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

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