         unsigned long bits;
888         __be32 data, pad;
889         size_t len;
890         int genbit, loop, nbit, ioc, ret, mtu;
891         u32 abort_code = RX_PROTOCOL_ERROR;
892         u8 *acks = NULL;
893 
894         //printk("\n--------------------\n");
895         _enter("{%d,%s,%lx} [%lu]",
896                call->debug_id, rxrpc_call_states[call->state], call->events,
897                (jiffies - call->creation_jif) / (HZ / 10));
898 
899         if (test_and_set_bit(RXRPC_CALL_PROC_BUSY, &call->flags)) {
900                 _debug("XXXXXXXXXXXXX RUNNING ON MULTIPLE CPUS XXXXXXXXXXXXX");
901                 return;
902         }
903 
904         /* there's a good chance we're going to have to send a message, so set
905          * one up in advance */
906         msg.msg_name    = &call->conn->trans->peer->srx.transport.sin;
907         msg.msg_namelen = sizeof(call->conn->trans->peer->srx.transport.sin);
908         msg.msg_control = NULL;
909         msg.msg_controllen = 0;
910         msg.msg_flags   = 0;
911 
912         hdr.epoch       = call->conn->epoch;
913         hdr.cid         = call->cid;
914         hdr.callNumber  = call->call_id;
915         hdr.seq         = 0;
916         hdr.type        = RXRPC_PACKET_TYPE_ACK;
917         hdr.flags       = call->conn->out_clientflag;
918         hdr.userStatus  = 0;
919         hdr.securityIndex = call->conn->security_ix;
920         hdr._rsvd       = 0;
921         hdr.serviceId   = call->conn->service_id;
922 
923         memset(iov, 0, sizeof(iov));
924         iov[0].iov_base = &hdr;
925         iov[0].iov_len  = sizeof(hdr);
926 
927         /* deal with events of a final nature */
928         if (test_bit(RXRPC_CALL_RELEASE, &call->events)) {
929                 rxrpc_release_call(call);
930                 clear_bit(RXRPC_CALL_RELEASE, &call->events);
931         }
932 
933         if (test_bit(RXRPC_CALL_RCVD_ERROR, &call->events)) {
934                 int error;
935 
936                 clear_bit(RXRPC_CALL_CONN_ABORT, &call->events);
937                 clear_bit(RXRPC_CALL_REJECT_BUSY, &call->events);
938                 clear_bit(RXRPC_CALL_ABORT, &call->events);
939 
940                 error = call->conn->trans->peer->net_error;
941                 _debug("post net error %d", error);
942 
943                 if (rxrpc_post_message(call, RXRPC_SKB_MARK_NET_ERROR,
944                                        error, true) < 0)
945                         goto no_mem;
946                 clear_bit(RXRPC_CALL_RCVD_ERROR, &call->events);
947                 goto kill_ACKs;
948         }
949 
950         if (test_bit(RXRPC_CALL_CONN_ABORT, &call->events)) {
951                 ASSERTCMP(call->state, >, RXRPC_CALL_COMPLETE);
952 
953                 clear_bit(RXRPC_CALL_REJECT_BUSY, &call->events);
954                 clear_bit(RXRPC_CALL_ABORT, &call->events);
955 
956                 _debug("post conn abort");
957 
958                 if (rxrpc_post_message(call, RXRPC_SKB_MARK_LOCAL_ERROR,
959                                        call->conn->error, true) < 0)
960                         goto no_mem;
961                 clear_bit(RXRPC_CALL_CONN_ABORT, &call->events);
962                 goto kill_ACKs;
963         }
964 
965         if (test_bit(RXRPC_CALL_REJECT_BUSY, &call->events)) {
966                 hdr.type = RXRPC_PACKET_TYPE_BUSY;
967                 genbit = RXRPC_CALL_REJECT_BUSY;
968                 goto send_message;
969         }
970 
971         if (test_bit(RXRPC_CALL_ABORT, &call->events)) {
972                 ASSERTCMP(call->state, >, RXRPC_CALL_COMPLETE);
973 
974                 if (rxrpc_post_message(call, RXRPC_SKB_MARK_LOCAL_ERROR,
975                                        ECONNABORTED, true) < 0)
976                         goto no_mem;
977                 hdr.type = RXRPC_PACKET_TYPE_ABORT;
978                 data = htonl(call->abort_code);
979                 iov[1].iov_base = &data;
980                 iov[1].iov_len = sizeof(data);
981                 genbit = RXRPC_CALL_ABORT;
982                 goto send_message;
983         }
984 
985         if (test_bit(RXRPC_CALL_ACK_FINAL, &call->events)) {
986                 genbit = RXRPC_CALL_ACK_FINAL;
987 
988                 ack.bufferSpace = htons(8);
989                 ack.maxSkew     = 0;
990                 ack.serial      = 0;
991                 ack.reason      = RXRPC_ACK_IDLE;
992                 ack.nAcks       = 0;
993                 call->ackr_reason = 0;
994 
995                 spin_lock_bh(&call->lock);
996                 ack.serial = call->ackr_serial;
997                 ack.previousPacket = call->ackr_prev_seq;
998                 ack.firstPacket = htonl(call->rx_data_eaten + 1);
999                 spin_unlock_bh(&call->lock);
1000 
1001                 pad = 0;
1002 
1003                 iov[1].iov_base = &ack;
1004                 iov[1].iov_len  = sizeof(ack);
1005                 iov[2].iov_base = &pad;
1006                 iov[2].iov_len  = 3;
1007                 iov[3].iov_base = &ackinfo;
1008                 iov[3].iov_len  = sizeof(ackinfo);
1009                 goto send_ACK;
1010         }
1011 
1012         if (call->events & ((1 << RXRPC_CALL_RCVD_BUSY) |
1013                             (1 << RXRPC_CALL_RCVD_ABORT))
1014             ) {
1015                 u32 mark;
1016 
1017                 if (test_bit(RXRPC_CALL_RCVD_ABORT, &call->events))
1018                         mark = RXRPC_SKB_MARK_REMOTE_ABORT;
1019                 else
1020                         mark = RXRPC_SKB_MARK_BUSY;
1021 
1022                 _debug("post abort/busy");
1023                 rxrpc_clear_tx_window(call);
1024                 if (rxrpc_post_message(call, mark, ECONNABORTED, true) < 0)
1025                         goto no_mem;
1026 
1027                 clear_bit(RXRPC_CALL_RCVD_BUSY, &call->events);
1028                 clear_bit(RXRPC_CALL_RCVD_ABORT, &call->events);
1029                 goto kill_ACKs;
1030         }
1031 
1032         if (test_and_clear_bit(RXRPC_CALL_RCVD_ACKALL, &call->events)) {
1033                 _debug("do implicit ackall");
1034                 rxrpc_clear_tx_window(call);
1035         }
1036 
1037         if (test_bit(RXRPC_CALL_LIFE_TIMER, &call->events)) {
1038                 write_lock_bh(&call->state_lock);
1039                 if (call->state <= RXRPC_CALL_COMPLETE) {
1040                         call->state = RXRPC_CALL_LOCALLY_ABORTED;
1041                         call->abort_code = RX_CALL_TIMEOUT;
1042                         set_bit(RXRPC_CALL_ABORT, &call->events);
1043                 }
1044                 write_unlock_bh(&call->state_lock);
1045 
1046                 _debug("post timeout");
1047                 if (rxrpc_post_message(call, RXRPC_SKB_MARK_LOCAL_ERROR,
1048                                        ETIME, true) < 0)
1049                         goto no_mem;
1050 
1051                 clear_bit(RXRPC_CALL_LIFE_TIMER, &call->events);
1052                 goto kill_ACKs;
1053         }
1054 
1055         /* deal with assorted inbound messages */
1056         if (!skb_queue_empty(&call->rx_queue)) {
1057                 switch (rxrpc_process_rx_queue(call, &abort_code)) {
1058                 case 0:
1059                 case -EAGAIN:
1060                         break;
1061                 case -ENOMEM:
1062                         goto no_mem;
1063                 case -EKEYEXPIRED:
1064                 case -EKEYREJECTED:
1065                 case -EPROTO:
1066                         rxrpc_abort_call(call, abort_code);
1067                         goto kill_ACKs;
1068                 }
1069         }
1070 
1071         /* handle resending */
1072         if (test_and_clear_bit(RXRPC_CALL_RESEND_TIMER, &call->events))
1073                 rxrpc_resend_timer(call);
1074         if (test_and_clear_bit(RXRPC_CALL_RESEND, &call->events))
1075                 rxrpc_resend(call);
1076 
1077         /* consider sending an ordinary ACK */
1078         if (test_bit(RXRPC_CALL_ACK, &call->events)) {
1079                 _debug("send ACK: window: %d - %d { %lx }",
1080                        call->rx_data_eaten, call->ackr_win_top,
1081                        call->ackr_window[0]);
1082 
1083                 if (call->state > RXRPC_CALL_SERVER_ACK_REQUEST &&
1084                     call->ackr_reason != RXRPC_ACK_PING_RESPONSE) {
1085                         /* ACK by sending reply DATA packet in this state */
1086                         clear_bit(RXRPC_CALL_ACK, &call->events);
1087                         goto maybe_reschedule;
1088                 }
1089 
1090                 genbit = RXRPC_CALL_ACK;
1091 
1092                 acks = kzalloc(call->ackr_win_top - call->rx_data_eaten,
1093                                GFP_NOFS);
1094                 if (!acks)
1095                         goto no_mem;
1096 
1097                 //hdr.flags     = RXRPC_SLOW_START_OK;
1098                 ack.bufferSpace = htons(8);
1099                 ack.maxSkew     = 0;
1100                 ack.serial      = 0;
1101                 ack.reason      = 0;
1102 
1103                 spin_lock_bh(&call->lock);
1104                 ack.reason = call->ackr_reason;
1105                 ack.serial = call->ackr_serial;
1106                 ack.previousPacket = call->ackr_prev_seq;
1107                 ack.firstPacket = htonl(call->rx_data_eaten + 1);
1108 
1109                 ack.nAcks = 0;
1110                 for (loop = 0; loop < RXRPC_ACKR_WINDOW_ASZ; loop++) {
1111                         nbit = loop * BITS_PER_LONG;
1112                         for (bits = call->ackr_window[loop]; bits; bits >>= 1
1113                              ) {
1114                                 _debug("- l=%d n=%d b=%lx", loop, nbit, bits);
1115                                 if (bits & 1) {
1116                                         acks[nbit] = RXRPC_ACK_TYPE_ACK;
1117                                         ack.nAcks = nbit + 1;
1118                                 }
1119                                 nbit++;
1120                         }
1121                 }
1122                 call->ackr_reason = 0;
1123                 spin_unlock_bh(&call->lock);
1124 
1125                 pad = 0;
1126 
1127                 iov[1].iov_base = &ack;
1128                 iov[1].iov_len  = sizeof(ack);
1129                 iov[2].iov_base = acks;
1130                 iov[2].iov_len  = ack.nAcks;
1131                 iov[3].iov_base = &pad;
1132                 iov[3].iov_len  = 3;
1133                 iov[4].iov_base = &ackinfo;
1134                 iov[4].iov_len  = sizeof(ackinfo);
1135 
1136                 switch (ack.reason) {
1137                 case RXRPC_ACK_REQUESTED:
1138                 case RXRPC_ACK_DUPLICATE:
1139                 case RXRPC_ACK_OUT_OF_SEQUENCE:
1140                 case RXRPC_ACK_EXCEEDS_WINDOW:
1141                 case RXRPC_ACK_NOSPACE:
1142                 case RXRPC_ACK_PING:
1143                 case RXRPC_ACK_PING_RESPONSE:
1144                         goto send_ACK_with_skew;
1145                 case RXRPC_ACK_DELAY:
1146                 case RXRPC_ACK_IDLE:
1147                         goto send_ACK;
1148                 }
1149         }
1150 
1151         /* handle completion of security negotiations on an incoming
1152          * connection */
1153         if (test_and_clear_bit(RXRPC_CALL_SECURED, &call->events)) {
1154                 _debug("secured");
1155                 spin_lock_bh(&call->lock);
1156 
1157                 if (call->state == RXRPC_CALL_SERVER_SECURING) {
1158                         _debug("securing");
1159                         write_lock(&call->conn->lock);
1160                         if (!test_bit(RXRPC_CALL_RELEASED, &call->flags) &&
1161                             !test_bit(RXRPC_CALL_RELEASE, &call->events)) {
1162                                 _debug("not released");
1163                                 call->state = RXRPC_CALL_SERVER_ACCEPTING;
1164                                 list_move_tail(&call->accept_link,
1165                                                &call->socket->acceptq);
1166                         }
1167                         write_unlock(&call->conn->lock);
1168                         read_lock(&call->state_lock);
1169                         if (call->state < RXRPC_CALL_COMPLETE)
1170                                 set_bit(RXRPC_CALL_POST_ACCEPT, &call->events);
1171                         read_unlock(&call->state_lock);
1172                 }
1173 
1174                 spin_unlock_bh(&call->lock);
1175                 if (!test_bit(RXRPC_CALL_POST_ACCEPT, &call->events))
1176                         goto maybe_reschedule;
1177         }
1178 
1179         /* post a notification of an acceptable connection to the app */
1180         if (test_bit(RXRPC_CALL_POST_ACCEPT, &call->events)) {
1181                 _debug("post accept");
1182                 if (rxrpc_post_message(call, RXRPC_SKB_MARK_NEW_CALL,
1183                                        0, false) < 0)
1184                         goto no_mem;
1185                 clear_bit(RXRPC_CALL_POST_ACCEPT, &call->events);
1186                 goto maybe_reschedule;
1187         }
1188 
1189         /* handle incoming call acceptance */
1190         if (test_and_clear_bit(RXRPC_CALL_ACCEPTED, &call->events)) {
1191                 _debug("accepted");
1192                 ASSERTCMP(call->rx_data_post, ==, 0);
1193                 call->rx_data_post = 1;
1194                 read_lock_bh(&call->state_lock);
1195                 if (call->state < RXRPC_CALL_COMPLETE)
1196                         set_bit(RXRPC_CALL_DRAIN_RX_OOS, &call->events);
1197                 read_unlock_bh(&call->state_lock);
1198         }
1199 
1200         /* drain the out of sequence received packet queue into the packet Rx
1201          * queue */
1202         if (test_and_clear_bit(RXRPC_CALL_DRAIN_RX_OOS, &call->events)) {
1203                 while (call->rx_data_post == call->rx_first_oos)
1204                         if (rxrpc_drain_rx_oos_queue(call) < 0)
1205                                 break;
1206                 goto maybe_reschedule;
1207         }
1208 
1209         /* other events may have been raised since we started checking */
1210         goto maybe_reschedule;
1211 
1212 send_ACK_with_skew:
1213         ack.maxSkew = htons(atomic_read(&call->conn->hi_serial) -
1214                             ntohl(ack.serial));
1215 send_ACK:
1216         mtu = call->conn->trans->peer->if_mtu;
1217         mtu -= call->conn->trans->peer->hdrsize;
1218         ackinfo.maxMTU  = htonl(mtu);
1219         ackinfo.rwind   = htonl(rxrpc_rx_window_size);
1220 
1221         /* permit the peer to send us jumbo packets if it wants to */
1222         ackinfo.rxMTU   = htonl(rxrpc_rx_mtu);
1223         ackinfo.jumbo_max = htonl(rxrpc_rx_jumbo_max);
1224 
1225         hdr.serial = htonl(atomic_inc_return(&call->conn->serial));
1226         _proto("Tx ACK %%%u { m=%hu f=#%u p=#%u s=%%%u r=%s n=%u }",
1227                ntohl(hdr.serial),
1228                ntohs(ack.maxSkew),
1229                ntohl(ack.firstPacket),
1230                ntohl(ack.previousPacket),
1231                ntohl(ack.serial),
1232                rxrpc_acks(ack.reason),
1233                ack.nAcks);
1234 
1235         del_timer_sync(&call->ack_timer);
1236         if (ack.nAcks > 0)
1237                 set_bit(RXRPC_CALL_TX_SOFT_ACK, &call->flags);
1238         goto send_message_2;
1239 
1240 send_message:
1241         _debug("send message");
1242 
1243         hdr.serial = htonl(atomic_inc_return(&call->conn->serial));
1244         _proto("Tx %s %%%u", rxrpc_pkts[hdr.type], ntohl(hdr.serial));
1245 send_message_2:
1246 
1247         len = iov[0].iov_len;
1248         ioc = 1;
1249         if (iov[4].iov_len) {
1250                 ioc = 5;
1251                 len += iov[4].iov_len;
1252                 len += iov[3].iov_len;
1253                 len += iov[2].iov_len;
1254                 len += iov[1].iov_len;
1255         } else if (iov[3].iov_len) {
1256                 ioc = 4;
1257                 len += iov[3].iov_len;
1258                 len += iov[2].iov_len;
1259                 len += iov[1].iov_len;
1260         } else if (iov[2].iov_len) {
1261                 ioc = 3;
1262                 len += iov[2].iov_len;
1263                 len += iov[1].iov_len;
1264         } else if (iov[1].iov_len) {
1265                 ioc = 2;
1266                 len += iov[1].iov_len;
1267         }
1268 
1269         ret = kernel_sendmsg(call->conn->trans->local->socket,
1270                              &msg, iov, ioc, len);
1271         if (ret < 0) {
1272                 _debug("sendmsg failed: %d", ret);
1273                 read_lock_bh(&call->state_lock);
1274                 if (call->state < RXRPC_CALL_DEAD)
1275                         rxrpc_queue_call(call);
1276                 read_unlock_bh(&call->state_lock);
1277                 goto error;
1278         }
1279 
1280         switch (genbit) {
1281         case RXRPC_CALL_ABORT:
1282                 clear_bit(genbit, &call->events);
1283                 clear_bit(RXRPC_CALL_RCVD_ABORT, &call->events);
1284                 goto kill_ACKs;
1285 
1286         case RXRPC_CALL_ACK_FINAL:
1287                 write_lock_bh(&call->state_lock);
1288                 if (call->state == RXRPC_CALL_CLIENT_FINAL_ACK)
1289                         call->state = RXRPC_CALL_COMPLETE;
1290                 write_unlock_bh(&call->state_lock);
1291                 goto kill_ACKs;
1292 
1293         default:
1294                 clear_bit(genbit, &call->events);
1295                 switch (call->state) {
1296                 case RXRPC_CALL_CLIENT_AWAIT_REPLY:
1297                 case RXRPC_CALL_CLIENT_RECV_REPLY:
1298                 case RXRPC_CALL_SERVER_RECV_REQUEST:
1299                 case RXRPC_CALL_SERVER_ACK_REQUEST:
1300                         _debug("start ACK timer");
1301                         rxrpc_propose_ACK(call, RXRPC_ACK_DELAY,
1302                                           call->ackr_serial, false);
1303                 default:
1304                         break;
1305                 }
1306                 goto maybe_reschedule;
1307         }
1308 
1309 kill_ACKs:
1310         del_timer_sync(&call->ack_timer);
1311         if (test_and_clear_bit(RXRPC_CALL_ACK_FINAL, &call->events))
1312                 rxrpc_put_call(call);
1313         clear_bit(RXRPC_CALL_ACK, &call->events);
1314 
1315 maybe_reschedule:
1316         if (call->events || !skb_queue_empty(&call->rx_queue)) {
1317                 read_lock_bh(&call->state_lock);
1318                 if (call->state < RXRPC_CALL_DEAD)
1319                         rxrpc_queue_call(call);
1320                 read_unlock_bh(&call->state_lock);
1321         }
1322 
1323         /* don't leave aborted connections on the accept queue */
1324         if (call->state >= RXRPC_CALL_COMPLETE &&
1325             !list_empty(&call->accept_link)) {
1326                 _debug("X unlinking once-pending call %p { e=%lx f=%lx c=%x }",
1327                        call, call->events, call->flags,
1328                        ntohl(call->conn->cid));
1329 
1330                 read_lock_bh(&call->state_lock);
1331                 if (!test_bit(RXRPC_CALL_RELEASED, &call->flags) &&
1332                     !test_and_set_bit(RXRPC_CALL_RELEASE, &call->events))
1333                         rxrpc_queue_call(call);
1334                 read_unlock_bh(&call->state_lock);
1335         }
1336 
1337 error:
1338         clear_bit(RXRPC_CALL_PROC_BUSY, &call->flags);
1339         kfree(acks);
1340 
1341         /* because we don't want two CPUs both processing the work item for one
1342          * call at the same time, we use a flag to note when it's busy; however
1343          * this means there's a race between clearing the flag and setting the
1344          * work pending bit and the work item being processed again */
1345         if (call->events && !work_pending(&call->processor)) {
1346                 _debug("jumpstart %x", ntohl(call->conn->cid));
1347                 rxrpc_queue_call(call);
1348         }
1349 
1350         _leave("");
1351         return;
1352 
1353 no_mem:
1354         _debug("out of memory");
1355         goto maybe_reschedule;
1356 }
1357 

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