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TOMOYO Linux Cross Reference
Linux/net/rds/send.c

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  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 <linux/moduleparam.h>
 35 #include <linux/gfp.h>
 36 #include <net/sock.h>
 37 #include <linux/in.h>
 38 #include <linux/list.h>
 39 #include <linux/ratelimit.h>
 40 #include <linux/export.h>
 41 
 42 #include "rds.h"
 43 
 44 /* When transmitting messages in rds_send_xmit, we need to emerge from
 45  * time to time and briefly release the CPU. Otherwise the softlock watchdog
 46  * will kick our shin.
 47  * Also, it seems fairer to not let one busy connection stall all the
 48  * others.
 49  *
 50  * send_batch_count is the number of times we'll loop in send_xmit. Setting
 51  * it to 0 will restore the old behavior (where we looped until we had
 52  * drained the queue).
 53  */
 54 static int send_batch_count = 64;
 55 module_param(send_batch_count, int, 0444);
 56 MODULE_PARM_DESC(send_batch_count, " batch factor when working the send queue");
 57 
 58 static void rds_send_remove_from_sock(struct list_head *messages, int status);
 59 
 60 /*
 61  * Reset the send state.  Callers must ensure that this doesn't race with
 62  * rds_send_xmit().
 63  */
 64 void rds_send_reset(struct rds_connection *conn)
 65 {
 66         struct rds_message *rm, *tmp;
 67         unsigned long flags;
 68 
 69         if (conn->c_xmit_rm) {
 70                 rm = conn->c_xmit_rm;
 71                 conn->c_xmit_rm = NULL;
 72                 /* Tell the user the RDMA op is no longer mapped by the
 73                  * transport. This isn't entirely true (it's flushed out
 74                  * independently) but as the connection is down, there's
 75                  * no ongoing RDMA to/from that memory */
 76                 rds_message_unmapped(rm);
 77                 rds_message_put(rm);
 78         }
 79 
 80         conn->c_xmit_sg = 0;
 81         conn->c_xmit_hdr_off = 0;
 82         conn->c_xmit_data_off = 0;
 83         conn->c_xmit_atomic_sent = 0;
 84         conn->c_xmit_rdma_sent = 0;
 85         conn->c_xmit_data_sent = 0;
 86 
 87         conn->c_map_queued = 0;
 88 
 89         conn->c_unacked_packets = rds_sysctl_max_unacked_packets;
 90         conn->c_unacked_bytes = rds_sysctl_max_unacked_bytes;
 91 
 92         /* Mark messages as retransmissions, and move them to the send q */
 93         spin_lock_irqsave(&conn->c_lock, flags);
 94         list_for_each_entry_safe(rm, tmp, &conn->c_retrans, m_conn_item) {
 95                 set_bit(RDS_MSG_ACK_REQUIRED, &rm->m_flags);
 96                 set_bit(RDS_MSG_RETRANSMITTED, &rm->m_flags);
 97         }
 98         list_splice_init(&conn->c_retrans, &conn->c_send_queue);
 99         spin_unlock_irqrestore(&conn->c_lock, flags);
100 }
101 
102 static int acquire_in_xmit(struct rds_connection *conn)
103 {
104         return test_and_set_bit(RDS_IN_XMIT, &conn->c_flags) == 0;
105 }
106 
107 static void release_in_xmit(struct rds_connection *conn)
108 {
109         clear_bit(RDS_IN_XMIT, &conn->c_flags);
110         smp_mb__after_clear_bit();
111         /*
112          * We don't use wait_on_bit()/wake_up_bit() because our waking is in a
113          * hot path and finding waiters is very rare.  We don't want to walk
114          * the system-wide hashed waitqueue buckets in the fast path only to
115          * almost never find waiters.
116          */
117         if (waitqueue_active(&conn->c_waitq))
118                 wake_up_all(&conn->c_waitq);
119 }
120 
121 /*
122  * We're making the conscious trade-off here to only send one message
123  * down the connection at a time.
124  *   Pro:
125  *      - tx queueing is a simple fifo list
126  *      - reassembly is optional and easily done by transports per conn
127  *      - no per flow rx lookup at all, straight to the socket
128  *      - less per-frag memory and wire overhead
129  *   Con:
130  *      - queued acks can be delayed behind large messages
131  *   Depends:
132  *      - small message latency is higher behind queued large messages
133  *      - large message latency isn't starved by intervening small sends
134  */
135 int rds_send_xmit(struct rds_connection *conn)
136 {
137         struct rds_message *rm;
138         unsigned long flags;
139         unsigned int tmp;
140         struct scatterlist *sg;
141         int ret = 0;
142         LIST_HEAD(to_be_dropped);
143 
144 restart:
145 
146         /*
147          * sendmsg calls here after having queued its message on the send
148          * queue.  We only have one task feeding the connection at a time.  If
149          * another thread is already feeding the queue then we back off.  This
150          * avoids blocking the caller and trading per-connection data between
151          * caches per message.
152          */
153         if (!acquire_in_xmit(conn)) {
154                 rds_stats_inc(s_send_lock_contention);
155                 ret = -ENOMEM;
156                 goto out;
157         }
158 
159         /*
160          * rds_conn_shutdown() sets the conn state and then tests RDS_IN_XMIT,
161          * we do the opposite to avoid races.
162          */
163         if (!rds_conn_up(conn)) {
164                 release_in_xmit(conn);
165                 ret = 0;
166                 goto out;
167         }
168 
169         if (conn->c_trans->xmit_prepare)
170                 conn->c_trans->xmit_prepare(conn);
171 
172         /*
173          * spin trying to push headers and data down the connection until
174          * the connection doesn't make forward progress.
175          */
176         while (1) {
177 
178                 rm = conn->c_xmit_rm;
179 
180                 /*
181                  * If between sending messages, we can send a pending congestion
182                  * map update.
183                  */
184                 if (!rm && test_and_clear_bit(0, &conn->c_map_queued)) {
185                         rm = rds_cong_update_alloc(conn);
186                         if (IS_ERR(rm)) {
187                                 ret = PTR_ERR(rm);
188                                 break;
189                         }
190                         rm->data.op_active = 1;
191 
192                         conn->c_xmit_rm = rm;
193                 }
194 
195                 /*
196                  * If not already working on one, grab the next message.
197                  *
198                  * c_xmit_rm holds a ref while we're sending this message down
199                  * the connction.  We can use this ref while holding the
200                  * send_sem.. rds_send_reset() is serialized with it.
201                  */
202                 if (!rm) {
203                         unsigned int len;
204 
205                         spin_lock_irqsave(&conn->c_lock, flags);
206 
207                         if (!list_empty(&conn->c_send_queue)) {
208                                 rm = list_entry(conn->c_send_queue.next,
209                                                 struct rds_message,
210                                                 m_conn_item);
211                                 rds_message_addref(rm);
212 
213                                 /*
214                                  * Move the message from the send queue to the retransmit
215                                  * list right away.
216                                  */
217                                 list_move_tail(&rm->m_conn_item, &conn->c_retrans);
218                         }
219 
220                         spin_unlock_irqrestore(&conn->c_lock, flags);
221 
222                         if (!rm)
223                                 break;
224 
225                         /* Unfortunately, the way Infiniband deals with
226                          * RDMA to a bad MR key is by moving the entire
227                          * queue pair to error state. We cold possibly
228                          * recover from that, but right now we drop the
229                          * connection.
230                          * Therefore, we never retransmit messages with RDMA ops.
231                          */
232                         if (rm->rdma.op_active &&
233                             test_bit(RDS_MSG_RETRANSMITTED, &rm->m_flags)) {
234                                 spin_lock_irqsave(&conn->c_lock, flags);
235                                 if (test_and_clear_bit(RDS_MSG_ON_CONN, &rm->m_flags))
236                                         list_move(&rm->m_conn_item, &to_be_dropped);
237                                 spin_unlock_irqrestore(&conn->c_lock, flags);
238                                 continue;
239                         }
240 
241                         /* Require an ACK every once in a while */
242                         len = ntohl(rm->m_inc.i_hdr.h_len);
243                         if (conn->c_unacked_packets == 0 ||
244                             conn->c_unacked_bytes < len) {
245                                 __set_bit(RDS_MSG_ACK_REQUIRED, &rm->m_flags);
246 
247                                 conn->c_unacked_packets = rds_sysctl_max_unacked_packets;
248                                 conn->c_unacked_bytes = rds_sysctl_max_unacked_bytes;
249                                 rds_stats_inc(s_send_ack_required);
250                         } else {
251                                 conn->c_unacked_bytes -= len;
252                                 conn->c_unacked_packets--;
253                         }
254 
255                         conn->c_xmit_rm = rm;
256                 }
257 
258                 /* The transport either sends the whole rdma or none of it */
259                 if (rm->rdma.op_active && !conn->c_xmit_rdma_sent) {
260                         rm->m_final_op = &rm->rdma;
261                         ret = conn->c_trans->xmit_rdma(conn, &rm->rdma);
262                         if (ret)
263                                 break;
264                         conn->c_xmit_rdma_sent = 1;
265 
266                         /* The transport owns the mapped memory for now.
267                          * You can't unmap it while it's on the send queue */
268                         set_bit(RDS_MSG_MAPPED, &rm->m_flags);
269                 }
270 
271                 if (rm->atomic.op_active && !conn->c_xmit_atomic_sent) {
272                         rm->m_final_op = &rm->atomic;
273                         ret = conn->c_trans->xmit_atomic(conn, &rm->atomic);
274                         if (ret)
275                                 break;
276                         conn->c_xmit_atomic_sent = 1;
277 
278                         /* The transport owns the mapped memory for now.
279                          * You can't unmap it while it's on the send queue */
280                         set_bit(RDS_MSG_MAPPED, &rm->m_flags);
281                 }
282 
283                 /*
284                  * A number of cases require an RDS header to be sent
285                  * even if there is no data.
286                  * We permit 0-byte sends; rds-ping depends on this.
287                  * However, if there are exclusively attached silent ops,
288                  * we skip the hdr/data send, to enable silent operation.
289                  */
290                 if (rm->data.op_nents == 0) {
291                         int ops_present;
292                         int all_ops_are_silent = 1;
293 
294                         ops_present = (rm->atomic.op_active || rm->rdma.op_active);
295                         if (rm->atomic.op_active && !rm->atomic.op_silent)
296                                 all_ops_are_silent = 0;
297                         if (rm->rdma.op_active && !rm->rdma.op_silent)
298                                 all_ops_are_silent = 0;
299 
300                         if (ops_present && all_ops_are_silent
301                             && !rm->m_rdma_cookie)
302                                 rm->data.op_active = 0;
303                 }
304 
305                 if (rm->data.op_active && !conn->c_xmit_data_sent) {
306                         rm->m_final_op = &rm->data;
307                         ret = conn->c_trans->xmit(conn, rm,
308                                                   conn->c_xmit_hdr_off,
309                                                   conn->c_xmit_sg,
310                                                   conn->c_xmit_data_off);
311                         if (ret <= 0)
312                                 break;
313 
314                         if (conn->c_xmit_hdr_off < sizeof(struct rds_header)) {
315                                 tmp = min_t(int, ret,
316                                             sizeof(struct rds_header) -
317                                             conn->c_xmit_hdr_off);
318                                 conn->c_xmit_hdr_off += tmp;
319                                 ret -= tmp;
320                         }
321 
322                         sg = &rm->data.op_sg[conn->c_xmit_sg];
323                         while (ret) {
324                                 tmp = min_t(int, ret, sg->length -
325                                                       conn->c_xmit_data_off);
326                                 conn->c_xmit_data_off += tmp;
327                                 ret -= tmp;
328                                 if (conn->c_xmit_data_off == sg->length) {
329                                         conn->c_xmit_data_off = 0;
330                                         sg++;
331                                         conn->c_xmit_sg++;
332                                         BUG_ON(ret != 0 &&
333                                                conn->c_xmit_sg == rm->data.op_nents);
334                                 }
335                         }
336 
337                         if (conn->c_xmit_hdr_off == sizeof(struct rds_header) &&
338                             (conn->c_xmit_sg == rm->data.op_nents))
339                                 conn->c_xmit_data_sent = 1;
340                 }
341 
342                 /*
343                  * A rm will only take multiple times through this loop
344                  * if there is a data op. Thus, if the data is sent (or there was
345                  * none), then we're done with the rm.
346                  */
347                 if (!rm->data.op_active || conn->c_xmit_data_sent) {
348                         conn->c_xmit_rm = NULL;
349                         conn->c_xmit_sg = 0;
350                         conn->c_xmit_hdr_off = 0;
351                         conn->c_xmit_data_off = 0;
352                         conn->c_xmit_rdma_sent = 0;
353                         conn->c_xmit_atomic_sent = 0;
354                         conn->c_xmit_data_sent = 0;
355 
356                         rds_message_put(rm);
357                 }
358         }
359 
360         if (conn->c_trans->xmit_complete)
361                 conn->c_trans->xmit_complete(conn);
362 
363         release_in_xmit(conn);
364 
365         /* Nuke any messages we decided not to retransmit. */
366         if (!list_empty(&to_be_dropped)) {
367                 /* irqs on here, so we can put(), unlike above */
368                 list_for_each_entry(rm, &to_be_dropped, m_conn_item)
369                         rds_message_put(rm);
370                 rds_send_remove_from_sock(&to_be_dropped, RDS_RDMA_DROPPED);
371         }
372 
373         /*
374          * Other senders can queue a message after we last test the send queue
375          * but before we clear RDS_IN_XMIT.  In that case they'd back off and
376          * not try and send their newly queued message.  We need to check the
377          * send queue after having cleared RDS_IN_XMIT so that their message
378          * doesn't get stuck on the send queue.
379          *
380          * If the transport cannot continue (i.e ret != 0), then it must
381          * call us when more room is available, such as from the tx
382          * completion handler.
383          */
384         if (ret == 0) {
385                 smp_mb();
386                 if (!list_empty(&conn->c_send_queue)) {
387                         rds_stats_inc(s_send_lock_queue_raced);
388                         goto restart;
389                 }
390         }
391 out:
392         return ret;
393 }
394 
395 static void rds_send_sndbuf_remove(struct rds_sock *rs, struct rds_message *rm)
396 {
397         u32 len = be32_to_cpu(rm->m_inc.i_hdr.h_len);
398 
399         assert_spin_locked(&rs->rs_lock);
400 
401         BUG_ON(rs->rs_snd_bytes < len);
402         rs->rs_snd_bytes -= len;
403 
404         if (rs->rs_snd_bytes == 0)
405                 rds_stats_inc(s_send_queue_empty);
406 }
407 
408 static inline int rds_send_is_acked(struct rds_message *rm, u64 ack,
409                                     is_acked_func is_acked)
410 {
411         if (is_acked)
412                 return is_acked(rm, ack);
413         return be64_to_cpu(rm->m_inc.i_hdr.h_sequence) <= ack;
414 }
415 
416 /*
417  * This is pretty similar to what happens below in the ACK
418  * handling code - except that we call here as soon as we get
419  * the IB send completion on the RDMA op and the accompanying
420  * message.
421  */
422 void rds_rdma_send_complete(struct rds_message *rm, int status)
423 {
424         struct rds_sock *rs = NULL;
425         struct rm_rdma_op *ro;
426         struct rds_notifier *notifier;
427         unsigned long flags;
428 
429         spin_lock_irqsave(&rm->m_rs_lock, flags);
430 
431         ro = &rm->rdma;
432         if (test_bit(RDS_MSG_ON_SOCK, &rm->m_flags) &&
433             ro->op_active && ro->op_notify && ro->op_notifier) {
434                 notifier = ro->op_notifier;
435                 rs = rm->m_rs;
436                 sock_hold(rds_rs_to_sk(rs));
437 
438                 notifier->n_status = status;
439                 spin_lock(&rs->rs_lock);
440                 list_add_tail(&notifier->n_list, &rs->rs_notify_queue);
441                 spin_unlock(&rs->rs_lock);
442 
443                 ro->op_notifier = NULL;
444         }
445 
446         spin_unlock_irqrestore(&rm->m_rs_lock, flags);
447 
448         if (rs) {
449                 rds_wake_sk_sleep(rs);
450                 sock_put(rds_rs_to_sk(rs));
451         }
452 }
453 EXPORT_SYMBOL_GPL(rds_rdma_send_complete);
454 
455 /*
456  * Just like above, except looks at atomic op
457  */
458 void rds_atomic_send_complete(struct rds_message *rm, int status)
459 {
460         struct rds_sock *rs = NULL;
461         struct rm_atomic_op *ao;
462         struct rds_notifier *notifier;
463         unsigned long flags;
464 
465         spin_lock_irqsave(&rm->m_rs_lock, flags);
466 
467         ao = &rm->atomic;
468         if (test_bit(RDS_MSG_ON_SOCK, &rm->m_flags)
469             && ao->op_active && ao->op_notify && ao->op_notifier) {
470                 notifier = ao->op_notifier;
471                 rs = rm->m_rs;
472                 sock_hold(rds_rs_to_sk(rs));
473 
474                 notifier->n_status = status;
475                 spin_lock(&rs->rs_lock);
476                 list_add_tail(&notifier->n_list, &rs->rs_notify_queue);
477                 spin_unlock(&rs->rs_lock);
478 
479                 ao->op_notifier = NULL;
480         }
481 
482         spin_unlock_irqrestore(&rm->m_rs_lock, flags);
483 
484         if (rs) {
485                 rds_wake_sk_sleep(rs);
486                 sock_put(rds_rs_to_sk(rs));
487         }
488 }
489 EXPORT_SYMBOL_GPL(rds_atomic_send_complete);
490 
491 /*
492  * This is the same as rds_rdma_send_complete except we
493  * don't do any locking - we have all the ingredients (message,
494  * socket, socket lock) and can just move the notifier.
495  */
496 static inline void
497 __rds_send_complete(struct rds_sock *rs, struct rds_message *rm, int status)
498 {
499         struct rm_rdma_op *ro;
500         struct rm_atomic_op *ao;
501 
502         ro = &rm->rdma;
503         if (ro->op_active && ro->op_notify && ro->op_notifier) {
504                 ro->op_notifier->n_status = status;
505                 list_add_tail(&ro->op_notifier->n_list, &rs->rs_notify_queue);
506                 ro->op_notifier = NULL;
507         }
508 
509         ao = &rm->atomic;
510         if (ao->op_active && ao->op_notify && ao->op_notifier) {
511                 ao->op_notifier->n_status = status;
512                 list_add_tail(&ao->op_notifier->n_list, &rs->rs_notify_queue);
513                 ao->op_notifier = NULL;
514         }
515 
516         /* No need to wake the app - caller does this */
517 }
518 
519 /*
520  * This is called from the IB send completion when we detect
521  * a RDMA operation that failed with remote access error.
522  * So speed is not an issue here.
523  */
524 struct rds_message *rds_send_get_message(struct rds_connection *conn,
525                                          struct rm_rdma_op *op)
526 {
527         struct rds_message *rm, *tmp, *found = NULL;
528         unsigned long flags;
529 
530         spin_lock_irqsave(&conn->c_lock, flags);
531 
532         list_for_each_entry_safe(rm, tmp, &conn->c_retrans, m_conn_item) {
533                 if (&rm->rdma == op) {
534                         atomic_inc(&rm->m_refcount);
535                         found = rm;
536                         goto out;
537                 }
538         }
539 
540         list_for_each_entry_safe(rm, tmp, &conn->c_send_queue, m_conn_item) {
541                 if (&rm->rdma == op) {
542                         atomic_inc(&rm->m_refcount);
543                         found = rm;
544                         break;
545                 }
546         }
547 
548 out:
549         spin_unlock_irqrestore(&conn->c_lock, flags);
550 
551         return found;
552 }
553 EXPORT_SYMBOL_GPL(rds_send_get_message);
554 
555 /*
556  * This removes messages from the socket's list if they're on it.  The list
557  * argument must be private to the caller, we must be able to modify it
558  * without locks.  The messages must have a reference held for their
559  * position on the list.  This function will drop that reference after
560  * removing the messages from the 'messages' list regardless of if it found
561  * the messages on the socket list or not.
562  */
563 static void rds_send_remove_from_sock(struct list_head *messages, int status)
564 {
565         unsigned long flags;
566         struct rds_sock *rs = NULL;
567         struct rds_message *rm;
568 
569         while (!list_empty(messages)) {
570                 int was_on_sock = 0;
571 
572                 rm = list_entry(messages->next, struct rds_message,
573                                 m_conn_item);
574                 list_del_init(&rm->m_conn_item);
575 
576                 /*
577                  * If we see this flag cleared then we're *sure* that someone
578                  * else beat us to removing it from the sock.  If we race
579                  * with their flag update we'll get the lock and then really
580                  * see that the flag has been cleared.
581                  *
582                  * The message spinlock makes sure nobody clears rm->m_rs
583                  * while we're messing with it. It does not prevent the
584                  * message from being removed from the socket, though.
585                  */
586                 spin_lock_irqsave(&rm->m_rs_lock, flags);
587                 if (!test_bit(RDS_MSG_ON_SOCK, &rm->m_flags))
588                         goto unlock_and_drop;
589 
590                 if (rs != rm->m_rs) {
591                         if (rs) {
592                                 rds_wake_sk_sleep(rs);
593                                 sock_put(rds_rs_to_sk(rs));
594                         }
595                         rs = rm->m_rs;
596                         sock_hold(rds_rs_to_sk(rs));
597                 }
598                 spin_lock(&rs->rs_lock);
599 
600                 if (test_and_clear_bit(RDS_MSG_ON_SOCK, &rm->m_flags)) {
601                         struct rm_rdma_op *ro = &rm->rdma;
602                         struct rds_notifier *notifier;
603 
604                         list_del_init(&rm->m_sock_item);
605                         rds_send_sndbuf_remove(rs, rm);
606 
607                         if (ro->op_active && ro->op_notifier &&
608                                (ro->op_notify || (ro->op_recverr && status))) {
609                                 notifier = ro->op_notifier;
610                                 list_add_tail(&notifier->n_list,
611                                                 &rs->rs_notify_queue);
612                                 if (!notifier->n_status)
613                                         notifier->n_status = status;
614                                 rm->rdma.op_notifier = NULL;
615                         }
616                         was_on_sock = 1;
617                         rm->m_rs = NULL;
618                 }
619                 spin_unlock(&rs->rs_lock);
620 
621 unlock_and_drop:
622                 spin_unlock_irqrestore(&rm->m_rs_lock, flags);
623                 rds_message_put(rm);
624                 if (was_on_sock)
625                         rds_message_put(rm);
626         }
627 
628         if (rs) {
629                 rds_wake_sk_sleep(rs);
630                 sock_put(rds_rs_to_sk(rs));
631         }
632 }
633 
634 /*
635  * Transports call here when they've determined that the receiver queued
636  * messages up to, and including, the given sequence number.  Messages are
637  * moved to the retrans queue when rds_send_xmit picks them off the send
638  * queue. This means that in the TCP case, the message may not have been
639  * assigned the m_ack_seq yet - but that's fine as long as tcp_is_acked
640  * checks the RDS_MSG_HAS_ACK_SEQ bit.
641  *
642  * XXX It's not clear to me how this is safely serialized with socket
643  * destruction.  Maybe it should bail if it sees SOCK_DEAD.
644  */
645 void rds_send_drop_acked(struct rds_connection *conn, u64 ack,
646                          is_acked_func is_acked)
647 {
648         struct rds_message *rm, *tmp;
649         unsigned long flags;
650         LIST_HEAD(list);
651 
652         spin_lock_irqsave(&conn->c_lock, flags);
653 
654         list_for_each_entry_safe(rm, tmp, &conn->c_retrans, m_conn_item) {
655                 if (!rds_send_is_acked(rm, ack, is_acked))
656                         break;
657 
658                 list_move(&rm->m_conn_item, &list);
659                 clear_bit(RDS_MSG_ON_CONN, &rm->m_flags);
660         }
661 
662         /* order flag updates with spin locks */
663         if (!list_empty(&list))
664                 smp_mb__after_clear_bit();
665 
666         spin_unlock_irqrestore(&conn->c_lock, flags);
667 
668         /* now remove the messages from the sock list as needed */
669         rds_send_remove_from_sock(&list, RDS_RDMA_SUCCESS);
670 }
671 EXPORT_SYMBOL_GPL(rds_send_drop_acked);
672 
673 void rds_send_drop_to(struct rds_sock *rs, struct sockaddr_in *dest)
674 {
675         struct rds_message *rm, *tmp;
676         struct rds_connection *conn;
677         unsigned long flags;
678         LIST_HEAD(list);
679 
680         /* get all the messages we're dropping under the rs lock */
681         spin_lock_irqsave(&rs->rs_lock, flags);
682 
683         list_for_each_entry_safe(rm, tmp, &rs->rs_send_queue, m_sock_item) {
684                 if (dest && (dest->sin_addr.s_addr != rm->m_daddr ||
685                              dest->sin_port != rm->m_inc.i_hdr.h_dport))
686                         continue;
687 
688                 list_move(&rm->m_sock_item, &list);
689                 rds_send_sndbuf_remove(rs, rm);
690                 clear_bit(RDS_MSG_ON_SOCK, &rm->m_flags);
691         }
692 
693         /* order flag updates with the rs lock */
694         smp_mb__after_clear_bit();
695 
696         spin_unlock_irqrestore(&rs->rs_lock, flags);
697 
698         if (list_empty(&list))
699                 return;
700 
701         /* Remove the messages from the conn */
702         list_for_each_entry(rm, &list, m_sock_item) {
703 
704                 conn = rm->m_inc.i_conn;
705 
706                 spin_lock_irqsave(&conn->c_lock, flags);
707                 /*
708                  * Maybe someone else beat us to removing rm from the conn.
709                  * If we race with their flag update we'll get the lock and
710                  * then really see that the flag has been cleared.
711                  */
712                 if (!test_and_clear_bit(RDS_MSG_ON_CONN, &rm->m_flags)) {
713                         spin_unlock_irqrestore(&conn->c_lock, flags);
714                         continue;
715                 }
716                 list_del_init(&rm->m_conn_item);
717                 spin_unlock_irqrestore(&conn->c_lock, flags);
718 
719                 /*
720                  * Couldn't grab m_rs_lock in top loop (lock ordering),
721                  * but we can now.
722                  */
723                 spin_lock_irqsave(&rm->m_rs_lock, flags);
724 
725                 spin_lock(&rs->rs_lock);
726                 __rds_send_complete(rs, rm, RDS_RDMA_CANCELED);
727                 spin_unlock(&rs->rs_lock);
728 
729                 rm->m_rs = NULL;
730                 spin_unlock_irqrestore(&rm->m_rs_lock, flags);
731 
732                 rds_message_put(rm);
733         }
734 
735         rds_wake_sk_sleep(rs);
736 
737         while (!list_empty(&list)) {
738                 rm = list_entry(list.next, struct rds_message, m_sock_item);
739                 list_del_init(&rm->m_sock_item);
740 
741                 rds_message_wait(rm);
742                 rds_message_put(rm);
743         }
744 }
745 
746 /*
747  * we only want this to fire once so we use the callers 'queued'.  It's
748  * possible that another thread can race with us and remove the
749  * message from the flow with RDS_CANCEL_SENT_TO.
750  */
751 static int rds_send_queue_rm(struct rds_sock *rs, struct rds_connection *conn,
752                              struct rds_message *rm, __be16 sport,
753                              __be16 dport, int *queued)
754 {
755         unsigned long flags;
756         u32 len;
757 
758         if (*queued)
759                 goto out;
760 
761         len = be32_to_cpu(rm->m_inc.i_hdr.h_len);
762 
763         /* this is the only place which holds both the socket's rs_lock
764          * and the connection's c_lock */
765         spin_lock_irqsave(&rs->rs_lock, flags);
766 
767         /*
768          * If there is a little space in sndbuf, we don't queue anything,
769          * and userspace gets -EAGAIN. But poll() indicates there's send
770          * room. This can lead to bad behavior (spinning) if snd_bytes isn't
771          * freed up by incoming acks. So we check the *old* value of
772          * rs_snd_bytes here to allow the last msg to exceed the buffer,
773          * and poll() now knows no more data can be sent.
774          */
775         if (rs->rs_snd_bytes < rds_sk_sndbuf(rs)) {
776                 rs->rs_snd_bytes += len;
777 
778                 /* let recv side know we are close to send space exhaustion.
779                  * This is probably not the optimal way to do it, as this
780                  * means we set the flag on *all* messages as soon as our
781                  * throughput hits a certain threshold.
782                  */
783                 if (rs->rs_snd_bytes >= rds_sk_sndbuf(rs) / 2)
784                         __set_bit(RDS_MSG_ACK_REQUIRED, &rm->m_flags);
785 
786                 list_add_tail(&rm->m_sock_item, &rs->rs_send_queue);
787                 set_bit(RDS_MSG_ON_SOCK, &rm->m_flags);
788                 rds_message_addref(rm);
789                 rm->m_rs = rs;
790 
791                 /* The code ordering is a little weird, but we're
792                    trying to minimize the time we hold c_lock */
793                 rds_message_populate_header(&rm->m_inc.i_hdr, sport, dport, 0);
794                 rm->m_inc.i_conn = conn;
795                 rds_message_addref(rm);
796 
797                 spin_lock(&conn->c_lock);
798                 rm->m_inc.i_hdr.h_sequence = cpu_to_be64(conn->c_next_tx_seq++);
799                 list_add_tail(&rm->m_conn_item, &conn->c_send_queue);
800                 set_bit(RDS_MSG_ON_CONN, &rm->m_flags);
801                 spin_unlock(&conn->c_lock);
802 
803                 rdsdebug("queued msg %p len %d, rs %p bytes %d seq %llu\n",
804                          rm, len, rs, rs->rs_snd_bytes,
805                          (unsigned long long)be64_to_cpu(rm->m_inc.i_hdr.h_sequence));
806 
807                 *queued = 1;
808         }
809 
810         spin_unlock_irqrestore(&rs->rs_lock, flags);
811 out:
812         return *queued;
813 }
814 
815 /*
816  * rds_message is getting to be quite complicated, and we'd like to allocate
817  * it all in one go. This figures out how big it needs to be up front.
818  */
819 static int rds_rm_size(struct msghdr *msg, int data_len)
820 {
821         struct cmsghdr *cmsg;
822         int size = 0;
823         int cmsg_groups = 0;
824         int retval;
825 
826         for (cmsg = CMSG_FIRSTHDR(msg); cmsg; cmsg = CMSG_NXTHDR(msg, cmsg)) {
827                 if (!CMSG_OK(msg, cmsg))
828                         return -EINVAL;
829 
830                 if (cmsg->cmsg_level != SOL_RDS)
831                         continue;
832 
833                 switch (cmsg->cmsg_type) {
834                 case RDS_CMSG_RDMA_ARGS:
835                         cmsg_groups |= 1;
836                         retval = rds_rdma_extra_size(CMSG_DATA(cmsg));
837                         if (retval < 0)
838                                 return retval;
839                         size += retval;
840 
841                         break;
842 
843                 case RDS_CMSG_RDMA_DEST:
844                 case RDS_CMSG_RDMA_MAP:
845                         cmsg_groups |= 2;
846                         /* these are valid but do no add any size */
847                         break;
848 
849                 case RDS_CMSG_ATOMIC_CSWP:
850                 case RDS_CMSG_ATOMIC_FADD:
851                 case RDS_CMSG_MASKED_ATOMIC_CSWP:
852                 case RDS_CMSG_MASKED_ATOMIC_FADD:
853                         cmsg_groups |= 1;
854                         size += sizeof(struct scatterlist);
855                         break;
856 
857                 default:
858                         return -EINVAL;
859                 }
860 
861         }
862 
863         size += ceil(data_len, PAGE_SIZE) * sizeof(struct scatterlist);
864 
865         /* Ensure (DEST, MAP) are never used with (ARGS, ATOMIC) */
866         if (cmsg_groups == 3)
867                 return -EINVAL;
868 
869         return size;
870 }
871 
872 static int rds_cmsg_send(struct rds_sock *rs, struct rds_message *rm,
873                          struct msghdr *msg, int *allocated_mr)
874 {
875         struct cmsghdr *cmsg;
876         int ret = 0;
877 
878         for (cmsg = CMSG_FIRSTHDR(msg); cmsg; cmsg = CMSG_NXTHDR(msg, cmsg)) {
879                 if (!CMSG_OK(msg, cmsg))
880                         return -EINVAL;
881 
882                 if (cmsg->cmsg_level != SOL_RDS)
883                         continue;
884 
885                 /* As a side effect, RDMA_DEST and RDMA_MAP will set
886                  * rm->rdma.m_rdma_cookie and rm->rdma.m_rdma_mr.
887                  */
888                 switch (cmsg->cmsg_type) {
889                 case RDS_CMSG_RDMA_ARGS:
890                         ret = rds_cmsg_rdma_args(rs, rm, cmsg);
891                         break;
892 
893                 case RDS_CMSG_RDMA_DEST:
894                         ret = rds_cmsg_rdma_dest(rs, rm, cmsg);
895                         break;
896 
897                 case RDS_CMSG_RDMA_MAP:
898                         ret = rds_cmsg_rdma_map(rs, rm, cmsg);
899                         if (!ret)
900                                 *allocated_mr = 1;
901                         break;
902                 case RDS_CMSG_ATOMIC_CSWP:
903                 case RDS_CMSG_ATOMIC_FADD:
904                 case RDS_CMSG_MASKED_ATOMIC_CSWP:
905                 case RDS_CMSG_MASKED_ATOMIC_FADD:
906                         ret = rds_cmsg_atomic(rs, rm, cmsg);
907                         break;
908 
909                 default:
910                         return -EINVAL;
911                 }
912 
913                 if (ret)
914                         break;
915         }
916 
917         return ret;
918 }
919 
920 int rds_sendmsg(struct kiocb *iocb, struct socket *sock, struct msghdr *msg,
921                 size_t payload_len)
922 {
923         struct sock *sk = sock->sk;
924         struct rds_sock *rs = rds_sk_to_rs(sk);
925         struct sockaddr_in *usin = (struct sockaddr_in *)msg->msg_name;
926         __be32 daddr;
927         __be16 dport;
928         struct rds_message *rm = NULL;
929         struct rds_connection *conn;
930         int ret = 0;
931         int queued = 0, allocated_mr = 0;
932         int nonblock = msg->msg_flags & MSG_DONTWAIT;
933         long timeo = sock_sndtimeo(sk, nonblock);
934 
935         /* Mirror Linux UDP mirror of BSD error message compatibility */
936         /* XXX: Perhaps MSG_MORE someday */
937         if (msg->msg_flags & ~(MSG_DONTWAIT | MSG_CMSG_COMPAT)) {
938                 ret = -EOPNOTSUPP;
939                 goto out;
940         }
941 
942         if (msg->msg_namelen) {
943                 /* XXX fail non-unicast destination IPs? */
944                 if (msg->msg_namelen < sizeof(*usin) || usin->sin_family != AF_INET) {
945                         ret = -EINVAL;
946                         goto out;
947                 }
948                 daddr = usin->sin_addr.s_addr;
949                 dport = usin->sin_port;
950         } else {
951                 /* We only care about consistency with ->connect() */
952                 lock_sock(sk);
953                 daddr = rs->rs_conn_addr;
954                 dport = rs->rs_conn_port;
955                 release_sock(sk);
956         }
957 
958         lock_sock(sk);
959         if (daddr == 0 || rs->rs_bound_addr == 0) {
960                 release_sock(sk);
961                 ret = -ENOTCONN; /* XXX not a great errno */
962                 goto out;
963         }
964         release_sock(sk);
965 
966         /* size of rm including all sgs */
967         ret = rds_rm_size(msg, payload_len);
968         if (ret < 0)
969                 goto out;
970 
971         rm = rds_message_alloc(ret, GFP_KERNEL);
972         if (!rm) {
973                 ret = -ENOMEM;
974                 goto out;
975         }
976 
977         /* Attach data to the rm */
978         if (payload_len) {
979                 rm->data.op_sg = rds_message_alloc_sgs(rm, ceil(payload_len, PAGE_SIZE));
980                 if (!rm->data.op_sg) {
981                         ret = -ENOMEM;
982                         goto out;
983                 }
984                 ret = rds_message_copy_from_user(rm, msg->msg_iov, payload_len);
985                 if (ret)
986                         goto out;
987         }
988         rm->data.op_active = 1;
989 
990         rm->m_daddr = daddr;
991 
992         /* rds_conn_create has a spinlock that runs with IRQ off.
993          * Caching the conn in the socket helps a lot. */
994         if (rs->rs_conn && rs->rs_conn->c_faddr == daddr)
995                 conn = rs->rs_conn;
996         else {
997                 conn = rds_conn_create_outgoing(rs->rs_bound_addr, daddr,
998                                         rs->rs_transport,
999                                         sock->sk->sk_allocation);
1000                 if (IS_ERR(conn)) {
1001                         ret = PTR_ERR(conn);
1002                         goto out;
1003                 }
1004                 rs->rs_conn = conn;
1005         }
1006 
1007         /* Parse any control messages the user may have included. */
1008         ret = rds_cmsg_send(rs, rm, msg, &allocated_mr);
1009         if (ret)
1010                 goto out;
1011 
1012         if (rm->rdma.op_active && !conn->c_trans->xmit_rdma) {
1013                 printk_ratelimited(KERN_NOTICE "rdma_op %p conn xmit_rdma %p\n",
1014                                &rm->rdma, conn->c_trans->xmit_rdma);
1015                 ret = -EOPNOTSUPP;
1016                 goto out;
1017         }
1018 
1019         if (rm->atomic.op_active && !conn->c_trans->xmit_atomic) {
1020                 printk_ratelimited(KERN_NOTICE "atomic_op %p conn xmit_atomic %p\n",
1021                                &rm->atomic, conn->c_trans->xmit_atomic);
1022                 ret = -EOPNOTSUPP;
1023                 goto out;
1024         }
1025 
1026         rds_conn_connect_if_down(conn);
1027 
1028         ret = rds_cong_wait(conn->c_fcong, dport, nonblock, rs);
1029         if (ret) {
1030                 rs->rs_seen_congestion = 1;
1031                 goto out;
1032         }
1033 
1034         while (!rds_send_queue_rm(rs, conn, rm, rs->rs_bound_port,
1035                                   dport, &queued)) {
1036                 rds_stats_inc(s_send_queue_full);
1037                 /* XXX make sure this is reasonable */
1038                 if (payload_len > rds_sk_sndbuf(rs)) {
1039                         ret = -EMSGSIZE;
1040                         goto out;
1041                 }
1042                 if (nonblock) {
1043                         ret = -EAGAIN;
1044                         goto out;
1045                 }
1046 
1047                 timeo = wait_event_interruptible_timeout(*sk_sleep(sk),
1048                                         rds_send_queue_rm(rs, conn, rm,
1049                                                           rs->rs_bound_port,
1050                                                           dport,
1051                                                           &queued),
1052                                         timeo);
1053                 rdsdebug("sendmsg woke queued %d timeo %ld\n", queued, timeo);
1054                 if (timeo > 0 || timeo == MAX_SCHEDULE_TIMEOUT)
1055                         continue;
1056 
1057                 ret = timeo;
1058                 if (ret == 0)
1059                         ret = -ETIMEDOUT;
1060                 goto out;
1061         }
1062 
1063         /*
1064          * By now we've committed to the send.  We reuse rds_send_worker()
1065          * to retry sends in the rds thread if the transport asks us to.
1066          */
1067         rds_stats_inc(s_send_queued);
1068 
1069         if (!test_bit(RDS_LL_SEND_FULL, &conn->c_flags))
1070                 rds_send_xmit(conn);
1071 
1072         rds_message_put(rm);
1073         return payload_len;
1074 
1075 out:
1076         /* If the user included a RDMA_MAP cmsg, we allocated a MR on the fly.
1077          * If the sendmsg goes through, we keep the MR. If it fails with EAGAIN
1078          * or in any other way, we need to destroy the MR again */
1079         if (allocated_mr)
1080                 rds_rdma_unuse(rs, rds_rdma_cookie_key(rm->m_rdma_cookie), 1);
1081 
1082         if (rm)
1083                 rds_message_put(rm);
1084         return ret;
1085 }
1086 
1087 /*
1088  * Reply to a ping packet.
1089  */
1090 int
1091 rds_send_pong(struct rds_connection *conn, __be16 dport)
1092 {
1093         struct rds_message *rm;
1094         unsigned long flags;
1095         int ret = 0;
1096 
1097         rm = rds_message_alloc(0, GFP_ATOMIC);
1098         if (!rm) {
1099                 ret = -ENOMEM;
1100                 goto out;
1101         }
1102 
1103         rm->m_daddr = conn->c_faddr;
1104         rm->data.op_active = 1;
1105 
1106         rds_conn_connect_if_down(conn);
1107 
1108         ret = rds_cong_wait(conn->c_fcong, dport, 1, NULL);
1109         if (ret)
1110                 goto out;
1111 
1112         spin_lock_irqsave(&conn->c_lock, flags);
1113         list_add_tail(&rm->m_conn_item, &conn->c_send_queue);
1114         set_bit(RDS_MSG_ON_CONN, &rm->m_flags);
1115         rds_message_addref(rm);
1116         rm->m_inc.i_conn = conn;
1117 
1118         rds_message_populate_header(&rm->m_inc.i_hdr, 0, dport,
1119                                     conn->c_next_tx_seq);
1120         conn->c_next_tx_seq++;
1121         spin_unlock_irqrestore(&conn->c_lock, flags);
1122 
1123         rds_stats_inc(s_send_queued);
1124         rds_stats_inc(s_send_pong);
1125 
1126         if (!test_bit(RDS_LL_SEND_FULL, &conn->c_flags))
1127                 queue_delayed_work(rds_wq, &conn->c_send_w, 0);
1128 
1129         rds_message_put(rm);
1130         return 0;
1131 
1132 out:
1133         if (rm)
1134                 rds_message_put(rm);
1135         return ret;
1136 }
1137 

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