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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 #include <linux/sizes.h>
 42 
 43 #include "rds.h"
 44 
 45 /* When transmitting messages in rds_send_xmit, we need to emerge from
 46  * time to time and briefly release the CPU. Otherwise the softlock watchdog
 47  * will kick our shin.
 48  * Also, it seems fairer to not let one busy connection stall all the
 49  * others.
 50  *
 51  * send_batch_count is the number of times we'll loop in send_xmit. Setting
 52  * it to 0 will restore the old behavior (where we looped until we had
 53  * drained the queue).
 54  */
 55 static int send_batch_count = SZ_1K;
 56 module_param(send_batch_count, int, 0444);
 57 MODULE_PARM_DESC(send_batch_count, " batch factor when working the send queue");
 58 
 59 static void rds_send_remove_from_sock(struct list_head *messages, int status);
 60 
 61 /*
 62  * Reset the send state.  Callers must ensure that this doesn't race with
 63  * rds_send_xmit().
 64  */
 65 void rds_send_reset(struct rds_connection *conn)
 66 {
 67         struct rds_message *rm, *tmp;
 68         unsigned long flags;
 69 
 70         if (conn->c_xmit_rm) {
 71                 rm = conn->c_xmit_rm;
 72                 conn->c_xmit_rm = NULL;
 73                 /* Tell the user the RDMA op is no longer mapped by the
 74                  * transport. This isn't entirely true (it's flushed out
 75                  * independently) but as the connection is down, there's
 76                  * no ongoing RDMA to/from that memory */
 77                 rds_message_unmapped(rm);
 78                 rds_message_put(rm);
 79         }
 80 
 81         conn->c_xmit_sg = 0;
 82         conn->c_xmit_hdr_off = 0;
 83         conn->c_xmit_data_off = 0;
 84         conn->c_xmit_atomic_sent = 0;
 85         conn->c_xmit_rdma_sent = 0;
 86         conn->c_xmit_data_sent = 0;
 87 
 88         conn->c_map_queued = 0;
 89 
 90         conn->c_unacked_packets = rds_sysctl_max_unacked_packets;
 91         conn->c_unacked_bytes = rds_sysctl_max_unacked_bytes;
 92 
 93         /* Mark messages as retransmissions, and move them to the send q */
 94         spin_lock_irqsave(&conn->c_lock, flags);
 95         list_for_each_entry_safe(rm, tmp, &conn->c_retrans, m_conn_item) {
 96                 set_bit(RDS_MSG_ACK_REQUIRED, &rm->m_flags);
 97                 set_bit(RDS_MSG_RETRANSMITTED, &rm->m_flags);
 98         }
 99         list_splice_init(&conn->c_retrans, &conn->c_send_queue);
100         spin_unlock_irqrestore(&conn->c_lock, flags);
101 }
102 
103 static int acquire_in_xmit(struct rds_connection *conn)
104 {
105         return test_and_set_bit(RDS_IN_XMIT, &conn->c_flags) == 0;
106 }
107 
108 static void release_in_xmit(struct rds_connection *conn)
109 {
110         clear_bit(RDS_IN_XMIT, &conn->c_flags);
111         smp_mb__after_atomic();
112         /*
113          * We don't use wait_on_bit()/wake_up_bit() because our waking is in a
114          * hot path and finding waiters is very rare.  We don't want to walk
115          * the system-wide hashed waitqueue buckets in the fast path only to
116          * almost never find waiters.
117          */
118         if (waitqueue_active(&conn->c_waitq))
119                 wake_up_all(&conn->c_waitq);
120 }
121 
122 /*
123  * We're making the conscious trade-off here to only send one message
124  * down the connection at a time.
125  *   Pro:
126  *      - tx queueing is a simple fifo list
127  *      - reassembly is optional and easily done by transports per conn
128  *      - no per flow rx lookup at all, straight to the socket
129  *      - less per-frag memory and wire overhead
130  *   Con:
131  *      - queued acks can be delayed behind large messages
132  *   Depends:
133  *      - small message latency is higher behind queued large messages
134  *      - large message latency isn't starved by intervening small sends
135  */
136 int rds_send_xmit(struct rds_connection *conn)
137 {
138         struct rds_message *rm;
139         unsigned long flags;
140         unsigned int tmp;
141         struct scatterlist *sg;
142         int ret = 0;
143         LIST_HEAD(to_be_dropped);
144         int batch_count;
145         unsigned long send_gen = 0;
146 
147 restart:
148         batch_count = 0;
149 
150         /*
151          * sendmsg calls here after having queued its message on the send
152          * queue.  We only have one task feeding the connection at a time.  If
153          * another thread is already feeding the queue then we back off.  This
154          * avoids blocking the caller and trading per-connection data between
155          * caches per message.
156          */
157         if (!acquire_in_xmit(conn)) {
158                 rds_stats_inc(s_send_lock_contention);
159                 ret = -ENOMEM;
160                 goto out;
161         }
162 
163         /*
164          * we record the send generation after doing the xmit acquire.
165          * if someone else manages to jump in and do some work, we'll use
166          * this to avoid a goto restart farther down.
167          *
168          * The acquire_in_xmit() check above ensures that only one
169          * caller can increment c_send_gen at any time.
170          */
171         conn->c_send_gen++;
172         send_gen = conn->c_send_gen;
173 
174         /*
175          * rds_conn_shutdown() sets the conn state and then tests RDS_IN_XMIT,
176          * we do the opposite to avoid races.
177          */
178         if (!rds_conn_up(conn)) {
179                 release_in_xmit(conn);
180                 ret = 0;
181                 goto out;
182         }
183 
184         if (conn->c_trans->xmit_prepare)
185                 conn->c_trans->xmit_prepare(conn);
186 
187         /*
188          * spin trying to push headers and data down the connection until
189          * the connection doesn't make forward progress.
190          */
191         while (1) {
192 
193                 rm = conn->c_xmit_rm;
194 
195                 /*
196                  * If between sending messages, we can send a pending congestion
197                  * map update.
198                  */
199                 if (!rm && test_and_clear_bit(0, &conn->c_map_queued)) {
200                         rm = rds_cong_update_alloc(conn);
201                         if (IS_ERR(rm)) {
202                                 ret = PTR_ERR(rm);
203                                 break;
204                         }
205                         rm->data.op_active = 1;
206 
207                         conn->c_xmit_rm = rm;
208                 }
209 
210                 /*
211                  * If not already working on one, grab the next message.
212                  *
213                  * c_xmit_rm holds a ref while we're sending this message down
214                  * the connction.  We can use this ref while holding the
215                  * send_sem.. rds_send_reset() is serialized with it.
216                  */
217                 if (!rm) {
218                         unsigned int len;
219 
220                         batch_count++;
221 
222                         /* we want to process as big a batch as we can, but
223                          * we also want to avoid softlockups.  If we've been
224                          * through a lot of messages, lets back off and see
225                          * if anyone else jumps in
226                          */
227                         if (batch_count >= send_batch_count)
228                                 goto over_batch;
229 
230                         spin_lock_irqsave(&conn->c_lock, flags);
231 
232                         if (!list_empty(&conn->c_send_queue)) {
233                                 rm = list_entry(conn->c_send_queue.next,
234                                                 struct rds_message,
235                                                 m_conn_item);
236                                 rds_message_addref(rm);
237 
238                                 /*
239                                  * Move the message from the send queue to the retransmit
240                                  * list right away.
241                                  */
242                                 list_move_tail(&rm->m_conn_item, &conn->c_retrans);
243                         }
244 
245                         spin_unlock_irqrestore(&conn->c_lock, flags);
246 
247                         if (!rm)
248                                 break;
249 
250                         /* Unfortunately, the way Infiniband deals with
251                          * RDMA to a bad MR key is by moving the entire
252                          * queue pair to error state. We cold possibly
253                          * recover from that, but right now we drop the
254                          * connection.
255                          * Therefore, we never retransmit messages with RDMA ops.
256                          */
257                         if (rm->rdma.op_active &&
258                             test_bit(RDS_MSG_RETRANSMITTED, &rm->m_flags)) {
259                                 spin_lock_irqsave(&conn->c_lock, flags);
260                                 if (test_and_clear_bit(RDS_MSG_ON_CONN, &rm->m_flags))
261                                         list_move(&rm->m_conn_item, &to_be_dropped);
262                                 spin_unlock_irqrestore(&conn->c_lock, flags);
263                                 continue;
264                         }
265 
266                         /* Require an ACK every once in a while */
267                         len = ntohl(rm->m_inc.i_hdr.h_len);
268                         if (conn->c_unacked_packets == 0 ||
269                             conn->c_unacked_bytes < len) {
270                                 __set_bit(RDS_MSG_ACK_REQUIRED, &rm->m_flags);
271 
272                                 conn->c_unacked_packets = rds_sysctl_max_unacked_packets;
273                                 conn->c_unacked_bytes = rds_sysctl_max_unacked_bytes;
274                                 rds_stats_inc(s_send_ack_required);
275                         } else {
276                                 conn->c_unacked_bytes -= len;
277                                 conn->c_unacked_packets--;
278                         }
279 
280                         conn->c_xmit_rm = rm;
281                 }
282 
283                 /* The transport either sends the whole rdma or none of it */
284                 if (rm->rdma.op_active && !conn->c_xmit_rdma_sent) {
285                         rm->m_final_op = &rm->rdma;
286                         /* The transport owns the mapped memory for now.
287                          * You can't unmap it while it's on the send queue
288                          */
289                         set_bit(RDS_MSG_MAPPED, &rm->m_flags);
290                         ret = conn->c_trans->xmit_rdma(conn, &rm->rdma);
291                         if (ret) {
292                                 clear_bit(RDS_MSG_MAPPED, &rm->m_flags);
293                                 wake_up_interruptible(&rm->m_flush_wait);
294                                 break;
295                         }
296                         conn->c_xmit_rdma_sent = 1;
297 
298                 }
299 
300                 if (rm->atomic.op_active && !conn->c_xmit_atomic_sent) {
301                         rm->m_final_op = &rm->atomic;
302                         /* The transport owns the mapped memory for now.
303                          * You can't unmap it while it's on the send queue
304                          */
305                         set_bit(RDS_MSG_MAPPED, &rm->m_flags);
306                         ret = conn->c_trans->xmit_atomic(conn, &rm->atomic);
307                         if (ret) {
308                                 clear_bit(RDS_MSG_MAPPED, &rm->m_flags);
309                                 wake_up_interruptible(&rm->m_flush_wait);
310                                 break;
311                         }
312                         conn->c_xmit_atomic_sent = 1;
313 
314                 }
315 
316                 /*
317                  * A number of cases require an RDS header to be sent
318                  * even if there is no data.
319                  * We permit 0-byte sends; rds-ping depends on this.
320                  * However, if there are exclusively attached silent ops,
321                  * we skip the hdr/data send, to enable silent operation.
322                  */
323                 if (rm->data.op_nents == 0) {
324                         int ops_present;
325                         int all_ops_are_silent = 1;
326 
327                         ops_present = (rm->atomic.op_active || rm->rdma.op_active);
328                         if (rm->atomic.op_active && !rm->atomic.op_silent)
329                                 all_ops_are_silent = 0;
330                         if (rm->rdma.op_active && !rm->rdma.op_silent)
331                                 all_ops_are_silent = 0;
332 
333                         if (ops_present && all_ops_are_silent
334                             && !rm->m_rdma_cookie)
335                                 rm->data.op_active = 0;
336                 }
337 
338                 if (rm->data.op_active && !conn->c_xmit_data_sent) {
339                         rm->m_final_op = &rm->data;
340                         ret = conn->c_trans->xmit(conn, rm,
341                                                   conn->c_xmit_hdr_off,
342                                                   conn->c_xmit_sg,
343                                                   conn->c_xmit_data_off);
344                         if (ret <= 0)
345                                 break;
346 
347                         if (conn->c_xmit_hdr_off < sizeof(struct rds_header)) {
348                                 tmp = min_t(int, ret,
349                                             sizeof(struct rds_header) -
350                                             conn->c_xmit_hdr_off);
351                                 conn->c_xmit_hdr_off += tmp;
352                                 ret -= tmp;
353                         }
354 
355                         sg = &rm->data.op_sg[conn->c_xmit_sg];
356                         while (ret) {
357                                 tmp = min_t(int, ret, sg->length -
358                                                       conn->c_xmit_data_off);
359                                 conn->c_xmit_data_off += tmp;
360                                 ret -= tmp;
361                                 if (conn->c_xmit_data_off == sg->length) {
362                                         conn->c_xmit_data_off = 0;
363                                         sg++;
364                                         conn->c_xmit_sg++;
365                                         BUG_ON(ret != 0 &&
366                                                conn->c_xmit_sg == rm->data.op_nents);
367                                 }
368                         }
369 
370                         if (conn->c_xmit_hdr_off == sizeof(struct rds_header) &&
371                             (conn->c_xmit_sg == rm->data.op_nents))
372                                 conn->c_xmit_data_sent = 1;
373                 }
374 
375                 /*
376                  * A rm will only take multiple times through this loop
377                  * if there is a data op. Thus, if the data is sent (or there was
378                  * none), then we're done with the rm.
379                  */
380                 if (!rm->data.op_active || conn->c_xmit_data_sent) {
381                         conn->c_xmit_rm = NULL;
382                         conn->c_xmit_sg = 0;
383                         conn->c_xmit_hdr_off = 0;
384                         conn->c_xmit_data_off = 0;
385                         conn->c_xmit_rdma_sent = 0;
386                         conn->c_xmit_atomic_sent = 0;
387                         conn->c_xmit_data_sent = 0;
388 
389                         rds_message_put(rm);
390                 }
391         }
392 
393 over_batch:
394         if (conn->c_trans->xmit_complete)
395                 conn->c_trans->xmit_complete(conn);
396         release_in_xmit(conn);
397 
398         /* Nuke any messages we decided not to retransmit. */
399         if (!list_empty(&to_be_dropped)) {
400                 /* irqs on here, so we can put(), unlike above */
401                 list_for_each_entry(rm, &to_be_dropped, m_conn_item)
402                         rds_message_put(rm);
403                 rds_send_remove_from_sock(&to_be_dropped, RDS_RDMA_DROPPED);
404         }
405 
406         /*
407          * Other senders can queue a message after we last test the send queue
408          * but before we clear RDS_IN_XMIT.  In that case they'd back off and
409          * not try and send their newly queued message.  We need to check the
410          * send queue after having cleared RDS_IN_XMIT so that their message
411          * doesn't get stuck on the send queue.
412          *
413          * If the transport cannot continue (i.e ret != 0), then it must
414          * call us when more room is available, such as from the tx
415          * completion handler.
416          *
417          * We have an extra generation check here so that if someone manages
418          * to jump in after our release_in_xmit, we'll see that they have done
419          * some work and we will skip our goto
420          */
421         if (ret == 0) {
422                 smp_mb();
423                 if ((test_bit(0, &conn->c_map_queued) ||
424                      !list_empty(&conn->c_send_queue)) &&
425                     send_gen == conn->c_send_gen) {
426                         rds_stats_inc(s_send_lock_queue_raced);
427                         if (batch_count < send_batch_count)
428                                 goto restart;
429                         queue_delayed_work(rds_wq, &conn->c_send_w, 1);
430                 }
431         }
432 out:
433         return ret;
434 }
435 EXPORT_SYMBOL_GPL(rds_send_xmit);
436 
437 static void rds_send_sndbuf_remove(struct rds_sock *rs, struct rds_message *rm)
438 {
439         u32 len = be32_to_cpu(rm->m_inc.i_hdr.h_len);
440 
441         assert_spin_locked(&rs->rs_lock);
442 
443         BUG_ON(rs->rs_snd_bytes < len);
444         rs->rs_snd_bytes -= len;
445 
446         if (rs->rs_snd_bytes == 0)
447                 rds_stats_inc(s_send_queue_empty);
448 }
449 
450 static inline int rds_send_is_acked(struct rds_message *rm, u64 ack,
451                                     is_acked_func is_acked)
452 {
453         if (is_acked)
454                 return is_acked(rm, ack);
455         return be64_to_cpu(rm->m_inc.i_hdr.h_sequence) <= ack;
456 }
457 
458 /*
459  * This is pretty similar to what happens below in the ACK
460  * handling code - except that we call here as soon as we get
461  * the IB send completion on the RDMA op and the accompanying
462  * message.
463  */
464 void rds_rdma_send_complete(struct rds_message *rm, int status)
465 {
466         struct rds_sock *rs = NULL;
467         struct rm_rdma_op *ro;
468         struct rds_notifier *notifier;
469         unsigned long flags;
470 
471         spin_lock_irqsave(&rm->m_rs_lock, flags);
472 
473         ro = &rm->rdma;
474         if (test_bit(RDS_MSG_ON_SOCK, &rm->m_flags) &&
475             ro->op_active && ro->op_notify && ro->op_notifier) {
476                 notifier = ro->op_notifier;
477                 rs = rm->m_rs;
478                 sock_hold(rds_rs_to_sk(rs));
479 
480                 notifier->n_status = status;
481                 spin_lock(&rs->rs_lock);
482                 list_add_tail(&notifier->n_list, &rs->rs_notify_queue);
483                 spin_unlock(&rs->rs_lock);
484 
485                 ro->op_notifier = NULL;
486         }
487 
488         spin_unlock_irqrestore(&rm->m_rs_lock, flags);
489 
490         if (rs) {
491                 rds_wake_sk_sleep(rs);
492                 sock_put(rds_rs_to_sk(rs));
493         }
494 }
495 EXPORT_SYMBOL_GPL(rds_rdma_send_complete);
496 
497 /*
498  * Just like above, except looks at atomic op
499  */
500 void rds_atomic_send_complete(struct rds_message *rm, int status)
501 {
502         struct rds_sock *rs = NULL;
503         struct rm_atomic_op *ao;
504         struct rds_notifier *notifier;
505         unsigned long flags;
506 
507         spin_lock_irqsave(&rm->m_rs_lock, flags);
508 
509         ao = &rm->atomic;
510         if (test_bit(RDS_MSG_ON_SOCK, &rm->m_flags)
511             && ao->op_active && ao->op_notify && ao->op_notifier) {
512                 notifier = ao->op_notifier;
513                 rs = rm->m_rs;
514                 sock_hold(rds_rs_to_sk(rs));
515 
516                 notifier->n_status = status;
517                 spin_lock(&rs->rs_lock);
518                 list_add_tail(&notifier->n_list, &rs->rs_notify_queue);
519                 spin_unlock(&rs->rs_lock);
520 
521                 ao->op_notifier = NULL;
522         }
523 
524         spin_unlock_irqrestore(&rm->m_rs_lock, flags);
525 
526         if (rs) {
527                 rds_wake_sk_sleep(rs);
528                 sock_put(rds_rs_to_sk(rs));
529         }
530 }
531 EXPORT_SYMBOL_GPL(rds_atomic_send_complete);
532 
533 /*
534  * This is the same as rds_rdma_send_complete except we
535  * don't do any locking - we have all the ingredients (message,
536  * socket, socket lock) and can just move the notifier.
537  */
538 static inline void
539 __rds_send_complete(struct rds_sock *rs, struct rds_message *rm, int status)
540 {
541         struct rm_rdma_op *ro;
542         struct rm_atomic_op *ao;
543 
544         ro = &rm->rdma;
545         if (ro->op_active && ro->op_notify && ro->op_notifier) {
546                 ro->op_notifier->n_status = status;
547                 list_add_tail(&ro->op_notifier->n_list, &rs->rs_notify_queue);
548                 ro->op_notifier = NULL;
549         }
550 
551         ao = &rm->atomic;
552         if (ao->op_active && ao->op_notify && ao->op_notifier) {
553                 ao->op_notifier->n_status = status;
554                 list_add_tail(&ao->op_notifier->n_list, &rs->rs_notify_queue);
555                 ao->op_notifier = NULL;
556         }
557 
558         /* No need to wake the app - caller does this */
559 }
560 
561 /*
562  * This is called from the IB send completion when we detect
563  * a RDMA operation that failed with remote access error.
564  * So speed is not an issue here.
565  */
566 struct rds_message *rds_send_get_message(struct rds_connection *conn,
567                                          struct rm_rdma_op *op)
568 {
569         struct rds_message *rm, *tmp, *found = NULL;
570         unsigned long flags;
571 
572         spin_lock_irqsave(&conn->c_lock, flags);
573 
574         list_for_each_entry_safe(rm, tmp, &conn->c_retrans, m_conn_item) {
575                 if (&rm->rdma == op) {
576                         atomic_inc(&rm->m_refcount);
577                         found = rm;
578                         goto out;
579                 }
580         }
581 
582         list_for_each_entry_safe(rm, tmp, &conn->c_send_queue, m_conn_item) {
583                 if (&rm->rdma == op) {
584                         atomic_inc(&rm->m_refcount);
585                         found = rm;
586                         break;
587                 }
588         }
589 
590 out:
591         spin_unlock_irqrestore(&conn->c_lock, flags);
592 
593         return found;
594 }
595 EXPORT_SYMBOL_GPL(rds_send_get_message);
596 
597 /*
598  * This removes messages from the socket's list if they're on it.  The list
599  * argument must be private to the caller, we must be able to modify it
600  * without locks.  The messages must have a reference held for their
601  * position on the list.  This function will drop that reference after
602  * removing the messages from the 'messages' list regardless of if it found
603  * the messages on the socket list or not.
604  */
605 static void rds_send_remove_from_sock(struct list_head *messages, int status)
606 {
607         unsigned long flags;
608         struct rds_sock *rs = NULL;
609         struct rds_message *rm;
610 
611         while (!list_empty(messages)) {
612                 int was_on_sock = 0;
613 
614                 rm = list_entry(messages->next, struct rds_message,
615                                 m_conn_item);
616                 list_del_init(&rm->m_conn_item);
617 
618                 /*
619                  * If we see this flag cleared then we're *sure* that someone
620                  * else beat us to removing it from the sock.  If we race
621                  * with their flag update we'll get the lock and then really
622                  * see that the flag has been cleared.
623                  *
624                  * The message spinlock makes sure nobody clears rm->m_rs
625                  * while we're messing with it. It does not prevent the
626                  * message from being removed from the socket, though.
627                  */
628                 spin_lock_irqsave(&rm->m_rs_lock, flags);
629                 if (!test_bit(RDS_MSG_ON_SOCK, &rm->m_flags))
630                         goto unlock_and_drop;
631 
632                 if (rs != rm->m_rs) {
633                         if (rs) {
634                                 rds_wake_sk_sleep(rs);
635                                 sock_put(rds_rs_to_sk(rs));
636                         }
637                         rs = rm->m_rs;
638                         if (rs)
639                                 sock_hold(rds_rs_to_sk(rs));
640                 }
641                 if (!rs)
642                         goto unlock_and_drop;
643                 spin_lock(&rs->rs_lock);
644 
645                 if (test_and_clear_bit(RDS_MSG_ON_SOCK, &rm->m_flags)) {
646                         struct rm_rdma_op *ro = &rm->rdma;
647                         struct rds_notifier *notifier;
648 
649                         list_del_init(&rm->m_sock_item);
650                         rds_send_sndbuf_remove(rs, rm);
651 
652                         if (ro->op_active && ro->op_notifier &&
653                                (ro->op_notify || (ro->op_recverr && status))) {
654                                 notifier = ro->op_notifier;
655                                 list_add_tail(&notifier->n_list,
656                                                 &rs->rs_notify_queue);
657                                 if (!notifier->n_status)
658                                         notifier->n_status = status;
659                                 rm->rdma.op_notifier = NULL;
660                         }
661                         was_on_sock = 1;
662                         rm->m_rs = NULL;
663                 }
664                 spin_unlock(&rs->rs_lock);
665 
666 unlock_and_drop:
667                 spin_unlock_irqrestore(&rm->m_rs_lock, flags);
668                 rds_message_put(rm);
669                 if (was_on_sock)
670                         rds_message_put(rm);
671         }
672 
673         if (rs) {
674                 rds_wake_sk_sleep(rs);
675                 sock_put(rds_rs_to_sk(rs));
676         }
677 }
678 
679 /*
680  * Transports call here when they've determined that the receiver queued
681  * messages up to, and including, the given sequence number.  Messages are
682  * moved to the retrans queue when rds_send_xmit picks them off the send
683  * queue. This means that in the TCP case, the message may not have been
684  * assigned the m_ack_seq yet - but that's fine as long as tcp_is_acked
685  * checks the RDS_MSG_HAS_ACK_SEQ bit.
686  */
687 void rds_send_drop_acked(struct rds_connection *conn, u64 ack,
688                          is_acked_func is_acked)
689 {
690         struct rds_message *rm, *tmp;
691         unsigned long flags;
692         LIST_HEAD(list);
693 
694         spin_lock_irqsave(&conn->c_lock, flags);
695 
696         list_for_each_entry_safe(rm, tmp, &conn->c_retrans, m_conn_item) {
697                 if (!rds_send_is_acked(rm, ack, is_acked))
698                         break;
699 
700                 list_move(&rm->m_conn_item, &list);
701                 clear_bit(RDS_MSG_ON_CONN, &rm->m_flags);
702         }
703 
704         /* order flag updates with spin locks */
705         if (!list_empty(&list))
706                 smp_mb__after_atomic();
707 
708         spin_unlock_irqrestore(&conn->c_lock, flags);
709 
710         /* now remove the messages from the sock list as needed */
711         rds_send_remove_from_sock(&list, RDS_RDMA_SUCCESS);
712 }
713 EXPORT_SYMBOL_GPL(rds_send_drop_acked);
714 
715 void rds_send_drop_to(struct rds_sock *rs, struct sockaddr_in *dest)
716 {
717         struct rds_message *rm, *tmp;
718         struct rds_connection *conn;
719         unsigned long flags;
720         LIST_HEAD(list);
721 
722         /* get all the messages we're dropping under the rs lock */
723         spin_lock_irqsave(&rs->rs_lock, flags);
724 
725         list_for_each_entry_safe(rm, tmp, &rs->rs_send_queue, m_sock_item) {
726                 if (dest && (dest->sin_addr.s_addr != rm->m_daddr ||
727                              dest->sin_port != rm->m_inc.i_hdr.h_dport))
728                         continue;
729 
730                 list_move(&rm->m_sock_item, &list);
731                 rds_send_sndbuf_remove(rs, rm);
732                 clear_bit(RDS_MSG_ON_SOCK, &rm->m_flags);
733         }
734 
735         /* order flag updates with the rs lock */
736         smp_mb__after_atomic();
737 
738         spin_unlock_irqrestore(&rs->rs_lock, flags);
739 
740         if (list_empty(&list))
741                 return;
742 
743         /* Remove the messages from the conn */
744         list_for_each_entry(rm, &list, m_sock_item) {
745 
746                 conn = rm->m_inc.i_conn;
747 
748                 spin_lock_irqsave(&conn->c_lock, flags);
749                 /*
750                  * Maybe someone else beat us to removing rm from the conn.
751                  * If we race with their flag update we'll get the lock and
752                  * then really see that the flag has been cleared.
753                  */
754                 if (!test_and_clear_bit(RDS_MSG_ON_CONN, &rm->m_flags)) {
755                         spin_unlock_irqrestore(&conn->c_lock, flags);
756                         spin_lock_irqsave(&rm->m_rs_lock, flags);
757                         rm->m_rs = NULL;
758                         spin_unlock_irqrestore(&rm->m_rs_lock, flags);
759                         continue;
760                 }
761                 list_del_init(&rm->m_conn_item);
762                 spin_unlock_irqrestore(&conn->c_lock, flags);
763 
764                 /*
765                  * Couldn't grab m_rs_lock in top loop (lock ordering),
766                  * but we can now.
767                  */
768                 spin_lock_irqsave(&rm->m_rs_lock, flags);
769 
770                 spin_lock(&rs->rs_lock);
771                 __rds_send_complete(rs, rm, RDS_RDMA_CANCELED);
772                 spin_unlock(&rs->rs_lock);
773 
774                 rm->m_rs = NULL;
775                 spin_unlock_irqrestore(&rm->m_rs_lock, flags);
776 
777                 rds_message_put(rm);
778         }
779 
780         rds_wake_sk_sleep(rs);
781 
782         while (!list_empty(&list)) {
783                 rm = list_entry(list.next, struct rds_message, m_sock_item);
784                 list_del_init(&rm->m_sock_item);
785                 rds_message_wait(rm);
786 
787                 /* just in case the code above skipped this message
788                  * because RDS_MSG_ON_CONN wasn't set, run it again here
789                  * taking m_rs_lock is the only thing that keeps us
790                  * from racing with ack processing.
791                  */
792                 spin_lock_irqsave(&rm->m_rs_lock, flags);
793 
794                 spin_lock(&rs->rs_lock);
795                 __rds_send_complete(rs, rm, RDS_RDMA_CANCELED);
796                 spin_unlock(&rs->rs_lock);
797 
798                 rm->m_rs = NULL;
799                 spin_unlock_irqrestore(&rm->m_rs_lock, flags);
800 
801                 rds_message_put(rm);
802         }
803 }
804 
805 /*
806  * we only want this to fire once so we use the callers 'queued'.  It's
807  * possible that another thread can race with us and remove the
808  * message from the flow with RDS_CANCEL_SENT_TO.
809  */
810 static int rds_send_queue_rm(struct rds_sock *rs, struct rds_connection *conn,
811                              struct rds_message *rm, __be16 sport,
812                              __be16 dport, int *queued)
813 {
814         unsigned long flags;
815         u32 len;
816 
817         if (*queued)
818                 goto out;
819 
820         len = be32_to_cpu(rm->m_inc.i_hdr.h_len);
821 
822         /* this is the only place which holds both the socket's rs_lock
823          * and the connection's c_lock */
824         spin_lock_irqsave(&rs->rs_lock, flags);
825 
826         /*
827          * If there is a little space in sndbuf, we don't queue anything,
828          * and userspace gets -EAGAIN. But poll() indicates there's send
829          * room. This can lead to bad behavior (spinning) if snd_bytes isn't
830          * freed up by incoming acks. So we check the *old* value of
831          * rs_snd_bytes here to allow the last msg to exceed the buffer,
832          * and poll() now knows no more data can be sent.
833          */
834         if (rs->rs_snd_bytes < rds_sk_sndbuf(rs)) {
835                 rs->rs_snd_bytes += len;
836 
837                 /* let recv side know we are close to send space exhaustion.
838                  * This is probably not the optimal way to do it, as this
839                  * means we set the flag on *all* messages as soon as our
840                  * throughput hits a certain threshold.
841                  */
842                 if (rs->rs_snd_bytes >= rds_sk_sndbuf(rs) / 2)
843                         __set_bit(RDS_MSG_ACK_REQUIRED, &rm->m_flags);
844 
845                 list_add_tail(&rm->m_sock_item, &rs->rs_send_queue);
846                 set_bit(RDS_MSG_ON_SOCK, &rm->m_flags);
847                 rds_message_addref(rm);
848                 rm->m_rs = rs;
849 
850                 /* The code ordering is a little weird, but we're
851                    trying to minimize the time we hold c_lock */
852                 rds_message_populate_header(&rm->m_inc.i_hdr, sport, dport, 0);
853                 rm->m_inc.i_conn = conn;
854                 rds_message_addref(rm);
855 
856                 spin_lock(&conn->c_lock);
857                 rm->m_inc.i_hdr.h_sequence = cpu_to_be64(conn->c_next_tx_seq++);
858                 list_add_tail(&rm->m_conn_item, &conn->c_send_queue);
859                 set_bit(RDS_MSG_ON_CONN, &rm->m_flags);
860                 spin_unlock(&conn->c_lock);
861 
862                 rdsdebug("queued msg %p len %d, rs %p bytes %d seq %llu\n",
863                          rm, len, rs, rs->rs_snd_bytes,
864                          (unsigned long long)be64_to_cpu(rm->m_inc.i_hdr.h_sequence));
865 
866                 *queued = 1;
867         }
868 
869         spin_unlock_irqrestore(&rs->rs_lock, flags);
870 out:
871         return *queued;
872 }
873 
874 /*
875  * rds_message is getting to be quite complicated, and we'd like to allocate
876  * it all in one go. This figures out how big it needs to be up front.
877  */
878 static int rds_rm_size(struct msghdr *msg, int data_len)
879 {
880         struct cmsghdr *cmsg;
881         int size = 0;
882         int cmsg_groups = 0;
883         int retval;
884 
885         for_each_cmsghdr(cmsg, msg) {
886                 if (!CMSG_OK(msg, cmsg))
887                         return -EINVAL;
888 
889                 if (cmsg->cmsg_level != SOL_RDS)
890                         continue;
891 
892                 switch (cmsg->cmsg_type) {
893                 case RDS_CMSG_RDMA_ARGS:
894                         cmsg_groups |= 1;
895                         retval = rds_rdma_extra_size(CMSG_DATA(cmsg));
896                         if (retval < 0)
897                                 return retval;
898                         size += retval;
899 
900                         break;
901 
902                 case RDS_CMSG_RDMA_DEST:
903                 case RDS_CMSG_RDMA_MAP:
904                         cmsg_groups |= 2;
905                         /* these are valid but do no add any size */
906                         break;
907 
908                 case RDS_CMSG_ATOMIC_CSWP:
909                 case RDS_CMSG_ATOMIC_FADD:
910                 case RDS_CMSG_MASKED_ATOMIC_CSWP:
911                 case RDS_CMSG_MASKED_ATOMIC_FADD:
912                         cmsg_groups |= 1;
913                         size += sizeof(struct scatterlist);
914                         break;
915 
916                 default:
917                         return -EINVAL;
918                 }
919 
920         }
921 
922         size += ceil(data_len, PAGE_SIZE) * sizeof(struct scatterlist);
923 
924         /* Ensure (DEST, MAP) are never used with (ARGS, ATOMIC) */
925         if (cmsg_groups == 3)
926                 return -EINVAL;
927 
928         return size;
929 }
930 
931 static int rds_cmsg_send(struct rds_sock *rs, struct rds_message *rm,
932                          struct msghdr *msg, int *allocated_mr)
933 {
934         struct cmsghdr *cmsg;
935         int ret = 0;
936 
937         for_each_cmsghdr(cmsg, msg) {
938                 if (!CMSG_OK(msg, cmsg))
939                         return -EINVAL;
940 
941                 if (cmsg->cmsg_level != SOL_RDS)
942                         continue;
943 
944                 /* As a side effect, RDMA_DEST and RDMA_MAP will set
945                  * rm->rdma.m_rdma_cookie and rm->rdma.m_rdma_mr.
946                  */
947                 switch (cmsg->cmsg_type) {
948                 case RDS_CMSG_RDMA_ARGS:
949                         ret = rds_cmsg_rdma_args(rs, rm, cmsg);
950                         break;
951 
952                 case RDS_CMSG_RDMA_DEST:
953                         ret = rds_cmsg_rdma_dest(rs, rm, cmsg);
954                         break;
955 
956                 case RDS_CMSG_RDMA_MAP:
957                         ret = rds_cmsg_rdma_map(rs, rm, cmsg);
958                         if (!ret)
959                                 *allocated_mr = 1;
960                         break;
961                 case RDS_CMSG_ATOMIC_CSWP:
962                 case RDS_CMSG_ATOMIC_FADD:
963                 case RDS_CMSG_MASKED_ATOMIC_CSWP:
964                 case RDS_CMSG_MASKED_ATOMIC_FADD:
965                         ret = rds_cmsg_atomic(rs, rm, cmsg);
966                         break;
967 
968                 default:
969                         return -EINVAL;
970                 }
971 
972                 if (ret)
973                         break;
974         }
975 
976         return ret;
977 }
978 
979 int rds_sendmsg(struct socket *sock, struct msghdr *msg, size_t payload_len)
980 {
981         struct sock *sk = sock->sk;
982         struct rds_sock *rs = rds_sk_to_rs(sk);
983         DECLARE_SOCKADDR(struct sockaddr_in *, usin, msg->msg_name);
984         __be32 daddr;
985         __be16 dport;
986         struct rds_message *rm = NULL;
987         struct rds_connection *conn;
988         int ret = 0;
989         int queued = 0, allocated_mr = 0;
990         int nonblock = msg->msg_flags & MSG_DONTWAIT;
991         long timeo = sock_sndtimeo(sk, nonblock);
992 
993         /* Mirror Linux UDP mirror of BSD error message compatibility */
994         /* XXX: Perhaps MSG_MORE someday */
995         if (msg->msg_flags & ~(MSG_DONTWAIT | MSG_CMSG_COMPAT)) {
996                 ret = -EOPNOTSUPP;
997                 goto out;
998         }
999 
1000         if (msg->msg_namelen) {
1001                 /* XXX fail non-unicast destination IPs? */
1002                 if (msg->msg_namelen < sizeof(*usin) || usin->sin_family != AF_INET) {
1003                         ret = -EINVAL;
1004                         goto out;
1005                 }
1006                 daddr = usin->sin_addr.s_addr;
1007                 dport = usin->sin_port;
1008         } else {
1009                 /* We only care about consistency with ->connect() */
1010                 lock_sock(sk);
1011                 daddr = rs->rs_conn_addr;
1012                 dport = rs->rs_conn_port;
1013                 release_sock(sk);
1014         }
1015 
1016         lock_sock(sk);
1017         if (daddr == 0 || rs->rs_bound_addr == 0) {
1018                 release_sock(sk);
1019                 ret = -ENOTCONN; /* XXX not a great errno */
1020                 goto out;
1021         }
1022         release_sock(sk);
1023 
1024         if (payload_len > rds_sk_sndbuf(rs)) {
1025                 ret = -EMSGSIZE;
1026                 goto out;
1027         }
1028 
1029         /* size of rm including all sgs */
1030         ret = rds_rm_size(msg, payload_len);
1031         if (ret < 0)
1032                 goto out;
1033 
1034         rm = rds_message_alloc(ret, GFP_KERNEL);
1035         if (!rm) {
1036                 ret = -ENOMEM;
1037                 goto out;
1038         }
1039 
1040         /* Attach data to the rm */
1041         if (payload_len) {
1042                 rm->data.op_sg = rds_message_alloc_sgs(rm, ceil(payload_len, PAGE_SIZE));
1043                 if (!rm->data.op_sg) {
1044                         ret = -ENOMEM;
1045                         goto out;
1046                 }
1047                 ret = rds_message_copy_from_user(rm, &msg->msg_iter);
1048                 if (ret)
1049                         goto out;
1050         }
1051         rm->data.op_active = 1;
1052 
1053         rm->m_daddr = daddr;
1054 
1055         /* rds_conn_create has a spinlock that runs with IRQ off.
1056          * Caching the conn in the socket helps a lot. */
1057         if (rs->rs_conn && rs->rs_conn->c_faddr == daddr)
1058                 conn = rs->rs_conn;
1059         else {
1060                 conn = rds_conn_create_outgoing(sock_net(sock->sk),
1061                                                 rs->rs_bound_addr, daddr,
1062                                         rs->rs_transport,
1063                                         sock->sk->sk_allocation);
1064                 if (IS_ERR(conn)) {
1065                         ret = PTR_ERR(conn);
1066                         goto out;
1067                 }
1068                 rs->rs_conn = conn;
1069         }
1070 
1071         /* Parse any control messages the user may have included. */
1072         ret = rds_cmsg_send(rs, rm, msg, &allocated_mr);
1073         if (ret)
1074                 goto out;
1075 
1076         if (rm->rdma.op_active && !conn->c_trans->xmit_rdma) {
1077                 printk_ratelimited(KERN_NOTICE "rdma_op %p conn xmit_rdma %p\n",
1078                                &rm->rdma, conn->c_trans->xmit_rdma);
1079                 ret = -EOPNOTSUPP;
1080                 goto out;
1081         }
1082 
1083         if (rm->atomic.op_active && !conn->c_trans->xmit_atomic) {
1084                 printk_ratelimited(KERN_NOTICE "atomic_op %p conn xmit_atomic %p\n",
1085                                &rm->atomic, conn->c_trans->xmit_atomic);
1086                 ret = -EOPNOTSUPP;
1087                 goto out;
1088         }
1089 
1090         rds_conn_connect_if_down(conn);
1091 
1092         ret = rds_cong_wait(conn->c_fcong, dport, nonblock, rs);
1093         if (ret) {
1094                 rs->rs_seen_congestion = 1;
1095                 goto out;
1096         }
1097 
1098         while (!rds_send_queue_rm(rs, conn, rm, rs->rs_bound_port,
1099                                   dport, &queued)) {
1100                 rds_stats_inc(s_send_queue_full);
1101 
1102                 if (nonblock) {
1103                         ret = -EAGAIN;
1104                         goto out;
1105                 }
1106 
1107                 timeo = wait_event_interruptible_timeout(*sk_sleep(sk),
1108                                         rds_send_queue_rm(rs, conn, rm,
1109                                                           rs->rs_bound_port,
1110                                                           dport,
1111                                                           &queued),
1112                                         timeo);
1113                 rdsdebug("sendmsg woke queued %d timeo %ld\n", queued, timeo);
1114                 if (timeo > 0 || timeo == MAX_SCHEDULE_TIMEOUT)
1115                         continue;
1116 
1117                 ret = timeo;
1118                 if (ret == 0)
1119                         ret = -ETIMEDOUT;
1120                 goto out;
1121         }
1122 
1123         /*
1124          * By now we've committed to the send.  We reuse rds_send_worker()
1125          * to retry sends in the rds thread if the transport asks us to.
1126          */
1127         rds_stats_inc(s_send_queued);
1128 
1129         ret = rds_send_xmit(conn);
1130         if (ret == -ENOMEM || ret == -EAGAIN)
1131                 queue_delayed_work(rds_wq, &conn->c_send_w, 1);
1132 
1133         rds_message_put(rm);
1134         return payload_len;
1135 
1136 out:
1137         /* If the user included a RDMA_MAP cmsg, we allocated a MR on the fly.
1138          * If the sendmsg goes through, we keep the MR. If it fails with EAGAIN
1139          * or in any other way, we need to destroy the MR again */
1140         if (allocated_mr)
1141                 rds_rdma_unuse(rs, rds_rdma_cookie_key(rm->m_rdma_cookie), 1);
1142 
1143         if (rm)
1144                 rds_message_put(rm);
1145         return ret;
1146 }
1147 
1148 /*
1149  * Reply to a ping packet.
1150  */
1151 int
1152 rds_send_pong(struct rds_connection *conn, __be16 dport)
1153 {
1154         struct rds_message *rm;
1155         unsigned long flags;
1156         int ret = 0;
1157 
1158         rm = rds_message_alloc(0, GFP_ATOMIC);
1159         if (!rm) {
1160                 ret = -ENOMEM;
1161                 goto out;
1162         }
1163 
1164         rm->m_daddr = conn->c_faddr;
1165         rm->data.op_active = 1;
1166 
1167         rds_conn_connect_if_down(conn);
1168 
1169         ret = rds_cong_wait(conn->c_fcong, dport, 1, NULL);
1170         if (ret)
1171                 goto out;
1172 
1173         spin_lock_irqsave(&conn->c_lock, flags);
1174         list_add_tail(&rm->m_conn_item, &conn->c_send_queue);
1175         set_bit(RDS_MSG_ON_CONN, &rm->m_flags);
1176         rds_message_addref(rm);
1177         rm->m_inc.i_conn = conn;
1178 
1179         rds_message_populate_header(&rm->m_inc.i_hdr, 0, dport,
1180                                     conn->c_next_tx_seq);
1181         conn->c_next_tx_seq++;
1182         spin_unlock_irqrestore(&conn->c_lock, flags);
1183 
1184         rds_stats_inc(s_send_queued);
1185         rds_stats_inc(s_send_pong);
1186 
1187         /* schedule the send work on rds_wq */
1188         queue_delayed_work(rds_wq, &conn->c_send_w, 1);
1189 
1190         rds_message_put(rm);
1191         return 0;
1192 
1193 out:
1194         if (rm)
1195                 rds_message_put(rm);
1196         return ret;
1197 }
1198 

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