sctp: Do not account for sizeof(struct sk_buff) in estimated rwnd
[linux-2.6.git] / net / rds / connection.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/list.h>
35 #include <linux/slab.h>
36 #include <net/inet_hashtables.h>
37
38 #include "rds.h"
39 #include "loop.h"
40
41 #define RDS_CONNECTION_HASH_BITS 12
42 #define RDS_CONNECTION_HASH_ENTRIES (1 << RDS_CONNECTION_HASH_BITS)
43 #define RDS_CONNECTION_HASH_MASK (RDS_CONNECTION_HASH_ENTRIES - 1)
44
45 /* converting this to RCU is a chore for another day.. */
46 static DEFINE_SPINLOCK(rds_conn_lock);
47 static unsigned long rds_conn_count;
48 static struct hlist_head rds_conn_hash[RDS_CONNECTION_HASH_ENTRIES];
49 static struct kmem_cache *rds_conn_slab;
50
51 static struct hlist_head *rds_conn_bucket(__be32 laddr, __be32 faddr)
52 {
53         /* Pass NULL, don't need struct net for hash */
54         unsigned long hash = inet_ehashfn(NULL,
55                                           be32_to_cpu(laddr), 0,
56                                           be32_to_cpu(faddr), 0);
57         return &rds_conn_hash[hash & RDS_CONNECTION_HASH_MASK];
58 }
59
60 #define rds_conn_info_set(var, test, suffix) do {               \
61         if (test)                                               \
62                 var |= RDS_INFO_CONNECTION_FLAG_##suffix;       \
63 } while (0)
64
65 /* rcu read lock must be held or the connection spinlock */
66 static struct rds_connection *rds_conn_lookup(struct hlist_head *head,
67                                               __be32 laddr, __be32 faddr,
68                                               struct rds_transport *trans)
69 {
70         struct rds_connection *conn, *ret = NULL;
71         struct hlist_node *pos;
72
73         hlist_for_each_entry_rcu(conn, pos, head, c_hash_node) {
74                 if (conn->c_faddr == faddr && conn->c_laddr == laddr &&
75                                 conn->c_trans == trans) {
76                         ret = conn;
77                         break;
78                 }
79         }
80         rdsdebug("returning conn %p for %pI4 -> %pI4\n", ret,
81                  &laddr, &faddr);
82         return ret;
83 }
84
85 /*
86  * This is called by transports as they're bringing down a connection.
87  * It clears partial message state so that the transport can start sending
88  * and receiving over this connection again in the future.  It is up to
89  * the transport to have serialized this call with its send and recv.
90  */
91 static void rds_conn_reset(struct rds_connection *conn)
92 {
93         rdsdebug("connection %pI4 to %pI4 reset\n",
94           &conn->c_laddr, &conn->c_faddr);
95
96         rds_stats_inc(s_conn_reset);
97         rds_send_reset(conn);
98         conn->c_flags = 0;
99
100         /* Do not clear next_rx_seq here, else we cannot distinguish
101          * retransmitted packets from new packets, and will hand all
102          * of them to the application. That is not consistent with the
103          * reliability guarantees of RDS. */
104 }
105
106 /*
107  * There is only every one 'conn' for a given pair of addresses in the
108  * system at a time.  They contain messages to be retransmitted and so
109  * span the lifetime of the actual underlying transport connections.
110  *
111  * For now they are not garbage collected once they're created.  They
112  * are torn down as the module is removed, if ever.
113  */
114 static struct rds_connection *__rds_conn_create(__be32 laddr, __be32 faddr,
115                                        struct rds_transport *trans, gfp_t gfp,
116                                        int is_outgoing)
117 {
118         struct rds_connection *conn, *parent = NULL;
119         struct hlist_head *head = rds_conn_bucket(laddr, faddr);
120         struct rds_transport *loop_trans;
121         unsigned long flags;
122         int ret;
123
124         rcu_read_lock();
125         conn = rds_conn_lookup(head, laddr, faddr, trans);
126         if (conn && conn->c_loopback && conn->c_trans != &rds_loop_transport &&
127             !is_outgoing) {
128                 /* This is a looped back IB connection, and we're
129                  * called by the code handling the incoming connect.
130                  * We need a second connection object into which we
131                  * can stick the other QP. */
132                 parent = conn;
133                 conn = parent->c_passive;
134         }
135         rcu_read_unlock();
136         if (conn)
137                 goto out;
138
139         conn = kmem_cache_zalloc(rds_conn_slab, gfp);
140         if (!conn) {
141                 conn = ERR_PTR(-ENOMEM);
142                 goto out;
143         }
144
145         INIT_HLIST_NODE(&conn->c_hash_node);
146         conn->c_laddr = laddr;
147         conn->c_faddr = faddr;
148         spin_lock_init(&conn->c_lock);
149         conn->c_next_tx_seq = 1;
150
151         init_waitqueue_head(&conn->c_waitq);
152         INIT_LIST_HEAD(&conn->c_send_queue);
153         INIT_LIST_HEAD(&conn->c_retrans);
154
155         ret = rds_cong_get_maps(conn);
156         if (ret) {
157                 kmem_cache_free(rds_conn_slab, conn);
158                 conn = ERR_PTR(ret);
159                 goto out;
160         }
161
162         /*
163          * This is where a connection becomes loopback.  If *any* RDS sockets
164          * can bind to the destination address then we'd rather the messages
165          * flow through loopback rather than either transport.
166          */
167         loop_trans = rds_trans_get_preferred(faddr);
168         if (loop_trans) {
169                 rds_trans_put(loop_trans);
170                 conn->c_loopback = 1;
171                 if (is_outgoing && trans->t_prefer_loopback) {
172                         /* "outgoing" connection - and the transport
173                          * says it wants the connection handled by the
174                          * loopback transport. This is what TCP does.
175                          */
176                         trans = &rds_loop_transport;
177                 }
178         }
179
180         conn->c_trans = trans;
181
182         ret = trans->conn_alloc(conn, gfp);
183         if (ret) {
184                 kmem_cache_free(rds_conn_slab, conn);
185                 conn = ERR_PTR(ret);
186                 goto out;
187         }
188
189         atomic_set(&conn->c_state, RDS_CONN_DOWN);
190         conn->c_reconnect_jiffies = 0;
191         INIT_DELAYED_WORK(&conn->c_send_w, rds_send_worker);
192         INIT_DELAYED_WORK(&conn->c_recv_w, rds_recv_worker);
193         INIT_DELAYED_WORK(&conn->c_conn_w, rds_connect_worker);
194         INIT_WORK(&conn->c_down_w, rds_shutdown_worker);
195         mutex_init(&conn->c_cm_lock);
196         conn->c_flags = 0;
197
198         rdsdebug("allocated conn %p for %pI4 -> %pI4 over %s %s\n",
199           conn, &laddr, &faddr,
200           trans->t_name ? trans->t_name : "[unknown]",
201           is_outgoing ? "(outgoing)" : "");
202
203         /*
204          * Since we ran without holding the conn lock, someone could
205          * have created the same conn (either normal or passive) in the
206          * interim. We check while holding the lock. If we won, we complete
207          * init and return our conn. If we lost, we rollback and return the
208          * other one.
209          */
210         spin_lock_irqsave(&rds_conn_lock, flags);
211         if (parent) {
212                 /* Creating passive conn */
213                 if (parent->c_passive) {
214                         trans->conn_free(conn->c_transport_data);
215                         kmem_cache_free(rds_conn_slab, conn);
216                         conn = parent->c_passive;
217                 } else {
218                         parent->c_passive = conn;
219                         rds_cong_add_conn(conn);
220                         rds_conn_count++;
221                 }
222         } else {
223                 /* Creating normal conn */
224                 struct rds_connection *found;
225
226                 found = rds_conn_lookup(head, laddr, faddr, trans);
227                 if (found) {
228                         trans->conn_free(conn->c_transport_data);
229                         kmem_cache_free(rds_conn_slab, conn);
230                         conn = found;
231                 } else {
232                         hlist_add_head_rcu(&conn->c_hash_node, head);
233                         rds_cong_add_conn(conn);
234                         rds_conn_count++;
235                 }
236         }
237         spin_unlock_irqrestore(&rds_conn_lock, flags);
238
239 out:
240         return conn;
241 }
242
243 struct rds_connection *rds_conn_create(__be32 laddr, __be32 faddr,
244                                        struct rds_transport *trans, gfp_t gfp)
245 {
246         return __rds_conn_create(laddr, faddr, trans, gfp, 0);
247 }
248 EXPORT_SYMBOL_GPL(rds_conn_create);
249
250 struct rds_connection *rds_conn_create_outgoing(__be32 laddr, __be32 faddr,
251                                        struct rds_transport *trans, gfp_t gfp)
252 {
253         return __rds_conn_create(laddr, faddr, trans, gfp, 1);
254 }
255 EXPORT_SYMBOL_GPL(rds_conn_create_outgoing);
256
257 void rds_conn_shutdown(struct rds_connection *conn)
258 {
259         /* shut it down unless it's down already */
260         if (!rds_conn_transition(conn, RDS_CONN_DOWN, RDS_CONN_DOWN)) {
261                 /*
262                  * Quiesce the connection mgmt handlers before we start tearing
263                  * things down. We don't hold the mutex for the entire
264                  * duration of the shutdown operation, else we may be
265                  * deadlocking with the CM handler. Instead, the CM event
266                  * handler is supposed to check for state DISCONNECTING
267                  */
268                 mutex_lock(&conn->c_cm_lock);
269                 if (!rds_conn_transition(conn, RDS_CONN_UP, RDS_CONN_DISCONNECTING)
270                  && !rds_conn_transition(conn, RDS_CONN_ERROR, RDS_CONN_DISCONNECTING)) {
271                         rds_conn_error(conn, "shutdown called in state %d\n",
272                                         atomic_read(&conn->c_state));
273                         mutex_unlock(&conn->c_cm_lock);
274                         return;
275                 }
276                 mutex_unlock(&conn->c_cm_lock);
277
278                 wait_event(conn->c_waitq,
279                            !test_bit(RDS_IN_XMIT, &conn->c_flags));
280
281                 conn->c_trans->conn_shutdown(conn);
282                 rds_conn_reset(conn);
283
284                 if (!rds_conn_transition(conn, RDS_CONN_DISCONNECTING, RDS_CONN_DOWN)) {
285                         /* This can happen - eg when we're in the middle of tearing
286                          * down the connection, and someone unloads the rds module.
287                          * Quite reproduceable with loopback connections.
288                          * Mostly harmless.
289                          */
290                         rds_conn_error(conn,
291                                 "%s: failed to transition to state DOWN, "
292                                 "current state is %d\n",
293                                 __func__,
294                                 atomic_read(&conn->c_state));
295                         return;
296                 }
297         }
298
299         /* Then reconnect if it's still live.
300          * The passive side of an IB loopback connection is never added
301          * to the conn hash, so we never trigger a reconnect on this
302          * conn - the reconnect is always triggered by the active peer. */
303         cancel_delayed_work_sync(&conn->c_conn_w);
304         rcu_read_lock();
305         if (!hlist_unhashed(&conn->c_hash_node)) {
306                 rcu_read_unlock();
307                 rds_queue_reconnect(conn);
308         } else {
309                 rcu_read_unlock();
310         }
311 }
312
313 /*
314  * Stop and free a connection.
315  *
316  * This can only be used in very limited circumstances.  It assumes that once
317  * the conn has been shutdown that no one else is referencing the connection.
318  * We can only ensure this in the rmmod path in the current code.
319  */
320 void rds_conn_destroy(struct rds_connection *conn)
321 {
322         struct rds_message *rm, *rtmp;
323         unsigned long flags;
324
325         rdsdebug("freeing conn %p for %pI4 -> "
326                  "%pI4\n", conn, &conn->c_laddr,
327                  &conn->c_faddr);
328
329         /* Ensure conn will not be scheduled for reconnect */
330         spin_lock_irq(&rds_conn_lock);
331         hlist_del_init_rcu(&conn->c_hash_node);
332         spin_unlock_irq(&rds_conn_lock);
333         synchronize_rcu();
334
335         /* shut the connection down */
336         rds_conn_drop(conn);
337         flush_work(&conn->c_down_w);
338
339         /* make sure lingering queued work won't try to ref the conn */
340         cancel_delayed_work_sync(&conn->c_send_w);
341         cancel_delayed_work_sync(&conn->c_recv_w);
342
343         /* tear down queued messages */
344         list_for_each_entry_safe(rm, rtmp,
345                                  &conn->c_send_queue,
346                                  m_conn_item) {
347                 list_del_init(&rm->m_conn_item);
348                 BUG_ON(!list_empty(&rm->m_sock_item));
349                 rds_message_put(rm);
350         }
351         if (conn->c_xmit_rm)
352                 rds_message_put(conn->c_xmit_rm);
353
354         conn->c_trans->conn_free(conn->c_transport_data);
355
356         /*
357          * The congestion maps aren't freed up here.  They're
358          * freed by rds_cong_exit() after all the connections
359          * have been freed.
360          */
361         rds_cong_remove_conn(conn);
362
363         BUG_ON(!list_empty(&conn->c_retrans));
364         kmem_cache_free(rds_conn_slab, conn);
365
366         spin_lock_irqsave(&rds_conn_lock, flags);
367         rds_conn_count--;
368         spin_unlock_irqrestore(&rds_conn_lock, flags);
369 }
370 EXPORT_SYMBOL_GPL(rds_conn_destroy);
371
372 static void rds_conn_message_info(struct socket *sock, unsigned int len,
373                                   struct rds_info_iterator *iter,
374                                   struct rds_info_lengths *lens,
375                                   int want_send)
376 {
377         struct hlist_head *head;
378         struct hlist_node *pos;
379         struct list_head *list;
380         struct rds_connection *conn;
381         struct rds_message *rm;
382         unsigned int total = 0;
383         unsigned long flags;
384         size_t i;
385
386         len /= sizeof(struct rds_info_message);
387
388         rcu_read_lock();
389
390         for (i = 0, head = rds_conn_hash; i < ARRAY_SIZE(rds_conn_hash);
391              i++, head++) {
392                 hlist_for_each_entry_rcu(conn, pos, head, c_hash_node) {
393                         if (want_send)
394                                 list = &conn->c_send_queue;
395                         else
396                                 list = &conn->c_retrans;
397
398                         spin_lock_irqsave(&conn->c_lock, flags);
399
400                         /* XXX too lazy to maintain counts.. */
401                         list_for_each_entry(rm, list, m_conn_item) {
402                                 total++;
403                                 if (total <= len)
404                                         rds_inc_info_copy(&rm->m_inc, iter,
405                                                           conn->c_laddr,
406                                                           conn->c_faddr, 0);
407                         }
408
409                         spin_unlock_irqrestore(&conn->c_lock, flags);
410                 }
411         }
412         rcu_read_unlock();
413
414         lens->nr = total;
415         lens->each = sizeof(struct rds_info_message);
416 }
417
418 static void rds_conn_message_info_send(struct socket *sock, unsigned int len,
419                                        struct rds_info_iterator *iter,
420                                        struct rds_info_lengths *lens)
421 {
422         rds_conn_message_info(sock, len, iter, lens, 1);
423 }
424
425 static void rds_conn_message_info_retrans(struct socket *sock,
426                                           unsigned int len,
427                                           struct rds_info_iterator *iter,
428                                           struct rds_info_lengths *lens)
429 {
430         rds_conn_message_info(sock, len, iter, lens, 0);
431 }
432
433 void rds_for_each_conn_info(struct socket *sock, unsigned int len,
434                           struct rds_info_iterator *iter,
435                           struct rds_info_lengths *lens,
436                           int (*visitor)(struct rds_connection *, void *),
437                           size_t item_len)
438 {
439         uint64_t buffer[(item_len + 7) / 8];
440         struct hlist_head *head;
441         struct hlist_node *pos;
442         struct rds_connection *conn;
443         size_t i;
444
445         rcu_read_lock();
446
447         lens->nr = 0;
448         lens->each = item_len;
449
450         for (i = 0, head = rds_conn_hash; i < ARRAY_SIZE(rds_conn_hash);
451              i++, head++) {
452                 hlist_for_each_entry_rcu(conn, pos, head, c_hash_node) {
453
454                         /* XXX no c_lock usage.. */
455                         if (!visitor(conn, buffer))
456                                 continue;
457
458                         /* We copy as much as we can fit in the buffer,
459                          * but we count all items so that the caller
460                          * can resize the buffer. */
461                         if (len >= item_len) {
462                                 rds_info_copy(iter, buffer, item_len);
463                                 len -= item_len;
464                         }
465                         lens->nr++;
466                 }
467         }
468         rcu_read_unlock();
469 }
470 EXPORT_SYMBOL_GPL(rds_for_each_conn_info);
471
472 static int rds_conn_info_visitor(struct rds_connection *conn,
473                                   void *buffer)
474 {
475         struct rds_info_connection *cinfo = buffer;
476
477         cinfo->next_tx_seq = conn->c_next_tx_seq;
478         cinfo->next_rx_seq = conn->c_next_rx_seq;
479         cinfo->laddr = conn->c_laddr;
480         cinfo->faddr = conn->c_faddr;
481         strncpy(cinfo->transport, conn->c_trans->t_name,
482                 sizeof(cinfo->transport));
483         cinfo->flags = 0;
484
485         rds_conn_info_set(cinfo->flags, test_bit(RDS_IN_XMIT, &conn->c_flags),
486                           SENDING);
487         /* XXX Future: return the state rather than these funky bits */
488         rds_conn_info_set(cinfo->flags,
489                           atomic_read(&conn->c_state) == RDS_CONN_CONNECTING,
490                           CONNECTING);
491         rds_conn_info_set(cinfo->flags,
492                           atomic_read(&conn->c_state) == RDS_CONN_UP,
493                           CONNECTED);
494         return 1;
495 }
496
497 static void rds_conn_info(struct socket *sock, unsigned int len,
498                           struct rds_info_iterator *iter,
499                           struct rds_info_lengths *lens)
500 {
501         rds_for_each_conn_info(sock, len, iter, lens,
502                                 rds_conn_info_visitor,
503                                 sizeof(struct rds_info_connection));
504 }
505
506 int rds_conn_init(void)
507 {
508         rds_conn_slab = kmem_cache_create("rds_connection",
509                                           sizeof(struct rds_connection),
510                                           0, 0, NULL);
511         if (!rds_conn_slab)
512                 return -ENOMEM;
513
514         rds_info_register_func(RDS_INFO_CONNECTIONS, rds_conn_info);
515         rds_info_register_func(RDS_INFO_SEND_MESSAGES,
516                                rds_conn_message_info_send);
517         rds_info_register_func(RDS_INFO_RETRANS_MESSAGES,
518                                rds_conn_message_info_retrans);
519
520         return 0;
521 }
522
523 void rds_conn_exit(void)
524 {
525         rds_loop_exit();
526
527         WARN_ON(!hlist_empty(rds_conn_hash));
528
529         kmem_cache_destroy(rds_conn_slab);
530
531         rds_info_deregister_func(RDS_INFO_CONNECTIONS, rds_conn_info);
532         rds_info_deregister_func(RDS_INFO_SEND_MESSAGES,
533                                  rds_conn_message_info_send);
534         rds_info_deregister_func(RDS_INFO_RETRANS_MESSAGES,
535                                  rds_conn_message_info_retrans);
536 }
537
538 /*
539  * Force a disconnect
540  */
541 void rds_conn_drop(struct rds_connection *conn)
542 {
543         atomic_set(&conn->c_state, RDS_CONN_ERROR);
544         queue_work(rds_wq, &conn->c_down_w);
545 }
546 EXPORT_SYMBOL_GPL(rds_conn_drop);
547
548 /*
549  * If the connection is down, trigger a connect. We may have scheduled a
550  * delayed reconnect however - in this case we should not interfere.
551  */
552 void rds_conn_connect_if_down(struct rds_connection *conn)
553 {
554         if (rds_conn_state(conn) == RDS_CONN_DOWN &&
555             !test_and_set_bit(RDS_RECONNECT_PENDING, &conn->c_flags))
556                 queue_delayed_work(rds_wq, &conn->c_conn_w, 0);
557 }
558 EXPORT_SYMBOL_GPL(rds_conn_connect_if_down);
559
560 /*
561  * An error occurred on the connection
562  */
563 void
564 __rds_conn_error(struct rds_connection *conn, const char *fmt, ...)
565 {
566         va_list ap;
567
568         va_start(ap, fmt);
569         vprintk(fmt, ap);
570         va_end(ap);
571
572         rds_conn_drop(conn);
573 }