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TOMOYO Linux Cross Reference
Linux/net/rxrpc/call_accept.c

Version: ~ [ linux-5.7-rc7 ] ~ [ linux-5.6.14 ] ~ [ linux-5.5.19 ] ~ [ linux-5.4.42 ] ~ [ linux-5.3.18 ] ~ [ linux-5.2.21 ] ~ [ linux-5.1.21 ] ~ [ linux-5.0.21 ] ~ [ linux-4.20.17 ] ~ [ linux-4.19.124 ] ~ [ linux-4.18.20 ] ~ [ linux-4.17.19 ] ~ [ linux-4.16.18 ] ~ [ linux-4.15.18 ] ~ [ linux-4.14.181 ] ~ [ linux-4.13.16 ] ~ [ linux-4.12.14 ] ~ [ linux-4.11.12 ] ~ [ linux-4.10.17 ] ~ [ linux-4.9.224 ] ~ [ linux-4.8.17 ] ~ [ linux-4.7.10 ] ~ [ linux-4.6.7 ] ~ [ linux-4.5.7 ] ~ [ linux-4.4.224 ] ~ [ linux-4.3.6 ] ~ [ linux-4.2.8 ] ~ [ linux-4.1.52 ] ~ [ linux-4.0.9 ] ~ [ linux-3.19.8 ] ~ [ linux-3.18.140 ] ~ [ linux-3.17.8 ] ~ [ linux-3.16.84 ] ~ [ linux-3.15.10 ] ~ [ linux-3.14.79 ] ~ [ linux-3.13.11 ] ~ [ linux-3.12.74 ] ~ [ linux-3.11.10 ] ~ [ linux-3.10.108 ] ~ [ linux-2.6.32.71 ] ~ [ linux-2.6.0 ] ~ [ linux-2.4.37.11 ] ~ [ unix-v6-master ] ~ [ ccs-tools-1.8.5 ] ~ [ policy-sample ] ~
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  1 /* incoming call handling
  2  *
  3  * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
  4  * Written by David Howells (dhowells@redhat.com)
  5  *
  6  * This program is free software; you can redistribute it and/or
  7  * modify it under the terms of the GNU General Public License
  8  * as published by the Free Software Foundation; either version
  9  * 2 of the License, or (at your option) any later version.
 10  */
 11 
 12 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
 13 
 14 #include <linux/module.h>
 15 #include <linux/net.h>
 16 #include <linux/skbuff.h>
 17 #include <linux/errqueue.h>
 18 #include <linux/udp.h>
 19 #include <linux/in.h>
 20 #include <linux/in6.h>
 21 #include <linux/icmp.h>
 22 #include <linux/gfp.h>
 23 #include <linux/circ_buf.h>
 24 #include <net/sock.h>
 25 #include <net/af_rxrpc.h>
 26 #include <net/ip.h>
 27 #include "ar-internal.h"
 28 
 29 /*
 30  * Preallocate a single service call, connection and peer and, if possible,
 31  * give them a user ID and attach the user's side of the ID to them.
 32  */
 33 static int rxrpc_service_prealloc_one(struct rxrpc_sock *rx,
 34                                       struct rxrpc_backlog *b,
 35                                       rxrpc_notify_rx_t notify_rx,
 36                                       rxrpc_user_attach_call_t user_attach_call,
 37                                       unsigned long user_call_ID, gfp_t gfp,
 38                                       unsigned int debug_id)
 39 {
 40         const void *here = __builtin_return_address(0);
 41         struct rxrpc_call *call;
 42         struct rxrpc_net *rxnet = rxrpc_net(sock_net(&rx->sk));
 43         int max, tmp;
 44         unsigned int size = RXRPC_BACKLOG_MAX;
 45         unsigned int head, tail, call_head, call_tail;
 46 
 47         max = rx->sk.sk_max_ack_backlog;
 48         tmp = rx->sk.sk_ack_backlog;
 49         if (tmp >= max) {
 50                 _leave(" = -ENOBUFS [full %u]", max);
 51                 return -ENOBUFS;
 52         }
 53         max -= tmp;
 54 
 55         /* We don't need more conns and peers than we have calls, but on the
 56          * other hand, we shouldn't ever use more peers than conns or conns
 57          * than calls.
 58          */
 59         call_head = b->call_backlog_head;
 60         call_tail = READ_ONCE(b->call_backlog_tail);
 61         tmp = CIRC_CNT(call_head, call_tail, size);
 62         if (tmp >= max) {
 63                 _leave(" = -ENOBUFS [enough %u]", tmp);
 64                 return -ENOBUFS;
 65         }
 66         max = tmp + 1;
 67 
 68         head = b->peer_backlog_head;
 69         tail = READ_ONCE(b->peer_backlog_tail);
 70         if (CIRC_CNT(head, tail, size) < max) {
 71                 struct rxrpc_peer *peer = rxrpc_alloc_peer(rx->local, gfp);
 72                 if (!peer)
 73                         return -ENOMEM;
 74                 b->peer_backlog[head] = peer;
 75                 smp_store_release(&b->peer_backlog_head,
 76                                   (head + 1) & (size - 1));
 77         }
 78 
 79         head = b->conn_backlog_head;
 80         tail = READ_ONCE(b->conn_backlog_tail);
 81         if (CIRC_CNT(head, tail, size) < max) {
 82                 struct rxrpc_connection *conn;
 83 
 84                 conn = rxrpc_prealloc_service_connection(rxnet, gfp);
 85                 if (!conn)
 86                         return -ENOMEM;
 87                 b->conn_backlog[head] = conn;
 88                 smp_store_release(&b->conn_backlog_head,
 89                                   (head + 1) & (size - 1));
 90 
 91                 trace_rxrpc_conn(conn, rxrpc_conn_new_service,
 92                                  atomic_read(&conn->usage), here);
 93         }
 94 
 95         /* Now it gets complicated, because calls get registered with the
 96          * socket here, particularly if a user ID is preassigned by the user.
 97          */
 98         call = rxrpc_alloc_call(rx, gfp, debug_id);
 99         if (!call)
100                 return -ENOMEM;
101         call->flags |= (1 << RXRPC_CALL_IS_SERVICE);
102         call->state = RXRPC_CALL_SERVER_PREALLOC;
103 
104         trace_rxrpc_call(call, rxrpc_call_new_service,
105                          atomic_read(&call->usage),
106                          here, (const void *)user_call_ID);
107 
108         write_lock(&rx->call_lock);
109         if (user_attach_call) {
110                 struct rxrpc_call *xcall;
111                 struct rb_node *parent, **pp;
112 
113                 /* Check the user ID isn't already in use */
114                 pp = &rx->calls.rb_node;
115                 parent = NULL;
116                 while (*pp) {
117                         parent = *pp;
118                         xcall = rb_entry(parent, struct rxrpc_call, sock_node);
119                         if (user_call_ID < xcall->user_call_ID)
120                                 pp = &(*pp)->rb_left;
121                         else if (user_call_ID > xcall->user_call_ID)
122                                 pp = &(*pp)->rb_right;
123                         else
124                                 goto id_in_use;
125                 }
126 
127                 call->user_call_ID = user_call_ID;
128                 call->notify_rx = notify_rx;
129                 rxrpc_get_call(call, rxrpc_call_got_kernel);
130                 user_attach_call(call, user_call_ID);
131                 rxrpc_get_call(call, rxrpc_call_got_userid);
132                 rb_link_node(&call->sock_node, parent, pp);
133                 rb_insert_color(&call->sock_node, &rx->calls);
134                 set_bit(RXRPC_CALL_HAS_USERID, &call->flags);
135         }
136 
137         list_add(&call->sock_link, &rx->sock_calls);
138 
139         write_unlock(&rx->call_lock);
140 
141         rxnet = call->rxnet;
142         write_lock(&rxnet->call_lock);
143         list_add_tail(&call->link, &rxnet->calls);
144         write_unlock(&rxnet->call_lock);
145 
146         b->call_backlog[call_head] = call;
147         smp_store_release(&b->call_backlog_head, (call_head + 1) & (size - 1));
148         _leave(" = 0 [%d -> %lx]", call->debug_id, user_call_ID);
149         return 0;
150 
151 id_in_use:
152         write_unlock(&rx->call_lock);
153         rxrpc_cleanup_call(call);
154         _leave(" = -EBADSLT");
155         return -EBADSLT;
156 }
157 
158 /*
159  * Preallocate sufficient service connections, calls and peers to cover the
160  * entire backlog of a socket.  When a new call comes in, if we don't have
161  * sufficient of each available, the call gets rejected as busy or ignored.
162  *
163  * The backlog is replenished when a connection is accepted or rejected.
164  */
165 int rxrpc_service_prealloc(struct rxrpc_sock *rx, gfp_t gfp)
166 {
167         struct rxrpc_backlog *b = rx->backlog;
168 
169         if (!b) {
170                 b = kzalloc(sizeof(struct rxrpc_backlog), gfp);
171                 if (!b)
172                         return -ENOMEM;
173                 rx->backlog = b;
174         }
175 
176         if (rx->discard_new_call)
177                 return 0;
178 
179         while (rxrpc_service_prealloc_one(rx, b, NULL, NULL, 0, gfp,
180                                           atomic_inc_return(&rxrpc_debug_id)) == 0)
181                 ;
182 
183         return 0;
184 }
185 
186 /*
187  * Discard the preallocation on a service.
188  */
189 void rxrpc_discard_prealloc(struct rxrpc_sock *rx)
190 {
191         struct rxrpc_backlog *b = rx->backlog;
192         struct rxrpc_net *rxnet = rxrpc_net(sock_net(&rx->sk));
193         unsigned int size = RXRPC_BACKLOG_MAX, head, tail;
194 
195         if (!b)
196                 return;
197         rx->backlog = NULL;
198 
199         /* Make sure that there aren't any incoming calls in progress before we
200          * clear the preallocation buffers.
201          */
202         spin_lock_bh(&rx->incoming_lock);
203         spin_unlock_bh(&rx->incoming_lock);
204 
205         head = b->peer_backlog_head;
206         tail = b->peer_backlog_tail;
207         while (CIRC_CNT(head, tail, size) > 0) {
208                 struct rxrpc_peer *peer = b->peer_backlog[tail];
209                 kfree(peer);
210                 tail = (tail + 1) & (size - 1);
211         }
212 
213         head = b->conn_backlog_head;
214         tail = b->conn_backlog_tail;
215         while (CIRC_CNT(head, tail, size) > 0) {
216                 struct rxrpc_connection *conn = b->conn_backlog[tail];
217                 write_lock(&rxnet->conn_lock);
218                 list_del(&conn->link);
219                 list_del(&conn->proc_link);
220                 write_unlock(&rxnet->conn_lock);
221                 kfree(conn);
222                 if (atomic_dec_and_test(&rxnet->nr_conns))
223                         wake_up_var(&rxnet->nr_conns);
224                 tail = (tail + 1) & (size - 1);
225         }
226 
227         head = b->call_backlog_head;
228         tail = b->call_backlog_tail;
229         while (CIRC_CNT(head, tail, size) > 0) {
230                 struct rxrpc_call *call = b->call_backlog[tail];
231                 rcu_assign_pointer(call->socket, rx);
232                 if (rx->discard_new_call) {
233                         _debug("discard %lx", call->user_call_ID);
234                         rx->discard_new_call(call, call->user_call_ID);
235                         rxrpc_put_call(call, rxrpc_call_put_kernel);
236                 }
237                 rxrpc_call_completed(call);
238                 rxrpc_release_call(rx, call);
239                 rxrpc_put_call(call, rxrpc_call_put);
240                 tail = (tail + 1) & (size - 1);
241         }
242 
243         kfree(b);
244 }
245 
246 /*
247  * Allocate a new incoming call from the prealloc pool, along with a connection
248  * and a peer as necessary.
249  */
250 static struct rxrpc_call *rxrpc_alloc_incoming_call(struct rxrpc_sock *rx,
251                                                     struct rxrpc_local *local,
252                                                     struct rxrpc_peer *peer,
253                                                     struct rxrpc_connection *conn,
254                                                     struct sk_buff *skb)
255 {
256         struct rxrpc_backlog *b = rx->backlog;
257         struct rxrpc_call *call;
258         unsigned short call_head, conn_head, peer_head;
259         unsigned short call_tail, conn_tail, peer_tail;
260         unsigned short call_count, conn_count;
261 
262         /* #calls >= #conns >= #peers must hold true. */
263         call_head = smp_load_acquire(&b->call_backlog_head);
264         call_tail = b->call_backlog_tail;
265         call_count = CIRC_CNT(call_head, call_tail, RXRPC_BACKLOG_MAX);
266         conn_head = smp_load_acquire(&b->conn_backlog_head);
267         conn_tail = b->conn_backlog_tail;
268         conn_count = CIRC_CNT(conn_head, conn_tail, RXRPC_BACKLOG_MAX);
269         ASSERTCMP(conn_count, >=, call_count);
270         peer_head = smp_load_acquire(&b->peer_backlog_head);
271         peer_tail = b->peer_backlog_tail;
272         ASSERTCMP(CIRC_CNT(peer_head, peer_tail, RXRPC_BACKLOG_MAX), >=,
273                   conn_count);
274 
275         if (call_count == 0)
276                 return NULL;
277 
278         if (!conn) {
279                 if (peer && !rxrpc_get_peer_maybe(peer))
280                         peer = NULL;
281                 if (!peer) {
282                         peer = b->peer_backlog[peer_tail];
283                         if (rxrpc_extract_addr_from_skb(&peer->srx, skb) < 0)
284                                 return NULL;
285                         b->peer_backlog[peer_tail] = NULL;
286                         smp_store_release(&b->peer_backlog_tail,
287                                           (peer_tail + 1) &
288                                           (RXRPC_BACKLOG_MAX - 1));
289 
290                         rxrpc_new_incoming_peer(rx, local, peer);
291                 }
292 
293                 /* Now allocate and set up the connection */
294                 conn = b->conn_backlog[conn_tail];
295                 b->conn_backlog[conn_tail] = NULL;
296                 smp_store_release(&b->conn_backlog_tail,
297                                   (conn_tail + 1) & (RXRPC_BACKLOG_MAX - 1));
298                 conn->params.local = rxrpc_get_local(local);
299                 conn->params.peer = peer;
300                 rxrpc_see_connection(conn);
301                 rxrpc_new_incoming_connection(rx, conn, skb);
302         } else {
303                 rxrpc_get_connection(conn);
304         }
305 
306         /* And now we can allocate and set up a new call */
307         call = b->call_backlog[call_tail];
308         b->call_backlog[call_tail] = NULL;
309         smp_store_release(&b->call_backlog_tail,
310                           (call_tail + 1) & (RXRPC_BACKLOG_MAX - 1));
311 
312         rxrpc_see_call(call);
313         call->conn = conn;
314         call->peer = rxrpc_get_peer(conn->params.peer);
315         call->cong_cwnd = call->peer->cong_cwnd;
316         return call;
317 }
318 
319 /*
320  * Set up a new incoming call.  Called in BH context with the RCU read lock
321  * held.
322  *
323  * If this is for a kernel service, when we allocate the call, it will have
324  * three refs on it: (1) the kernel service, (2) the user_call_ID tree, (3) the
325  * retainer ref obtained from the backlog buffer.  Prealloc calls for userspace
326  * services only have the ref from the backlog buffer.  We want to pass this
327  * ref to non-BH context to dispose of.
328  *
329  * If we want to report an error, we mark the skb with the packet type and
330  * abort code and return NULL.
331  *
332  * The call is returned with the user access mutex held.
333  */
334 struct rxrpc_call *rxrpc_new_incoming_call(struct rxrpc_local *local,
335                                            struct rxrpc_sock *rx,
336                                            struct sk_buff *skb)
337 {
338         struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
339         struct rxrpc_connection *conn;
340         struct rxrpc_peer *peer = NULL;
341         struct rxrpc_call *call;
342 
343         _enter("");
344 
345         spin_lock(&rx->incoming_lock);
346         if (rx->sk.sk_state == RXRPC_SERVER_LISTEN_DISABLED ||
347             rx->sk.sk_state == RXRPC_CLOSE) {
348                 trace_rxrpc_abort(0, "CLS", sp->hdr.cid, sp->hdr.callNumber,
349                                   sp->hdr.seq, RX_INVALID_OPERATION, ESHUTDOWN);
350                 skb->mark = RXRPC_SKB_MARK_REJECT_ABORT;
351                 skb->priority = RX_INVALID_OPERATION;
352                 _leave(" = NULL [close]");
353                 call = NULL;
354                 goto out;
355         }
356 
357         /* The peer, connection and call may all have sprung into existence due
358          * to a duplicate packet being handled on another CPU in parallel, so
359          * we have to recheck the routing.  However, we're now holding
360          * rx->incoming_lock, so the values should remain stable.
361          */
362         conn = rxrpc_find_connection_rcu(local, skb, &peer);
363 
364         call = rxrpc_alloc_incoming_call(rx, local, peer, conn, skb);
365         if (!call) {
366                 skb->mark = RXRPC_SKB_MARK_REJECT_BUSY;
367                 _leave(" = NULL [busy]");
368                 call = NULL;
369                 goto out;
370         }
371 
372         trace_rxrpc_receive(call, rxrpc_receive_incoming,
373                             sp->hdr.serial, sp->hdr.seq);
374 
375         /* Lock the call to prevent rxrpc_kernel_send/recv_data() and
376          * sendmsg()/recvmsg() inconveniently stealing the mutex once the
377          * notification is generated.
378          *
379          * The BUG should never happen because the kernel should be well
380          * behaved enough not to access the call before the first notification
381          * event and userspace is prevented from doing so until the state is
382          * appropriate.
383          */
384         if (!mutex_trylock(&call->user_mutex))
385                 BUG();
386 
387         /* Make the call live. */
388         rxrpc_incoming_call(rx, call, skb);
389         conn = call->conn;
390 
391         if (rx->notify_new_call)
392                 rx->notify_new_call(&rx->sk, call, call->user_call_ID);
393         else
394                 sk_acceptq_added(&rx->sk);
395 
396         spin_lock(&conn->state_lock);
397         switch (conn->state) {
398         case RXRPC_CONN_SERVICE_UNSECURED:
399                 conn->state = RXRPC_CONN_SERVICE_CHALLENGING;
400                 set_bit(RXRPC_CONN_EV_CHALLENGE, &call->conn->events);
401                 rxrpc_queue_conn(call->conn);
402                 break;
403 
404         case RXRPC_CONN_SERVICE:
405                 write_lock(&call->state_lock);
406                 if (call->state < RXRPC_CALL_COMPLETE) {
407                         if (rx->discard_new_call)
408                                 call->state = RXRPC_CALL_SERVER_RECV_REQUEST;
409                         else
410                                 call->state = RXRPC_CALL_SERVER_ACCEPTING;
411                 }
412                 write_unlock(&call->state_lock);
413                 break;
414 
415         case RXRPC_CONN_REMOTELY_ABORTED:
416                 rxrpc_set_call_completion(call, RXRPC_CALL_REMOTELY_ABORTED,
417                                           conn->abort_code, conn->error);
418                 break;
419         case RXRPC_CONN_LOCALLY_ABORTED:
420                 rxrpc_abort_call("CON", call, sp->hdr.seq,
421                                  conn->abort_code, conn->error);
422                 break;
423         default:
424                 BUG();
425         }
426         spin_unlock(&conn->state_lock);
427 
428         if (call->state == RXRPC_CALL_SERVER_ACCEPTING)
429                 rxrpc_notify_socket(call);
430 
431         /* We have to discard the prealloc queue's ref here and rely on a
432          * combination of the RCU read lock and refs held either by the socket
433          * (recvmsg queue, to-be-accepted queue or user ID tree) or the kernel
434          * service to prevent the call from being deallocated too early.
435          */
436         rxrpc_put_call(call, rxrpc_call_put);
437 
438         _leave(" = %p{%d}", call, call->debug_id);
439 out:
440         spin_unlock(&rx->incoming_lock);
441         return call;
442 }
443 
444 /*
445  * handle acceptance of a call by userspace
446  * - assign the user call ID to the call at the front of the queue
447  * - called with the socket locked.
448  */
449 struct rxrpc_call *rxrpc_accept_call(struct rxrpc_sock *rx,
450                                      unsigned long user_call_ID,
451                                      rxrpc_notify_rx_t notify_rx)
452         __releases(&rx->sk.sk_lock.slock)
453         __acquires(call->user_mutex)
454 {
455         struct rxrpc_call *call;
456         struct rb_node *parent, **pp;
457         int ret;
458 
459         _enter(",%lx", user_call_ID);
460 
461         ASSERT(!irqs_disabled());
462 
463         write_lock(&rx->call_lock);
464 
465         if (list_empty(&rx->to_be_accepted)) {
466                 write_unlock(&rx->call_lock);
467                 release_sock(&rx->sk);
468                 kleave(" = -ENODATA [empty]");
469                 return ERR_PTR(-ENODATA);
470         }
471 
472         /* check the user ID isn't already in use */
473         pp = &rx->calls.rb_node;
474         parent = NULL;
475         while (*pp) {
476                 parent = *pp;
477                 call = rb_entry(parent, struct rxrpc_call, sock_node);
478 
479                 if (user_call_ID < call->user_call_ID)
480                         pp = &(*pp)->rb_left;
481                 else if (user_call_ID > call->user_call_ID)
482                         pp = &(*pp)->rb_right;
483                 else
484                         goto id_in_use;
485         }
486 
487         /* Dequeue the first call and check it's still valid.  We gain
488          * responsibility for the queue's reference.
489          */
490         call = list_entry(rx->to_be_accepted.next,
491                           struct rxrpc_call, accept_link);
492         write_unlock(&rx->call_lock);
493 
494         /* We need to gain the mutex from the interrupt handler without
495          * upsetting lockdep, so we have to release it there and take it here.
496          * We are, however, still holding the socket lock, so other accepts
497          * must wait for us and no one can add the user ID behind our backs.
498          */
499         if (mutex_lock_interruptible(&call->user_mutex) < 0) {
500                 release_sock(&rx->sk);
501                 kleave(" = -ERESTARTSYS");
502                 return ERR_PTR(-ERESTARTSYS);
503         }
504 
505         write_lock(&rx->call_lock);
506         list_del_init(&call->accept_link);
507         sk_acceptq_removed(&rx->sk);
508         rxrpc_see_call(call);
509 
510         /* Find the user ID insertion point. */
511         pp = &rx->calls.rb_node;
512         parent = NULL;
513         while (*pp) {
514                 parent = *pp;
515                 call = rb_entry(parent, struct rxrpc_call, sock_node);
516 
517                 if (user_call_ID < call->user_call_ID)
518                         pp = &(*pp)->rb_left;
519                 else if (user_call_ID > call->user_call_ID)
520                         pp = &(*pp)->rb_right;
521                 else
522                         BUG();
523         }
524 
525         write_lock_bh(&call->state_lock);
526         switch (call->state) {
527         case RXRPC_CALL_SERVER_ACCEPTING:
528                 call->state = RXRPC_CALL_SERVER_RECV_REQUEST;
529                 break;
530         case RXRPC_CALL_COMPLETE:
531                 ret = call->error;
532                 goto out_release;
533         default:
534                 BUG();
535         }
536 
537         /* formalise the acceptance */
538         call->notify_rx = notify_rx;
539         call->user_call_ID = user_call_ID;
540         rxrpc_get_call(call, rxrpc_call_got_userid);
541         rb_link_node(&call->sock_node, parent, pp);
542         rb_insert_color(&call->sock_node, &rx->calls);
543         if (test_and_set_bit(RXRPC_CALL_HAS_USERID, &call->flags))
544                 BUG();
545 
546         write_unlock_bh(&call->state_lock);
547         write_unlock(&rx->call_lock);
548         rxrpc_notify_socket(call);
549         rxrpc_service_prealloc(rx, GFP_KERNEL);
550         release_sock(&rx->sk);
551         _leave(" = %p{%d}", call, call->debug_id);
552         return call;
553 
554 out_release:
555         _debug("release %p", call);
556         write_unlock_bh(&call->state_lock);
557         write_unlock(&rx->call_lock);
558         rxrpc_release_call(rx, call);
559         rxrpc_put_call(call, rxrpc_call_put);
560         goto out;
561 
562 id_in_use:
563         ret = -EBADSLT;
564         write_unlock(&rx->call_lock);
565 out:
566         rxrpc_service_prealloc(rx, GFP_KERNEL);
567         release_sock(&rx->sk);
568         _leave(" = %d", ret);
569         return ERR_PTR(ret);
570 }
571 
572 /*
573  * Handle rejection of a call by userspace
574  * - reject the call at the front of the queue
575  */
576 int rxrpc_reject_call(struct rxrpc_sock *rx)
577 {
578         struct rxrpc_call *call;
579         bool abort = false;
580         int ret;
581 
582         _enter("");
583 
584         ASSERT(!irqs_disabled());
585 
586         write_lock(&rx->call_lock);
587 
588         if (list_empty(&rx->to_be_accepted)) {
589                 write_unlock(&rx->call_lock);
590                 return -ENODATA;
591         }
592 
593         /* Dequeue the first call and check it's still valid.  We gain
594          * responsibility for the queue's reference.
595          */
596         call = list_entry(rx->to_be_accepted.next,
597                           struct rxrpc_call, accept_link);
598         list_del_init(&call->accept_link);
599         sk_acceptq_removed(&rx->sk);
600         rxrpc_see_call(call);
601 
602         write_lock_bh(&call->state_lock);
603         switch (call->state) {
604         case RXRPC_CALL_SERVER_ACCEPTING:
605                 __rxrpc_abort_call("REJ", call, 1, RX_USER_ABORT, -ECONNABORTED);
606                 abort = true;
607                 /* fall through */
608         case RXRPC_CALL_COMPLETE:
609                 ret = call->error;
610                 goto out_discard;
611         default:
612                 BUG();
613         }
614 
615 out_discard:
616         write_unlock_bh(&call->state_lock);
617         write_unlock(&rx->call_lock);
618         if (abort) {
619                 rxrpc_send_abort_packet(call);
620                 rxrpc_release_call(rx, call);
621                 rxrpc_put_call(call, rxrpc_call_put);
622         }
623         rxrpc_service_prealloc(rx, GFP_KERNEL);
624         _leave(" = %d", ret);
625         return ret;
626 }
627 
628 /*
629  * rxrpc_kernel_charge_accept - Charge up socket with preallocated calls
630  * @sock: The socket on which to preallocate
631  * @notify_rx: Event notification function for the call
632  * @user_attach_call: Func to attach call to user_call_ID
633  * @user_call_ID: The tag to attach to the preallocated call
634  * @gfp: The allocation conditions.
635  * @debug_id: The tracing debug ID.
636  *
637  * Charge up the socket with preallocated calls, each with a user ID.  A
638  * function should be provided to effect the attachment from the user's side.
639  * The user is given a ref to hold on the call.
640  *
641  * Note that the call may be come connected before this function returns.
642  */
643 int rxrpc_kernel_charge_accept(struct socket *sock,
644                                rxrpc_notify_rx_t notify_rx,
645                                rxrpc_user_attach_call_t user_attach_call,
646                                unsigned long user_call_ID, gfp_t gfp,
647                                unsigned int debug_id)
648 {
649         struct rxrpc_sock *rx = rxrpc_sk(sock->sk);
650         struct rxrpc_backlog *b = rx->backlog;
651 
652         if (sock->sk->sk_state == RXRPC_CLOSE)
653                 return -ESHUTDOWN;
654 
655         return rxrpc_service_prealloc_one(rx, b, notify_rx,
656                                           user_attach_call, user_call_ID,
657                                           gfp, debug_id);
658 }
659 EXPORT_SYMBOL(rxrpc_kernel_charge_accept);
660 

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