Root/net/rds/send.c

1/*
2 * Copyright (c) 2006 Oracle. All rights reserved.
3 *
4 * This software is available to you under a choice of one of two
5 * licenses. You may choose to be licensed under the terms of the GNU
6 * General Public License (GPL) Version 2, available from the file
7 * COPYING in the main directory of this source tree, or the
8 * OpenIB.org BSD license below:
9 *
10 * Redistribution and use in source and binary forms, with or
11 * without modification, are permitted provided that the following
12 * conditions are met:
13 *
14 * - Redistributions of source code must retain the above
15 * copyright notice, this list of conditions and the following
16 * disclaimer.
17 *
18 * - Redistributions in binary form must reproduce the above
19 * copyright notice, this list of conditions and the following
20 * disclaimer in the documentation and/or other materials
21 * provided with the distribution.
22 *
23 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
24 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
25 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
26 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
27 * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
28 * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
29 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
30 * SOFTWARE.
31 *
32 */
33#include <linux/kernel.h>
34#include <linux/gfp.h>
35#include <net/sock.h>
36#include <linux/in.h>
37#include <linux/list.h>
38
39#include "rds.h"
40#include "rdma.h"
41
42/* When transmitting messages in rds_send_xmit, we need to emerge from
43 * time to time and briefly release the CPU. Otherwise the softlock watchdog
44 * will kick our shin.
45 * Also, it seems fairer to not let one busy connection stall all the
46 * others.
47 *
48 * send_batch_count is the number of times we'll loop in send_xmit. Setting
49 * it to 0 will restore the old behavior (where we looped until we had
50 * drained the queue).
51 */
52static int send_batch_count = 64;
53module_param(send_batch_count, int, 0444);
54MODULE_PARM_DESC(send_batch_count, " batch factor when working the send queue");
55
56/*
57 * Reset the send state. Caller must hold c_send_lock when calling here.
58 */
59void rds_send_reset(struct rds_connection *conn)
60{
61    struct rds_message *rm, *tmp;
62    unsigned long flags;
63
64    if (conn->c_xmit_rm) {
65        /* Tell the user the RDMA op is no longer mapped by the
66         * transport. This isn't entirely true (it's flushed out
67         * independently) but as the connection is down, there's
68         * no ongoing RDMA to/from that memory */
69        rds_message_unmapped(conn->c_xmit_rm);
70        rds_message_put(conn->c_xmit_rm);
71        conn->c_xmit_rm = NULL;
72    }
73    conn->c_xmit_sg = 0;
74    conn->c_xmit_hdr_off = 0;
75    conn->c_xmit_data_off = 0;
76    conn->c_xmit_rdma_sent = 0;
77
78    conn->c_map_queued = 0;
79
80    conn->c_unacked_packets = rds_sysctl_max_unacked_packets;
81    conn->c_unacked_bytes = rds_sysctl_max_unacked_bytes;
82
83    /* Mark messages as retransmissions, and move them to the send q */
84    spin_lock_irqsave(&conn->c_lock, flags);
85    list_for_each_entry_safe(rm, tmp, &conn->c_retrans, m_conn_item) {
86        set_bit(RDS_MSG_ACK_REQUIRED, &rm->m_flags);
87        set_bit(RDS_MSG_RETRANSMITTED, &rm->m_flags);
88    }
89    list_splice_init(&conn->c_retrans, &conn->c_send_queue);
90    spin_unlock_irqrestore(&conn->c_lock, flags);
91}
92
93/*
94 * We're making the concious trade-off here to only send one message
95 * down the connection at a time.
96 * Pro:
97 * - tx queueing is a simple fifo list
98 * - reassembly is optional and easily done by transports per conn
99 * - no per flow rx lookup at all, straight to the socket
100 * - less per-frag memory and wire overhead
101 * Con:
102 * - queued acks can be delayed behind large messages
103 * Depends:
104 * - small message latency is higher behind queued large messages
105 * - large message latency isn't starved by intervening small sends
106 */
107int rds_send_xmit(struct rds_connection *conn)
108{
109    struct rds_message *rm;
110    unsigned long flags;
111    unsigned int tmp;
112    unsigned int send_quota = send_batch_count;
113    struct scatterlist *sg;
114    int ret = 0;
115    int was_empty = 0;
116    LIST_HEAD(to_be_dropped);
117
118    /*
119     * sendmsg calls here after having queued its message on the send
120     * queue. We only have one task feeding the connection at a time. If
121     * another thread is already feeding the queue then we back off. This
122     * avoids blocking the caller and trading per-connection data between
123     * caches per message.
124     *
125     * The sem holder will issue a retry if they notice that someone queued
126     * a message after they stopped walking the send queue but before they
127     * dropped the sem.
128     */
129    if (!mutex_trylock(&conn->c_send_lock)) {
130        rds_stats_inc(s_send_sem_contention);
131        ret = -ENOMEM;
132        goto out;
133    }
134
135    if (conn->c_trans->xmit_prepare)
136        conn->c_trans->xmit_prepare(conn);
137
138    /*
139     * spin trying to push headers and data down the connection until
140     * the connection doens't make forward progress.
141     */
142    while (--send_quota) {
143        /*
144         * See if need to send a congestion map update if we're
145         * between sending messages. The send_sem protects our sole
146         * use of c_map_offset and _bytes.
147         * Note this is used only by transports that define a special
148         * xmit_cong_map function. For all others, we create allocate
149         * a cong_map message and treat it just like any other send.
150         */
151        if (conn->c_map_bytes) {
152            ret = conn->c_trans->xmit_cong_map(conn, conn->c_lcong,
153                        conn->c_map_offset);
154            if (ret <= 0)
155                break;
156
157            conn->c_map_offset += ret;
158            conn->c_map_bytes -= ret;
159            if (conn->c_map_bytes)
160                continue;
161        }
162
163        /* If we're done sending the current message, clear the
164         * offset and S/G temporaries.
165         */
166        rm = conn->c_xmit_rm;
167        if (rm != NULL &&
168            conn->c_xmit_hdr_off == sizeof(struct rds_header) &&
169            conn->c_xmit_sg == rm->m_nents) {
170            conn->c_xmit_rm = NULL;
171            conn->c_xmit_sg = 0;
172            conn->c_xmit_hdr_off = 0;
173            conn->c_xmit_data_off = 0;
174            conn->c_xmit_rdma_sent = 0;
175
176            /* Release the reference to the previous message. */
177            rds_message_put(rm);
178            rm = NULL;
179        }
180
181        /* If we're asked to send a cong map update, do so.
182         */
183        if (rm == NULL && test_and_clear_bit(0, &conn->c_map_queued)) {
184            if (conn->c_trans->xmit_cong_map != NULL) {
185                conn->c_map_offset = 0;
186                conn->c_map_bytes = sizeof(struct rds_header) +
187                    RDS_CONG_MAP_BYTES;
188                continue;
189            }
190
191            rm = rds_cong_update_alloc(conn);
192            if (IS_ERR(rm)) {
193                ret = PTR_ERR(rm);
194                break;
195            }
196
197            conn->c_xmit_rm = rm;
198        }
199
200        /*
201         * Grab the next message from the send queue, if there is one.
202         *
203         * c_xmit_rm holds a ref while we're sending this message down
204         * the connction. We can use this ref while holding the
205         * send_sem.. rds_send_reset() is serialized with it.
206         */
207        if (rm == NULL) {
208            unsigned int len;
209
210            spin_lock_irqsave(&conn->c_lock, flags);
211
212            if (!list_empty(&conn->c_send_queue)) {
213                rm = list_entry(conn->c_send_queue.next,
214                        struct rds_message,
215                        m_conn_item);
216                rds_message_addref(rm);
217
218                /*
219                 * Move the message from the send queue to the retransmit
220                 * list right away.
221                 */
222                list_move_tail(&rm->m_conn_item, &conn->c_retrans);
223            }
224
225            spin_unlock_irqrestore(&conn->c_lock, flags);
226
227            if (rm == NULL) {
228                was_empty = 1;
229                break;
230            }
231
232            /* Unfortunately, the way Infiniband deals with
233             * RDMA to a bad MR key is by moving the entire
234             * queue pair to error state. We cold possibly
235             * recover from that, but right now we drop the
236             * connection.
237             * Therefore, we never retransmit messages with RDMA ops.
238             */
239            if (rm->m_rdma_op &&
240                test_bit(RDS_MSG_RETRANSMITTED, &rm->m_flags)) {
241                spin_lock_irqsave(&conn->c_lock, flags);
242                if (test_and_clear_bit(RDS_MSG_ON_CONN, &rm->m_flags))
243                    list_move(&rm->m_conn_item, &to_be_dropped);
244                spin_unlock_irqrestore(&conn->c_lock, flags);
245                rds_message_put(rm);
246                continue;
247            }
248
249            /* Require an ACK every once in a while */
250            len = ntohl(rm->m_inc.i_hdr.h_len);
251            if (conn->c_unacked_packets == 0 ||
252                conn->c_unacked_bytes < len) {
253                __set_bit(RDS_MSG_ACK_REQUIRED, &rm->m_flags);
254
255                conn->c_unacked_packets = rds_sysctl_max_unacked_packets;
256                conn->c_unacked_bytes = rds_sysctl_max_unacked_bytes;
257                rds_stats_inc(s_send_ack_required);
258            } else {
259                conn->c_unacked_bytes -= len;
260                conn->c_unacked_packets--;
261            }
262
263            conn->c_xmit_rm = rm;
264        }
265
266        /*
267         * Try and send an rdma message. Let's see if we can
268         * keep this simple and require that the transport either
269         * send the whole rdma or none of it.
270         */
271        if (rm->m_rdma_op && !conn->c_xmit_rdma_sent) {
272            ret = conn->c_trans->xmit_rdma(conn, rm->m_rdma_op);
273            if (ret)
274                break;
275            conn->c_xmit_rdma_sent = 1;
276            /* The transport owns the mapped memory for now.
277             * You can't unmap it while it's on the send queue */
278            set_bit(RDS_MSG_MAPPED, &rm->m_flags);
279        }
280
281        if (conn->c_xmit_hdr_off < sizeof(struct rds_header) ||
282            conn->c_xmit_sg < rm->m_nents) {
283            ret = conn->c_trans->xmit(conn, rm,
284                          conn->c_xmit_hdr_off,
285                          conn->c_xmit_sg,
286                          conn->c_xmit_data_off);
287            if (ret <= 0)
288                break;
289
290            if (conn->c_xmit_hdr_off < sizeof(struct rds_header)) {
291                tmp = min_t(int, ret,
292                        sizeof(struct rds_header) -
293                        conn->c_xmit_hdr_off);
294                conn->c_xmit_hdr_off += tmp;
295                ret -= tmp;
296            }
297
298            sg = &rm->m_sg[conn->c_xmit_sg];
299            while (ret) {
300                tmp = min_t(int, ret, sg->length -
301                              conn->c_xmit_data_off);
302                conn->c_xmit_data_off += tmp;
303                ret -= tmp;
304                if (conn->c_xmit_data_off == sg->length) {
305                    conn->c_xmit_data_off = 0;
306                    sg++;
307                    conn->c_xmit_sg++;
308                    BUG_ON(ret != 0 &&
309                           conn->c_xmit_sg == rm->m_nents);
310                }
311            }
312        }
313    }
314
315    /* Nuke any messages we decided not to retransmit. */
316    if (!list_empty(&to_be_dropped))
317        rds_send_remove_from_sock(&to_be_dropped, RDS_RDMA_DROPPED);
318
319    if (conn->c_trans->xmit_complete)
320        conn->c_trans->xmit_complete(conn);
321
322    /*
323     * We might be racing with another sender who queued a message but
324     * backed off on noticing that we held the c_send_lock. If we check
325     * for queued messages after dropping the sem then either we'll
326     * see the queued message or the queuer will get the sem. If we
327     * notice the queued message then we trigger an immediate retry.
328     *
329     * We need to be careful only to do this when we stopped processing
330     * the send queue because it was empty. It's the only way we
331     * stop processing the loop when the transport hasn't taken
332     * responsibility for forward progress.
333     */
334    mutex_unlock(&conn->c_send_lock);
335
336    if (conn->c_map_bytes || (send_quota == 0 && !was_empty)) {
337        /* We exhausted the send quota, but there's work left to
338         * do. Return and (re-)schedule the send worker.
339         */
340        ret = -EAGAIN;
341    }
342
343    if (ret == 0 && was_empty) {
344        /* A simple bit test would be way faster than taking the
345         * spin lock */
346        spin_lock_irqsave(&conn->c_lock, flags);
347        if (!list_empty(&conn->c_send_queue)) {
348            rds_stats_inc(s_send_sem_queue_raced);
349            ret = -EAGAIN;
350        }
351        spin_unlock_irqrestore(&conn->c_lock, flags);
352    }
353out:
354    return ret;
355}
356
357static void rds_send_sndbuf_remove(struct rds_sock *rs, struct rds_message *rm)
358{
359    u32 len = be32_to_cpu(rm->m_inc.i_hdr.h_len);
360
361    assert_spin_locked(&rs->rs_lock);
362
363    BUG_ON(rs->rs_snd_bytes < len);
364    rs->rs_snd_bytes -= len;
365
366    if (rs->rs_snd_bytes == 0)
367        rds_stats_inc(s_send_queue_empty);
368}
369
370static inline int rds_send_is_acked(struct rds_message *rm, u64 ack,
371                    is_acked_func is_acked)
372{
373    if (is_acked)
374        return is_acked(rm, ack);
375    return be64_to_cpu(rm->m_inc.i_hdr.h_sequence) <= ack;
376}
377
378/*
379 * Returns true if there are no messages on the send and retransmit queues
380 * which have a sequence number greater than or equal to the given sequence
381 * number.
382 */
383int rds_send_acked_before(struct rds_connection *conn, u64 seq)
384{
385    struct rds_message *rm, *tmp;
386    int ret = 1;
387
388    spin_lock(&conn->c_lock);
389
390    list_for_each_entry_safe(rm, tmp, &conn->c_retrans, m_conn_item) {
391        if (be64_to_cpu(rm->m_inc.i_hdr.h_sequence) < seq)
392            ret = 0;
393        break;
394    }
395
396    list_for_each_entry_safe(rm, tmp, &conn->c_send_queue, m_conn_item) {
397        if (be64_to_cpu(rm->m_inc.i_hdr.h_sequence) < seq)
398            ret = 0;
399        break;
400    }
401
402    spin_unlock(&conn->c_lock);
403
404    return ret;
405}
406
407/*
408 * This is pretty similar to what happens below in the ACK
409 * handling code - except that we call here as soon as we get
410 * the IB send completion on the RDMA op and the accompanying
411 * message.
412 */
413void rds_rdma_send_complete(struct rds_message *rm, int status)
414{
415    struct rds_sock *rs = NULL;
416    struct rds_rdma_op *ro;
417    struct rds_notifier *notifier;
418
419    spin_lock(&rm->m_rs_lock);
420
421    ro = rm->m_rdma_op;
422    if (test_bit(RDS_MSG_ON_SOCK, &rm->m_flags) &&
423        ro && ro->r_notify && ro->r_notifier) {
424        notifier = ro->r_notifier;
425        rs = rm->m_rs;
426        sock_hold(rds_rs_to_sk(rs));
427
428        notifier->n_status = status;
429        spin_lock(&rs->rs_lock);
430        list_add_tail(&notifier->n_list, &rs->rs_notify_queue);
431        spin_unlock(&rs->rs_lock);
432
433        ro->r_notifier = NULL;
434    }
435
436    spin_unlock(&rm->m_rs_lock);
437
438    if (rs) {
439        rds_wake_sk_sleep(rs);
440        sock_put(rds_rs_to_sk(rs));
441    }
442}
443EXPORT_SYMBOL_GPL(rds_rdma_send_complete);
444
445/*
446 * This is the same as rds_rdma_send_complete except we
447 * don't do any locking - we have all the ingredients (message,
448 * socket, socket lock) and can just move the notifier.
449 */
450static inline void
451__rds_rdma_send_complete(struct rds_sock *rs, struct rds_message *rm, int status)
452{
453    struct rds_rdma_op *ro;
454
455    ro = rm->m_rdma_op;
456    if (ro && ro->r_notify && ro->r_notifier) {
457        ro->r_notifier->n_status = status;
458        list_add_tail(&ro->r_notifier->n_list, &rs->rs_notify_queue);
459        ro->r_notifier = NULL;
460    }
461
462    /* No need to wake the app - caller does this */
463}
464
465/*
466 * This is called from the IB send completion when we detect
467 * a RDMA operation that failed with remote access error.
468 * So speed is not an issue here.
469 */
470struct rds_message *rds_send_get_message(struct rds_connection *conn,
471                     struct rds_rdma_op *op)
472{
473    struct rds_message *rm, *tmp, *found = NULL;
474    unsigned long flags;
475
476    spin_lock_irqsave(&conn->c_lock, flags);
477
478    list_for_each_entry_safe(rm, tmp, &conn->c_retrans, m_conn_item) {
479        if (rm->m_rdma_op == op) {
480            atomic_inc(&rm->m_refcount);
481            found = rm;
482            goto out;
483        }
484    }
485
486    list_for_each_entry_safe(rm, tmp, &conn->c_send_queue, m_conn_item) {
487        if (rm->m_rdma_op == op) {
488            atomic_inc(&rm->m_refcount);
489            found = rm;
490            break;
491        }
492    }
493
494out:
495    spin_unlock_irqrestore(&conn->c_lock, flags);
496
497    return found;
498}
499EXPORT_SYMBOL_GPL(rds_send_get_message);
500
501/*
502 * This removes messages from the socket's list if they're on it. The list
503 * argument must be private to the caller, we must be able to modify it
504 * without locks. The messages must have a reference held for their
505 * position on the list. This function will drop that reference after
506 * removing the messages from the 'messages' list regardless of if it found
507 * the messages on the socket list or not.
508 */
509void rds_send_remove_from_sock(struct list_head *messages, int status)
510{
511    unsigned long flags = 0; /* silence gcc :P */
512    struct rds_sock *rs = NULL;
513    struct rds_message *rm;
514
515    local_irq_save(flags);
516    while (!list_empty(messages)) {
517        rm = list_entry(messages->next, struct rds_message,
518                m_conn_item);
519        list_del_init(&rm->m_conn_item);
520
521        /*
522         * If we see this flag cleared then we're *sure* that someone
523         * else beat us to removing it from the sock. If we race
524         * with their flag update we'll get the lock and then really
525         * see that the flag has been cleared.
526         *
527         * The message spinlock makes sure nobody clears rm->m_rs
528         * while we're messing with it. It does not prevent the
529         * message from being removed from the socket, though.
530         */
531        spin_lock(&rm->m_rs_lock);
532        if (!test_bit(RDS_MSG_ON_SOCK, &rm->m_flags))
533            goto unlock_and_drop;
534
535        if (rs != rm->m_rs) {
536            if (rs) {
537                spin_unlock(&rs->rs_lock);
538                rds_wake_sk_sleep(rs);
539                sock_put(rds_rs_to_sk(rs));
540            }
541            rs = rm->m_rs;
542            spin_lock(&rs->rs_lock);
543            sock_hold(rds_rs_to_sk(rs));
544        }
545
546        if (test_and_clear_bit(RDS_MSG_ON_SOCK, &rm->m_flags)) {
547            struct rds_rdma_op *ro = rm->m_rdma_op;
548            struct rds_notifier *notifier;
549
550            list_del_init(&rm->m_sock_item);
551            rds_send_sndbuf_remove(rs, rm);
552
553            if (ro && ro->r_notifier && (status || ro->r_notify)) {
554                notifier = ro->r_notifier;
555                list_add_tail(&notifier->n_list,
556                        &rs->rs_notify_queue);
557                if (!notifier->n_status)
558                    notifier->n_status = status;
559                rm->m_rdma_op->r_notifier = NULL;
560            }
561            rds_message_put(rm);
562            rm->m_rs = NULL;
563        }
564
565unlock_and_drop:
566        spin_unlock(&rm->m_rs_lock);
567        rds_message_put(rm);
568    }
569
570    if (rs) {
571        spin_unlock(&rs->rs_lock);
572        rds_wake_sk_sleep(rs);
573        sock_put(rds_rs_to_sk(rs));
574    }
575    local_irq_restore(flags);
576}
577
578/*
579 * Transports call here when they've determined that the receiver queued
580 * messages up to, and including, the given sequence number. Messages are
581 * moved to the retrans queue when rds_send_xmit picks them off the send
582 * queue. This means that in the TCP case, the message may not have been
583 * assigned the m_ack_seq yet - but that's fine as long as tcp_is_acked
584 * checks the RDS_MSG_HAS_ACK_SEQ bit.
585 *
586 * XXX It's not clear to me how this is safely serialized with socket
587 * destruction. Maybe it should bail if it sees SOCK_DEAD.
588 */
589void rds_send_drop_acked(struct rds_connection *conn, u64 ack,
590             is_acked_func is_acked)
591{
592    struct rds_message *rm, *tmp;
593    unsigned long flags;
594    LIST_HEAD(list);
595
596    spin_lock_irqsave(&conn->c_lock, flags);
597
598    list_for_each_entry_safe(rm, tmp, &conn->c_retrans, m_conn_item) {
599        if (!rds_send_is_acked(rm, ack, is_acked))
600            break;
601
602        list_move(&rm->m_conn_item, &list);
603        clear_bit(RDS_MSG_ON_CONN, &rm->m_flags);
604    }
605
606    /* order flag updates with spin locks */
607    if (!list_empty(&list))
608        smp_mb__after_clear_bit();
609
610    spin_unlock_irqrestore(&conn->c_lock, flags);
611
612    /* now remove the messages from the sock list as needed */
613    rds_send_remove_from_sock(&list, RDS_RDMA_SUCCESS);
614}
615EXPORT_SYMBOL_GPL(rds_send_drop_acked);
616
617void rds_send_drop_to(struct rds_sock *rs, struct sockaddr_in *dest)
618{
619    struct rds_message *rm, *tmp;
620    struct rds_connection *conn;
621    unsigned long flags, flags2;
622    LIST_HEAD(list);
623    int wake = 0;
624
625    /* get all the messages we're dropping under the rs lock */
626    spin_lock_irqsave(&rs->rs_lock, flags);
627
628    list_for_each_entry_safe(rm, tmp, &rs->rs_send_queue, m_sock_item) {
629        if (dest && (dest->sin_addr.s_addr != rm->m_daddr ||
630                 dest->sin_port != rm->m_inc.i_hdr.h_dport))
631            continue;
632
633        wake = 1;
634        list_move(&rm->m_sock_item, &list);
635        rds_send_sndbuf_remove(rs, rm);
636        clear_bit(RDS_MSG_ON_SOCK, &rm->m_flags);
637
638        /* If this is a RDMA operation, notify the app. */
639        __rds_rdma_send_complete(rs, rm, RDS_RDMA_CANCELED);
640    }
641
642    /* order flag updates with the rs lock */
643    if (wake)
644        smp_mb__after_clear_bit();
645
646    spin_unlock_irqrestore(&rs->rs_lock, flags);
647
648    if (wake)
649        rds_wake_sk_sleep(rs);
650
651    conn = NULL;
652
653    /* now remove the messages from the conn list as needed */
654    list_for_each_entry(rm, &list, m_sock_item) {
655        /* We do this here rather than in the loop above, so that
656         * we don't have to nest m_rs_lock under rs->rs_lock */
657        spin_lock_irqsave(&rm->m_rs_lock, flags2);
658        rm->m_rs = NULL;
659        spin_unlock_irqrestore(&rm->m_rs_lock, flags2);
660
661        /*
662         * If we see this flag cleared then we're *sure* that someone
663         * else beat us to removing it from the conn. If we race
664         * with their flag update we'll get the lock and then really
665         * see that the flag has been cleared.
666         */
667        if (!test_bit(RDS_MSG_ON_CONN, &rm->m_flags))
668            continue;
669
670        if (conn != rm->m_inc.i_conn) {
671            if (conn)
672                spin_unlock_irqrestore(&conn->c_lock, flags);
673            conn = rm->m_inc.i_conn;
674            spin_lock_irqsave(&conn->c_lock, flags);
675        }
676
677        if (test_and_clear_bit(RDS_MSG_ON_CONN, &rm->m_flags)) {
678            list_del_init(&rm->m_conn_item);
679            rds_message_put(rm);
680        }
681    }
682
683    if (conn)
684        spin_unlock_irqrestore(&conn->c_lock, flags);
685
686    while (!list_empty(&list)) {
687        rm = list_entry(list.next, struct rds_message, m_sock_item);
688        list_del_init(&rm->m_sock_item);
689
690        rds_message_wait(rm);
691        rds_message_put(rm);
692    }
693}
694
695/*
696 * we only want this to fire once so we use the callers 'queued'. It's
697 * possible that another thread can race with us and remove the
698 * message from the flow with RDS_CANCEL_SENT_TO.
699 */
700static int rds_send_queue_rm(struct rds_sock *rs, struct rds_connection *conn,
701                 struct rds_message *rm, __be16 sport,
702                 __be16 dport, int *queued)
703{
704    unsigned long flags;
705    u32 len;
706
707    if (*queued)
708        goto out;
709
710    len = be32_to_cpu(rm->m_inc.i_hdr.h_len);
711
712    /* this is the only place which holds both the socket's rs_lock
713     * and the connection's c_lock */
714    spin_lock_irqsave(&rs->rs_lock, flags);
715
716    /*
717     * If there is a little space in sndbuf, we don't queue anything,
718     * and userspace gets -EAGAIN. But poll() indicates there's send
719     * room. This can lead to bad behavior (spinning) if snd_bytes isn't
720     * freed up by incoming acks. So we check the *old* value of
721     * rs_snd_bytes here to allow the last msg to exceed the buffer,
722     * and poll() now knows no more data can be sent.
723     */
724    if (rs->rs_snd_bytes < rds_sk_sndbuf(rs)) {
725        rs->rs_snd_bytes += len;
726
727        /* let recv side know we are close to send space exhaustion.
728         * This is probably not the optimal way to do it, as this
729         * means we set the flag on *all* messages as soon as our
730         * throughput hits a certain threshold.
731         */
732        if (rs->rs_snd_bytes >= rds_sk_sndbuf(rs) / 2)
733            __set_bit(RDS_MSG_ACK_REQUIRED, &rm->m_flags);
734
735        list_add_tail(&rm->m_sock_item, &rs->rs_send_queue);
736        set_bit(RDS_MSG_ON_SOCK, &rm->m_flags);
737        rds_message_addref(rm);
738        rm->m_rs = rs;
739
740        /* The code ordering is a little weird, but we're
741           trying to minimize the time we hold c_lock */
742        rds_message_populate_header(&rm->m_inc.i_hdr, sport, dport, 0);
743        rm->m_inc.i_conn = conn;
744        rds_message_addref(rm);
745
746        spin_lock(&conn->c_lock);
747        rm->m_inc.i_hdr.h_sequence = cpu_to_be64(conn->c_next_tx_seq++);
748        list_add_tail(&rm->m_conn_item, &conn->c_send_queue);
749        set_bit(RDS_MSG_ON_CONN, &rm->m_flags);
750        spin_unlock(&conn->c_lock);
751
752        rdsdebug("queued msg %p len %d, rs %p bytes %d seq %llu\n",
753             rm, len, rs, rs->rs_snd_bytes,
754             (unsigned long long)be64_to_cpu(rm->m_inc.i_hdr.h_sequence));
755
756        *queued = 1;
757    }
758
759    spin_unlock_irqrestore(&rs->rs_lock, flags);
760out:
761    return *queued;
762}
763
764static int rds_cmsg_send(struct rds_sock *rs, struct rds_message *rm,
765             struct msghdr *msg, int *allocated_mr)
766{
767    struct cmsghdr *cmsg;
768    int ret = 0;
769
770    for (cmsg = CMSG_FIRSTHDR(msg); cmsg; cmsg = CMSG_NXTHDR(msg, cmsg)) {
771        if (!CMSG_OK(msg, cmsg))
772            return -EINVAL;
773
774        if (cmsg->cmsg_level != SOL_RDS)
775            continue;
776
777        /* As a side effect, RDMA_DEST and RDMA_MAP will set
778         * rm->m_rdma_cookie and rm->m_rdma_mr.
779         */
780        switch (cmsg->cmsg_type) {
781        case RDS_CMSG_RDMA_ARGS:
782            ret = rds_cmsg_rdma_args(rs, rm, cmsg);
783            break;
784
785        case RDS_CMSG_RDMA_DEST:
786            ret = rds_cmsg_rdma_dest(rs, rm, cmsg);
787            break;
788
789        case RDS_CMSG_RDMA_MAP:
790            ret = rds_cmsg_rdma_map(rs, rm, cmsg);
791            if (!ret)
792                *allocated_mr = 1;
793            break;
794
795        default:
796            return -EINVAL;
797        }
798
799        if (ret)
800            break;
801    }
802
803    return ret;
804}
805
806int rds_sendmsg(struct kiocb *iocb, struct socket *sock, struct msghdr *msg,
807        size_t payload_len)
808{
809    struct sock *sk = sock->sk;
810    struct rds_sock *rs = rds_sk_to_rs(sk);
811    struct sockaddr_in *usin = (struct sockaddr_in *)msg->msg_name;
812    __be32 daddr;
813    __be16 dport;
814    struct rds_message *rm = NULL;
815    struct rds_connection *conn;
816    int ret = 0;
817    int queued = 0, allocated_mr = 0;
818    int nonblock = msg->msg_flags & MSG_DONTWAIT;
819    long timeo = sock_rcvtimeo(sk, nonblock);
820
821    /* Mirror Linux UDP mirror of BSD error message compatibility */
822    /* XXX: Perhaps MSG_MORE someday */
823    if (msg->msg_flags & ~(MSG_DONTWAIT | MSG_CMSG_COMPAT)) {
824        printk(KERN_INFO "msg_flags 0x%08X\n", msg->msg_flags);
825        ret = -EOPNOTSUPP;
826        goto out;
827    }
828
829    if (msg->msg_namelen) {
830        /* XXX fail non-unicast destination IPs? */
831        if (msg->msg_namelen < sizeof(*usin) || usin->sin_family != AF_INET) {
832            ret = -EINVAL;
833            goto out;
834        }
835        daddr = usin->sin_addr.s_addr;
836        dport = usin->sin_port;
837    } else {
838        /* We only care about consistency with ->connect() */
839        lock_sock(sk);
840        daddr = rs->rs_conn_addr;
841        dport = rs->rs_conn_port;
842        release_sock(sk);
843    }
844
845    /* racing with another thread binding seems ok here */
846    if (daddr == 0 || rs->rs_bound_addr == 0) {
847        ret = -ENOTCONN; /* XXX not a great errno */
848        goto out;
849    }
850
851    rm = rds_message_copy_from_user(msg->msg_iov, payload_len);
852    if (IS_ERR(rm)) {
853        ret = PTR_ERR(rm);
854        rm = NULL;
855        goto out;
856    }
857
858    rm->m_daddr = daddr;
859
860    /* rds_conn_create has a spinlock that runs with IRQ off.
861     * Caching the conn in the socket helps a lot. */
862    if (rs->rs_conn && rs->rs_conn->c_faddr == daddr)
863        conn = rs->rs_conn;
864    else {
865        conn = rds_conn_create_outgoing(rs->rs_bound_addr, daddr,
866                    rs->rs_transport,
867                    sock->sk->sk_allocation);
868        if (IS_ERR(conn)) {
869            ret = PTR_ERR(conn);
870            goto out;
871        }
872        rs->rs_conn = conn;
873    }
874
875    /* Parse any control messages the user may have included. */
876    ret = rds_cmsg_send(rs, rm, msg, &allocated_mr);
877    if (ret)
878        goto out;
879
880    if ((rm->m_rdma_cookie || rm->m_rdma_op) &&
881        conn->c_trans->xmit_rdma == NULL) {
882        if (printk_ratelimit())
883            printk(KERN_NOTICE "rdma_op %p conn xmit_rdma %p\n",
884                rm->m_rdma_op, conn->c_trans->xmit_rdma);
885        ret = -EOPNOTSUPP;
886        goto out;
887    }
888
889    /* If the connection is down, trigger a connect. We may
890     * have scheduled a delayed reconnect however - in this case
891     * we should not interfere.
892     */
893    if (rds_conn_state(conn) == RDS_CONN_DOWN &&
894        !test_and_set_bit(RDS_RECONNECT_PENDING, &conn->c_flags))
895        queue_delayed_work(rds_wq, &conn->c_conn_w, 0);
896
897    ret = rds_cong_wait(conn->c_fcong, dport, nonblock, rs);
898    if (ret)
899        goto out;
900
901    while (!rds_send_queue_rm(rs, conn, rm, rs->rs_bound_port,
902                  dport, &queued)) {
903        rds_stats_inc(s_send_queue_full);
904        /* XXX make sure this is reasonable */
905        if (payload_len > rds_sk_sndbuf(rs)) {
906            ret = -EMSGSIZE;
907            goto out;
908        }
909        if (nonblock) {
910            ret = -EAGAIN;
911            goto out;
912        }
913
914        timeo = wait_event_interruptible_timeout(*sk->sk_sleep,
915                    rds_send_queue_rm(rs, conn, rm,
916                              rs->rs_bound_port,
917                              dport,
918                              &queued),
919                    timeo);
920        rdsdebug("sendmsg woke queued %d timeo %ld\n", queued, timeo);
921        if (timeo > 0 || timeo == MAX_SCHEDULE_TIMEOUT)
922            continue;
923
924        ret = timeo;
925        if (ret == 0)
926            ret = -ETIMEDOUT;
927        goto out;
928    }
929
930    /*
931     * By now we've committed to the send. We reuse rds_send_worker()
932     * to retry sends in the rds thread if the transport asks us to.
933     */
934    rds_stats_inc(s_send_queued);
935
936    if (!test_bit(RDS_LL_SEND_FULL, &conn->c_flags))
937        rds_send_worker(&conn->c_send_w.work);
938
939    rds_message_put(rm);
940    return payload_len;
941
942out:
943    /* If the user included a RDMA_MAP cmsg, we allocated a MR on the fly.
944     * If the sendmsg goes through, we keep the MR. If it fails with EAGAIN
945     * or in any other way, we need to destroy the MR again */
946    if (allocated_mr)
947        rds_rdma_unuse(rs, rds_rdma_cookie_key(rm->m_rdma_cookie), 1);
948
949    if (rm)
950        rds_message_put(rm);
951    return ret;
952}
953
954/*
955 * Reply to a ping packet.
956 */
957int
958rds_send_pong(struct rds_connection *conn, __be16 dport)
959{
960    struct rds_message *rm;
961    unsigned long flags;
962    int ret = 0;
963
964    rm = rds_message_alloc(0, GFP_ATOMIC);
965    if (rm == NULL) {
966        ret = -ENOMEM;
967        goto out;
968    }
969
970    rm->m_daddr = conn->c_faddr;
971
972    /* If the connection is down, trigger a connect. We may
973     * have scheduled a delayed reconnect however - in this case
974     * we should not interfere.
975     */
976    if (rds_conn_state(conn) == RDS_CONN_DOWN &&
977        !test_and_set_bit(RDS_RECONNECT_PENDING, &conn->c_flags))
978        queue_delayed_work(rds_wq, &conn->c_conn_w, 0);
979
980    ret = rds_cong_wait(conn->c_fcong, dport, 1, NULL);
981    if (ret)
982        goto out;
983
984    spin_lock_irqsave(&conn->c_lock, flags);
985    list_add_tail(&rm->m_conn_item, &conn->c_send_queue);
986    set_bit(RDS_MSG_ON_CONN, &rm->m_flags);
987    rds_message_addref(rm);
988    rm->m_inc.i_conn = conn;
989
990    rds_message_populate_header(&rm->m_inc.i_hdr, 0, dport,
991                    conn->c_next_tx_seq);
992    conn->c_next_tx_seq++;
993    spin_unlock_irqrestore(&conn->c_lock, flags);
994
995    rds_stats_inc(s_send_queued);
996    rds_stats_inc(s_send_pong);
997
998    queue_delayed_work(rds_wq, &conn->c_send_w, 0);
999    rds_message_put(rm);
1000    return 0;
1001
1002out:
1003    if (rm)
1004        rds_message_put(rm);
1005    return ret;
1006}
1007

Archive Download this file



interactive