net: Move && and || to end of previous line
[linux-3.10.git] / net / rds / send.c
1 /*
2  * Copyright (c) 2006 Oracle.  All rights reserved.
3  *
4  * This software is available to you under a choice of one of two
5  * licenses.  You may choose to be licensed under the terms of the GNU
6  * General Public License (GPL) Version 2, available from the file
7  * COPYING in the main directory of this source tree, or the
8  * OpenIB.org BSD license below:
9  *
10  *     Redistribution and use in source and binary forms, with or
11  *     without modification, are permitted provided that the following
12  *     conditions are met:
13  *
14  *      - Redistributions of source code must retain the above
15  *        copyright notice, this list of conditions and the following
16  *        disclaimer.
17  *
18  *      - Redistributions in binary form must reproduce the above
19  *        copyright notice, this list of conditions and the following
20  *        disclaimer in the documentation and/or other materials
21  *        provided with the distribution.
22  *
23  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
24  * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
25  * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
26  * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
27  * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
28  * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
29  * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
30  * SOFTWARE.
31  *
32  */
33 #include <linux/kernel.h>
34 #include <net/sock.h>
35 #include <linux/in.h>
36 #include <linux/list.h>
37
38 #include "rds.h"
39 #include "rdma.h"
40
41 /* When transmitting messages in rds_send_xmit, we need to emerge from
42  * time to time and briefly release the CPU. Otherwise the softlock watchdog
43  * will kick our shin.
44  * Also, it seems fairer to not let one busy connection stall all the
45  * others.
46  *
47  * send_batch_count is the number of times we'll loop in send_xmit. Setting
48  * it to 0 will restore the old behavior (where we looped until we had
49  * drained the queue).
50  */
51 static int send_batch_count = 64;
52 module_param(send_batch_count, int, 0444);
53 MODULE_PARM_DESC(send_batch_count, " batch factor when working the send queue");
54
55 /*
56  * Reset the send state. Caller must hold c_send_lock when calling here.
57  */
58 void rds_send_reset(struct rds_connection *conn)
59 {
60         struct rds_message *rm, *tmp;
61         unsigned long flags;
62
63         if (conn->c_xmit_rm) {
64                 /* Tell the user the RDMA op is no longer mapped by the
65                  * transport. This isn't entirely true (it's flushed out
66                  * independently) but as the connection is down, there's
67                  * no ongoing RDMA to/from that memory */
68                 rds_message_unmapped(conn->c_xmit_rm);
69                 rds_message_put(conn->c_xmit_rm);
70                 conn->c_xmit_rm = NULL;
71         }
72         conn->c_xmit_sg = 0;
73         conn->c_xmit_hdr_off = 0;
74         conn->c_xmit_data_off = 0;
75         conn->c_xmit_rdma_sent = 0;
76
77         conn->c_map_queued = 0;
78
79         conn->c_unacked_packets = rds_sysctl_max_unacked_packets;
80         conn->c_unacked_bytes = rds_sysctl_max_unacked_bytes;
81
82         /* Mark messages as retransmissions, and move them to the send q */
83         spin_lock_irqsave(&conn->c_lock, flags);
84         list_for_each_entry_safe(rm, tmp, &conn->c_retrans, m_conn_item) {
85                 set_bit(RDS_MSG_ACK_REQUIRED, &rm->m_flags);
86                 set_bit(RDS_MSG_RETRANSMITTED, &rm->m_flags);
87         }
88         list_splice_init(&conn->c_retrans, &conn->c_send_queue);
89         spin_unlock_irqrestore(&conn->c_lock, flags);
90 }
91
92 /*
93  * We're making the concious trade-off here to only send one message
94  * down the connection at a time.
95  *   Pro:
96  *      - tx queueing is a simple fifo list
97  *      - reassembly is optional and easily done by transports per conn
98  *      - no per flow rx lookup at all, straight to the socket
99  *      - less per-frag memory and wire overhead
100  *   Con:
101  *      - queued acks can be delayed behind large messages
102  *   Depends:
103  *      - small message latency is higher behind queued large messages
104  *      - large message latency isn't starved by intervening small sends
105  */
106 int rds_send_xmit(struct rds_connection *conn)
107 {
108         struct rds_message *rm;
109         unsigned long flags;
110         unsigned int tmp;
111         unsigned int send_quota = send_batch_count;
112         struct scatterlist *sg;
113         int ret = 0;
114         int was_empty = 0;
115         LIST_HEAD(to_be_dropped);
116
117         /*
118          * sendmsg calls here after having queued its message on the send
119          * queue.  We only have one task feeding the connection at a time.  If
120          * another thread is already feeding the queue then we back off.  This
121          * avoids blocking the caller and trading per-connection data between
122          * caches per message.
123          *
124          * The sem holder will issue a retry if they notice that someone queued
125          * a message after they stopped walking the send queue but before they
126          * dropped the sem.
127          */
128         if (!mutex_trylock(&conn->c_send_lock)) {
129                 rds_stats_inc(s_send_sem_contention);
130                 ret = -ENOMEM;
131                 goto out;
132         }
133
134         if (conn->c_trans->xmit_prepare)
135                 conn->c_trans->xmit_prepare(conn);
136
137         /*
138          * spin trying to push headers and data down the connection until
139          * the connection doens't make forward progress.
140          */
141         while (--send_quota) {
142                 /*
143                  * See if need to send a congestion map update if we're
144                  * between sending messages.  The send_sem protects our sole
145                  * use of c_map_offset and _bytes.
146                  * Note this is used only by transports that define a special
147                  * xmit_cong_map function. For all others, we create allocate
148                  * a cong_map message and treat it just like any other send.
149                  */
150                 if (conn->c_map_bytes) {
151                         ret = conn->c_trans->xmit_cong_map(conn, conn->c_lcong,
152                                                 conn->c_map_offset);
153                         if (ret <= 0)
154                                 break;
155
156                         conn->c_map_offset += ret;
157                         conn->c_map_bytes -= ret;
158                         if (conn->c_map_bytes)
159                                 continue;
160                 }
161
162                 /* If we're done sending the current message, clear the
163                  * offset and S/G temporaries.
164                  */
165                 rm = conn->c_xmit_rm;
166                 if (rm != NULL &&
167                     conn->c_xmit_hdr_off == sizeof(struct rds_header) &&
168                     conn->c_xmit_sg == rm->m_nents) {
169                         conn->c_xmit_rm = NULL;
170                         conn->c_xmit_sg = 0;
171                         conn->c_xmit_hdr_off = 0;
172                         conn->c_xmit_data_off = 0;
173                         conn->c_xmit_rdma_sent = 0;
174
175                         /* Release the reference to the previous message. */
176                         rds_message_put(rm);
177                         rm = NULL;
178                 }
179
180                 /* If we're asked to send a cong map update, do so.
181                  */
182                 if (rm == NULL && test_and_clear_bit(0, &conn->c_map_queued)) {
183                         if (conn->c_trans->xmit_cong_map != NULL) {
184                                 conn->c_map_offset = 0;
185                                 conn->c_map_bytes = sizeof(struct rds_header) +
186                                         RDS_CONG_MAP_BYTES;
187                                 continue;
188                         }
189
190                         rm = rds_cong_update_alloc(conn);
191                         if (IS_ERR(rm)) {
192                                 ret = PTR_ERR(rm);
193                                 break;
194                         }
195
196                         conn->c_xmit_rm = rm;
197                 }
198
199                 /*
200                  * Grab the next message from the send queue, if there is one.
201                  *
202                  * c_xmit_rm holds a ref while we're sending this message down
203                  * the connction.  We can use this ref while holding the
204                  * send_sem.. rds_send_reset() is serialized with it.
205                  */
206                 if (rm == NULL) {
207                         unsigned int len;
208
209                         spin_lock_irqsave(&conn->c_lock, flags);
210
211                         if (!list_empty(&conn->c_send_queue)) {
212                                 rm = list_entry(conn->c_send_queue.next,
213                                                 struct rds_message,
214                                                 m_conn_item);
215                                 rds_message_addref(rm);
216
217                                 /*
218                                  * Move the message from the send queue to the retransmit
219                                  * list right away.
220                                  */
221                                 list_move_tail(&rm->m_conn_item, &conn->c_retrans);
222                         }
223
224                         spin_unlock_irqrestore(&conn->c_lock, flags);
225
226                         if (rm == NULL) {
227                                 was_empty = 1;
228                                 break;
229                         }
230
231                         /* Unfortunately, the way Infiniband deals with
232                          * RDMA to a bad MR key is by moving the entire
233                          * queue pair to error state. We cold possibly
234                          * recover from that, but right now we drop the
235                          * connection.
236                          * Therefore, we never retransmit messages with RDMA ops.
237                          */
238                         if (rm->m_rdma_op &&
239                             test_bit(RDS_MSG_RETRANSMITTED, &rm->m_flags)) {
240                                 spin_lock_irqsave(&conn->c_lock, flags);
241                                 if (test_and_clear_bit(RDS_MSG_ON_CONN, &rm->m_flags))
242                                         list_move(&rm->m_conn_item, &to_be_dropped);
243                                 spin_unlock_irqrestore(&conn->c_lock, flags);
244                                 rds_message_put(rm);
245                                 continue;
246                         }
247
248                         /* Require an ACK every once in a while */
249                         len = ntohl(rm->m_inc.i_hdr.h_len);
250                         if (conn->c_unacked_packets == 0 ||
251                             conn->c_unacked_bytes < len) {
252                                 __set_bit(RDS_MSG_ACK_REQUIRED, &rm->m_flags);
253
254                                 conn->c_unacked_packets = rds_sysctl_max_unacked_packets;
255                                 conn->c_unacked_bytes = rds_sysctl_max_unacked_bytes;
256                                 rds_stats_inc(s_send_ack_required);
257                         } else {
258                                 conn->c_unacked_bytes -= len;
259                                 conn->c_unacked_packets--;
260                         }
261
262                         conn->c_xmit_rm = rm;
263                 }
264
265                 /*
266                  * Try and send an rdma message.  Let's see if we can
267                  * keep this simple and require that the transport either
268                  * send the whole rdma or none of it.
269                  */
270                 if (rm->m_rdma_op && !conn->c_xmit_rdma_sent) {
271                         ret = conn->c_trans->xmit_rdma(conn, rm->m_rdma_op);
272                         if (ret)
273                                 break;
274                         conn->c_xmit_rdma_sent = 1;
275                         /* The transport owns the mapped memory for now.
276                          * You can't unmap it while it's on the send queue */
277                         set_bit(RDS_MSG_MAPPED, &rm->m_flags);
278                 }
279
280                 if (conn->c_xmit_hdr_off < sizeof(struct rds_header) ||
281                     conn->c_xmit_sg < rm->m_nents) {
282                         ret = conn->c_trans->xmit(conn, rm,
283                                                   conn->c_xmit_hdr_off,
284                                                   conn->c_xmit_sg,
285                                                   conn->c_xmit_data_off);
286                         if (ret <= 0)
287                                 break;
288
289                         if (conn->c_xmit_hdr_off < sizeof(struct rds_header)) {
290                                 tmp = min_t(int, ret,
291                                             sizeof(struct rds_header) -
292                                             conn->c_xmit_hdr_off);
293                                 conn->c_xmit_hdr_off += tmp;
294                                 ret -= tmp;
295                         }
296
297                         sg = &rm->m_sg[conn->c_xmit_sg];
298                         while (ret) {
299                                 tmp = min_t(int, ret, sg->length -
300                                                       conn->c_xmit_data_off);
301                                 conn->c_xmit_data_off += tmp;
302                                 ret -= tmp;
303                                 if (conn->c_xmit_data_off == sg->length) {
304                                         conn->c_xmit_data_off = 0;
305                                         sg++;
306                                         conn->c_xmit_sg++;
307                                         BUG_ON(ret != 0 &&
308                                                conn->c_xmit_sg == rm->m_nents);
309                                 }
310                         }
311                 }
312         }
313
314         /* Nuke any messages we decided not to retransmit. */
315         if (!list_empty(&to_be_dropped))
316                 rds_send_remove_from_sock(&to_be_dropped, RDS_RDMA_DROPPED);
317
318         if (conn->c_trans->xmit_complete)
319                 conn->c_trans->xmit_complete(conn);
320
321         /*
322          * We might be racing with another sender who queued a message but
323          * backed off on noticing that we held the c_send_lock.  If we check
324          * for queued messages after dropping the sem then either we'll
325          * see the queued message or the queuer will get the sem.  If we
326          * notice the queued message then we trigger an immediate retry.
327          *
328          * We need to be careful only to do this when we stopped processing
329          * the send queue because it was empty.  It's the only way we
330          * stop processing the loop when the transport hasn't taken
331          * responsibility for forward progress.
332          */
333         mutex_unlock(&conn->c_send_lock);
334
335         if (conn->c_map_bytes || (send_quota == 0 && !was_empty)) {
336                 /* We exhausted the send quota, but there's work left to
337                  * do. Return and (re-)schedule the send worker.
338                  */
339                 ret = -EAGAIN;
340         }
341
342         if (ret == 0 && was_empty) {
343                 /* A simple bit test would be way faster than taking the
344                  * spin lock */
345                 spin_lock_irqsave(&conn->c_lock, flags);
346                 if (!list_empty(&conn->c_send_queue)) {
347                         rds_stats_inc(s_send_sem_queue_raced);
348                         ret = -EAGAIN;
349                 }
350                 spin_unlock_irqrestore(&conn->c_lock, flags);
351         }
352 out:
353         return ret;
354 }
355
356 static void rds_send_sndbuf_remove(struct rds_sock *rs, struct rds_message *rm)
357 {
358         u32 len = be32_to_cpu(rm->m_inc.i_hdr.h_len);
359
360         assert_spin_locked(&rs->rs_lock);
361
362         BUG_ON(rs->rs_snd_bytes < len);
363         rs->rs_snd_bytes -= len;
364
365         if (rs->rs_snd_bytes == 0)
366                 rds_stats_inc(s_send_queue_empty);
367 }
368
369 static inline int rds_send_is_acked(struct rds_message *rm, u64 ack,
370                                     is_acked_func is_acked)
371 {
372         if (is_acked)
373                 return is_acked(rm, ack);
374         return be64_to_cpu(rm->m_inc.i_hdr.h_sequence) <= ack;
375 }
376
377 /*
378  * Returns true if there are no messages on the send and retransmit queues
379  * which have a sequence number greater than or equal to the given sequence
380  * number.
381  */
382 int rds_send_acked_before(struct rds_connection *conn, u64 seq)
383 {
384         struct rds_message *rm, *tmp;
385         int ret = 1;
386
387         spin_lock(&conn->c_lock);
388
389         list_for_each_entry_safe(rm, tmp, &conn->c_retrans, m_conn_item) {
390                 if (be64_to_cpu(rm->m_inc.i_hdr.h_sequence) < seq)
391                         ret = 0;
392                 break;
393         }
394
395         list_for_each_entry_safe(rm, tmp, &conn->c_send_queue, m_conn_item) {
396                 if (be64_to_cpu(rm->m_inc.i_hdr.h_sequence) < seq)
397                         ret = 0;
398                 break;
399         }
400
401         spin_unlock(&conn->c_lock);
402
403         return ret;
404 }
405
406 /*
407  * This is pretty similar to what happens below in the ACK
408  * handling code - except that we call here as soon as we get
409  * the IB send completion on the RDMA op and the accompanying
410  * message.
411  */
412 void rds_rdma_send_complete(struct rds_message *rm, int status)
413 {
414         struct rds_sock *rs = NULL;
415         struct rds_rdma_op *ro;
416         struct rds_notifier *notifier;
417
418         spin_lock(&rm->m_rs_lock);
419
420         ro = rm->m_rdma_op;
421         if (test_bit(RDS_MSG_ON_SOCK, &rm->m_flags) &&
422             ro && ro->r_notify && ro->r_notifier) {
423                 notifier = ro->r_notifier;
424                 rs = rm->m_rs;
425                 sock_hold(rds_rs_to_sk(rs));
426
427                 notifier->n_status = status;
428                 spin_lock(&rs->rs_lock);
429                 list_add_tail(&notifier->n_list, &rs->rs_notify_queue);
430                 spin_unlock(&rs->rs_lock);
431
432                 ro->r_notifier = NULL;
433         }
434
435         spin_unlock(&rm->m_rs_lock);
436
437         if (rs) {
438                 rds_wake_sk_sleep(rs);
439                 sock_put(rds_rs_to_sk(rs));
440         }
441 }
442 EXPORT_SYMBOL_GPL(rds_rdma_send_complete);
443
444 /*
445  * This is the same as rds_rdma_send_complete except we
446  * don't do any locking - we have all the ingredients (message,
447  * socket, socket lock) and can just move the notifier.
448  */
449 static inline void
450 __rds_rdma_send_complete(struct rds_sock *rs, struct rds_message *rm, int status)
451 {
452         struct rds_rdma_op *ro;
453
454         ro = rm->m_rdma_op;
455         if (ro && ro->r_notify && ro->r_notifier) {
456                 ro->r_notifier->n_status = status;
457                 list_add_tail(&ro->r_notifier->n_list, &rs->rs_notify_queue);
458                 ro->r_notifier = NULL;
459         }
460
461         /* No need to wake the app - caller does this */
462 }
463
464 /*
465  * This is called from the IB send completion when we detect
466  * a RDMA operation that failed with remote access error.
467  * So speed is not an issue here.
468  */
469 struct rds_message *rds_send_get_message(struct rds_connection *conn,
470                                          struct rds_rdma_op *op)
471 {
472         struct rds_message *rm, *tmp, *found = NULL;
473         unsigned long flags;
474
475         spin_lock_irqsave(&conn->c_lock, flags);
476
477         list_for_each_entry_safe(rm, tmp, &conn->c_retrans, m_conn_item) {
478                 if (rm->m_rdma_op == op) {
479                         atomic_inc(&rm->m_refcount);
480                         found = rm;
481                         goto out;
482                 }
483         }
484
485         list_for_each_entry_safe(rm, tmp, &conn->c_send_queue, m_conn_item) {
486                 if (rm->m_rdma_op == op) {
487                         atomic_inc(&rm->m_refcount);
488                         found = rm;
489                         break;
490                 }
491         }
492
493 out:
494         spin_unlock_irqrestore(&conn->c_lock, flags);
495
496         return found;
497 }
498 EXPORT_SYMBOL_GPL(rds_send_get_message);
499
500 /*
501  * This removes messages from the socket's list if they're on it.  The list
502  * argument must be private to the caller, we must be able to modify it
503  * without locks.  The messages must have a reference held for their
504  * position on the list.  This function will drop that reference after
505  * removing the messages from the 'messages' list regardless of if it found
506  * the messages on the socket list or not.
507  */
508 void rds_send_remove_from_sock(struct list_head *messages, int status)
509 {
510         unsigned long flags = 0; /* silence gcc :P */
511         struct rds_sock *rs = NULL;
512         struct rds_message *rm;
513
514         local_irq_save(flags);
515         while (!list_empty(messages)) {
516                 rm = list_entry(messages->next, struct rds_message,
517                                 m_conn_item);
518                 list_del_init(&rm->m_conn_item);
519
520                 /*
521                  * If we see this flag cleared then we're *sure* that someone
522                  * else beat us to removing it from the sock.  If we race
523                  * with their flag update we'll get the lock and then really
524                  * see that the flag has been cleared.
525                  *
526                  * The message spinlock makes sure nobody clears rm->m_rs
527                  * while we're messing with it. It does not prevent the
528                  * message from being removed from the socket, though.
529                  */
530                 spin_lock(&rm->m_rs_lock);
531                 if (!test_bit(RDS_MSG_ON_SOCK, &rm->m_flags))
532                         goto unlock_and_drop;
533
534                 if (rs != rm->m_rs) {
535                         if (rs) {
536                                 spin_unlock(&rs->rs_lock);
537                                 rds_wake_sk_sleep(rs);
538                                 sock_put(rds_rs_to_sk(rs));
539                         }
540                         rs = rm->m_rs;
541                         spin_lock(&rs->rs_lock);
542                         sock_hold(rds_rs_to_sk(rs));
543                 }
544
545                 if (test_and_clear_bit(RDS_MSG_ON_SOCK, &rm->m_flags)) {
546                         struct rds_rdma_op *ro = rm->m_rdma_op;
547                         struct rds_notifier *notifier;
548
549                         list_del_init(&rm->m_sock_item);
550                         rds_send_sndbuf_remove(rs, rm);
551
552                         if (ro && ro->r_notifier && (status || ro->r_notify)) {
553                                 notifier = ro->r_notifier;
554                                 list_add_tail(&notifier->n_list,
555                                                 &rs->rs_notify_queue);
556                                 if (!notifier->n_status)
557                                         notifier->n_status = status;
558                                 rm->m_rdma_op->r_notifier = NULL;
559                         }
560                         rds_message_put(rm);
561                         rm->m_rs = NULL;
562                 }
563
564 unlock_and_drop:
565                 spin_unlock(&rm->m_rs_lock);
566                 rds_message_put(rm);
567         }
568
569         if (rs) {
570                 spin_unlock(&rs->rs_lock);
571                 rds_wake_sk_sleep(rs);
572                 sock_put(rds_rs_to_sk(rs));
573         }
574         local_irq_restore(flags);
575 }
576
577 /*
578  * Transports call here when they've determined that the receiver queued
579  * messages up to, and including, the given sequence number.  Messages are
580  * moved to the retrans queue when rds_send_xmit picks them off the send
581  * queue. This means that in the TCP case, the message may not have been
582  * assigned the m_ack_seq yet - but that's fine as long as tcp_is_acked
583  * checks the RDS_MSG_HAS_ACK_SEQ bit.
584  *
585  * XXX It's not clear to me how this is safely serialized with socket
586  * destruction.  Maybe it should bail if it sees SOCK_DEAD.
587  */
588 void rds_send_drop_acked(struct rds_connection *conn, u64 ack,
589                          is_acked_func is_acked)
590 {
591         struct rds_message *rm, *tmp;
592         unsigned long flags;
593         LIST_HEAD(list);
594
595         spin_lock_irqsave(&conn->c_lock, flags);
596
597         list_for_each_entry_safe(rm, tmp, &conn->c_retrans, m_conn_item) {
598                 if (!rds_send_is_acked(rm, ack, is_acked))
599                         break;
600
601                 list_move(&rm->m_conn_item, &list);
602                 clear_bit(RDS_MSG_ON_CONN, &rm->m_flags);
603         }
604
605         /* order flag updates with spin locks */
606         if (!list_empty(&list))
607                 smp_mb__after_clear_bit();
608
609         spin_unlock_irqrestore(&conn->c_lock, flags);
610
611         /* now remove the messages from the sock list as needed */
612         rds_send_remove_from_sock(&list, RDS_RDMA_SUCCESS);
613 }
614 EXPORT_SYMBOL_GPL(rds_send_drop_acked);
615
616 void rds_send_drop_to(struct rds_sock *rs, struct sockaddr_in *dest)
617 {
618         struct rds_message *rm, *tmp;
619         struct rds_connection *conn;
620         unsigned long flags, flags2;
621         LIST_HEAD(list);
622         int wake = 0;
623
624         /* get all the messages we're dropping under the rs lock */
625         spin_lock_irqsave(&rs->rs_lock, flags);
626
627         list_for_each_entry_safe(rm, tmp, &rs->rs_send_queue, m_sock_item) {
628                 if (dest && (dest->sin_addr.s_addr != rm->m_daddr ||
629                              dest->sin_port != rm->m_inc.i_hdr.h_dport))
630                         continue;
631
632                 wake = 1;
633                 list_move(&rm->m_sock_item, &list);
634                 rds_send_sndbuf_remove(rs, rm);
635                 clear_bit(RDS_MSG_ON_SOCK, &rm->m_flags);
636
637                 /* If this is a RDMA operation, notify the app. */
638                 __rds_rdma_send_complete(rs, rm, RDS_RDMA_CANCELED);
639         }
640
641         /* order flag updates with the rs lock */
642         if (wake)
643                 smp_mb__after_clear_bit();
644
645         spin_unlock_irqrestore(&rs->rs_lock, flags);
646
647         if (wake)
648                 rds_wake_sk_sleep(rs);
649
650         conn = NULL;
651
652         /* now remove the messages from the conn list as needed */
653         list_for_each_entry(rm, &list, m_sock_item) {
654                 /* We do this here rather than in the loop above, so that
655                  * we don't have to nest m_rs_lock under rs->rs_lock */
656                 spin_lock_irqsave(&rm->m_rs_lock, flags2);
657                 rm->m_rs = NULL;
658                 spin_unlock_irqrestore(&rm->m_rs_lock, flags2);
659
660                 /*
661                  * If we see this flag cleared then we're *sure* that someone
662                  * else beat us to removing it from the conn.  If we race
663                  * with their flag update we'll get the lock and then really
664                  * see that the flag has been cleared.
665                  */
666                 if (!test_bit(RDS_MSG_ON_CONN, &rm->m_flags))
667                         continue;
668
669                 if (conn != rm->m_inc.i_conn) {
670                         if (conn)
671                                 spin_unlock_irqrestore(&conn->c_lock, flags);
672                         conn = rm->m_inc.i_conn;
673                         spin_lock_irqsave(&conn->c_lock, flags);
674                 }
675
676                 if (test_and_clear_bit(RDS_MSG_ON_CONN, &rm->m_flags)) {
677                         list_del_init(&rm->m_conn_item);
678                         rds_message_put(rm);
679                 }
680         }
681
682         if (conn)
683                 spin_unlock_irqrestore(&conn->c_lock, flags);
684
685         while (!list_empty(&list)) {
686                 rm = list_entry(list.next, struct rds_message, m_sock_item);
687                 list_del_init(&rm->m_sock_item);
688
689                 rds_message_wait(rm);
690                 rds_message_put(rm);
691         }
692 }
693
694 /*
695  * we only want this to fire once so we use the callers 'queued'.  It's
696  * possible that another thread can race with us and remove the
697  * message from the flow with RDS_CANCEL_SENT_TO.
698  */
699 static int rds_send_queue_rm(struct rds_sock *rs, struct rds_connection *conn,
700                              struct rds_message *rm, __be16 sport,
701                              __be16 dport, int *queued)
702 {
703         unsigned long flags;
704         u32 len;
705
706         if (*queued)
707                 goto out;
708
709         len = be32_to_cpu(rm->m_inc.i_hdr.h_len);
710
711         /* this is the only place which holds both the socket's rs_lock
712          * and the connection's c_lock */
713         spin_lock_irqsave(&rs->rs_lock, flags);
714
715         /*
716          * If there is a little space in sndbuf, we don't queue anything,
717          * and userspace gets -EAGAIN. But poll() indicates there's send
718          * room. This can lead to bad behavior (spinning) if snd_bytes isn't
719          * freed up by incoming acks. So we check the *old* value of
720          * rs_snd_bytes here to allow the last msg to exceed the buffer,
721          * and poll() now knows no more data can be sent.
722          */
723         if (rs->rs_snd_bytes < rds_sk_sndbuf(rs)) {
724                 rs->rs_snd_bytes += len;
725
726                 /* let recv side know we are close to send space exhaustion.
727                  * This is probably not the optimal way to do it, as this
728                  * means we set the flag on *all* messages as soon as our
729                  * throughput hits a certain threshold.
730                  */
731                 if (rs->rs_snd_bytes >= rds_sk_sndbuf(rs) / 2)
732                         __set_bit(RDS_MSG_ACK_REQUIRED, &rm->m_flags);
733
734                 list_add_tail(&rm->m_sock_item, &rs->rs_send_queue);
735                 set_bit(RDS_MSG_ON_SOCK, &rm->m_flags);
736                 rds_message_addref(rm);
737                 rm->m_rs = rs;
738
739                 /* The code ordering is a little weird, but we're
740                    trying to minimize the time we hold c_lock */
741                 rds_message_populate_header(&rm->m_inc.i_hdr, sport, dport, 0);
742                 rm->m_inc.i_conn = conn;
743                 rds_message_addref(rm);
744
745                 spin_lock(&conn->c_lock);
746                 rm->m_inc.i_hdr.h_sequence = cpu_to_be64(conn->c_next_tx_seq++);
747                 list_add_tail(&rm->m_conn_item, &conn->c_send_queue);
748                 set_bit(RDS_MSG_ON_CONN, &rm->m_flags);
749                 spin_unlock(&conn->c_lock);
750
751                 rdsdebug("queued msg %p len %d, rs %p bytes %d seq %llu\n",
752                          rm, len, rs, rs->rs_snd_bytes,
753                          (unsigned long long)be64_to_cpu(rm->m_inc.i_hdr.h_sequence));
754
755                 *queued = 1;
756         }
757
758         spin_unlock_irqrestore(&rs->rs_lock, flags);
759 out:
760         return *queued;
761 }
762
763 static int rds_cmsg_send(struct rds_sock *rs, struct rds_message *rm,
764                          struct msghdr *msg, int *allocated_mr)
765 {
766         struct cmsghdr *cmsg;
767         int ret = 0;
768
769         for (cmsg = CMSG_FIRSTHDR(msg); cmsg; cmsg = CMSG_NXTHDR(msg, cmsg)) {
770                 if (!CMSG_OK(msg, cmsg))
771                         return -EINVAL;
772
773                 if (cmsg->cmsg_level != SOL_RDS)
774                         continue;
775
776                 /* As a side effect, RDMA_DEST and RDMA_MAP will set
777                  * rm->m_rdma_cookie and rm->m_rdma_mr.
778                  */
779                 switch (cmsg->cmsg_type) {
780                 case RDS_CMSG_RDMA_ARGS:
781                         ret = rds_cmsg_rdma_args(rs, rm, cmsg);
782                         break;
783
784                 case RDS_CMSG_RDMA_DEST:
785                         ret = rds_cmsg_rdma_dest(rs, rm, cmsg);
786                         break;
787
788                 case RDS_CMSG_RDMA_MAP:
789                         ret = rds_cmsg_rdma_map(rs, rm, cmsg);
790                         if (!ret)
791                                 *allocated_mr = 1;
792                         break;
793
794                 default:
795                         return -EINVAL;
796                 }
797
798                 if (ret)
799                         break;
800         }
801
802         return ret;
803 }
804
805 int rds_sendmsg(struct kiocb *iocb, struct socket *sock, struct msghdr *msg,
806                 size_t payload_len)
807 {
808         struct sock *sk = sock->sk;
809         struct rds_sock *rs = rds_sk_to_rs(sk);
810         struct sockaddr_in *usin = (struct sockaddr_in *)msg->msg_name;
811         __be32 daddr;
812         __be16 dport;
813         struct rds_message *rm = NULL;
814         struct rds_connection *conn;
815         int ret = 0;
816         int queued = 0, allocated_mr = 0;
817         int nonblock = msg->msg_flags & MSG_DONTWAIT;
818         long timeo = sock_rcvtimeo(sk, nonblock);
819
820         /* Mirror Linux UDP mirror of BSD error message compatibility */
821         /* XXX: Perhaps MSG_MORE someday */
822         if (msg->msg_flags & ~(MSG_DONTWAIT | MSG_CMSG_COMPAT)) {
823                 printk(KERN_INFO "msg_flags 0x%08X\n", msg->msg_flags);
824                 ret = -EOPNOTSUPP;
825                 goto out;
826         }
827
828         if (msg->msg_namelen) {
829                 /* XXX fail non-unicast destination IPs? */
830                 if (msg->msg_namelen < sizeof(*usin) || usin->sin_family != AF_INET) {
831                         ret = -EINVAL;
832                         goto out;
833                 }
834                 daddr = usin->sin_addr.s_addr;
835                 dport = usin->sin_port;
836         } else {
837                 /* We only care about consistency with ->connect() */
838                 lock_sock(sk);
839                 daddr = rs->rs_conn_addr;
840                 dport = rs->rs_conn_port;
841                 release_sock(sk);
842         }
843
844         /* racing with another thread binding seems ok here */
845         if (daddr == 0 || rs->rs_bound_addr == 0) {
846                 ret = -ENOTCONN; /* XXX not a great errno */
847                 goto out;
848         }
849
850         rm = rds_message_copy_from_user(msg->msg_iov, payload_len);
851         if (IS_ERR(rm)) {
852                 ret = PTR_ERR(rm);
853                 rm = NULL;
854                 goto out;
855         }
856
857         rm->m_daddr = daddr;
858
859         /* rds_conn_create has a spinlock that runs with IRQ off.
860          * Caching the conn in the socket helps a lot. */
861         if (rs->rs_conn && rs->rs_conn->c_faddr == daddr)
862                 conn = rs->rs_conn;
863         else {
864                 conn = rds_conn_create_outgoing(rs->rs_bound_addr, daddr,
865                                         rs->rs_transport,
866                                         sock->sk->sk_allocation);
867                 if (IS_ERR(conn)) {
868                         ret = PTR_ERR(conn);
869                         goto out;
870                 }
871                 rs->rs_conn = conn;
872         }
873
874         /* Parse any control messages the user may have included. */
875         ret = rds_cmsg_send(rs, rm, msg, &allocated_mr);
876         if (ret)
877                 goto out;
878
879         if ((rm->m_rdma_cookie || rm->m_rdma_op) &&
880             conn->c_trans->xmit_rdma == NULL) {
881                 if (printk_ratelimit())
882                         printk(KERN_NOTICE "rdma_op %p conn xmit_rdma %p\n",
883                                 rm->m_rdma_op, conn->c_trans->xmit_rdma);
884                 ret = -EOPNOTSUPP;
885                 goto out;
886         }
887
888         /* If the connection is down, trigger a connect. We may
889          * have scheduled a delayed reconnect however - in this case
890          * we should not interfere.
891          */
892         if (rds_conn_state(conn) == RDS_CONN_DOWN &&
893             !test_and_set_bit(RDS_RECONNECT_PENDING, &conn->c_flags))
894                 queue_delayed_work(rds_wq, &conn->c_conn_w, 0);
895
896         ret = rds_cong_wait(conn->c_fcong, dport, nonblock, rs);
897         if (ret)
898                 goto out;
899
900         while (!rds_send_queue_rm(rs, conn, rm, rs->rs_bound_port,
901                                   dport, &queued)) {
902                 rds_stats_inc(s_send_queue_full);
903                 /* XXX make sure this is reasonable */
904                 if (payload_len > rds_sk_sndbuf(rs)) {
905                         ret = -EMSGSIZE;
906                         goto out;
907                 }
908                 if (nonblock) {
909                         ret = -EAGAIN;
910                         goto out;
911                 }
912
913                 timeo = wait_event_interruptible_timeout(*sk->sk_sleep,
914                                         rds_send_queue_rm(rs, conn, rm,
915                                                           rs->rs_bound_port,
916                                                           dport,
917                                                           &queued),
918                                         timeo);
919                 rdsdebug("sendmsg woke queued %d timeo %ld\n", queued, timeo);
920                 if (timeo > 0 || timeo == MAX_SCHEDULE_TIMEOUT)
921                         continue;
922
923                 ret = timeo;
924                 if (ret == 0)
925                         ret = -ETIMEDOUT;
926                 goto out;
927         }
928
929         /*
930          * By now we've committed to the send.  We reuse rds_send_worker()
931          * to retry sends in the rds thread if the transport asks us to.
932          */
933         rds_stats_inc(s_send_queued);
934
935         if (!test_bit(RDS_LL_SEND_FULL, &conn->c_flags))
936                 rds_send_worker(&conn->c_send_w.work);
937
938         rds_message_put(rm);
939         return payload_len;
940
941 out:
942         /* If the user included a RDMA_MAP cmsg, we allocated a MR on the fly.
943          * If the sendmsg goes through, we keep the MR. If it fails with EAGAIN
944          * or in any other way, we need to destroy the MR again */
945         if (allocated_mr)
946                 rds_rdma_unuse(rs, rds_rdma_cookie_key(rm->m_rdma_cookie), 1);
947
948         if (rm)
949                 rds_message_put(rm);
950         return ret;
951 }
952
953 /*
954  * Reply to a ping packet.
955  */
956 int
957 rds_send_pong(struct rds_connection *conn, __be16 dport)
958 {
959         struct rds_message *rm;
960         unsigned long flags;
961         int ret = 0;
962
963         rm = rds_message_alloc(0, GFP_ATOMIC);
964         if (rm == NULL) {
965                 ret = -ENOMEM;
966                 goto out;
967         }
968
969         rm->m_daddr = conn->c_faddr;
970
971         /* If the connection is down, trigger a connect. We may
972          * have scheduled a delayed reconnect however - in this case
973          * we should not interfere.
974          */
975         if (rds_conn_state(conn) == RDS_CONN_DOWN &&
976             !test_and_set_bit(RDS_RECONNECT_PENDING, &conn->c_flags))
977                 queue_delayed_work(rds_wq, &conn->c_conn_w, 0);
978
979         ret = rds_cong_wait(conn->c_fcong, dport, 1, NULL);
980         if (ret)
981                 goto out;
982
983         spin_lock_irqsave(&conn->c_lock, flags);
984         list_add_tail(&rm->m_conn_item, &conn->c_send_queue);
985         set_bit(RDS_MSG_ON_CONN, &rm->m_flags);
986         rds_message_addref(rm);
987         rm->m_inc.i_conn = conn;
988
989         rds_message_populate_header(&rm->m_inc.i_hdr, 0, dport,
990                                     conn->c_next_tx_seq);
991         conn->c_next_tx_seq++;
992         spin_unlock_irqrestore(&conn->c_lock, flags);
993
994         rds_stats_inc(s_send_queued);
995         rds_stats_inc(s_send_pong);
996
997         queue_delayed_work(rds_wq, &conn->c_send_w, 0);
998         rds_message_put(rm);
999         return 0;
1000
1001 out:
1002         if (rm)
1003                 rds_message_put(rm);
1004         return ret;
1005 }